The maintenance of flagellar length is believed to require both anterograde and retrograde intraflagellar transport (IFT). However, it is difficult to uncouple the functions of retrograde transport from anterograde, as null mutants in dynein heavy ch
Bacteria propel themselves through liquid environments using rotation of a propeller like organelle, the flagellum. Flagella are energized by the membrane ion gradient and enable bacteria to swim towards nutrients and away from harmful substances. This unique nanomachine shares structural and functional similarities to the needle-like injectisome complex that pathogenic bacteria employ to inject virulence factors into eukaryotic host cells. Bacterial flagella and injectisomes contain a specialized protein export system, termed type III secretion, that functions to deliver structural subunits and effector proteins to the outside of the cytoplasmic membrane. Type III secretion systems are made of multiple proteins, however, the function of individual subunits and the molecular mechanism of protein translocation is poorly understood.,br /,The first part of this thesis reports that the flagellar type III secretion system functions as a proton-driven protein exporter and demonstrates that many ...
Flagella and flagellum-mediated motility are integral to the virulence of several gastrointestinal bacterial pathogens (10). For L. monocytogenes, no link has been made between flagella and virulence, although the flagella are important for efficient invasion of tissue culture cells (2, 6). In this study, we investigated the mechanism by which flagella influence the ability of L. monocytogenes to invade host cells and the role of flagella in colonizing mice early in infection. Our results clearly indicate that L. monocytogenes flagella do not function as adhesins to enhance bacterial attachment to and invasion of epithelial cells, but rather function as motility devices contributing more to invasion than a mere increase in probability of bacterium-host cell interaction. Moreover, we show that motile bacteria outcompete nonmotile bacteria for initial colonization of the intestinal tract and liver by L. monocytogenes.. Flagella can function as adhesins, independent of motility, to enhance ...
Shop Flagellar hook protein ELISA Kit, Recombinant Protein and Flagellar hook protein Antibody at MyBioSource. Custom ELISA Kit, Recombinant Protein and Antibody are available.
Some bacteria boast a marvelous swimming device, the flagellum, which has no counterpart in more complex cells. In 1973 it was discovered that some bacteria swim by rotating their flagella. So the bacterial flagellum acts as a rotary propellor -- in contrast to the cilium, which acts more like an oar.. The structure of a flagellum is quite different from that of a cilium. The flagellum is a long, hairlike filament embedded in the cell membrane. The external filament consists of a single type of protein, called flagellin. The flagellin filament is the paddle surface that contacts the the liquid during swimming. At the end of the flagellin filament near the surface of the cell, there is a bulge in the thickness of the flagellum. It is here that the filament attaches to the rotor drive. The attachment material is comprised of something called hook protein. The filament of a bacterial flagellum, unlike a cilium, contains no motor protein; if it is broken off, the filament just floats stiffly in ...
The flagella connector (FC) of procyclic trypanosomes is a mobile, transmembrane junction important in providing cytotactic morphogenetic information to the daughter cell. Quantitative analyses of FC positioning along the old flagellum, involving direct observations and use of the MPM2 anti-phosphoprotein monoclonal reveals a `stop point is reached on the old flagellum which correlates well with the initiation of basal body migration and kinetoplast segregation. This demonstrates further complexities of the FC and its movement in morphogenetic events in trypanosomes than have hitherto been described. We used intraflagellar transport RNAi mutants to ablate the formation of a new flagellum. Intriguingly the FC could still move, indicating that a motor function beyond the new flagellum is sufficient to move it. When such a FC moves, it drags a sleeve of new flagellar membrane out of the flagellar pocket. This axoneme-less flagellar membrane maintains appropriate developmental relationships to the ...
cells have a single polar flagellum whose helical pitch and diameter characteristically change near the midpoint, resulting in a tapered wave. by three geometrical parameters: pitch, helical diameter, and handedness.5 There are three families of flagella defined by distinctive helical parameters: family I includes peritrichous flagella with large pitches and diameters, family II includes polar flagella with medium pitches and diameters, and family III contains lateral flagella with small pitches and diameters.6 There are exceptions that do not belong to these three families because their flagella have an irregular shape. Interestingly, the outstanding flagella are mostly produced by alpha-proteobacteria.6 Although are in the delta-proteobacteria, its flagella belong to this irregularly shaped group of flagella. Flagellar genes of are scattered all over the genome, forming small clusters buy 897383-62-9 of two or three genes,7 similar to those of or and and are both sheathed with a membranous ...
