Membrane-bound hydrogenase and sulfur reductase of the hyperthermophilic and acidophilic archaeon Acidianus ambivalens. (1/31)A sulfur reductase (SR) and a hydrogenase were purified from solubilized membrane fractions of anaerobically grown cells of the sulfur-dependent archaeon Acidianus ambivalens and the corresponding genes were sequenced. The SR reduced elemental sulfur with hydrogen as electron donor [45 U (mg protein)(-1)] in the presence of hydrogenase and either 2,3-dimethylnaphthoquinone (DMN) or cytochrome c in the enzyme assay. The SR could not be separated from the hydrogenase during purification without loss of activity, whereas the hydrogenase could be separated from the SR. The specific activity of the hydrogenase was 170 U (mg protein)(-1) with methyl viologen and 833 U (mg protein)(-1) with DMN as electron acceptors. Both holoenzymes showed molecular masses of 250 kDa. In SDS gels of active fractions, protein bands with apparent masses of 110 (SreA), 66 (HynL), 41 (HynS) and 29 kDa were present. Enriched hydrogenase fractions contained 14 micro mol Fe and 2 micromol Ni (g protein)(-1); in addition, 2.5 micromol Mo (g protein)(-1) was found in the membrane fraction. Two overlapping genomic cosmid clones were sequenced, encoding a five-gene SR cluster (sre) including the 110 kDa subunit gene (sreA), and a 12-gene hydrogenase cluster (hyn) including the large and small subunit genes and genes encoding proteins required for the maturation of NiFe hydrogenases. A phylogenetic analysis of the SR amino acid sequence revealed that the protein belonged to the DMSO reductase family of molybdoenzymes and that the family showed a novel clustering. A model of sulfur respiration in Acidianus developed from the biochemical results and the data of the amino acid sequence comparisons is discussed. (+info)
AFV1, a novel virus infecting hyperthermophilic archaea of the genus acidianus. (2/31)We describe a novel virus, AFV1, of the hyperthermophilic archaeal genus Acidianus. Filamentous virions are covered with a lipid envelope and contain at least five different proteins with molecular masses in the range of 23-130 kDa and a 20.8-kb-long linear double-stranded DNA. The virus has been assigned to the family Lipothrixviridae on the basis of morphotypic characteristics. Host range is confined to several strains of Acidianus and the virus persists in its hosts in a stable carrier state. The latent period of virus infection is about 4 h. Viral DNA was sequenced and sequence similarities were found to the lipothrixvirus SIFV, the rudiviruses SIRV1 and SIRV2, as well as to conjugative plasmids and chromosomes of the genus Sulfolobus. Exceptionally for the linear genomes of archaeal viruses, many short direct repeats, with the sequence TTGTT or close variants thereof, are closely clustered over 300 bp at each end of the genome. They are reminiscent of the telomeric ends of linear eukaryal chromosomes. (+info)
The sulphur oxygenase reductase from Acidianus ambivalens is a multimeric protein containing a low-potential mononuclear non-haem iron centre. (3/31)The SOR (sulphur oxygenase reductase) is the initial enzyme in the sulphur-oxidation pathway of Acidianus ambivalens. Expression of the sor gene in Escherichia coli resulted in active, soluble SOR and in inclusion bodies from which active SOR could be refolded as long as ferric ions were present in the refolding solution. Wild-type, recombinant and refolded SOR possessed indistinguishable properties. Conformational stability studies showed that the apparent unfolding free energy in water is approx. 5 kcal x mol(-1) (1 kcal=4.184 kJ), at pH 7. The analysis of the quaternary structures showed a ball-shaped assembly with a central hollow core probably consisting of 24 subunits in a 432 symmetry. The subunits form homodimers as the building blocks of the holoenzyme. Iron was found in the wild-type enzyme at a stoichiometry of one iron atom/subunit. EPR spectroscopy of the colourless SOR resulted in a single isotropic signal at g=4.3, characteristic of high-spin ferric iron. The signal disappeared upon reduction with dithionite or incubation with sulphur at elevated temperature. Thus both EPR and chemical analysis indicate the presence of a mononuclear iron centre, which has a reduction potential of -268 mV at pH 6.5. Protein database inspection identified four SOR protein homologues, but no other significant similarities. The spectroscopic data and the sequence comparison led to the proposal that the Acidianus ambivalens SOR typifies a new type of non-haem iron enzyme containing a mononuclear iron centre co-ordinated by carboxylate and/or histidine ligands. (+info)
