Journal Article: Small-Molecule Transport by CarO, an Abundant Eight-Stranded beta-Barrel Outer Membrane Protein from Acinetobacter Baumannii ...
TY - JOUR. T1 - A set of two monoclonal antibodies specific for the cell surface-exposed 39K major outer membrane protein of Haemophilus influenzae type b defines all strains of this pathogen. AU - Gulig, P. A.. AU - Frisch, C. F.. AU - Hansen, E. J.. PY - 1983. Y1 - 1983. N2 - Six murine plasma cell hybridomas producing monoclonal antibodies (mabs) directed against the 39,000-molecular-weight (39K) major outer membrane protein of Haemophilus influenzae type b were employed in the antigenic analysis of the 39K protein. The initial characterization of the mabs by radioimmunoprecipitation analysis showed that four of these mabs reacted with antigenic determinants of the 39K protein that are exposed on the bacterial cell surface and accessible to antibody. The other two mabs reacted with antigenic determinants of the 39K protein that are either not exposed on the H. influenzae type b cell surface or not accessible to antibody (internal determinants). A total of 126 clinical isolates of H. ...
A vast number of studies have been completed on the virulence determinants of Yersinia spp.; however, the focus of many of these studies has been on the virulence plasmid and the plasmid-encoded Type three secretion system. Nevertheless, many chromosomal genes whose products are directly involved in virulence have also been identified. Some of these critical virulence determinants are outer membrane proteins. Outer membrane proteins of Gram-negative bacteria often have important physiological roles; however, some have also been found to be important for pathogenesis. In this thesis, we investigated two Yersinia. pestis outer membrane proteins, Ail and OmpA, and their roles in virulence. We provide evidence that Y. pestis Ail is a highly expressed outer membrane protein that is absolutely essential for Y. pestis to resist the killing action of the complement system present in human blood and tissues, as well as the blood and tissues of other mammalian hosts. Furthermore, Ail was important for ...
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The toxR gene of Vibrio cholerae encodes a transmembrane, DNA-binding protein that activates transcription of the cholera toxin operon and a gene (tcpA) for the major subunit of a pilus colonization factor. We constructed site-directed insertion mutations in the toxR gene by a novel method employing the chromosomal integration of a mobilizable suicide plasmid containing a portion of the toxR coding sequence. Mutants containing these new toxR alleles had an altered outer membrane protein profile, suggesting that two major outer membrane proteins (OmpT and OmpU) might be under the control of toxR. Physiological studies indicated that varying the concentration of the amino acids asparagine, arginine, glutamate, and serine caused coordinate changes in the expression of cholera toxin, TcpA, OmpT, and OmpU. Changes in the osmolarity of a tryptone-based medium also produced coordinate changes in the expression of these proteins. Other environmental signals (temperature and pH) had a more pronounced ...
Drugs and certain proteins are transported across the membranes of Gram-negative bacteria by energy-activated pumps. The outer membrane component of these pumps is a channel that opens from a sealed resting state during the transport process. We describe two crystal structures of the Escherichia coli outer membrane protein TolC in its partially open state. Opening is accompanied by the exposure of three shallow intraprotomer grooves in the TolC trimer, where our mutagenesis data identify a contact point with the periplasmic component of a drug efflux pump, AcrA. We suggest that the assembly of multidrug efflux pumps is accompanied by induced fit of TolC driven mainly by accommodation of the periplasmic component.,br/, ...
Cloning and characterization of the major outer membrane protein gene (ompH) of Pasteurella multocida X-73.: The major outer membrane protein (OmpH) of Pasteure
PCR methods.Holland et al. (31) developed a major outer membrane protein (MOMP)-based PCR test that could identify three species of Chlamydia (C. trachomatis, C. pneumoniae, and C. psittaci) using three primer pairs and one restriction enzyme digestion.. Rasmussen et al. (73) described a protocol that amplifies a conserved genus-specific target of the chlamydial MOMP gene followed by restriction enzyme digestion for species identification.. Watson et al. (89) developed a PCR assay based on amplification of the 60-kDa cysteine-rich outer membrane protein genes of C. psittaci, C. pneumoniae, and C. trachomatis, followed by species differentiation with four restriction endonuclease digestion enzymes. Similarly, Tjhie et al. (84) developed a general PCR with a target within the MOMP gene. Subsequent species-specific differentiation of C. trachomatis, C. pneumoniae, and C. psittaciwas performed by hybridization of the amplified PCR product with internal probes.. Several of the early methods described ...
Khandelwal and colleagues succeeded in identifying the insecticidal factor. The active component was found in a large complex normally associated with the bacterial outer membrane, and was also present in or on outer membrane vesicles (OMVs) released from the bacterial surface, says Khandelwal. They then searched through OMV components and identified a small (17 kDa) toxic protein. When purified, this protein was toxic to cultured larval cells and directly killed H. armigera larvae. Gene cloning and sequencing showed this protein is related to a class of bacterial outer membrane proteins that form protrusions, called pili or fimbriae, which often help bacteria attach to host cells during infection. Similar to pili proteins, the purified 17 kDa protein self-associated to form oligomers, each of which was connected to the next by a strand. Most importantly, the recombinant 17 kDa protein killed H. armigera larvae, demonstrating its potential as a biological control agent in a world desperately in ...
Dispensable loops shield the functionally-important extracellular loops of the essential Gram-negative bacterial outer membrane protein LptD from antibody interference.
p>The checksum is a form of redundancy check that is calculated from the sequence. It is useful for tracking sequence updates.,/p> ,p>It should be noted that while, in theory, two different sequences could have the same checksum value, the likelihood that this would happen is extremely low.,/p> ,p>However UniProtKB may contain entries with identical sequences in case of multiple genes (paralogs).,/p> ,p>The checksum is computed as the sequence 64-bit Cyclic Redundancy Check value (CRC64) using the generator polynomial: x,sup>64,/sup> + x,sup>4,/sup> + x,sup>3,/sup> + x + 1. The algorithm is described in the ISO 3309 standard. ,/p> ,p class="publication">Press W.H., Flannery B.P., Teukolsky S.A. and Vetterling W.T.,br /> ,strong>Cyclic redundancy and other checksums,/strong>,br /> ,a href="http://www.nrbook.com/b/bookcpdf.php">Numerical recipes in C 2nd ed., pp896-902, Cambridge University Press (1993),/a>),/p> Checksum:i ...
Bacterial OMPs are synthesized in the cytosol as precursor proteins with an amino‐terminal signal sequence that guides the proteins to the Sec machinery for crossing the inner membrane and is cleaved off in the periplasm. Periplasmic chaperones then escort OMPs through the aqueous periplasmic space in a partly unfolded state. On reaching the outer membrane, OMPs assemble into a β‐barrel structure and insert into the outer membrane with the help of the BAM complex. The bacterial OMP insertion pathway can be compared to the assembly pathway of MBOMPs from the mitochondrial intermembrane space into the outer membrane. MBOMPs are synthesized in the cytosol and imported into the intermembrane space by the outer membrane translocator TOM40. The subsequent chaperone‐mediated escort across the intermembrane space and insertion into the outer membrane by the TOB complex is similar to the OMP assembly process. Notably, the BAM and TOB complexes share the homologous β‐barrel proteins BamA and ...
