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David Prangishvili - One of the best experts on this subject based on the ideXlab platform.
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ICTV Virus Taxonomy Profile: Bicaudaviridae
Journal of General Virology, 2018Co-Authors: David Prangishvili, Mart Krupovic, Ictv Report ConsortiumAbstract:The family Bicaudaviridae includes viruses that infect hyperthermophilic archaea in the genus Acidianus. The circular double-stranded DNA genome of Acidianus two-tailed virus consists of 62 730 bp, and replication can be either lytic or lysogenic. Virions undergo unique extracellular morphogenesis, being released from host cells as spindle-shaped particles that subsequently develop long tails, one at each of the two pointed ends. The spindle-shaped morphology represents a group of archaea-specific virion morphotypes. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Bicaudaviridae which is available at www.ictv.global/report/bicaudaviridae.
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ORIGINAL PAPER Genomic analysis of Acidianus hospitalis W1 a host for studying crenarchaeal virus and plasmid life cycles
2016Co-Authors: Xiao-yan You, David Prangishvili, Shuangjiang Liu, Chao Liu, Shengyue Wang, Cheng-ying Jiang, Shiraz A. Shah, Qunxin She, Roger A. GarrettAbstract:of a minimally sized chromosome of about 2.13 Mb and a conjugative plasmid pAH1 and it is a host for the model filamentous lipothrixvirus AFV1. The chromosome carries three putative replication origins in conserved genomic regions and two large regions where non-essential genes are clustered. Within these variable regions, a few orphan orfB and other elements of the IS200/607/605 family are con-centrated with a novel class of MITE-like repeat elements. There are also 26 highly diverse vapBC antitoxin–toxin gene pairs proposed to facilitate maintenance of local chromo-somal regions and to minimise the impact of environmental stress. Complex and partially defective CRISPR/Cas/Cmr immune systems are present and interspersed with five vapBC gene pairs. Remnants of integrated viral genomes and plasmids are located at five intron-less tRNA genes and several non-coding RNA genes are predicted that are con-served in other Sulfolobus genomes. The putative metabolic pathways for sulphur metabolism show some significant differences from those proposed for other Acidianus and Sulfolobus species. The small and relatively stable genome of A. hospitalis W1 renders it a promising candidate for developing the first Acidianus genetic systems
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Archaeal tetrathionate hydrolase goes viral: secretion of a sulfur metabolism enzyme in the form of virus-like particles
Applied and Environmental Microbiology, 2012Co-Authors: Mart Krupovic, M. Bettstetter, Nuno Peixeiro, Reinhard Rachel, David PrangishviliAbstract:In the course of screening for virus-host systems in extreme thermal environments, we have isolated a strain of the hyperthermophilic archaeaon Acidianus hospitalis producing unusual filamentous particles with a zipper-like appearance. The particles were shown to represent a secreted form of a genuine cellular enzyme, tetrathionate hydrolase, involved in sulfur metabolism.
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Genomic analysis of Acidianus hospitalis W1 a host for studying crenarchaeal virus and plasmid life cycles
Extremophiles : life under extreme conditions, 2011Co-Authors: Xiao-yan You, David Prangishvili, Shuangjiang Liu, Chao Liu, Shengyue Wang, Cheng-ying Jiang, Shiraz A. Shah, Qunxin She, Roger A. GarrettAbstract:The Acidianus hospitalis W1 genome consists of a minimally sized chromosome of about 2.13 Mb and a conjugative plasmid pAH1 and it is a host for the model filamentous lipothrixvirus AFV1. The chromosome carries three putative replication origins in conserved genomic regions and two large regions where non-essential genes are clustered. Within these variable regions, a few orphan orfB and other elements of the IS200/607/605 family are concentrated with a novel class of MITE-like repeat elements. There are also 26 highly diverse vapBC antitoxin–toxin gene pairs proposed to facilitate maintenance of local chromosomal regions and to minimise the impact of environmental stress. Complex and partially defective CRISPR/Cas/Cmr immune systems are present and interspersed with five vapBC gene pairs. Remnants of integrated viral genomes and plasmids are located at five intron-less tRNA genes and several non-coding RNA genes are predicted that are conserved in other Sulfolobus genomes. The putative metabolic pathways for sulphur metabolism show some significant differences from those proposed for other Acidianus and Sulfolobus species. The small and relatively stable genome of A. hospitalis W1 renders it a promising candidate for developing the first Acidianus genetic systems.