Active site structure of the aa3 quinol oxidase of Acidianus ambivalens. (4/31)The membrane bound aa(3)-type quinol:oxygen oxidoreductase from the hyperthermophilic archaeon, Acidianus ambivalens, which thrives at a pH of 2.5 and a temperature of 80 degrees C, has several unique structural and functional features as compared to the other members of the heme-copper oxygen reductase superfamily, but shares the common redox-coupled, proton-pumping function. To better understand the properties of the heme a(3)-Cu(B) catalytic site, a resonance Raman spectroscopic study of the enzyme under a variety of conditions and in the presence of various ligands was carried out. Assignments of several heme vibrational modes as well as iron-ligand stretching modes are made to serve as a basis for comparing the structure of the enzyme to that of other oxygen reductases. The CO-bound oxidase has conformations that are similar to those of other oxygen reductases. However, the addition of CO to the resting enzyme does not generate a mixed valence species as in the bovine aa(3) enzyme. The cyanide complex of the oxidized enzyme of A. ambivalens does not display the high stability of its bovine counterpart, and a redox titration demonstrates that there is an extensive heme-heme interaction reflected in the midpoint potentials of the cyanide adduct. The A. ambivalens oxygen reductase is very stable under acidic conditions, but it undergoes an earlier alkaline transition than the bovine enzyme. The A. ambivalens enzyme exhibits a redox-linked reversible conformational transition in the heme a(3)-Cu(B) center. The pH dependence and H/D exchange demonstrate that the conformational transition is associated with proton movements involving a group or groups with a pK(a) of approximately 3.8. The observed reversibility and involvement of protons in the redox-coupled conformational transition support the proton translocation model presented earlier. The implications of such conformational changes are discussed in relation to general redox-coupled proton pumping mechanisms in the heme-copper oxygen reductases. (+info)
Theoretical identification of proton channels in the quinol oxidase aa3 from Acidianus ambivalens. (5/31)Heme-copper oxidases are membrane proteins found in the respiratory chain of aerobic organisms. They are the terminal electron acceptors coupling the translocation of protons across the membrane with the reduction of oxygen to water. Because the catalytic process occurs in the heme cofactors positioned well inside the protein matrix, proton channels must exist. However, due to the high structural divergence among this kind of proteins, the proton channels previously described are not necessarily conserved. In this work we modeled the structure of the quinol oxidase from Acidianus ambivalens using comparative modeling techniques for identifying proton channels. Additionally, given the high importance that water molecules may have in this process, we have developed a methodology, within the context of comparative modeling, to identify high water probability zones and to deconvolute them into chains of ordered water molecules. From our results, and from the existent information from other proteins from the same superfamily, we were able to suggest three possible proton channels: one K-, one D-, and one Q-spatial homologous proton channels. This methodology can be applied to other systems where water molecules are important for their biological function. (+info)
Key role of cysteine residues in catalysis and subcellular localization of sulfur oxygenase-reductase of Acidianus tengchongensis. (6/31)Analysis of known sulfur oxygenase-reductases (SORs) and the SOR-like sequences identified from public databases indicated that they all possess three cysteine residues within two conserved motifs (V-G-P-K-V-C(31) and C(101)-X-X-C(104); numbering according to the Acidianus tengchongensis numbering system). The thio-modifying reagent N-ethylmaleimide and Zn(2+) strongly inhibited the activities of the SORs of A. tengchongensis, suggesting that cysteine residues are important. Site-directed mutagenesis was used to construct four mutant SORs with cysteines replaced by serine or alanine. The purified mutant proteins were investigated in parallel with the wild-type SOR. Replacement of any cysteine reduced SOR activity by 98.4 to 100%, indicating that all the cysteine residues are crucial to SOR activities. Circular-dichroism and fluorescence spectrum analyses revealed that the wild-type and mutant SORs have similar structures