Author: Anbazhagan, V. et al.; Genre: Journal Article; Published in Print: 2008-06-10; Title: Incorporation of outer membrane protein OmpG in lipid membranes: protein−lipid interactions and β-barrel orientation.
Allison, Heather, Smith, Darren, Loughnane, Paul, Saunders, Jon and McCarthy, Alan (2004) Identification of an outer membrane protein that enables infection of Escherichia coli by Shiga toxin encoding bacteriophage. In: 155th Society for General Microbiology Meeting, September 2004, Dublin, Ireland. Full text not available from this repository. (Request a copy ...
Download Free Full-Text of an article EXTRACTION OF THE OUTER MEMBRANE PROTEINS OF H. PYLORI AND EVALUATION OF THEIR PRESENCE IN STOOL OF THE INFECTED INDIVIDUALS
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We compare several spectral domain based clustering methods for partitioning protein sequence data. The main instrument for this exercise is the spectral density ratio model, which specifies that the logarithmic ratio of two or more unknown spectral density functions has a parametric linear combination of cosines. Maximum likelihood inference is worked out in detail and it is shown that its output yields several distance measures among independent stationary time series. These similarity indices are suitable for clustering time series data based on their second order properties. Other spectral domain based distances are investigated as well; and we compare all methods and distances to the problem of producing segmentations of bacterial outer membrane proteins consistent with their transmembrane topology. Protein sequences are transformed to time series data by employing numerical scales of physicochemical parameters. We also present interesting results on the prediction of transmembrane ...
Subunit Of Both The ERMES And The SAM Complex; Component Of ERMES Complex Which Acts As A Molecular Tether Between The Mitochondria And The ER, Necessary For Efficient Phospholipid Exchange Between Organelles And For Mitophagy; SAM/TOB Complex Component That Functions In The Assembly Of Outer Membrane Beta-barrel Proteins; Involved In Mitochondrial Inheritance And Morphology; ERMES Complex Is Often Co-localized With Peroxisomes And Concentrated Areas Of Pyruvate Dehydrogenase
The mitochondrial outer membrane plays a crucial role in the biogenesis, inheritance and dynamics of the organelle and forms the functional and signaling link between mitochondria and the rest of the eukaryotic cell. This membrane contains a diverse set of proteins that are synthesized in the cytosol and harbor signals that are essential for their subsequent import into mitochondria. We investigate the molecular mechanisms by which the various mitochondrial outer membrane proteins are targeted to mitochondria, inserted into the outer membrane and assembled into functional complexes within the membrane. In addition, we study the mechanisms and components that regulate lipids homeostasis in mitochondria. For our studies we use both yeast and mammalian tissue cultures as experimental systems.. ...
The mitochondrial outer membrane plays a crucial role in the biogenesis, inheritance and dynamics of the organelle and forms the functional and signaling link between mitochondria and the rest of the eukaryotic cell. This membrane contains a diverse set of proteins that are synthesized in the cytosol and harbor signals that are essential for their subsequent import into mitochondria. We investigate the molecular mechanisms by which the various mitochondrial outer membrane proteins are targeted to mitochondria, inserted into the outer membrane and assembled into functional complexes within the membrane. In addition, we study the mechanisms and components that regulate lipids homeostasis in mitochondria. For our studies we use both yeast and mammalian tissue cultures as experimental systems.. ...
Nair, S A and Rathinavelan, Thenmalarchelvi (2015) Bidirectional water conductivity of E.coli outer membrane lectin(Wzi) is regulated by surface aromatic residues and luminal hydrophobic plug. In: National Symposium on Biophysics and Golden Jubilee Meeting of Indian Biophysical Society, Center for Interdisciplinary Research in Basic Sciences, 14-17 February 2015, New Delhi, India. Full text not available from this repository. (Request a copy ...
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Bacterial proteins with MCE domains were first described as being important for Mammalian Cell Entry. More recent evidence suggests they are components of lipid ABC transporters. In Escherichia coli, the single-domain protein MlaD is known to be part of an inner membrane transporter that is important for maintenance of outer membrane lipid asymmetry. Here we describe two multi MCE domain-containing proteins in Escherichia coli, PqiB and YebT, the latter of which is an orthologue of MAM-7 that was previously reported to be an outer membrane protein. We show that all three MCE domain-containing proteins localise to the inner membrane. Bioinformatic analyses revealed that MCE domains are widely distributed across bacterial phyla but multi MCE domain-containing proteins evolved in Proteobacteria from single-domain proteins. Mutants defective in mlaD, pqiAB and yebST were shown to have distinct but partially overlapping phenotypes, but the primary functions of PqiB and YebT differ from MlaD. Complementing
Syma Khalid (Investigator) Many bacteria have an outer membrane which is the interface between the cell and its environment. The components of this membrane are well studied at an individual level, but there is a need to model and understand the outer membrane as a whole. In this project we aim to develop such a model of a bacterial outer membrane, linking computer simulations of the component molecules through to a more systems biology approach to modelling the outer membrane as a whole. Such an approach to modelling an OM must be multi-scale i.e. it must embrace a number of levels ranging from atomistic level modelling of e.g. the component proteins through to higher level agent-based modelling of the interplay of multiple components within the outer membrane as a whole. The different levels of description will be integrated to enable predictive modelling in order to explore the roles of outer membrane changes in e.g. antibiotic resistance.. ...
The relationship between iron acquisition and microbial pathogenesis (1, 38, 51, 84, 104) underscores the importance of the role of TonB in cell envelope physiology. Passage of ferric complexes through the OM requires TonB activity, and one theory of this requirement is that TonB participates in transport energetics by capturing proton motive force from the IM (where its N terminus resides) and distributing it to the OM transporters (14, 23, 76, 82, 95). According to the "shuttle" model of TonB action, it associates with the IM proteins ExbB and ExbD (42, 56), acquires proton motive force-generated energy by an unknown structural transition, and transmits (15) or physically transports (55, 57) the energy across the periplasm to the OM. The proposed interaction of "energized" TonB with OM proteins entails recognition of ligand-bound receptors and release of the stored force to them by protein-protein interactions between the C-terminal residues of TonB and the TonB box sequence of the LGP (76, ...
We describe a lesion, lamB701-708, affecting the hydrophilic portion of the lambda receptor signal sequence. The C to A transversion of the sixth codon of the signal sequence changes a positively charged arginine to a neutral serine. The phenotype conferred by this alteration is unique among previously described signal sequence mutations. The results suggest an essential role for the charged amino acids of the hydrophilic segment in the initial interaction between a nascent secreted protein and a membrane export site. The results further suggest that synthesis of lambda receptor is coupled to its export ...