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Acidianus filamentous virus 1 coat proteins display a helical fold spanning the filamentous archaeal viruses lineage.
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Adeline Goulet, Stéphanie Blangy, David Prangishvili, Valérie Campanacci, Peter Redder, Catarina Felisberto-rodrigues, Patrick Forterre, Christian CambillauAbstract:Acidianus filamentous virus 1 (AFV1), a member of the Lipothrixviridae family, infects the hyperthermophilic, acidophilic crenarchaeaon Acidianus hospitalis. The virion, covered with a lipidic outer shell, is 9,100-A long and contains a 20.8-kb linear dsDNA genome. We have identified the two major coat proteins of the virion (MCPs; 132 and 140 amino acids). They bind DNA and form filaments when incubated with linear dsDNA. A C-terminal domain is identified in their crystal structure with a four-helix-bundle fold. In the topological model of the virion filament core, the genomic dsDNA superhelix wraps around the AFV1-132 basic protein, and the AFV1-140 basic N terminus binds genomic DNA, while its lipophilic C-terminal domain is imbedded in the lipidic outer shell. The four-helix bundle fold of the MCPs from AFV1 is identical to that of the coat protein (CP) of Sulfolobus islandicus rod-shaped virus (SIRV), a member of the Rudiviridae family. Despite low sequence identity between these proteins, their high degree of structural similarity suggests that they could have derived from a common ancestor and could thus define an yet undescribed viral lineage.
Cláudio M. Gomes - One of the best experts on this subject based on the ideXlab platform.
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The sulphur oxygenase reductase from Acidianus ambivalens is a multimeric protein containing a low-potential mononuclear non-haem iron centre.
Biochemical Journal, 2004Co-Authors: Tim Urich, Tiago M. Bandeiras, Cláudio M. Gomes, Miguel Teixeira, Reinhard Rachel, Sónia S. Leal, Till Albrecht, Peter Zimmermann, Corinna B. Scholz, Arnulf KletzinAbstract: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.
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Dissimilatory Oxidation and Reduction of Elemental Sulfur in Thermophilic Archaea
Journal of Bioenergetics and Biomembranes, 2004Co-Authors: Arnulf Kletzin, Tim Urich, Fabian Müller, Tiago M. Bandeiras, Cláudio M. GomesAbstract:The oxidation and reduction of elemental sulfur and reduced inorganic sulfur species are some of the most important energy-yielding reactions for microorganisms living in volcanic hot springs, solfataras, and submarine hydrothermal vents, including both heterotrophic, mixotrophic, and chemolithoautotrophic, carbon dioxide-fixing species. Elemental sulfur is the electron donor in aerobic archaea like Acidianus and Sulfolobus. It is oxidized via sulfite and thiosulfate in a pathway involving both soluble and membrane-bound enzymes. This pathway was recently found to be coupled to the aerobic respiratory chain, eliciting a link between sulfur oxidation and oxygen reduction at the level of the respiratory heme copper oxidase. In contrast, elemental sulfur is the electron acceptor in a short electron transport chain consisting of a membrane-bound hydrogenase and a sulfur reductase in (facultatively) anaerobic chemolithotrophic archaea Acidianus and Pyrodictium species. It is also the electron acceptor in organoheterotrophic anaerobic species like Pyrococcus and Thermococcus , however, an electron transport chain has not been described as yet. The current knowledge on the composition and properties of the aerobic and anaerobic pathways of dissimilatory elemental sulfur metabolism in thermophilic archaea is summarized in this contribution.