and that none of them form any disulfide bond. Thus, it is proposed that three cysteine residues, C(31) and C(101)-X-X-C(104), in the conserved domains constitute the putative binding and catalytic sites of SOR. Furthermore, enzymatic activity assays of the subcellular fractions and immune electron microscopy indicated that SOR is not only present in the cytoplasm but also associated with the cytoplasmic membrane of A. tengchongensis. The membrane-associated SOR activity was colocalized with the activities of sulfite:acceptor oxidoreductase and thiosulfate:acceptor oxidoreductase. We tentatively propose that these enzymes are located in close proximity on the membrane to catalyze sulfur oxidation in A. tengchongensis. (+info)
The sulfur oxygenase reductase from Acidianus ambivalens is an icosatetramer as shown by crystallization and Patterson analysis. (7/31)The sulfur oxygenase reductase (SOR) is the initial enzyme in the aerobic sulfur metabolism of the thermoacidophilic and chemolithoautotrophic crenarchaeote Acidianus ambivalens. Single colorless polyhedral crystals were obtained under two crystallization conditions from SOR preparations heterologously overproduced in Escherichia coli. They belonged to space-group I4 and diffraction data were collected up to 1.7 A resolution. Their Patterson symmetry shows additional 4-, 3- and 2-fold non-crystallographic symmetry rotation axes, characteristic of the point group 432. Taking into account the molecular mass of SOR, the crystal unit cell volume, the non-crystallographic symmetry operators and previous electron microscopy studies of the SOR, it was deduced that the quaternary structure of the functionally active enzyme is an icosatetramer with 871 kDa molecular mass. (+info)
A Rieske ferredoxin typifying a subtype within Rieske proteins: spectroscopic, biochemical and stability studies. (8/31)A new subtype of archaeal Rieske ferredoxin (RFd) has been identified in the genome of the thermoacidophilic archaeon Acidianus ambivalens. The gene is inserted in an atypical genomic context in a gene cluster encoding a NiFe hydrogenase. Sequence and phyletic analysis showed that the protein is related to bacterial RFd but not to any of the known archaeal Rieske proteins. The recombinant 14 kDa protein isolated from Escherichia coli behaved as a dimer in solution. It contained approximately 2 Fe/mol and all visible and EPR spectroscopic features typical of Rieske centre-containing proteins. However, its redox potential (+170 mV) was significantly higher than those of canonical RFd. This difference is rationalized in terms of the protein structure environment, as discrete amino acid substitutions in key positions around the metal centre account for the higher potential. (+info)
'Acidianus' is a genus of thermoacidophilic archaea, which are extremophiles that thrive in extremely acidic and hot environments. These microorganisms are commonly found in volcanic areas, such as sulfur-rich hot springs and deep-sea hydrothermal vents, where the pH levels can be as low as 0 and the temperature can reach up to 90°C (194°F).
The name 'Acidianus' is derived from the Latin word "acidus," meaning sour or acidic, and the Greek word "ianos," meaning belonging to. Therefore, the medical definition of 'Acidianus' refers to a genus of archaea that are adapted to survive in highly acidic environments.
These microorganisms have developed unique metabolic pathways to generate energy from sulfur compounds and other reduced substances present in their environment. They play an essential role in the global carbon and sulfur cycles, contributing to the breakdown of organic matter and the formation of elemental sulfur and sulfate.
Understanding the biology and ecology of 'Acidianus' and other thermoacidophilic archaea can provide insights into the limits of life on Earth and help us explore the potential for extraterrestrial life in extreme environments, such as those found on Mars or other planets.
Lipothrixviridae is a family of enveloped, rod-shaped viruses that infect archaea. These viruses have a unique lipid membrane derived from the host cell and a linear, double-stranded DNA genome. The virions are typically long and thin, with a hollow core and helical symmetry. Lipothrixviridae is named after its characteristic lipid membrane and rigid structure.
The family Lipothrixviridae includes only one genus, Thermopolisibacteriovirus, which contains several species of viruses that infect thermophilic archaea in the order Crenarchaeota. The prototypical member of this family is the virus SIRV2 (Sulfolobus islandicus rod-shaped virus 2).