The outer membrane of most Gram-negative bacteria is made up of LPS, and in nearly all bacteria that contain LPS it is essential for the life of the organism. The lipid portion of this molecule, lipid A, also known as endotoxin, is a potent activator of the innate immune response. More than 50 genes are required to synthesize LPS and assemble it at the cell surface. Enormous progress has been made in elucidating the structure and biosynthesis of LPS, but until recently the cellular components required for its transport from its site of synthesis in the inner membrane to its final cellular location at the cell surface remained elusive. Here we describe the identification of a protein complex that functions to assemble LPS at the surface of the cell. This complex contains two proteins: Imp, already identified as an essential outer-membrane protein implicated in LPS assembly; another protein, RlpB, heretofore identified only as a rare lipoprotein. We show that RlpB is also essential for cell viability and
The [email protected] Centre provides a platform for research students to deposit their Ph.D. theses and make it available to the entire scholarly community in open access. Shodhganga Mirror Site ...
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CPn0444 is similar to CT871, CT874, CT413, CT812, CT872, CT414, CT412, CT870, CT869, and CT456. They are predicted outer membrane proteins. CT871 is a predicted pmpG outer membrane protein G. Residues 470-1407 are 28% similar to CT871 ...
22, Table 33. Their outer membrane proteins contain cross- reactive antigens and surface-exposed epitopes that are species specific.
An outer membrane protein T (OmpT) could play a vital role in the pathogenesis of the neonatal meningitis Escherichia coli (NMEC) in human and animals. However, whether ompT plays a role in avian pathogenic E. coli (APEC) infection remains unclear. In this study we evaluated the potential of ompT in APEC pathogenesis. An ompT gene was deleted from APEC mutant strain (TW-XM) was constructed and cha ...
sample_1: KpOmpA transmembrane domain, [U-13C; U-15N; U-2H], 1 mM; DHPC 300 mM; NaH2PO4 20 mM; NaCl 100 mM; H2O 90%; D2O 10%. sample_2: KpOmpA transmembrane domain, [U-13C; U-15N; U-2H]/[L,V,I(delta1)-13CH3], 1 mM; DHPC 300 mM; NaH2PO4 20 mM; NaCl 100 mM; H2O 90%; D2O 10%. sample_3: KpOmpA transmembrane domain, [U-15N; 10% 13C], 1 mM; DHPC 300 mM; NaH2PO4 20 mM; NaCl 100 mM; H2O 90%; D2O 10%. sample_4: KpOmpA transmembrane domain, [U-13C; U-15N; U-2H]/[L,V,I(delta1)-13CH3], 1 mM; DHPC 300 mM; NaH2PO4 20 mM; NaCl 100 mM; H2O 90%; D2O 10%. sample_conditions_1: ionic strength: 0.1 M; pH: 6.5; pressure: 1 atm; temperature: 313 K ...
Michalik, M.; Orwick-Rydmark, M.; Habeck, M.; Alva, V.; Arnold, T.; Linke, D.: An evolutionarily conserved glycine-tyrosine motif forms a folding core in outer membrane proteins. PLoS One 12 (8) (2017 ...
View Notes - cells2 from BIOL 20204 at TCU. II. The Cell- Basic Unit of Life A. Cell or Plasma membrane-found @ outer surface of cell 1. Structure i. Thickness-75 ancryms=3/10,000,000 ii. Fluid
A murine immunoglobulin G monoclonal antibody (MAb) raised against outer membrane vesicles of Moraxella catarrhalis 035E was shown to bind to a surface-exposed epitope of a major outer membrane protein of this organism. This outer membrane protein, which had an apparent molecular weight of approximately 80,000 in sodium dodecyl sulfate-polyacrylamide gels, was designated CopB. MAb 10F3, reactive with CopB, bound to a majority (70%) of M. catarrhalis strains tested. More importantly, mice passively immunized with MAb 10F3 exhibited an enhanced ability to clear a bolus challenge of M. catarrhalis from their lungs, a result which suggested that CopB might have potential as a vaccine candidate. The M. catarrhalis gene encoding CopB was cloned in Escherichia coli, and nucleotide sequence analysis of the copB gene indicated that the CopB protein was synthesized with a leader peptide, a finding confirmed by N-terminal amino acid sequence analysis of the mature CopB protein purified from M. catarrhalis ...
Analysis of major outer membrane protein (MOMP) profiles of various meningococci by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of 0 to 2 low-molecular-weight, heat-modifiable MOMPs (molecular weight, 25,000 to 32,000) and 1 to 3 high-molecular-weight MOMPs (molecular weight, 32,000 to 46,000). Heat modifiability was investigated by comparing MOMP profiles after heating in SDS solutions at 100°C for 5 min or at 40°C for 1 h. Low-molecular-weight MOMPs shifted to higher apparent molecular weights after being heated at 100°C. Heat modifiability of high-molecular-weight MOMPs varied among strains; whenever modified these proteins shifted to lower apparent molecular weights after complete denaturation. Variability of low-molecular-weight, heat-modifiable MOMPs was demonstrated when MOMP profiles were compared of (i) isolates from index cases and associated cases and carriers among contacts, (ii) different isolates from the same individual, and ...
The signal peptide of the outer membrane lipoprotein (OMLP) of Escherichia coli was shown to be capable of promoting protein translocation across mammalian microsomal membranes in vitro. We assayed translocation of a fusion protein containing the OMLP signal peptide and nine amino acids of OMLP fused in frame to beta-lactamase. The efficiency with which the mammalian translocation machinery recognizes and accepts the OMLP signal peptide as substrate is indistinguishable from that of mammalian secretory proteins. Upon translocation mammalian signal peptidase processes the pre-OMLP-beta-lactamase protein at different sites than are utilized in vivo by E. coli OMLP signal peptidase (signal peptidase II) but that can be predicted as mammalian signal peptidase cleavage sites. Mutants in the OMLP signal peptide were tested for their ability to promote translocation of the fusion protein in this assay system. It has been shown previously that mutants in the positively charged amino acids at the amino ...
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Part of the outer membrane protein assembly complex, which is involved in assembly and insertion of beta-barrel proteins into the outer membrane. Constitutes, with BamD, the core component of the assembly machinery.
The availability of genome sequences and the corresponding translated protein databases have enabled studies on the meningococcal proteome, particularly the detailed composition of outer membrane fractions. In early studies, Frasch and colleagues [20] were able to distinguish only five major classes of proteins in outer membrane preparations from meningococci. Subsequently, additional proteins were identified that were present in lower amounts or only expressed when the bacteria had been grown under nutrient limitation (reviewed in [21]). The total number of proteins identified in outer membrane preparations remained relatively few until the development of more sensitive proteomic methods. This combined with the availability of the translated genome sequences has enabled much more detailed study of outer membrane preparations and the vesicle/vaccine preparations derived from them by deoxycholate extraction. One-dimensional SDS-PAGE of an OMV vaccine preparation followed by tandem mass ...