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A New Type-II NADH Dehydrogenase from the Archaeon Acidianus ambivalens: Characterization and in vitro Reconstitution of the Respiratory Chain
Journal of Bioenergetics and Biomembranes, 2001Co-Authors: Cláudio M. Gomes, Tiago M. Bandeiras, Miguel TeixeiraAbstract:A new type-II NADH dehydrogenase (NDH-II) was isolated from the hyperthermoacidophilic archaeon Acidianus ambivalens. This enzyme is a monomer with an apparent molecular mass of 47 kDa, containing a covalently bound flavin, and no iron–sulfur clusters. Upon isolation, NDH-II loses activity, which can, nevertheless, be restored by incubation with phospholipids. Catalytically, it is a proficient NADH:caldariella quinone oxidoreductase (130 mmol NADH oxidized/mg protein^-1/min^-1) but it can also donate electrons to synthetic quinones, strongly suggesting its involvement in the respiratory chain. The apparent K_m for NADH was found to be ∼6 μM, both for the purified and membrane-integrated enzyme, thus showing that detergent solubilization and purification did not affect the substrate binding site. Further, it is the first example of a type-II NADH dehydrogenase that contains the flavin covalently attached, which may be related to the need to stabilize the otherwise labile cofactor in a thermophilic environment. A fully operative minimal version of Acidianus ambivalens respiratory system was successfully reconstituted into artificial liposomes, using three basic components isolated from the organism: the type-II NADH dehydrogenase, caldariella quinone, the organism-specific quinone, and the aa_3 type quinol oxidase. This system, which mimics the in vivo chain, is efficiently energized by NADH, driving oxygen consumption by means of the terminal oxidase.
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Stability and folding of the ferredoxin from the hyperthermophilic archaeon Acidianus ambivalens.
Journal of inorganic biochemistry, 2000Co-Authors: Pernilla Wittung-stafshede, Cláudio M. Gomes, Miguel TeixeiraAbstract:The ferredoxin from the thermophilic archaeon Acidianus ambivalens is a small monomeric protein containing two iron-sulfur centres, one [3Fe-4S](1+/0) and one [4Fe-4S](2+/1+). It is an intrinsically hyperstable protein, being expressed at the organism's extreme optimal growth temperature: 80 degrees C. Using spectroscopic methods we have investigated the unfolding reaction of the Acidianus ambivalens ferredoxin. No unfolding of the oxidised ferredoxin was observed at pH 7.0, even in the presence of 8 M GuHCl. Upon increasing the pH to 10.0, the unfolding transition showed a midpoint at 6.3 M GuHCl and an unfolding-free energy of 70 kJ mol(-1) in buffer (pH 10) was estimated. Kinetic-unfolding experiments showed that the polypeptide unfolding correlated with rearrangement of the iron-sulfur centres to new ones which had strong absorption maxima at 520 and 610 nm. These new, possibly linear three-iron, clusters were coordinated to the unfolded protein but degraded slowly. From thermal experiments in the presence of GuHCl we estimated the melting temperature for the Acidianus ambivalens ferredoxin in buffer (at pH 7) to be 122 degrees C. Possible structural properties that contribute to the large thermal stability of the Acidianus ambivalens ferredoxin are discussed using a three-dimensional protein model.
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Dynamics of the Binuclear Center of the Quinol Oxidase from Acidianus ambivalens
Biochemistry, 1999Co-Authors: Anna Aagaard, Cláudio M. Gomes, Miguel Teixeira, Gwen Gilderson, Peter BrzezinskiAbstract:We have investigated the kinetic and thermodynamic properties of carbon monoxide binding to the fully reduced quinol oxidase (cytochrome aa3) from the hyperthermophilic archaeon Acidianus ambivalen...
Miguel Teixeira - One of the best experts on this subject based on the ideXlab platform.
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The sulphur oxygenase reductase from Acidianus ambivalens is a multimeric protein containing a low-potential mononuclear non-haem iron centre.
Biochemical Journal, 2004Co-Authors: Tim Urich, Tiago M. Bandeiras, Cláudio M. Gomes, Miguel Teixeira, Reinhard Rachel, Sónia S. Leal, Till Albrecht, Peter Zimmermann, Corinna B. Scholz, Arnulf KletzinAbstract: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.