Lipothrixviridae viruses have a complex life cycle, involving attachment to the host cell surface, membrane fusion, and injection of the viral genome into the host cytoplasm. The viral DNA is then replicated using the host's replication machinery, and new virions are assembled in the host cell before being released by lysis or extrusion.
Infection with Lipothrixviridae viruses can have significant impacts on the host archaea, including alterations to their metabolism, growth rate, and morphology. However, the precise mechanisms of these effects are not well understood and require further study.
Sulfolobaceae is a family of archaea within the order Sulfolobales. These are thermophilic and acidophilic organisms, meaning they thrive in high temperature and low pH conditions. They are commonly found in volcanic hot springs and other extreme environments. Members of this family obtain energy through the oxidation of sulfur compounds and are therefore also called sulfur-oxidizing archaea. The type genus of this family is Sulfolobus.
Archaeal viruses are viruses that infect and replicate within archaea, which are single-celled microorganisms without a nucleus. These viruses have unique characteristics that distinguish them from bacterial and eukaryotic viruses. They often possess distinct morphologies, such as icosahedral or filamentous shapes, and their genomes can be composed of double-stranded DNA (dsDNA), single-stranded DNA (ssDNA), double-stranded RNA (dsRNA), or single-stranded RNA (ssRNA).
Archaeal viruses have evolved various strategies to hijack the host cell's machinery for replication, packaging, and release of new virus particles. Some archaeal viruses even encode their own proteins for transcription and translation, suggesting a more complex relationship with their hosts than previously thought. The study of archaeal viruses provides valuable insights into the evolution of viruses and their hosts and has implications for understanding the origins of life on Earth.
Archaeal proteins are proteins that are encoded by the genes found in archaea, a domain of single-celled microorganisms. These proteins are crucial for various cellular functions and structures in archaea, which are adapted to survive in extreme environments such as high temperatures, high salt concentrations, and low pH levels.
Archaeal proteins share similarities with both bacterial and eukaryotic proteins, but they also have unique features that distinguish them from each other. For example, many archaeal proteins contain unusual amino acids or modifications that are not commonly found in other organisms. Additionally, the three-dimensional structures of some archaeal proteins are distinct from their bacterial and eukaryotic counterparts.
Studying archaeal proteins is important for understanding the biology of these unique organisms and for gaining insights into the evolution of life on Earth. Furthermore, because some archaea can survive in extreme environments, their proteins may have properties that make them useful in industrial and medical applications.
Sulfolobales is not a medical term, but a taxonomic category in the field of microbiology. It refers to an order of extremophilic archaea, which are single-celled organisms that lack a nucleus and other membrane-bound organelles.
Members of Sulfolobales are characterized by their ability to thrive in harsh environments with high temperatures (often above 80°C) and acidic pH levels (typically below 4). They are commonly found in volcanic hot springs, sulfur-rich mudpots, and other geothermal areas.
The order Sulfolobales includes several genera of archaea, such as Sulfolobus, Acidianus, and Metallosphaera, among others. These organisms have attracted scientific interest due to their unique metabolic pathways and potential applications in biotechnology.
Archaeal RNA refers to the Ribonucleic acid (RNA) molecules that are present in archaea, which are a domain of single-celled microorganisms. RNA is a nucleic acid that plays a crucial role in various biological processes, such as protein synthesis, gene expression, and regulation of cellular activities.
Archaeal RNAs can be categorized into different types based on their functions, including:
1. Messenger RNA (mRNA): It carries genetic information from DNA to the ribosome, where it is translated into proteins.
2. Transfer RNA (tRNA): It helps in translating the genetic code present in mRNA into specific amino acids during protein synthesis.
3. Ribosomal RNA (rRNA): It is a structural and functional component of ribosomes, where protein synthesis occurs.
4. Non-coding RNA: These are RNAs that do not code for proteins but have regulatory functions in gene expression and other cellular processes.