Outer membrane porin D is a protein family containing bacterial outer membrane porins which are involved in transport of cationic amino acids, peptides, antibiotics and other compounds. It was also described as having some serine protease activity. However many of these proteins are not peptidases and are classified as non-peptidase homologues as they either have been found experimentally to be without peptidase activity, or lack amino acid residues that are believed to be essential for the catalytic activity of peptidases in the S43 family. Yoshihara E, Yoneyama H, Ono T, Nakae T (June 1998). "Identification of the catalytic triad of the protein D2 protease in Pseudomonas aeruginosa". Biochem. Biophys. Res. Commun. 247 (1): 142-5. doi:10.1006/bbrc.1998.8745. PMID 9636669. This article incorporates text from the public domain Pfam and InterPro ...
No information on the cytokine profile to be used as a marker of Campylobacter jejuni infection protection. For this study, we used the outer membrane protein (MOMP [Pora]) as a vaccine for the protection and spleen cell cytokine as a marker of protection. We cloned and expressed Pora from C. jejuni111 and mice immunized with intraperitoneal route. Subsequently, the mice orally challenged with C. jejuni 111. live vaccine-induced protection as evidenced by a decrease in fecal excretion C. jejuni111. Cytokines were measured in vitro after stimulation of spleen cells with MOMP. Levels of pro-inflammatory cytokines, IL-12, TNF-α, IL-17A and IL-17F are similar in the control and test mice. Levels of pro-inflammatory cytokines, IL-2 and IFN-γ were higher in mice than in control mice test, and the level of pro-inflammatory cytokines, IL-8 and IL-1β was higher in the test mice than in control mice. In between the two anti-inflammatory cytokines, the same level of IL-10 but higher for IL-4 in the test ...
The Tar chemoreceptor of Escherichia coli is a membrane-bound sensory protein that facilitates bacterial chemotaxis in response to aspartate. The EnvZ molecule has a membrane topology similar to Tar and is a putative osmosensor that is required for osmoregulation of the genes for the major outer membrane porin proteins, OmpF and OmpC. The cytoplasmic signaling domain of Tar was replaced with the carboxyl portion of EnvZ, and the resulting chimeric receptor activated transcription of the ompC gene in response to aspartate. The activation of ompC by the chimeric receptor was absolutely dependent on OmpR, a transcriptional activator for ompF and ompC. ...
Gonorrheal urethritis was induced in three males by intraurethral instillation of predominantly pilus+ protein II- gonococci. Virtually all gonococci reisolated from the infected men exhibited protein II+ phenotype. The reisolated gonococci expressed five distinct outer membrane protein II species. Protein IIc+ organisms predominated in urines of all three subjects, but variants expressing this particular protein II were rarely spawned in vitro by input organisms. Protein IIc+ gonococci appeared early in one mans infection; they were joined later by variants that displayed eight other protein II phenotypes, including protein II-. These results show that input protein II- gonococci are supplanted by protein IIc+ variants during incipient gonorrheal urethritis. As infection progresses, a broader variety of protein II+ variants appears. ...
Looking for online definition of outer membrane in the Medical Dictionary? outer membrane explanation free. What is outer membrane? Meaning of outer membrane medical term. What does outer membrane mean?
PubMed journal article Export of the outer membrane lipoprotein is defective in secD, secE, and secF mutants of Escherichia col were found in PRIME PubMed. Download Prime PubMed App to iPhone or iPad.
Bacteria outer membrane lipoprotein I: vaccine candidate; antigenically cross-reacts with all serotype strains of the International Antigenic Typing Scheme; amino acid sequence given in first source
Genome analysis identified a large number of genes that would enable utilization of dilute carbon sources and provides a comprehensive picture of the strategies used by C. crescentus for survival in nutrient-limiting conditions. Unlike E. coli and Vibrio cholerae, C. crescentus has no OmpF-type outer membrane porins that allow the passive diffusion of hydrophilic substrates across the outer membrane. However, it does possess 65 members of the family of TonB-dependent outer membrane channels that catalyze energy-dependent transport across the outer membrane. This is more than any other organism thus far characterized, with the next highest being 34 in Pseudomonas aeruginosa (32), and with no other sequenced proteobacteria possessing more than 10. C. crescentus has substantially fewer cytoplasmic membrane transporters relative to genome size than either E. coli or V. cholerae (33). Given C. crescentus low nutrient habitat, it is surprising that PTS or ATP-binding cassette domain transporters, ...
A mutant variant of a septicemic Escherichia coli strain (L3) isolated from an outbreak in chickens was constructed by the insertion of TnphoA transposon. Seven mutant derivatives were analyzed regarding the pathogenicity. Two of them (XP2, XP4) were less pathogenic in the one-day-old chick pathogenicity assay. The expression of several outer membrane proteins of mutant XP2 strain was suppressed, and strain XP4 had a 47.8(kDa) protein that was not expressed. None of these proteins was correlated to the iron-acquisition system. Mutant XP2 could have suppression of a regulatory protein responsible for the expression of other proteins not related to pathogenicity but important for the rapid bacterial growth, while mutant XP4 did not express a 47.8(kDa) protein. We propose that the 47.8(kDa) protein could be associated to the pathogenicity process of Escherichia coli strains responsible for septicemia in poultry ...
The membrane assembly of outer membrane proteins is more complex than that of transmembrane helical proteins owing to the intervention of many charged and polar residues in the membrane. Accordingly, the predictive accuracy of transmembrane beta strands is considerably lower than that of transmembrane alpha helices. In this paper we develop a set of conformational parameters for membrane spanning beta strands. We formulate an algorithm to predict the transmembrane beta strands in the family of bacterial porins based on the conformational parameters and surrounding hydrophobicities of amino acid residues. A Fortran program has been developed which takes the amino acid sequence as the input file and gives the predicted transmembrane beta strand as output. The present method predicts at an accuracy level of 82% for all the bacterial porins considered.
The susceptibility of the E. coli B strain to a variety of stressful conditions and antibiotics revealed by PM tests (Figure S3 in Additional file 1) can be explained by several observations (Figure 5). First, differences in the composition of the LPS core and expression of outer membrane proteins may influence the permeability and integrity of the cell envelope. B strains produce more OmpF porin than K-12 strains because the B genome lacks micF, which post-transcriptionally prevents production of OmpF [24]. This is further supported by the transcriptome data showing high levels of ompF expression in the B strain and high expression of ompC and ompA in the K-12 strain (Figure 4). These observations were also consistent with results of proteome analysis of the outer membrane fractions (Figure S2B in Additional file 1). Noxious agents such as antibiotics and bile acids diffuse more easily through OmpF than OmpC because the former produces a channel with a larger pore size [25]. Second, synthesis ...