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A New Type-II NADH Dehydrogenase from the Archaeon Acidianus ambivalens: Characterization and in vitro Reconstitution of the Respiratory Chain
Journal of Bioenergetics and Biomembranes, 2001Co-Authors: Cláudio M. Gomes, Tiago M. Bandeiras, Miguel TeixeiraAbstract:A new type-II NADH dehydrogenase (NDH-II) was isolated from the hyperthermoacidophilic archaeon Acidianus ambivalens. This enzyme is a monomer with an apparent molecular mass of 47 kDa, containing a covalently bound flavin, and no iron–sulfur clusters. Upon isolation, NDH-II loses activity, which can, nevertheless, be restored by incubation with phospholipids. Catalytically, it is a proficient NADH:caldariella quinone oxidoreductase (130 mmol NADH oxidized/mg protein^-1/min^-1) but it can also donate electrons to synthetic quinones, strongly suggesting its involvement in the respiratory chain. The apparent K_m for NADH was found to be ∼6 μM, both for the purified and membrane-integrated enzyme, thus showing that detergent solubilization and purification did not affect the substrate binding site. Further, it is the first example of a type-II NADH dehydrogenase that contains the flavin covalently attached, which may be related to the need to stabilize the otherwise labile cofactor in a thermophilic environment. A fully operative minimal version of Acidianus ambivalens respiratory system was successfully reconstituted into artificial liposomes, using three basic components isolated from the organism: the type-II NADH dehydrogenase, caldariella quinone, the organism-specific quinone, and the aa_3 type quinol oxidase. This system, which mimics the in vivo chain, is efficiently energized by NADH, driving oxygen consumption by means of the terminal oxidase.
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Stability and folding of the ferredoxin from the hyperthermophilic archaeon Acidianus ambivalens.
Journal of inorganic biochemistry, 2000Co-Authors: Pernilla Wittung-stafshede, Cláudio M. Gomes, Miguel TeixeiraAbstract:The ferredoxin from the thermophilic archaeon Acidianus ambivalens is a small monomeric protein containing two iron-sulfur centres, one [3Fe-4S](1+/0) and one [4Fe-4S](2+/1+). It is an intrinsically hyperstable protein, being expressed at the organism's extreme optimal growth temperature: 80 degrees C. Using spectroscopic methods we have investigated the unfolding reaction of the Acidianus ambivalens ferredoxin. No unfolding of the oxidised ferredoxin was observed at pH 7.0, even in the presence of 8 M GuHCl. Upon increasing the pH to 10.0, the unfolding transition showed a midpoint at 6.3 M GuHCl and an unfolding-free energy of 70 kJ mol(-1) in buffer (pH 10) was estimated. Kinetic-unfolding experiments showed that the polypeptide unfolding correlated with rearrangement of the iron-sulfur centres to new ones which had strong absorption maxima at 520 and 610 nm. These new, possibly linear three-iron, clusters were coordinated to the unfolded protein but degraded slowly. From thermal experiments in the presence of GuHCl we estimated the melting temperature for the Acidianus ambivalens ferredoxin in buffer (at pH 7) to be 122 degrees C. Possible structural properties that contribute to the large thermal stability of the Acidianus ambivalens ferredoxin are discussed using a three-dimensional protein model.
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Dynamics of the Binuclear Center of the Quinol Oxidase from Acidianus ambivalens
Biochemistry, 1999Co-Authors: Anna Aagaard, Cláudio M. Gomes, Miguel Teixeira, Gwen Gilderson, Peter BrzezinskiAbstract:We have investigated the kinetic and thermodynamic properties of carbon monoxide binding to the fully reduced quinol oxidase (cytochrome aa3) from the hyperthermophilic archaeon Acidianus ambivalen...
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The unusual iron sulfur composition of the Acidianus ambivalens succinate dehydrogenase complex.
