Publications

molecular characterisation of a dna ligase gene of the extremely thermophilic archaeon desulfurolobus ambivalens shows close phylogenetic relationship to eukaryotic ligases.	a 3382 bp fragment containing a gene for a dna ligase from the extremely thermophilic, acidophilic, and facultatively anaerobic archaeon (archaebacterium) desulfurolobus ambivalens was cloned and sequenced. the deduced amino acid sequence (600 amino acids, 67619 molecular weight) showed 30-34% sequence identity with the atp-dependent eucaryal (eukaryotic) dna ligases of schizosaccharomyces pombe, saccharomyces cerevisiae, the human dna ligase i, and with the vaccinia dna ligase. distant similari ...	1992	1437556
molecular characterization of the sor gene, which encodes the sulfur oxygenase/reductase of the thermoacidophilic archaeum desulfurolobus ambivalens.	a 5.8-kbp hindiii fragment containing the sor gene which encodes the aerobically induced sulfur oxygenase/reductase of the thermoacidophilic, chemolithoautotrophic, and facultatively anaerobic archaeum desulfurolobus ambivalens, was cloned in puc18 by using an oligonucleotide derived from the n-terminal amino acid sequence for identification (psor-1/17). the native enzyme is a 550,000-molecular-weight oligomer composed of single 40,000-molecular-weight subunits; this oligomer is capable of the s ...	1992	1522063
pyrite oxidation by thermophilic archaebacteria.	three species of thermophilic archaebacteria of the genera sulfolobus (sulfolobus acidocaldarius and s. solfataricus) and acidianus (acidianus brierleyi) were tested for their ability to oxidize pyrite and to grow autotrophically on pyrite, to explore their potential for use in coal desulfurization. only a. brierleyi was able to oxidize and grow autotrophically on pyrite. jarosite was formed during the pyrite oxidation, resulting in the precipitation of sulfate and iron. the medium composition a ...	1990	2107795
coupled enzymatic production of sulfite, thiosulfate, and hydrogen sulfide from sulfur: purification and properties of a sulfur oxygenase reductase from the facultatively anaerobic archaebacterium desulfurolobus ambivalens.	from aerobically grown cells of the extremely thermophilic, facultatively anaerobic chemolithoautotrophic archaebacterium desulfurolobus ambivalens (dsm 3772), a soluble oxygenase reductase (sor) was purified which was not detectable in anaerobically grown cells. in the presence of oxygen but not under a hydrogen atmosphere, the enzyme simultaneously produced sulfite, thiosulfate, and hydrogen sulfide from sulfur. nonenzymatic control experiments showed that thiosulfate was produced mainly in a ...	1989	2493451
5'-methylbenzimidazolyl-cobamides are the corrinoids from some sulfate-reducing and sulfur-metabolizing bacteria.	the sulfate-reducing bacteria desulfobacterium autotrophicum, desulfobulbus propionicus and archaeoglobus fulgidus (vc-16) and the sulfur-metabolizing archaebacteria desulfurolobus ambivalens and thermoplasma acidophilum were found to contain considerable amounts of corrinoids, that were isolated and crystallized in their co beta-cyano form. in three other sulfur-metabolizing archaebacteria, thermoproteus neutrophilus, pyrodictium occultum and staphylothermus marinus significant amounts of corri ...	1988	3416881
using protein synthesis inhibitors to establish the phylogenetic relationships of the sulfolobales order.	the sensitivity of the cell-free protein synthesis systems from acidanus brierleyi, acidianus infernus, and metallosphaera sedula, members of the archaeal order sulfolobales, to 40 antibiotics with different specificities has been studied. the sensitivity patterns were compared to those of sulfolobus solfataricus and other archaeal, bacterial, and eukaryotic systems. the comparative analysis shows that ribosomes from the sulfolobales are the most refractory to inhibitors of protein synthesis des ...	1994	7807541