Archaeal RNAs share similarities with both bacterial and eukaryotic RNAs, but they also possess unique features that distinguish them from the other two domains of life. For example, archaeal rRNAs contain unique sequence motifs and secondary structures that are not found in bacteria or eukaryotes. These differences suggest that archaeal RNAs have evolved to adapt to the extreme environments where many archaea live.
Overall, understanding the structure, function, and evolution of archaeal RNA is essential for gaining insights into the biology of these unique microorganisms and their roles in various cellular processes.
Sulfur is not typically referred to in the context of a medical definition, as it is an element found in nature and not a specific medical condition or concept. However, sulfur does have some relevance to certain medical topics:
* Sulfur is an essential element that is a component of several amino acids (the building blocks of proteins) and is necessary for the proper functioning of enzymes and other biological processes in the body.
* Sulfur-containing compounds, such as glutathione, play important roles in antioxidant defense and detoxification in the body.
* Some medications and supplements contain sulfur or sulfur-containing compounds, such as dimethyl sulfoxide (DMSO), which is used topically for pain relief and inflammation.
* Sulfur baths and other forms of sulfur-based therapies have been used historically in alternative medicine to treat various conditions, although their effectiveness is not well-established by scientific research.
It's important to note that while sulfur itself is not a medical term, it can be relevant to certain medical topics and should be discussed with a healthcare professional if you have any questions or concerns about its use in medications, supplements, or therapies.
List of taxa with candidatus status
List of Archaea genera
List of bacterial genera named after mythological figures
Carbon disulfide hydrolase
List of sequenced archaeal genomes
Mars habitability analogue environments on Earth
List of MeSH codes (B07)
List of virus species
Microbial oxidation of sulfur
Acidianus - Wikipedia
RCSB PDB - 3J1B: Cryo-EM structure of 8-fold symmetric rATcpn-alpha in apo state
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- Parc de Yellowstone (Etats-Unis) où vit le virus hyperthermophile Acidianus hospitalis Filamentous Virus 1. (pasteur.fr)
- Acidianus hospitalis Filamentous Virus 1 lives in the bubbling pools of acid of Yellowstone National Park. (pasteur.fr)
- Acidianus hospitalis Filamentous Virus 1 was discovered in the hot springs of Yellowstone National Park in 2003 1 by David Prangishvili, a researcher from the Molecular Biology of the Gene in Extremophiles Unit at the Institut Pasteur. (pasteur.fr)
- In taxonomy, Acidianus is a genus of the Sulfolobaceae. (wikipedia.org)
- 1. Bettstetter M, Peng X, Garrett RA, and Prangishvili D. AFV1, a novel virus infecting hyperthermophilic archaea of the genus Acidianus. (pasteur.fr)
- The Acidianus genus consists of acidothermophiles which grow optimally and slowly in the temperature range 65-95 degrees C and at pH 2-4 and belongs to the order Sulfolobales. (up.ac.za)
- The family Bicaudaviridae includes viruses that infect hyperthermophilic archaea in the genus Acidianus. (hal.science)
- The circular double-stranded DNA genome of Acidianus two-tailed virus consists of 62 730 bp, and replication can be either lytic or lysogenic. (hal.science)
- Schwefel-Mobilisierung bei Acidianus ambivalens. (tu-darmstadt.de)
- Sulfolobus metallicus, some Acidianus species, and Metallosphaera sedula can remove metals from metal sulphide minerals and have high resistance to metal toxicity. (morethingsjapanese.com)
- The present work focused on investigations of biofilm dynamics and EPS production of the thermoacidophilic archaeon Acidianus sp. (ufz.de)
- nov., and Acidianus brierleyi comb. (wikipedia.org)
- Acidianus brierleyi has a diverged pccA split into two pieces. (lbl.gov)
- In this research work, the bioleaching of chalcopyrite concentrate by the thermophilic Acidianus brierleyi was studied, and the microbial growth, copper dissolution, iron oxidation, and jarosite precipitation were monitored in different initial pH (pHi) values. (ac.ir)
- 2023. Energy metabolism shifts glycerol dibiphytanyl glycerol tetraether lipid composition cyclization in the thermoacidophilic archaeon, Acidianus . (geoboydology.com)