Biochimica et biophysica acta, 1999Co-Authors: Cláudio M. Gomes, Harald Huber, Karl O Stetter, Arnulf Kletzin, Miguel Teixeira, Rita S. Lemos, Günter Schäfer, Stefan AnemüllerAbstract:The succinate dehydrogenase complex of the thermoacidophilic archaeon Acidianus ambivalens was investigated kinetically and by EPR spectroscopy in its most intact form, i.e., membrane bound. Here it is shown that this respiratory complex has an unusual iron-sulfur cluster composition in respect to that of the canonical succinate dehydrogenases known. The spectroscopic studies show that center S3, the succinate responsive [3Fe-4S]1+/0 cluster of succinate dehydrogenases, is not present in membranes prepared from aerobically grown A. ambivalens, nor in partially purified complex fractions. On the other hand, EPR features associated to the remaining centers, clusters S1 ([2Fe-2S]1+/2+) and S2 ([4Fe-4S]2+/1+), could be observed. Similar findings were made in other archaea, namely Acidianus infernus and Sulfolobus solfataricus. Kinetic investigations showed that the A. ambivalens enzyme is reversible, capable of operating as a fumarate reductase - a required activity if this obligate autotroph performs CO2 fixation via a reductive citric acid cycle. Sequencing of the sdh operon confirmed the spectroscopic data. Center S3 ([3Fe-4S]) is indeed replaced by a second [4Fe-4S] center, by incorporation of an additional cysteine, at the cysteine cluster binding motif (CxxYxxCxxxC-->CxxCxxCxxxC). Genomic analysis shows that genes encoding for succinate dehydrogenases similar to the ones here outlined are also present in bacteria, which may indicate a novel family of succinate/fumarate oxidoreductases, spread among the Archaea and Bacteria domains.
Edgardo R. Donati - One of the best experts on this subject based on the ideXlab platform.
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Extremophilic Patagonian Microorganisms Working in Biomining
Biology and Biotechnology of Patagonian Microorganisms, 2016Co-Authors: P. Chiacchiarini, Edgardo R. Donati, L. Lavalle, María Sofía Urbieta, Ricardo Ulloa, Alejandra GiavenoAbstract:The microorganisms known as extremophiles have become a powerful tool in the field of biotechnology. Among them, acidophilic and thermophilic microorganisms capable of oxidizing iron(II) or sulfur compounds are very important in ore-processing operations as they are able to enhance the dissolution of sulfide ores. The aim of this chapter is to describe the physiological and phylogenetic characteristics of the main acidophilic species and communities found in geothermal and mining environments in Neuquen Province, Patagonia Argentina, and the advances done by our research group in their application to biomining and bioremediation of heavy metals. Additionally, the chapter includes the description of a novel thermoacidophilic archaeon from the genus Acidianus (Acidianus copahuensis) autochthonous of the Copahue geothermal area isolated and characterized by our research group.
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Biofilm formation and interspecies interactions in mixed cultures of thermo-acidophilic archaea Acidianus spp. and Sulfolobus metallicus.
Research in microbiology, 2016Co-Authors: Camila Castro, Edgardo R. Donati, Ruiyong Zhang, Jing Liu, Wolfgang Sand, Thomas R. Neu, Sören Bellenberg, Mario VeraAbstract:The understanding of biofilm formation by bioleaching microorganisms is of great importance for influencing mineral dissolution rates and to prevent acid mine drainage (AMD). Thermo-acidophilic archaea such as Acidianus, Sulfolobus and Metallosphaera are of special interest due to their ability to perform leaching at high temperatures, thereby enhancing leaching rates. In this work, leaching experiments and visualization by microscopy of cell attachment and biofilm formation patterns of the crenarchaeotes Sulfolobus metallicus DSM 6482(T) and the Acidianus isolates DSM 29038 and DSM 29099 in pure and mixed cultures on sulfur or pyrite were studied. Confocal laser scanning microscopy (CLSM) combined with fluorescent dyes as well as fluorescently labeled lectins were used to visualize different components (e.g. DNA, proteins or glycoconjugates) of the aforementioned species. The data indicate that cell attachment and the subsequently formed biofilms were species- and substrate-dependent. Pyrite leaching experiments coupled with pre-colonization and further inoculation with a second species suggest that both species may negatively influence each other during pyrite leaching with respect to initial attachment and pyrite dissolution rates. In addition, the investigation of binary biofilms on pyrite showed that both species were heterogeneously distributed on pyrite surfaces in the form of individual cells or microcolonies. Physical contact between the two species seems to occur, as revealed by specific lectins able to specifically bind single species within mixed cultures.