... and retrograde intraflagellar transport (IFT). particles. The IFT particles then associate into linear arrays known as IFT trains (Pigino et al., 2009), which move processively from the base of the flagellum out to the tip. This anterograde transport Mouse monoclonal to CD74(PE) is driven by kinesin-2, a heterotrimeric complex composed of the FLA10 and FLA8 motor subunits (Walther et al., 1994) and the buy BS-181 HCl kinesin-associated protein KAP (Cole et al., 1993; Mueller et al., 2005). After their anterograde motion to the flagellar tip, IFT particles rearrange into a new set of IFT trains that move back to the base of the flagellum. This retrograde transport is powered by cytoplasmic dynein 1b, a large complex composed of the heavy chain motor subunit DHC1b (Pazour et al., 1999a; Porter et al., 1999; Signor et al., 1999) and numerous smaller components including D1bLIC (Perrone et al., 2003; Schafer et al., 2003; Hou ...
During a complex digenetic life cycle flagellated Leishmania parasites alternate between promastigote and amastigote forms which differ significantly in cellular morphology and flagellum length. Recent studies have provided important new insights into mechanisms by which Leishmania regulate expression of genes required for flagellum assembly, and mechanisms used to modify flagellum length. While the critical role of the promastigote flagellum in parasite biology has long been appreciated, the importance of the amastigote flagellum has often been disregarded. However, recent work suggests that the rudimentary amastigote flagellum may serve indispensable roles in cellular organisation, and/or sensory perception, which are critical for intracellular survival of Leishmania within host macrophages.. ...
Although a great deal is known about molecular motors that drive movement of the eukaryotic flagellum, little is known about mechanisms that regulate/coordinate flagellar beat (Cosson, 1996). Our results demonstrate that trypanin is required for directional cell motility in T. brucei. EM studies revealed that the unusual cell motility defect of trypanin(−) mutants results from uncoupling of the flagellar apparatus from the subpellicular cytoskeleton. The punctate distribution of trypanin along the cell body side of the paraflagellar rod (Fig. 5) supports the interpretation that trypanin is part of the attachment complex that connects the flagellum to the subpellicular cytoskeleton. Our data further indicate that this flagellum attachment complex has two components, a cytoskeletal component, of which trypanin is a part, and a membrane component that operates even in the absence of trypanin and stabilizes the direct cytoskeleton connection (Balber, 1990; Hemphill et al., 1991). The only other ...
Fig. 5. Adaptation of the L. mexicana flagellar pocket and FAZ structures in the amastigote. (A) Lateral view of the flagellar pocket structure of a representative amastigote 1K1N L. mexicana cell (see C), as determined using serial section electron tomography. Flagellum, flagellar pocket and associated structures are shown, relative to a small portion of the pellicular microtubules and membrane. The inferred path of the MtQ out of the tomogram volume is indicated with dashed structures. Generated from Tomogram AL2. (B) The structure shown in A rotated 90° around the horizontal axis. (C) Low-magnification electron micrograph of the cell whose flagellar pocket is shown in A and B. Section 1 of the three used to build the tomogram is shown. The location of the nucleus (N), kinetoplast (K), flagellar pocket (FP) and region reconstructed by using electron tomography (box) are indicated. (D-G) 10-nm virtual longitudinal sections (generated from tomogram volumes), illustrating electron densities ...
TY - JOUR. T1 - The Drosophila pericentrin-like protein is essential for cilia/flagella function, but appears to be dispensable for mitosis. AU - Martinez-Campos, Maruxa. AU - Basto, Renata. AU - Baker, James. AU - Kernan, Maurice. AU - Raff, Jordan W.. PY - 2004/6/7. Y1 - 2004/6/7. N2 - Centrosomes consist of a pair of centrioles surrounded by an amorphous pericentriolar material (PCM). Proteins that contain a Pericentrin/AKAP450 centrosomal targeting (PACT) domain have been implicated in recruiting several proteins to the PCM. We show that the only PACT domain protein in Drosophila (the Drosophila pericentrin-like protein [D-PLP]) is associated with both the centrioles and the PCM, and is essential for the efficient centrosomal recruitment of all six PCM components that we tested. Surprisingly, however, all six PCM components are eventually recruited to centrosomes during mitosis in d-plp mutant cells, and mitosis is not dramatically perturbed. Although viable, d-plp mutant flies are severely ...