a seven-iron ferredoxin from the thermoacidophilic archaeon desulfurolobus ambivalens.	a seven-iron ferredoxin was isolated from aerobically grown cells of the hyperthermoacidophilic archaeon desulfurolobus ambivalens (dsm 3772). the protein is monomeric, with an apparent molecular mass of 15 kda and contains 7 iron atoms/molecule. the n-terminal sequence shows a large similarity (70% identity) with that of the ferredoxin isolated from the archaeon sulfolobus acidocaldarius. the epr characteristics in both the native (oxidized) and dithionite-reduced states of this protein allowed ...	1995	7851403
occurrence of tertiary and quaternary branched polyamines in thermophilic archaebacteria.	polyamines of thermophilic archaebacteria were analysed by high-performance liquid chromatography and gas chromatography. thermoplasma acidophilum and thermoplasma volcanium ubiquitously contained spermidine and spermine. four species of sulfolobus, s. acidocaldarius, s. solfataricus, s. metallicus and s. shibatae, two species of acidianus, a. brierleyi and a. infernus, and metallosphaera sedula, contained norspermidine and norspermine in addition to spermidine and spermine, but quantitative dis ...	1994	7968661
paramagnetic nmr analysis of the seven-iron ferredoxin from the hyperthermoacidophilic archaeon desulfurolobus ambivalens reveals structural similarity to other dicluster ferredoxins.	the seven-iron ferredoxin from the hyperthermophilic archaeon desulfurolobus ambivalens has been investigated by one-dimensional and two-dimensional 1h-nmr in its oxidized and dithionite-reduced states. all iron atoms of both the three-iron and the four-iron cluster are bound to cysteine residues whose hyperfine-shifted resonances were characterized. the pattern of these resonances is similar to those from three-iron, four-iron and eight-iron ferredoxins previously described in the literature, b ...	1996	8617291
viruses, plasmids and other genetic elements of thermophilic and hyperthermophilic archaea.	we review and update the work on genetic elements, e.g., viruses and plasmids (exluding is elements and transposons) in the kingdom crenarchaeota (thermoproteales and sulfolobales) and the orders thermococcales and thermoplasmales in the kingdom euryarchaeota of the archael domain, including unpublished data from our laboratory. the viruses of crenarchaeota represent four novel virus families. the fuselloviridae represented by ssvi of s. shibatae and relatives in other sulfolobus strains have th ...	1996	8639330
the terminal quinol oxidase of the hyperthermophilic archaeon acidianus ambivalens exhibits a novel subunit structure and gene organization.	a terminal quinol oxidase has been isolated from the plasma membrane of the crenarchaeon acidianus ambivalens (dsm 3772) (formerly desulfurolobus ambivalens), cloned, and sequenced. the detergent-solubilized complex oxidizes caldariella quinol at high rates and is completely inhibited by cyanide and by quinolone analogs, potent inhibitors of quinol oxidases. it is composed of at least five different subunits of 64.9, 38, 20.4, 18.8, and 7.2 kda; their genes are located in two different operons. ...	1997	9023221
autotrophic carbon dioxide fixation in acidianus brierleyi.	the autotrophic co2 fixation pathway in acidianus brierleyi, a facultatively anaerobic thermoacidophilic archaebacterium, was investigated by measuring enzymatic activities from autotrophic, mixotrophic, and heterotrophic cultures. contrary to the published report that the reductive tricarboxylic acid cycle operates in a. brierleyi, the enzymatic activity of atp:citrate lyase, the key enzyme of the cycle, was not detected. instead, activities of acetyl-coa carboxylase and propionyl-coa carboxyla ...	1996	9082912
the signal recognition particle receptor alpha subunit of the hyperthermophilic archaeon acidianus ambivalens exhibits an intrinsic gtp-hydrolyzing activity.	two adjacent genes of the acidophilic and hyperthermophilic crenarchaeon acidianus ambivalens were cloned and sequenced. the 1.6 kb genomic nucleotide sequence under investigation consists of the 1.12 kb sra gene encoding the putative signal recognition particle receptor alpha subunit (sr alpha, 42.2 kda) and the 186 basepair sece gene coding for the putative secretory component sece subunit (6800 da). the sr alpha protein is structured by three distinct regions: the n-terminal hydrophilic h-reg ...	1997	9133659