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Draft Genome Sequence of the Novel Thermoacidophilic Archaeon Acidianus copahuensis Strain ALE1, Isolated from the Copahue Volcanic Area in Neuquén, Argentina
Genome Announcements, 2014Co-Authors: M. Sofía Urbieta, M. Alejandra Giaveno, Santiago Revale, Camila Castro, Nicolas Rascovan, Martin Vazquez, Edgardo R. DonatiAbstract:ABSTRACT Acidianus copahuensis is a recently characterized thermoacidophilic archaeon isolated from the Copahue volcanic area in Argentina. Here, we present its draft genome sequence, in which we found genes involved in key metabolic pathways for developing under Copahue9s extreme environmental conditions, such as sulfur and iron oxidation, carbon fixation, and metal tolerance.
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Physiologic Versatility and Growth Flexibility as the Main Characteristics of a Novel Thermoacidophilic Acidianus Strain Isolated from Copahue Geothermal Area in Argentina
Microbial Ecology, 2013Co-Authors: M. Alejandra Giaveno, M. Sofía Urbieta, J. Ricardo Ulloa, Elena González Toril, Edgardo R. DonatiAbstract:A novel thermoacidophilic archaeal strain has been isolated from three geothermal acidic hot springs in Copahue, Argentina. One of the most striking characteristic of ALE1 isolate is its metabolic versatility. It grows on sulphur, tetrathionate, iron (II) and sucrose under aerobic conditions, but it can also develop under anaerobic conditions using iron (III) or sulphur as electron acceptors and sulphur or hydrogen as electron donors autotrophically. A temperature of 75 °C and a pH between 2.5 and 3.0 are strain ALE1 optimal growth conditions, but it is able to oxidise iron (II) even at pH 1.0. Cells are irregular cocci surrounded by a regularly arrayed glycoprotein layer (S-layer). Phylogenetic analysis shows that strain ALE1 belongs to the family Sulfolobaceae in the class Thermoprotei , within the phylum Crenarchaeota . Based on 16S rRNA gene sequence similarity on NCBI database, ALE1 does not have closely related relatives, neither in culture nor uncultured, which is more surprising. Its closest related species are strains of Acidianus hospitalis (91 % of sequence similarity), Acidianus infernus (90 %), Acidianus ambivalens (90 %) and Acidianus manzanensis (90 %). Its DNA base composition of 34.5 % mol C + G is higher than that reported for other Acidianus species. Considering physiological and phylogenetic characteristics of strain ALE1, we considered it to represent a novel species of the genus Acidianus ( candidatus “ Acidianus copahuensis ”). The aim of this study is to physiologically characterise this novel archaea in order to understand its role in iron and sulphur geochemical cycles in the Copahue geothermal area and to evaluate its potential applications in bioleaching and biooxidation.