Protein TonB; Interacts with outer membrane receptor proteins that carry out high-affinity binding and energy dependent uptake into the periplasmic space of specific substrates. It could act to transduce energy from the cytoplasmic membrane to specific energy- requiring processes in the outer membrane, resulting in the release into the periplasm of ligands bound by these outer membrane proteins (249 aa ...
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Motivation: Transmembrane beta-barrels exist in the outer membrane of gram-negative bacteria as well as in chloroplast and mitochondria. They are often involved in transport processes and are promising antimicrobial drug targets. Structures of only a few beta-barrel protein families are known. Therefore, a method that could automatically generate such models would be valuable. The symmetrical arrangement of the barrels suggests that an approach based on idealized geometries may be successful. Results: Here, we present tobmodel; a method for generating 3D models of beta-barrel transmembrane proteins. First, alternative topologies are obtained from the BOCTOPUS topology predictor. Thereafter, several 3D models are constructed by using different angles of the beta-sheets. Finally, the best model is selected based on agreement with a novel predictor, ZPRED3, which predicts the distance from the center of the membrane for each residue, i.e. the Z-coordinate. The Z-coordinate prediction has an average ...
Specific assembly proteins are required for the folding and integration of autotransporters into the outer membrane. Employing x-ray crystallography, the authors of the study decoded the atomic structure of the autotransporter assembly protein TamA of the intestinal bacterium Escherichia Coli.. "The protein TamA", explains Fabian Gruss, first author and recipient of a Werner-Siemens PhD fellowship, "also forms a barrel with a pore. The pore is closed to the outside by a lid but a particular kink in the barrel wall provides a gate for autotransporter substrates." When an unfolded autotransporter is delivered, TamA hooks onto one end of the substrate polypeptide chain and integrates it step by step via the gate into its own barrel structure. The TamA barrel is thus expanded; the pore widens and opens such that passenger substrates traverse to the exterior. The assembly process ends when TamA releases the autotransporter into the surrounding membrane. "The autotransporter insertion mechanism was ...
Structural relatedness of enteric bacterial porins assessed with monoclonal antibodies to Salmonella typhimurium OmpD and OmpC.: The immunochemistry and structu
The periplasm (the space between the inner and outer membranes of bacteria) is the site of activation of the periplasmic stress response. Like the cytosolic stress response and the eukaryotic endoplasmic and cytosolic stress responses, unfolded proteins trigger a transcriptional activation profile that allows cells to produce more chaperones and protein-folding agents (see Young and Hartl). Although, the periplasmic stress response is fairly well characterized, the sensor that initiates the process has remained elusive. The response consists of activation of the protease DegS, which cleaves transmembrane protein RseA, which then releases the transcription factor σE to allow the activation of stress response genes. Walsh et al. show that DegS is inhibited by its PDZ domain and that binding of the PDZ domain toYQF motifs of outer membrane protein porins activates the protease. Bacteria expressing DegS lacking the PDZ domain showed increased σE activity. Using an oriented peptide library, a ...
The outer membrane (OM) of Gram-negative pathogenic bacteria represents a platform for the secretion and presentation of surface-localized virulence factors. Th...
1GFN: Structural and functional characterization of OmpF porin mutants selected for larger pore size. I. Crystallographic analysis.
TY - JOUR. T1 - Proteolytic activation of Vibrio mimicus (Vm) major outer membrane protein haemagglutinin (HA) with Vm-HA/Protease. T2 - Implication for understanding bacterial adherence. AU - Alam, Munirul. AU - Miyoshi, Shin Ichi. AU - Ahmed, Kabir Uddin. AU - Hasan, Nur A.. AU - Tomochika, Ken Ichi. AU - Shinoda, Sumio. PY - 2006/1/1. Y1 - 2006/1/1. N2 - Vibrio mimicus (Vm) haemagglutinins (HAs), such as an extracellular HA/protease (Vm-HA/protease) and a major outer membrane protein-HA (Vm-OMPHA), have been recognized as the putative adherence factors for the bacterium. However, the mechanism by which HAs coordinate the adherence function of the bacterium remains as yet unknown. We report herein the positive interaction between Vm-HA/protease and Vm-OMPHA resulting in significant enhancement of the haemagglutinating ability. In this interaction, no cleaved polypeptide was detected; however, limited proteolysis of Vm-OMPHA was confirmed by SDS-PAGE. The proteolytic activation of the native ...
Xanthomonas campestris pv. campestris (Xcc) is the phytopathogen that causes black rot in crucifers. The xanthan polysaccharide and extracellular enzymes produced by this organism are virulence factors, the expression of which is upregulated by Clp (CRP-like protein) and DSF (diffusible signal factor), which is synthesized by RpfF. It is also known that biofilm formation/dispersal, regulated by the effect of controlled synthesis of DSF on cell-cell signalling, is required for virulence. Furthermore, a deficiency in DSF causes cell aggregation with concomitant production of a gum-like substance that can be dispersed by addition of DSF or digested by exogenous endo-β-1,4-mannanase expressed by Xcc. In this study, Western blotting of proteins from a mopB mutant (XcMopB) showed Xcc MopB to be the major outer-membrane protein (OMP); Xcc MopB shared over 97 % identity with homologues from other members of Xanthomonas. Similarly to the rpfF mutant, XcMopB formed aggregates with simultaneous production of a
Chlamydia psittaci is an obligate intracellular bacterium that can cause significant disease among a broad range of hosts. In humans, this organism may cause psittacosis, a respiratory disease that can spread to involve multiple organs, and in rare untreated cases may be fatal. There are ten known genotypes based on sequencing the major outer-membrane protein gene, ompA, of C. psittaci. Each genotype has overlapping host preferences and virulence characteristics. Recent studies have compared C. psittaci among other members of the Chlamydiaceae family and showed that this species frequently switches hosts and has undergone multiple genomic rearrangements. In this study, we sequenced five genomes of C. psittaci strains representing four genotypes, A, B, D and E. Due to the known association of the type III secretion system (T3SS) and polymorphic outer-membrane proteins (Pmps) with host tropism and virulence potential, we performed a comparative analysis of these elements among these five strains ...
The fucose binding lectin LecB affects biofilm formation and is involved in pathogenicity of Pseudomonas aeruginosa. LecB resides in the outer membrane and can be released specifically by treatment of an outer membrane fraction with fucose suggesting that it binds to specific ligands. Here, we report that LecB binds to the outer membrane protein OprF. In an OprF-deficient P. aeruginosa mutant, LecB is no longer detectable in the membrane but instead in the culture supernatant indicating a specific interaction between LecB and OprF.