functional properties of the quinol oxidase from acidianus ambivalens and the possible catalytic role of its electron donor--studies on the membrane-integrated and purified enzyme.	the aa3 quinol oxidase has been purified from the thermoacidophilic archaea acidianus ambivalens as a three-redox-centers enzyme. the functional properties of this oxidase both as purified and in its most integral form (i.e. in native membranes and in intact cells) were investigated by stopped-flow spectrophotometry. the results suggest that the enzyme interacts in vivo with a redox-active molecule, which favours the electron entry via heme a and provides the fourth electron demanded for catalys ...	1997	9428688
the nadh oxidase from the thermoacidophilic archaea acidianus ambivalens: isolation and physicochemical characterisation.	a flavoprotein with nadh oxidising activity (nadh: acceptor oxidoreductase) was isolated from the soluble fraction of the thermoacidophilic archaea acidianus ambivalens. the protein is a monomer with a molecular mass of 70 kda and contains fad as single cofactor. its activity as nadh:o2 oxidoreductase is fad, but not fmn, dependent and yields hydrogen peroxide as the reaction product. the activity decreases with ph in the range 4.5 to 9.8, and increases with the temperature, as tested from 30 de ...	1998	9480823
estimation of genome sizes of hyperthermophiles.	genomes of various hyperthermophilic and extremely thermophilic prokaryotes were analyzed with respect to size, physical organization, and 16s rdna copy number. our results show that all the genomes are circular, and they are in the size range of 1.6-1.8 mb for pyrodictium abyssi, methanococcus igneus, pyrobaculum aerophilum, archaeoglobus fulgidus, archaeoglobus lithotrophicus, and archaeoglobus profundus (the two bacteria fervidobacterium islandicum and thermosipho africanus possess genomes of ...	1998	9672684
ambineela, an unusual blue protein isolated from the archaeon acidianus ambivalens.	a novel blue protein, named ambineela, was isolated from the soluble extract of the thermoacidophilic archaeon acidianus ambivalens. in solution, the purified protein is a monomer with 50 kda and has a basic character (pi approximately 8.7). the electronic spectrum shows two bands, centred at 395 and 625 nm (a625/a395 = 0.7). the protein does not contain any transition metal; its blue colour is due to an unidentified non-fluorescent cofactor, covalently bound to it. ambineela n-terminal sequence ...	1998	9705824
sulfurisphaera ohwakuensis gen. nov., sp. nov., a novel extremely thermophilic acidophile of the order sulfolobales.	three spherical thermoacidophilic archaea (strains ta-1t, ta-13, ta-14) were obtained from acidic hot springs located in ohwaku valley, hakone, japan. all the isolates are facultatively anaerobic, and grew optimally at around 85 degrees c, ph 2.0. isolate ta-1t was characterized further. the g + c content of dna from ta-1t is 33 mol%. although these properties resemble those of the genus acidianus, the sequence of the 16s rrna gene from strain ta-1t was more similar to that of species of stygiol ...	1998	9731283
domain structure, gtp-hydrolyzing activity and 7s rna binding of acidianus ambivalens ffh-homologous protein suggest an srp-like complex in archaea.	in this study we provide, for the first time, experimental evidence that a protein homologous to bacterial ffh is part of an srp-like ribonucleoprotein complex in hyperthermophilic archaea. the gene encoding the ffh homologue in the hyperthermophilic archaeote acidianus ambivalens has been cloned and sequenced. recombinant ffh protein was expressed in e. coli and subjected to biochemical and functional studies. a. ambivalens ffh encodes a 50.4-kda protein that is structured by three distinct reg ...	1999	9914525