Trypanosomes are flagellated protozoan parasites responsible for devastating diseases in human and cattle. Recently, they have emerged as new models to study cilia and flagella thanks to powerful reverse genetics approaches coupled to the full sequencing of the genome of several species. In this chapter, we describe the ultra-structural features of the Trypanosoma brucei flagellum, revealing evolutionarily conserved aspects of the axoneme or the basal body and specific elements such as the paraflagellar rod or the flagellum attachment zone. We update the numerous functions demonstrated for this organelle, keeping in mind that most data were obtained from cultured parasites. The next challenges will be the determination of the role of the flagellum in the complex T. brucei life cycle, transiting through tissues of the tsetse fly vector and swimming in the bloodstream of mammals. ...
The observation that the membranes of flagella are enriched in sterols and sphingolipids has led to the hypothesis that flagella might be enriched in raft-forming lipids. However, a detailed lipidomic analysis of flagellar membranes is not available. Novel protocols to detach and isolate intact flagella from Trypanosoma brucei procyclic forms in combination with reverse-phase liquid chromatography high-resolution tandem mass spectrometry allowed us to determine the phospholipid composition of flagellar membranes relative to whole cells. Our analyses revealed that phosphatidylethanolamine, phosphatidylserine, ceramide and the sphingolipids inositol phosphorylceramide and sphingomyelin are enriched in flagella relative to whole cells. In contrast, phosphatidylcholine and phosphatidylinositol are strongly depleted in flagella. Within individual glycerophospholipid classes, we observed a preference for ether-type over diacyl-type molecular species in membranes of flagella. Our study provides direct ...
The microtubule axoneme is an iconic structure in eukaryotic cell biology and the defining structure in all eukaryotic flagella (or cilia). Flagella occur in taxa spanning the breadth of eukaryotic evolution, which indicates that the organelles origin predates the radiation of extant eukaryotes from a last common ancestor. During evolution, the flagellar architecture has been subject to both elaboration and moderation. Even conservation of 9+2 architecture-the classic microtubule configuration seen in most axonemes-belies surprising variation in protein content. Classically considered as organelles of motility that support cell swimming or fast movement of material across a cell surface, it is now clear that the functions of flagella are also far broader; for instance, the involvement of flagella in sensory perception and protein secretion has recently been made evident in both protists and animals. Here, we review and discuss, in an evolutionary context, recent advances in our understanding of ...
We show in this study that P. aeruginosa, already known for its swimming and twitching motility, is also able to propagate on semisolid surfaces by swarming. This makes P. aeruginosa one of the rare bacteria to possess three types of motility. Swarming, described so far only for peritrichously flagellated organisms, requires in P. aeruginosa the interplay of several features, namely amino acids as a nitrogen source, the presence of both flagella and type IV pili, and the secretion of rhamnolipids as a surface-active compound.. The surprising finding that P. aeruginosa swarmer cells can express two polar flagella is in agreement with a recent report of afleN mutant of P. aeruginosa (13) which was found to express between three and six polar flagella. Although the fleN mutant was nonmotile, this observation suggests that flagellum number is indeed regulated in this organism. Swarming could be a natural situation where flagellum upregulation could provide a more efficient propagation on semisolid ...
Cell biologists are becoming increasingly aware that cilia and flagella are important sensory organelles, which detect changes in the extracellular environment and convey these signals to the cell body. The biflagellate green alga, Chlamydomonas, is a model organism for the study of flagella function and has allowed researchers to link ciliary dysfunction to a range of human genetic disorders. We are using molecular, biochemical and cell physiological techniques to study signalling processes in Chlamydomonas flagella. We have developed techniques to image Ca2+ in both the cytosol and the flagella of Chlamydomonas and have recently demonstrated that intraflagellar Ca2+ elevations regulate the important process of intraflagellar transport (IFT) (Collingridge et al, 2013). This project aims to understand the mechanisms that generate Ca2+ signals in flagella and how they act to regulate the transport of flagellar proteins ...