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Visualization of attachment and colonization of pyrite surfaces by a novel species of Acidianus
Advanced Materials Research, 2013Co-Authors: Camila Castro, Edgardo R. Donati, Mario Vera, Wolfgang SandAbstract:In this work we have studied the attachment and colonization of pyrite surfaces by the recently isolated thermophilic archaeon Candidatus Acidianus copahuensis (isolated from the geothermal Caviahue-Copahue system, Argentina). Cells pregrown with sulfur, iron (II) or pyrite were tested. In order to characterize the EPS glycoconjugates of this strain, fluorescent lectins were used. Concanavalin A (ConA) gave the best signal and was selected for further studies. Coupons and grains of pyrite were treated with DAPI (to stain attached cells) and TRITC-ConA (to stain polysaccharides from EPS). Pyrite surfaces were imaged by epifluorescence (EFM) and confocal laser microscopy (CLSM). Initial cell attachment to pyrite grains was estimated to be 26%, 35% and 43% when cells were pregrown with sulfur, iron (II) and pyrite as electron donors, respectively. It was observed that the cell adhesion correlated with an increase of EPS production; both processes were favoured when cells were pregrown with pyrite or iron (II). Also the effect of phosphate (Pi) starvation in the attachment of Acidianus was studied in similar tests using a base medium without Pi. An increase of cell attachment under Pi starvation conditions was detectable.
Shuangjiang Liu - One of the best experts on this subject based on the ideXlab platform.
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ORIGINAL PAPER Genomic analysis of Acidianus hospitalis W1 a host for studying crenarchaeal virus and plasmid life cycles
2016Co-Authors: Xiao-yan You, David Prangishvili, Shuangjiang Liu, Chao Liu, Shengyue Wang, Cheng-ying Jiang, Shiraz A. Shah, Qunxin She, Roger A. GarrettAbstract:of a minimally sized chromosome of about 2.13 Mb and a conjugative plasmid pAH1 and it is a host for the model filamentous lipothrixvirus AFV1. The chromosome carries three putative replication origins in conserved genomic regions and two large regions where non-essential genes are clustered. Within these variable regions, a few orphan orfB and other elements of the IS200/607/605 family are con-centrated with a novel class of MITE-like repeat elements. There are also 26 highly diverse vapBC antitoxin–toxin gene pairs proposed to facilitate maintenance of local chromo-somal regions and to minimise the impact of environmental stress. Complex and partially defective CRISPR/Cas/Cmr immune systems are present and interspersed with five vapBC gene pairs. Remnants of integrated viral genomes and plasmids are located at five intron-less tRNA genes and several non-coding RNA genes are predicted that are con-served in other Sulfolobus genomes. The putative metabolic pathways for sulphur metabolism show some significant differences from those proposed for other Acidianus and Sulfolobus species. The small and relatively stable genome of A. hospitalis W1 renders it a promising candidate for developing the first Acidianus genetic systems
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Genomic analysis of Acidianus hospitalis W1 a host for studying crenarchaeal virus and plasmid life cycles
Extremophiles : life under extreme conditions, 2011Co-Authors: Xiao-yan You, David Prangishvili, Shuangjiang Liu, Chao Liu, Shengyue Wang, Cheng-ying Jiang, Shiraz A. Shah, Qunxin She, Roger A. GarrettAbstract:The Acidianus hospitalis W1 genome consists of a minimally sized chromosome of about 2.13 Mb and a conjugative plasmid pAH1 and it is a host for the model filamentous lipothrixvirus AFV1. The chromosome carries three putative replication origins in conserved genomic regions and two large regions where non-essential genes are clustered. Within these variable regions, a few orphan orfB and other elements of the IS200/607/605 family are concentrated with a novel class of MITE-like repeat elements. There are also 26 highly diverse vapBC antitoxin–toxin gene pairs proposed to facilitate maintenance of local chromosomal regions and to minimise the impact of environmental stress. Complex and partially defective CRISPR/Cas/Cmr immune systems are present and interspersed with five vapBC gene pairs. Remnants of integrated viral genomes and plasmids are located at five intron-less tRNA genes and several non-coding RNA genes are predicted that are conserved in other Sulfolobus genomes. The putative metabolic pathways for sulphur metabolism show some significant differences from those proposed for other Acidianus and Sulfolobus species. The small and relatively stable genome of A. hospitalis W1 renders it a promising candidate for developing the first Acidianus genetic systems.