presence of acetyl coenzyme a (coa) carboxylase and propionyl-coa carboxylase in autotrophic crenarchaeota and indication for operation of a 3-hydroxypropionate cycle in autotrophic carbon fixation.	the pathway of autotrophic co2 fixation was studied in the phototrophic bacterium chloroflexus aurantiacus and in the aerobic thermoacidophilic archaeon metallosphaera sedula. in both organisms, none of the key enzymes of the reductive pentose phosphate cycle, the reductive citric acid cycle, and the reductive acetyl coenzyme a (acetyl-coa) pathway were detectable. however, cells contained the biotin-dependent acetyl-coa carboxylase and propionyl-coa carboxylase as well as phosphoenolpyruvate ca ...	1999	9973333
effect of yeast extract supplementation in leach solution on bioleaching rate of pyrite by acidophilic thermophile acidianus brierleyi	the bioleaching rate of pyrite (fes2) by the acidophilic thermophile acidianus brierleyi was studied at 65 degrees c and ph 1.5 with leach solutions supplemented with yeast extract. in the absence of yeast extract supplementation, a. brierleyi could grow autotrophically on pyrite, and the leaching percentage of pyrite particles (25-44 μm) reached 25% for 7 d. the bacterial growth and consequent pyrite oxidation were enhanced by the addition of yeast extract between 0.005 and 0.25% w/v: the pyrit ...	1998	10099306
the unusual iron sulfur composition of the acidianus ambivalens succinate dehydrogenase complex.	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 membran ...	1999	10216159
two modes of sulfite oxidation in the extremely thermophilic and acidophilic archaeon acidianus ambivalens	sulfite-oxidizing enzyme activities were analyzed in cell-free extracts of aerobically grown cells of acidianus ambivalens, an extremely thermophilic and chemolithoautotrophic archaeon. in the membrane and cytoplasmic fractions, two distinct enzyme activities were found. in the membrane fraction, a sulfite:acceptor oxidoreductase activity was found [530 mu (mg protein)(-1); apparent k(m) for sulfite, 3.6 mm]. in the cytoplasmic fraction the following enzyme activities were found and are indicati ...	1999	10415168
molecular analysis of pdl10 from acidianus ambivalens reveals a family of related plasmids from extremely thermophilic and acidophilic archaea.	the 7598-bp plasmid pdl10 from the extremely thermophilic, acidophilic, and chemolithoautotrophic archaeon acidianus ambivalens was sequenced. it contains 10 open reading frames (orfs) organized in five putative operons. the deduced amino acid sequence of the largest orf (909 aa) showed similarity to bacterial rep proteins known from phages and plasmids with rolling-circle (rc) replication. from the comparison of the amino acid sequences, a novel family of rc rep proteins was defined. the pdl10 ...	1999	10430561
dynamics of the binuclear center of the quinol oxidase from acidianus ambivalens.	we have investigated the kinetic and thermodynamic properties of carbon monoxide binding to the fully reduced quinol oxidase (cytochrome aa(3)) from the hyperthermophilic archaeon acidianus ambivalens. after flash photolysis of co from heme a(3), the complex recombines with an apparent rate constant of approximately 3 s(-1), which is much slower than with the bovine cytochrome c oxidase (approximately 80 s(-1)). investigation of the co-recombination rate as a function of the co concentration sho ...	1999	10433710
kinetics of the bioleaching of chalcopyrite concentrate by acidophilic thermophile acidianus brierleyi	the kinetics of leaching of high-grade chalcopyrite (cufes(2)) concentrate (38-53 &mgr;m) by the acidophilic thermophilic bacterium, acidianus brierleyi, was studied at 65 degrees c and ph 1.2 in a batch stirred reactor. the adsorption of a. brierleyi cells between the sulfide surface and solution was attained within the first 20 min of exposure to the mineral, and the equilibrium adsorption data were correlated with the langmuir isotherm. the bioleaching was markedly accelerated in the presence ...	1999	10441359