Shop Flagella synthesis protein ELISA Kit, Recombinant Protein and Flagella synthesis protein Antibody at MyBioSource. Custom ELISA Kit, Recombinant Protein and Antibody are available.
The bacterial flagellum. (A) Electron micrograph of a Salmonella cell. (B) Electron micrograph of the Salmonella flagellum. (C) Schematic diagram of the flagellum. The flagellum consists of at least three part: the basal body as a bi-directional rotary motor, the hook as a universal joint and the filament as a helical screw.
To perform their multiple functions, cilia and flagella are precisely positioned at the cell surface by mechanisms that remain poorly understood. The protist
Most biological processes are performed by multiprotein complexes. Traditionally described as static entities, evidence is now emerging that their components can be highly dynamic, exchanging constantly with cellular pools. The bacterial flagellar motor contains approximately 13 different proteins and provides an ideal system to study functional molecular complexes. It is powered by transmembrane ion flux through a ring of stator complexes that push on a central rotor. The Escherichia coli motor switches direction stochastically in response to binding of the response regulator CheY to the rotor switch component FliM. Much is known of the static motor structure, but we are just beginning to understand the dynamics of its individual components. Here we measure the stoichiometry and turnover of FliM in functioning flagellar motors, by using high-resolution fluorescence microscopy of E. coli expressing genomically encoded YPet derivatives of FliM at physiological levels. We show that the approximately 30
Japans largest platform for academic e-journals: J-STAGE is a full text database for reviewed academic papers published by Japanese societies
What function might a flagellar membrane-associated CrKCBP have? One function might include a role in intraflagellar transport (IFT). IFT involves a plus-end-directed heterotrimeric kinesin as well as a minus-end-directed cytoplasmic dynein and is required for the assembly, disassembly and structural maintenance of cilia and flagella (for a review, see Cole, 2003). Presumably, a minus-end-directed kinesin (CrKCBP) and cytoplasmic dynein would have redundant functions in IFT. However, it is possible that two minus-end-directed motors are required during rapid flagellar resorption. In Chlamydomonas, flagellar resorption can be induced by removal of Ca2+ from the medium and is reversed by re-addition of Ca2+ to the medium (Lefebvre et al., 1978). If CrKCBP is negatively regulated by Ca2+-calmodulin in the same way as AtKCBP (see Song et al., 1997), removal of Ca2+ from the medium would activate KCBP, consistent with a role for CrKCBP during flagellar resorption.. Several key observations provide ...
Many species of bacteria actively propel themselves in a low Reynolds number environment via the rotation of one or more flagella. At the base of each flagella, you find Natures version of the rotary motor, called the Bacterial Flagellar Motor (BFM). At a diameter of 50 nm and composed of about a dozen different proteins, the BFM is able to rotate at hundreds of hertz, change direction within milliseconds, and attain very high thermodynamic efficiencies. Moreover, the motor can sense the environmental conditions and dynamically adapt its power output accordingly. This talk will introduce some of the basic physical mechanisms underlying the operation of this remarkable molecular machine which drives bacterial motility, with a particular focus on the motors ability to sense its mechanical environment.. ...
The flagellar systems of Escherichia coli and Salmonella enterica exhibit a significant level of genetic and functional synteny. Both systems are controlled by the flagellar specific master regulator FlhD4C2. Since the early days of genetic analyses of flagellar systems it has been known that E. coli flhDC can complement a ∆flhDC mutant in S. enterica. The genomic revolution has identified how genetic changes to transcription factors and/or DNA binding sites can impact the phenotypic outcome across related species. We were therefore interested in asking: using modern tools to interrogate flagellar gene expression and assembly, what would the impact be of replacing the flhDC coding sequences in S. enterica for the E. coli genes at the flhDC S. entercia chromosomal locus? We show that even though all strains created are motile, flagellar gene expression is measurably lower when flhDCEC are present. These changes can be attributed to the impact of FlhD4C2 DNA recognition and the protein-protein ...