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Site-directed mutagenesis reveals new and essential elements for iron-coordination of the sulfur oxygenase reductase from the acidothermophilic Acidianus tengchongensis
Chinese Science Bulletin, 2009Co-Authors: Zhiwei Chen, Cheng-ying Jiang, Shuangjiang LiuAbstract:Previous study on refolding of sulfur oxygenase reductase (SOR) inclusion bodies from recombinant Escherichia coli showed that iron was critical to the activity of the SOR from Acidianus ambivalens. In this study, enzymatic assays showed that 2,2′-Dipyridyl, Tiron and 8-hydroxyquinoline, which are specific for chelating ferrous or ferric ions, strongly inhibited the activity of SOR from A. tengchongensis, suggesting that iron atom is essential for SOR activity. Alignment of several functionally identified SORs and SOR-like sequences from genome database revealed a conserved, putative iron binding motif, H86-X3-H90-Xn-E114-Xn-E129 (numbering according to the Acidianus tengchongensis SOR sequence). Three mutants of SOR were generated by site-directed mutagenesis of H86, H90 and E129 into phenylalanine or alanine residue in this study. Circular dichroism spectrum determination indicated that there was no change of the secondary structures of mutant SORs, H86F, H90F and E129A, but all mutants were completely inactive. Through determination of iron contents we found that SOR mutants of H86F, H90F and E129A completely or partially lost iron, while mutants of C31S, C101S, and C104S (generated in a previous study) did not. This result indicated that H86, H90 and E129 but not C31, C101, and C104 were involved in binding to iron atom. Based on this and previous studies, it is proposed that the conserved motifs, C31-Xn-C101-X2-C104 and H86-X3-H90-X23-E114-X14-(E/D)129, are respectively for sulfur and molecular oxygen binding and activation. These two conserved motifs are essential elements for the SOR activity.
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Crystal structure studies on sulfur oxygenase reductase from Acidianus tengchongensis.
Biochemical and biophysical research communications, 2008Co-Authors: Zhiwei Chen, Shuangjiang Liu, Cheng-ying Jiang, Pingfeng Zhang, Xiaowei Pan, Wenrui ChangAbstract:Sulfur oxygenase reductase (SOR) simultaneously catalyzes oxidation and reduction of elemental sulfur to produce sulfite, thiosulfate, and sulfide in the presence of molecular oxygen. In this study, crystal structures of wild type and mutants of SOR from Acidianus tengchongensis (SOR-AT) in two different crystal forms were determined and it was observed that 24 identical SOR monomers form a hollow sphere. Within the icosatetramer sphere, the tetramer and trimer channels were proposed as the paths for the substrate and products, respectively. Moreover, a comparison of SOR-AT with SOR-AA (SOR from Acidianus ambivalens) structures showed that significant differences existed at the active site. Firstly, Cys31 is not persulfurated in SOR-AT structures. Secondly, the iron atom is five-coordinated rather than six-coordinated, since one of the water molecules ligated to the iron atom in the SOR-AA structure is lost. Consequently, the binding sites of substrates and a hypothetical catalytic process of SOR were proposed.
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Purification and properties of the sulfur oxygenase/reductase from the acidothermophilic archaeon, Acidianus strain S5.
Extremophiles : life under extreme conditions, 2003Co-Authors: Cui-wei Sun, Pei-jin Zhou, Zhiwei Chen, Shuangjiang LiuAbstract:The sulfur oxygenase/reductase (SOR) of Acidianus strain S5 was purified and characterized after expressing the SOR gene in a recombinant strain of Escherichia coli. The N-terminal sequence of the purified SOR protein was the same as the deduced amino acid sequence from previously cloned SOR genes. Enzymatic studies indicated that the SOR catalyzed the conversion of elemental sulfur (So) to sulfite, thiosulfate, and sulfide. The optimal pH and temperature were 5.0 and 70 °C, respectively. Comparison of this SOR and that of A. ambivalens revealed several differences between these two SORs. The most striking difference is that the SOR of Acidianus S5 had maximal activity at acidic pH. By application of anti-SOR serum and the Western blot technique, it was found that SOR proteins existed in A. brierleyi and in Acidianus S5 cells cultivated with thiosulfate as the sole energy source, indicating that SOR may also play a role in thiosulfate metabolism.