TonB-dependent receptors (TBDRs) are outer membrane proteins mainly known for the active transport of iron siderophore complexes in Gram-negative bacteria. Analysis of the genome of the phytopathogenic bacterium Xanthomonas campestris pv. campestris (Xcc), predicts 72 TBDRs. Such an overrepresentation is common in Xanthomonas species but is limited to only a small number of bacteria. Here, we show that one Xcc TBDR transports sucrose with a very high affinity, suggesting that it might be a sucrose scavenger. This TBDR acts with an inner membrane transporter, an amylosucrase and a regulator to utilize sucrose, thus defining a new type of carbohydrate utilization locus, named CUT locus, involving a TBDR for the transport of substrate across the outer membrane. This sucrose CUT locus is required for full pathogenicity on Arabidopsis, showing its importance for the adaptation to host plants. A systematic analysis of Xcc TBDR genes and a genome context survey suggested that several Xcc TBDRs belong to other
Antibiotic-resistant Burkholderia (Pseudomonas) cepacia is an important etiologic agent of nosocomial and cystic fibrosis infections. The primary resistance mechanism which has been reported is decreased outer membrane permeability. We previously reported the cloning and characterization of a chloramphenicol resistance determinant from an isolate of B. cepacia from a patient with cystic fibrosis that resulted in decreased drug accumulation. In the present studies we subcloned and sequenced the resistance determinant and identified gene products related to decreased drug accumulation. Additional drug resistances encoded by the determinant include resistances to trimethoprim and ciprofloxacin. Sequence analysis of a 3.4-kb subcloned fragment identified one complete and one partial open reading frame which are homologous with two of three components of a potential antibiotic efflux operon from Pseudomonas aeruginosa (mexA-mexB-oprM). On the basis of sequence data, outer membrane protein analysis, ...
View all domain architectures containing the Outer membrane lipoprotein domain in Salmonella enterica subsp. enterica serovar Bareilly str. CFSAN000189.
Membrane proteins serve essential functions in both bacterial and mammalian cells making them important therapeutic targets. While the mechanism for membrane integration has been well established for alpha-helical membrane proteins, the mechanism for insertion of beta-barrel membrane proteins remains elusive. For Gram-negative bacteria, a complex called the beta-barrel assembly machinery (BAM) complex, consisting of BamA (a beta-barrel membrane protein itself) and four lipoproteins called BamB, BamC, BamD, and BamE, is required for membrane integration. Work from several labs, including ours, has led to the 3D structures of all the components of the BAM complex except for full length BamA, however, they have failed to lead to a plausible mechanism for membrane integration, suggesting that the structure of BamA is likely required in order to understand this unique mechanism. To this end, we have determined the crystal structures of two BamA homologs, including a full length structure which ...
TY - JOUR. T1 - Reconstitution of a nanomachine driving the assembly of proteins into bacterial outer membranes. AU - Shen, Hsin-Hui. AU - Leyton, Denisse L. AU - Shiota, Takuya. AU - Belousoff, Matthew J. AU - Noinaj, Nicholas. AU - Lu, Jingxiong. AU - Holt, Stephen A. AU - Tan, Kher Shing. AU - Selkrig, Joel Pearson. AU - Webb, Chaille T. AU - Buchanan, Susan K. AU - Martin, Lisandra L. AU - Lithgow, Trevor J. PY - 2014. Y1 - 2014. N2 - In biological membranes, various protein secretion devices function as nanomachines, and measuring the internal movements of their component parts is a major technological challenge. The translocation and assembly module (TAM) is a nanomachine required for virulence of bacterial pathogens. We have reconstituted a membrane containing the TAM onto a gold surface for characterization by quartz crystal microbalance with dissipation (QCM-D) and magnetic contrast neutron reflectrometry (MCNR). The MCNR studies provided structural resolution down to 1 A, enabling ...
1997) Identification of Serpulina pilosicoli outer membrane proteins by screening a genomic library with monoclonal antibodies. In: 8th Annual Combined Biological Sciences Meeting, 15 August, Perth, Western Australia. ...
The chaperone-usher (CU) pathway is a translocation system used to assemble adhesive multi-subunit fibres on the outer surface of gram-negative bacteria. CU pili are formed by the non-covalent polymerisation of several hundreds or thousands of pilus subunits which consist of an incomplete immunoglobulin (Ig)-like fold lacking the C-terminal ß-strand. In the periplasm, a cognate chaperone assists in pilus subunit folding by donating a b-strand to complement the truncated Ig-like fold of the pilus subunit, a process termed donor-strand complementation (Figure 69, A*) [1]. Chaperone:subunit complexes are then recruited to a pilus assembly platform in the outer membrane (OM) called the "usher". The usher catalyses ordered subunit polymerisation and mediates translocation of the nascent pilus to the cell surface. Polymerisation of pilus subunits occurs through an intermolecular fold complementation mechanism involving the first 10-20 residues (termed "N-terminal extension" or Nte) of the pilus ...
The aim of this study was to characterize the mechanisms by which C4b and streptococcal M proteins interact with C4BP. Furthermore, we wanted to identify a key recognition area in the C4BP α-chain involved in the binding of these ligands. To address this question, we used nine C4BP mutants and compared the ability of these molecules to interact with C4b and with the M proteins Arp4 and Sir22. Effects of NaCl and mAbs were also tested, and the experimental results were then evaluated in conjunction with structural analysis of a recently reported 3D model structure of human (8) and mouse C4BP. Taken together, our data show that the key binding region for C4b overlaps with the surface interacting with Arp4/Sir22 and is located on CCP1 and CCP2. However, the recognition areas are not identical and the molecular mechanisms involved in these two processes differ.. Previously published data from our group (10) together with the present results show that Arg39, Lys63, Arg64, and His67 are crucial for ...
Gram-negative bacteria are harmful in various surroundings. In the food industy their metabolites are potential cause of spoilage and this group also includes many severe or potential pathogens, such as Salmonella. Due to their ability to produce biofilms Gram-negative bacteria also cause problems in many industrial processes as well as in clinical surroundings. Control of Gram-negative bacteria is hampered by the outer membrane (OM) in the outermost layer of the cells. This layer is an intrinsic barrier for many hydrophobic agents and macromolecules. Permeabilizers are compounds that weaken OM and can thus increase the activity of antimicrobials by facililating entry of hydrophobic compounds and macromolecules into the cell where they can reach their target sites and inhibit or destroy cellular functions. The work described in this thesis shows that lactic acid acts as a permeabilizer and destabilizes the OM of Gram-negative bacteria. In addition, organic acids present in berriers, i.e. malic, ...
Outer membrane protein A (OmpA) is a key outer membrane protein found in Gram-negative bacteria that contributes to several crucial processes in bacterial virulence. In Porphyromonas gingivalis, OmpA is predicted as a heterotrimer of OmpA1 and OmpA2 subunits encoded by adjacent genes. Here we describe the role of OmpA and its individual subunits in the interaction of P. gingivalis with oral cells. Using knockout mutagenesis, we show that OmpA2 plays a significant role in biofilm formation and interaction with human epithelial cells. We used protein structure prediction software to identify extracellular loops of OmpA2, and determined these are involved in interactions with epithelial cells as evidenced by inhibition of adherence and invasion of P. gingivalis by synthetic extracellular loop peptides and the ability of the peptides to mediate interaction of latex beads with human cells. In particular, we observe that OmpA2-loop 4 plays an important role in the interaction with host cells. These ...