redox-linked transient deprotonation at the binuclear site in the aa(3)-type quinol oxidase from acidianus ambivalens: implications for proton translocation.	the hyperthermophilic archaeon acidianus ambivalens expresses a membrane-bound aa(3)-type quinol oxidase, when grown aerobically, that we have studied by resonance raman spectroscopy. the purified aa(3) oxidase, which does not contain bound quinol, undergoes a reversible slow conformational change at heme a(3) upon reduction, as indicated by a change in the frequency of its heme formyl stretching mode, from 1,660 cm(-1) to 1,667 cm(-1). in contrast, upon reduction of the integral membrane enzyme ...	1999	10449737
crystallization and preliminary x-ray diffraction studies on the conserved gtpase domain of the signal recognition particle from acidianus ambivalens.	the signal recognition particle (srp) of bacteria consists of only one protein, known as ffh or the srp54 homologue, which forms a complex with 4.5s rna. it also binds to signal peptides and contains a gtpase which displays interesting differences to ras gtpases. the conserved ng-domain of ffh from the archaebacterium acidianus ambivalens was cloned and overexpressed with a c-terminal his tag in escherichia coli. crystallization experiments of the native protein as well as of the thr112ala mutan ...	1999	10531505
functional characterization of an extremely thermophilic atpase in membranes of the crenarchaeon acidianus ambivalens.	a plasma membrane-bound adenosine triphosphatase with specific activities up to 0.2 micromol min(-1) (mg protein)(-1) at 80 degrees c was detected in the thermoacidophilic crenarchaeon acidianus ambivalens (dsm 3772). the enzymatic activity exhibited a broad ph-optimum in the neutral range with two suboptima at ph 5.5 and 7.0, respectively. sulfite activation resulted in only one ph optimum at 6.25. in the presence of the divalent cations mg2+ and mn2+ the atpase activity was maximal. remarkably ...	1999	10543443
ferredoxin iii of desulfovibrio africanus: sequencing of the native gene and characterization of a histidine-tagged form.	desulfovibrio africanus ferredoxin iii (da fdiii) contains one [4fe-4s](2+/1+) cluster and one [3fe-4s](1+/0) cluster, bound by seven cys residues, in which the [3fe-4s] cluster is co-ordinated by the unusual sequence, cys(11)-xaa-xaa-asp(14)-xaa-xaa-cys(17)-xaa(n)-cys(51)-glu. the [3fe-4s] core of this ferredoxin is so far unique in showing rapid bi-directional [3fe-4s]<-->[4fe-4s] cluster interconversion with a wide range of metal ions. in order to obtain protein for mutagenesis studies da fdi ...	2000	10677356
improved purification of the membrane-bound hydrogenase-sulfur-reductase complex from thermophilic archaea using epsilon-aminocaproic acid-containing chromatography buffers.	a hydrogenase-sulfur reductase (sr) complex was purified from membrane preparations of the extremely thermophilic, acidophilic archaeon acidianus ambivalens using a combination of sucrose density gradient centrifugation and column chromatography (fplc). all chromatographic steps were performed in the presence of 0.5% epsilon-aminocaproic acid resulting in the elution of the sr complex as a sharp peak. in contrast, chromatography using buffers without epsilon-aminocaproic acid, or in the presence ...	2000	10681051
stability and folding of the ferredoxin from the hyperthermophilic archaeon acidianus ambivalens.	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 ...	2000	10714703
the crystal structure of the conserved gtpase of srp54 from the archaeon acidianus ambivalens and its comparison with related structures suggests a model for the srp-srp receptor complex.	protein targeting to the endoplasmic reticulum in eukaryotes and to the cell membrane in prokaryotes is mediated by the signal recognition particle (srp) and its receptor (sr). both contain conserved gtpase domains in the signal-peptide-binding proteins (srp54 and ffh) and the sr proteins (sralpha and ftsy). these gtpases are involved in the regulation of protein targeting. most studies so far have focussed on the srp machinery of mammals and bacteria, leaving the srp system of archaea less well ...	2000	10801496