The bacterial flagellum is an amazingly complex molecular machine with a diversity of roles in pathogenesis including reaching the optimal host site, colonization or invasion, maintenance at the infection site, and post-infection dispersal. Multi-megadalton flagellar motors self-assemble across the cell wall to form a reversible rotary motor that spins a helical propeller - the flagellum itself - to drive the motility of diverse bacterial pathogens. The flagellar motor responds to the chemoreceptor system to redirect swimming toward beneficial environments, thus enabling flagellated pathogens to seek out their site of infection. At their target site, additional roles of surface swimming and mechanosensing are mediated by flagella to trigger pathogenesis. Yet while these motility-related functions have long been recognized as virulence factors in bacteria, many bacteria have capitalized upon flagellar structure and function by adapting it to roles in other stages of the infection process. Once at their
Central microtubule function in eukaryotic flagella and cilia - posted in Research Idea, Design and Collaboration: Hi! I am an undergrad student at U of C in Calgary, Alberta, Canada. I asked my professor a question about the function of the central pair of microtubules enclosed by the central sheath in eukaryotic cilia and flagella and he replied simply saying that it is not clearly understood. I am wondering if anyone can either direct me to a peer-reviewed journal article that...
InterPro provides functional analysis of proteins by classifying them into families and predicting domains and important sites. We combine protein signatures from a number of member databases into a single searchable resource, capitalising on their individual strengths to produce a powerful integrated database and diagnostic tool.
In recent years, different studies of bacterial flagella have unmasked novel features regarding their complex and sophisticated structure as well as their biological relevance beyond motility. This chapter focuses on these new structural and functional features of flagella, with emphasis on their ability to favor adherence, colonization, penetration, and translocation by bacterial pathogens and the resulting activation of innate immunity. For most bacterial pathogens, flagella and flagellum-driven motility are recognized as essential elements in their virulence scheme. Klose and Mekalanos constructed an rpoN (encoding s54)-null mutant of Vibrio cholerae and found that this strain was defective in motility, flagellation, and colonization in the infant-mouse colonization assay. In this study, they also identified three flagellar regulatory genes (flrABC), among which flrA and flrC encode σ54-activators; mutations in these two genes yielded mutants defective in colonization. Flagella purified from
In nearly all of the contexts in biology in which groups of cilia or flagella are found they exhibit some form of synchronized behaviour. Since the experimental observations of Lord Rothschild in the late 1940s and G.I. Taylors celebrated waving-sheet model, it has been a working hypothesis that synchrony is due in large part to hydrodynamic interactions between beating filaments. But it is only in the last few years that suitable methods have been developed to test this hypothesis. Those methods have led to the discovery of significant intrinsic biochemical noise in the beating of eukaryotic flagella. This stochasticity occurs at the level of individual beats, with interesting variations within the cycle, and is correlated and even recurrent, with memory extending to hundreds of beats. Possible biological origins of this behaviour will be discussed ...
cells have a single polar flagellum whose helical pitch and diameter characteristically change near the midpoint, resulting in a tapered wave. by three geometrical parameters: pitch, helical diameter, and handedness.5 There are three families of flagella defined by distinctive helical parameters: family I includes peritrichous flagella with large pitches and diameters, family II includes polar flagella with medium pitches and diameters, and family III contains lateral flagella with small pitches and diameters.6 There are exceptions that do not belong to these three families because their flagella have an irregular shape. Interestingly, the outstanding flagella are mostly produced by alpha-proteobacteria.6 Although are in the delta-proteobacteria, its flagella belong to this irregularly shaped group of flagella. Flagellar genes of are scattered all over the genome, forming small clusters buy 897383-62-9 of two or three genes,7 similar to those of or and and are both sheathed with a membranous ...
Cilia and flagella are widespread cell organelles which have been highly conserved throughout development and play important functions in motility, sensory belief, and the life cycles of eukaryotes ranging from protists to humans. to miss many proteins that function in both the flagellum and cytoplasm. In contrast, such proteins can be readily recognized by a proteomics approach, which also can uniquely provide an indication of the abundance of a protein and its distribution in the flagellum. A preliminary proteomic analysis of detergent-extracted ciliary axonemes from cultured human being bronchial epithelial cells recognized 214 proteins (Ostrowski et al., 2002); however, this study was jeopardized by the presence of additional cellular constructions in PF 431396 IC50 the axonemal preparation, and by restrictions in the quantity of materials available and/or series data obtained, with the full total end result that only 89 from the proteins were identified by greater than a single peptide. ...