The asymmetric outer membrane of Gram-negative bacteria is formed of the inner leaflet with phospholipids and the outer leaflet with lipopolysaccharides (LPS). Outer membrane protein F (OmpF) is a trimeric porin responsible for the passive transport of small molecules across the outer membrane of Escherichia coli. Here, we report the impact of different levels of heterogeneity in LPS environments on the structure and dynamics of OmpF using all-atom molecular dynamics simulations. The simulations provide insight into the flexibility and dynamics of LPS components that are highly dependent on local environments, with lipid A being the most rigid and O-antigen being the most flexible. Increased flexibility of O-antigen polysaccharides is observed in heterogeneous LPS systems, where the adjacent O-antigen repeating units are weakly interacting and thus more dynamic, compared to homogeneous LPS systems in which LPS interacts strongly with each other with limited overall flexibility due to dense ...
In Gram-negative bacteria, multi-component machines that span the inner and outer membranes actively extrude drugs and other toxic small compounds. Many of these machines are assembled principally from three different types of components: i) an outer membrane protein that acts as a channel and opens from a sealed resting state during the transport process, ii) an inner membrane protein that transduces proton electrochemical energy into vectorial displacement of the transported compounds, and iii) a bridging, periplasmic component that links the inner and outer membrane proteins. The pumps may assemble transiently, and the association of components is favoured by engaged substrate and the trans-membrane electrochemical potential. We describe recent structural and functional studies on the individual pump components and discuss models that explain how they associate in the dynamic, active assembly. Based on the available data, we suggest that the assembly of these multi-drug efflux pumps is ...
Interaction of bacterial outer membrane secretin PulD with its dedicated lipoprotein chaperone PulS relies on a disorder-to-order transition of the chaperone
Trimeric autotransporters are a family of secreted outer membrane proteins in Gram-negative bacteria. These obligate homotrimeric proteins share a conserved C-terminal region, termed the translocation unit. This domain consists of an integral membrane β-barrel anchor and associated α-helices which pass through the pore of the barrel. The α-helices link to the extracellular portion of the protein, the passenger domain. Autotransportation refers to the way in which the passenger domain is secreted into the extracellular space. It appears that the translocation unit mediates the transport of the passenger domain across the outer membrane, and no external factors, such as ATP, ion gradients nor other proteins, are required. The passenger domain of autotransporters contains the specific activities of each protein. These are usually related to virulence. In trimeric autotransporters, the main function of the proteins is to act as adhesins. One such protein is the Yersinia adhesin YadA, found in ...
YfiBNR, a tripartite cyclic-di-GMP (c-di-GMP) signalling system, plays an important role in biofilm formation of the gram-negative bacterium P. aeruginosa, which regulates the cellular processes strongly associated with chronic lung infections and drug resistance. The outer-membrane lipoprotein YfiB can release the inhibition of the inner membrane protein YfiN by sequestering the periplasmatic protein YfiR, resulting in the activation of diguanylate cyclase activity of YfiN and the production of c-di-GMP. In contrast to the extensive studies on c-di-GMP, little is known about how GMP acts in the YfiBNR system ...
Our lab is cross-disciplinary, bringing together computational biology, protein design, and molecular biology approaches. We assess the structural bioinformatics of OMPs (outer membrane proteins) and apply the results to de novo OMP protein design and to native OMP manipulation.. OMPs are a ripe target for cancer therapeutics. Mitochondria have recently become a focus of cancer therapies due to the fact that mitochondrial outer membrane permeabilization leads to apoptosis or necrosis. We explore mitochondrial membrane permeabilization through manipulation of the OMP pores that already exist in the mitochondrial outer membrane. This may have pharmaceutical consequences because tumorigenic mitochondrial membranes can be selectively targeted in themselves as they have been shown to accumulate lipophilic cations.. Beyond this mechanistic understanding, knowledge of the relationship between OMP chemistry and structure will allow new OMPs to be designed for use in vaccines and will facilitate ...
For whole cell protease treatment method, E. coli cells have been harvested, washed and resuspended in one ml Tris HCl. Proteinase K was additional to final concentrations in between 0. two mg mL 1 and 0. 5 mg mL 1 and cells had been incubated for one hour at 37 C. Digestion was stopped by washing the cells twice with Tris HCl containing 10% fetal calf serum and outer membrane proteins were ready as described over. For outer membrane proteins that have been applied for ac tivity assays, cells werent handled with Proteinase K. SDS Page Outer membrane isolates were diluted with sam ple buffer containing 4% SDS, 0. 2% bromophenol blue, 200 mM dithiothreitol and 20% glycerol boiled for 10 minutes and analyzed on 10% polyacrylamid gels. Proteins had been stained with Coomassie brilliant blue.. To correlate molecu lar masses of protein bands of curiosity, a molecular fat conventional was employed. Flow cytometer evaluation E. coli BL21 pAT kinase inhibitor MLN0128 LipBc cells were grown and ex ...
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Towards the preparation of synthetic outer membrane vesicle models with micromolar affinity to wheat germ agglutinin using a dialkyl thioglycoside
5.B.3 The Geobacter Nanowire Electron Transfer (G-NET) Family Bacteria have the capacity to transfer electrons from cytoplasmic electron donors to extracellular substances. Geobacter and other bacteria from diverse bacterial kingdoms have this capacity. Geobacter utilizes nanowires distantly related to type IV pili (fimbriae) to transfer electrons to iron oxide (Fe2O3; rust) to generate soluble Fe2+ and solid magnetite. The entire pathway of electron transfer has been elucidated (see Lovley, 2006). An electron pair is transferred from NADH to menaquinone, and then single electrons are transferred through the chain to iron oxide via an inner membrane (IM), periplasm, outer membrane (OM) pathway as follows:. NADH → NADHDH (3.D.1.4.1) → Menaquinone → MacA (IM) → PpcA (periplasm). → OmcB (a trans OM protein) → OmcE (outer surface of the OM) →. OmcS (outer surface of the OM) → pilin → Fe2O3.. These proteins are all c-type cytochromes (Lovley, 2006). Extracellular reduction of ...
Biopharmaceutical industries have been exploiting microbial organisms such as Escherichia coli to manufacture recombinant proteins that mostly are intended for therapeutic applications. For extraction of accumulated proteins in the periplasm, a method of cell lysis must take place which has a number of significant drawbacks such as numerous recovery and purification steps which leads to further reduction of the overall yield. Also, as well as the product, contaminants such as DNA and HCP are released which may be difficult to remove. Antisense technology offers a platform that once optimized can reduce the named drawbacks. Antisense RNA can target and inhibit the synthesis of proteins made by the cell, particularly outer membrane proteins in order to facilitate secretion of the recombinant product out of the cell during fermentation. This project aims to investigate the impact of inhibition of synthesis of selected outer membrane proteins on the secretion levels, thus having an effective release ...