The radial spoke is known to play a role in the mechanical movement of the flagellum/cilium. For example, mutant organisms lacking properly functioning radial spokes have flagella and cilia that are immotile. Radial spokes also influence the cilium "waveform"; that is, the exact bending pattern the cilium repeats. How the radial spoke carries out this function is poorly understood. Radial spokes are believed to interact with both the central pair microtubules and the dynein arms, perhaps in a way that maintains the rhythmic activation of the dynein motors. For example, one of the radial spoke subunits, RSP3, is an anchor protein predicted to hold another protein called protein kinase A (PKA). PKA would theoretically then be able to activate/inactivate the adjacent dynein arms via its kinase activity. However, the identities and functions of the many radial spoke subunits are just beginning to be elucidated. ...
The flagellum is sheathed by an apparent extension of the cell membrane (2). The mechanism of how a sheathed flagellum rotates has not been elucidated. Potentially, the flagellar filament could rotate within the sheath or the two could rotate as a unit (50). Little is known about the composition, formation, or function of flagellar sheaths, which are found in many bacteria, including marine Vibrio species, V. cholerae, B. bacteriovorus, and Helicobacter pylori (reviewed in reference 164). Evidence from these organisms suggests that the sheath contains both lipopolysaccharide and proteins and that it may exist as a stable membrane domain distinct from the outer membrane (42, 51, 58, 69, 144). The lipid content of the sheath of B. bacteriovorus is distinct from that of the outer membrane, and the sheath appears to be a highly fluid, symmetric bilayer (179). How the sheath is formed remains essentially uninvestigated. It has been postulated that the sheath forms concomitantly with the elongation of ...
That biological features may change their function during evolution has long been recognized. Particularly, the acquisition of new functions by molecules involved in developmental pathways is suspected to cause important morphologic novelties. However, the current terminology describing functional changes during evolution (co-option or recruitment) fails to recognize important biologic distinctions between diverse evolutionary routes involving functional shifts. The main goal of our work is to stress the importance of an apparently trivial distinction: Whether or not the element that adopts a new function (anything from a morphologic structure to a protein domain) is a single or a duplicated element. We propose that natural selection must act in a radically different way, depending on the historic succession of co-option and duplication events; that is, co-option may provide the selective pressure for a subsequent gene duplication or could be a stabilizing factor that helps maintain redundancy ...
Bacterial flagella are many, diverse, and complicated. Behe concludes that any bacterial flagellum is composed of at least three parts: a paddle, a rotor, and a motor, and so with swimming as the specified function must be IC (page 72). Even at this crude level, the ICness of a flagellum is not so clear. The problem is that there are additional parts to a complete flagellum. For instance, there are proteins at the base that react to external stimuli and turn the motor on and off, and in some flagella cause it to change directions. And there are other proteins that are arranged in rings where the flagellum passes through the cell membrane. But the more interesting question is: could a flagellum be IC with proteins, not paddles etc. as parts? Remember, IC is supposed to be the biochemical challenge to evolution. Weve already seen that it isnt such a challenge after all, but so much has been made of the purported ICness of the flagellum that one should be well informed on the subject just to be ...
CsgD, the master regulator of biofilm formation, activates the synthesis of curli fimbriae and extracellular polysaccharides in Escherichia coli. To obtain insights into its regulatory role, we have identified a total of 20 novel regulation target genes on the E. coli genome by using chromatin immunoprecipitation (ChIP)-on-chip analysis with a high-density DNA microarray. By DNase I footprinting, the consensus CsgD-binding sequence predicted from a total of 18 target sites was found to include AAAAGNG(N(2))AAAWW. After a promoter-lacZ fusion assay, the CsgD targets were classified into two groups: group I genes, such as fliE and yhbT, are repressed by CsgD, while group II genes, including yccT and adrA, are activated by CsgD. The fliE and fliEFGH operons for flagellum formation are directly repressed by CsgD, while CsgD activates the adrA gene, which encodes an enzyme for synthesis of cyclic di-GMP, a bacterial second messenger, which in turn inhibits flagellum production and rotation. Taking these
The basic point about the flagella stain is that the combination of chemicals produces a thickened coat around the flagella, making them more easily seen with a light microscope. Flagella are extremely thin and of small diameter, so they are below the resolution of the light microscope if unstained. We will not be making our own flagella stains for a variety of reasons:. ...
The flagellum of a bacterium is a supramolecular structure of extreme complexity comprising simultaneously both a unique system of protein transport and a molecular machine that enables the bacterial cell movement. The cascade of expression of genes encoding flagellar components is closely coordinated with the steps of molecular machine assembly, constituting an amazing regulatory system. Data on structure, assembly, and regulation of flagellar gene expression are summarized in this review. The regulatory mechanisms and correlation of the process of regulation of gene expression and flagellum assembly known from the literature are described ...
Flagellar motor switch protein FliN; FliN is one of three proteins (FliG, FliN, FliM) that form a switch complex that is proposed to be located at the base of the basal body. This complex interacts with the CheY and CheZ chemotaxis proteins, in addition to contacting components of the motor that determine the direction of flagellar ...
Dean S, Moreira-Leite F, Gull K (2019). Basalin is an evolutionarily unconstrained protein revealed via a conserved role in flagellum basal plate function. eLife 8: e42282. 10.7554/eLife.42282. Sunter JD, Yanase R, Wang Z, Catta-Preta CMC, Moreira-Leite F, Myskova J, Pruzinova K, Volf P, Mottram JC, Gull K (2019). Leishmania flagellum attachment zone is critical for flagellar pocket shape, development in the sand fly, and pathogenicity in the host. PNAS 116:6351-6360. 10.1073/pnas.1812462116.. Sunter JD, Moreira-Leite F, Gull K. (2018). Dependency relationships between IFT-dependent flagellum elongation and cell morphogenesis in Leishmania. Open Biol 8:180124. 10.1098/rsob.180124.. Edwards BFL, Wheeler RJ, Barker AR, Moreira-Leite FF, Gull K, Sunter JD (2018). Direction of flagellum beat propagation is controlled by proximal/distal outer dynein arm asymmetry. PNAS 115:E7341-E7350. 10.1073/pnas.1805827115. Varga V, Moreira-Leite F, Portman N, Gull K (2017). Protein diversity in discrete ...
Motility has been shown to be a key factor for the ability ofH. pylori to colonize the gastric mucosa (11). While a few structural components of the flagella (23, 30) and the flagellar motor switch protein CheY (4) have been characterized in some detail, little is known about factors that regulate expression of genes involved in motility and chemotaxis.. We have identified the flagellar regulon of H. pylori, whose transcription is under the positive control of the alternative sigma factor ς54 and the transcriptional activator FlgR. A line of evidence demonstrating that FlgR and ς54 regulate the basal body and hook genes is based on the finding that ς54 is unable to activate transcription of the regulon in a FlgR− background. Conversely, flaA, the gene encoding the major flagellin, is regulated by the alternative sigma factor ς28 (23). Interestingly, transcription from the flaA promoter (P601) is enhanced in the FlgR− background, suggesting a negative feedback exerted by FlgR on ...
The bacterial flagellum is one of natures smallest motors, rotating at up to 60,000 revolutions per minute. To function properly and propel the bacterium, the flagellum requires all of its components to fit together to exacting measurements. In a study published in Science, University of Utah researchers report the eludication of a mechanism that regulates the length of the flagellums 25 nanometer driveshaft-like rod and answers a long-standing question about how cells are held together.. While the biomechanical controls that determine the dimensions of other flagellar components have already been determined, the control of the length of the rod, a rigid shaft that transfers torque from the flagellar motor in the interior of the cell to the external propeller filament, were unknown. Since the majority of the machine is assembled outside the cell there have to be mechanisms for self-assembly and also to determine optimal lengths of different components, says biology professor Kelly Hughes. ...