关键词: 单分子FRET, 荧光相关谱, OmpT折叠, Tween-20, DDM Abstract: The cell envelope of gram-negative bacteria consists of the outer membrane (OM), inner membrane (IM), and periplasm. The β-barrel outer membrane proteins (OMPs) embedded in the OM perform diverse and significant functions such as signaling, transporting, and proteolysis. The OMPs of gram-negative bacteria share similar folding pathways with that of mitochondria and chloroplasts. Therefore, the study of the OMP folding mechanism not only provides insights into antimicrobial drug design but also helps elucidate mitochondrial and chloroplast biogenesis. Most knowledge about OMP folding was obtained from ensemble experiments where OMPs were usually at micromolar concentrations and prone to aggregate, which is different from the physiological environment in the cells. Unlike ensemble techniques, single-molecule detection (SMD) can measure OMPs from nano- to picomolar concentrations and prevent aggregation. In this work, ...
figure taken from the reference below). Murein means peptidoglycan cell wall and the cytoplasm denotes the inside of the cell. In this scenario, the double-membraned proto-bacteria (which has spend the last half-a-billion years or so evolving a well adjusted double membrane system) suddenly looses the outer membrane. A very simple genetic change would lead to a massively overgrown cell wall, which would rip the outer membrane away. The cell looses all its outer membrane porins, and signal systems, but in return gains a highly protective cell wall, which potentially allows it to survive in different niches. How these aspects are lost genetically is another matter, and the paper rather hand-waves away by saying that unused genes tend to get lost eventually. Which is true in bacteria, they have such a small genome they dont want it getting filled up with unnecessary genes, but I have a feeling genes tend to leave something behind. Even so, the question of where the now-unnecessary genes go is ...
BamB is the largest of four lipoproteins in the β-barrel assembly machinery (BAM) complex. for cell viability and OMP biogenesis5. Similar mechanisms for OMP biogenesis exist for both mitochondria and chloroplasts providing further evidence of the evolutionary relationships of these organelles6 7 Structures of large portions of the BamA periplasmic domain were solved recently by X-ray crystallography8-10 and NMR11 which provided insight into how BamA recognizes BamB and possibly even nascent OMPs. Still structures of additional BAM components (and eventually of the intact assembly) are needed in order to fully understand how the BAM complex takes nascent OMPs and then folds and inserts them into the outer membrane. In BMS-777607 and the complex behaves as a monomer with a presumed stoichiometry of 1 1:1:1:1:1. This complex can fold and place a β-barrel protein into liposomes in a reaction that requires no energy source as long as a soluble chaperone SurA is usually present13. When BamB is ...
p,Gram-negative bacteria have a double-membrane cellular envelope that enables them to colonize harsh environments and prevents the entry of many clinically available antibiotics. A main component of most outer membranes is lipopolysaccharide (LPS), a glycolipid containing several fatty acyl chains and up to hundreds of sugars that is synthesized in the cytoplasm. In the past two decades, the proteins that are responsible for transporting LPS across the cellular envelope and assembling it at the cell surface in Escherichia coli have been identified, but it remains unclear how they function. In this Review, we discuss recent advances in this area and present a model that explains how energy from the cytoplasm is used to power LPS transport across the cellular envelope to the cell surface.,/p,. ...
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Mitochondrion-dependent N-terminal processing of outer membrane Mcl-1 protein removes an essential Mule/Lasu1 protein-binding site
Hi, I am trying to express in E. coli four different membrane proteins (ABC transporter) in either a pET vector with an N-terminal 6x his-tag or an pASK-IBA vector (tet promotor) with N- or C-terminal strep-tag, respectively. I tried different concentrations of inductor, different times of expression, different temperatures... Under all condition the proteins seem to be toxic (decrease in OD), and I cannot detect anything of the right size after fractionation and column purifcation or just fractionation western blotting, antibody detection. Has anyone an idea how I can get my proteins? Thanks for your advice! punzel http://biowww.net/mynews/tree.php?group_name=bionet_molbio_proteins&begin=0 ...
Affiliation:大阪大学,微生物病研究所,准教授, Research Field:Bacteriology (including Mycology),Bacteriology (including mycology),Pathology, Infection/Immunology, and related fields,Immunology,Morphological basic dentistry, Keywords:細菌,微生物,ヘリコバクターピロリ,感染症,ワクチン,感染,シグナル伝達,バクテリオファージ,パイエル板,外来因子, # of Research Projects:13, # of Research Products:86, Ongoing Project:Elucidation of the mechanisms of substance-selective introduction into bacterial outer membrane vesicles
Fabric structures with raceways and methods of making same are disclosed. In some embodiments, the fabric structures are air supported structures that form an enclosure via internal pressurized air. The air supported structures include an outer membrane that defined an outer surface of the structure. The air supported structures further include a plurality of inner segments formed of tab members coupled to and extending from the outer membrane toward the interior of the enclosure, and at least one inner liner panel coupled to and extending between adjacent tab members spaced inwardly from the outer membrane to form at least one air pocket therebetween. An attachment portion of the tab members extends inwardly past the at least one inner liner panel into the enclosure and forms at least one hardware attachment point.
1GFM: Structural and functional characterization of OmpF porin mutants selected for larger pore size. I. Crystallographic analysis.
The membranes of mitochondria are composed of lipid and proteins. The outer membrane of mitochondria contains 40% of lipids and 60% of proteins and inner membrane contains 20% of lipids and 80% of proteins. Thus, the ratio of lipid/protein in the outer membrane is 2 by 3 ratio and inner membrane is 1 by 4 ratio. Outer membrane contains a large amount of cholesterol. Inner membrane contains electron acceptors of electron transport chain and many enzymes. So, it has high contents of proteins.. ...
In order to find new and efficient vaccine targets, NovartisVaccines tested the immunogenicity and protective activity in vivo of a large number of cell surface-exposed proteins from Meningococcus B. Amongst these only a limited number of proteins was able to induce protective antibodies. One protein, NMB033, induces protective immunity in mice. Immunological studies demonstrated that this is due to the ability of the protein to efficiently mimic an unrelated epitope of a well-known antigen named porA. Structural information is a fundamental element in elucidating such molecular mimicry, as well as in understanding the mechanisms through which some antibodies elicit microbicidal response.. Results ...
Chloroplast outer membrane proteins with β-barrel-shaped transmembrane domains are sorted to the chloroplasts by amino-terminal transit peptides and/or intrinsic targeting information, but in both cases the proteins use the general import apparatus that also serves proteins destined for the interior compartments of the chloroplast. ...
Ruskamo, S.; Yadav, R.P.; Sharma, S.; Lehtimäki, M.; Laulumaa, S.; Aggarwal, S.; Simons, M.; Bürck, J.; Ulrich, A.S.; Juffer, A.H.; Kursula, I.; Kursula, P ...