The bacterial flagellum is the most common and thoroughly studied prokaryotic motility structure. It resembles a spinning propeller-like structure that is used for swimming in aqueous environments and in some organisms enables swarming across solid surfaces. The flagellum is a very complex organelle consisting of over 20 proteins (flg, flh, fli, flj variants) and as many as 30 proteins assisting in regulation and assembly. Each Escherichia coli or Salmonella cell typically has 6-8 structures. The export system for assembly of the filament structure represents a flagellum-specific Type III secretion system (T3SS) in which flagellin subunits are passaged through the hollow flagellar filament structure to the distal end for assembly. The main structure consists of 3 main substructures: the basal body, which anchors the structure in the cell membrane and contains the motor; the filament which acts as the propeller; and the hook, a joint which connects the basal body and filament. Rotation of the ...
Höhn and colleagues imaged Volvox globator during inversion using selective plane illumination microscopy and used the resulting measurements to fit a mathematical model of inversion. Inversion is crucial for all of the algae in the family Volvocaceae, since they find themselves in an awkward configuration at the end of cell division: with their flagella pointing inward. Having your flagella on the inside is obviously not much use for swimming. Through changes in cell shape and movements relative to the cytoplasmic bridges that connect cells, these algae turn themselves completely inside out, ending with the flagella on the surface where they can do some good ...
Peritrichous bacteria, such as E. coli, are covered by multiple flagella, which are essential for their locomotion. An individual flagellum is of helical shape and driven by a rotary motor attached to the bacterial cell body. When all left-handed flagella turn counterclockwise, they form a single helical bundle and the bacterium moves forward. This concerted motion of the bundle requires a synchronized rotation of the various flagella. The steady forward motion is interrupted by short periods of tumbling. This allows the bacteria to change their direction of motion, and to perform a biased random walk to adjust to environmental conditions, such as a search for food.. We investigate the synchronization and bundling process of bacterial flagella by mesoscale hydrodynamic simulations. A flagellum is modelled as a helical structure with bending and torsional rigidity. The characteristic times for synchronization and bundling are analyzed in terms of (equal) motor torques, separation, and number of ...
Fahrner, K.A. and Berg, H.C. Mutations that stimulate flhDC expression in Escherichia coli K-12. J. Bacteriol. 197 No.19, 3087-3096 (2015).. Yuan, J., Fahrner, K.A., Turner, L., and Berg, H.C. Asymmetry in the clockwise and counter-clockwise rotation of the bacterial flagellar motor. Proc. Natl. Acad. Sci. USA 107, 12846-12849 (2010).. Yuan, J., Fahrner, K. A. & Berg, H. C. Switching of the bacterial flagellar motor near zero load. J. Mol. Biol. 390, 394-400 (2009). Bates, D., Epstein, J., Boyle, E., Fahrner, K., Berg, H. and Kleckner, N. The Escherichia coli baby cell column: a novel cell synchronization method provides new insight into the bacterial cell cycle. Molec. Microbiol. 57, 380-391 (2005). Fahrner, K.A., Ryu, W.S. and Berg, H.C. Bacterial flagellar switching under load. Nature 423, 938 (2003). Scharf, B.E., Fahrner, K.A. and Berg, H.C. CheZ has no effect on flagellar motors activated by CheY13DK106YW. J. Bacteriol. 180, 5123-5128 (1998). Fahrner, K.A., Block, S.M., Krishnaswamy, S., ...
It turns out that when the eubacterial flagellum is assembled, the rotor housing (FliF) forms first, followed by the rotor/switch (FliG,M,N), followed by the protein export apparatus (FlhA,B,FliO,P,Q,R), followed by the motor proteins (MotA,B); then the rod, the secretory P and L rings, and finally the hook, junction, cap and filament. The implications of this sequence are very significant. Since the assembly sequence which is most plausible from a historical perspective is quite dissimilar to the actual assembly sequence, something is clearly wrong with Musgraves model. In all evolutionary models, the export and secretory systems are always assumed very early on. In reality, however, the switch complex must be formed first in order to incorporate the export apparatus. Since the switch and rotor only function as part of the rotary flagellum system, the rotary propeller function of the flagellum is implicit from the beginning - a clear case of "teleological assembly ...
Crepe Correcting Body Complex is formulated with advanced firming and hydrating ingredients to smooth and firm the appearance of wrinkled,
Crepe Correcting Body Complex is formulated with advanced firming and hydrating ingredients to smooth and firm the appearance of wrinkled,