microbiology of acidic, geothermal springs of montserrat: environmental rdna analysis.	dna was extracted from water and sediment samples taken from acidic, geothermal pools on the caribbean island of montserrat. 16s rrna genes were amplified by pcr, cloned, sequenced, and examined to indicate some of the organisms that might be significant components of the in situ microbiota. a clone bank representing the lowest temperature pool that was sampled (33 degrees c) was dominated by genes corresponding to two types of acidophiles: acidiphilium-like mesophilic heterotrophs and thermotol ...	2000	11057917
cloning and heterologous expression of a sulfur oxygenase/reductase gene from the thermoacidophilic archaeon acidianus sp. s5 in escherichia coli.	a thermoacidophilic, obligately chemolithotrophic, facultatively aerobic archaebacterium, acidianus sp. s5, was isolated from acidothermal springs in southwest china. the sulfur oxygenase/reductase (sor) gene of acidianus sp. s5 was cloned and expressed in escherichia coli. several primers were designed and successfully applied for detection and cloning of the sor gene. a 3.7-kb ecori fragment containing the sor gene and three neighboring open reading frames was sequenced. sequence analysis indi ...	2000	11111027
kinetics of electron and proton transfer during o(2) reduction in cytochrome aa(3) from a. ambivalens: an enzyme lacking glu(i-286).	acidianus ambivalens is a hyperthermoacidophilic archaeon which grows optimally at approximately 80 degrees c and ph 2.5. the terminal oxidase of its respiratory system is a membrane-bound quinol oxidase (cytochrome aa(3)) which belongs to the heme-copper oxidase superfamily. one difference between this quinol oxidase and a majority of the other members of this family is that it lacks the highly-conserved glutamate (glu(i-286), e. coli ubiquinol oxidase numbering) which has been shown to play a ...	2001	11115638
the hyper-thermostable fe-superoxide dismutase from the archaeon acidianus ambivalens: characterization, recombinant expression, crystallization and effects of metal exchange.	an iron-containing superoxide dismutase (sod; ec 1.15.1.1) of the hyperthermophilic archaeon acidianus ambivalens (aa-sod) has been purified and characterized and the gene has been cloned and sequenced. the sod from the facultatively aerobic member of the crenarchaeota could be expressed in e. coli. both, the native as well as the heterologously overproduced protein turned out to have extraordinarily high melting temperatures of 128 degrees c and 124.5 degrees c, respectively. to the best of our ...	2000	11154067
acidianus ambivalens complex ii typifies a novel family of succinate dehydrogenases.	complex ii from the thermoacidophilic archaeon acidianus ambivalens, an archetype of an emerging class of succinate dehydrogenases (sdh), was extracted from intact membranes and purified to homogeneity. the complex contains one molecule of covalently bound fad and 10 fe atoms. epr studies showed that the complex contains the canonical centres s1 ([2fe-2s]2+/1+) and s2 ([4fe-4s]+2/+1) but lacks centre s3 ([3fe-4s]+1/0); these observations agree with the fact that the iron-sulfur subunit contains ...	2001	11178972
heme-copper oxidases with modified d- and k-pathways are yet efficient proton pumps.	the cytochrome aa(3)-type quinol oxidase from the archaeon acidianus ambivalens and the ba(3)-type cytochrome c oxidase from thermus thermophilus are divergent members of the heme-copper oxidase superfamily of enzymes. in particular they lack most of the key residues involved in the proposed proton transfer pathways. the pumping capability of the a. ambivalens enzyme was investigated and found to occur with the same efficiency as the canonical enzymes. this is the first demonstration of pumping ...	2001	11377432
a new type-ii nadh dehydrogenase from the archaeon acidianus ambivalens: characterization and in vitro reconstitution of the respiratory chain.	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 ...	2001	11460922
high stability of a ferredoxin from the hyperthermophilic archaeon a. ambivalens: involvement of electrostatic interactions and cofactors.	the ferredoxin from the thermophilic archaeon acidianus ambivalens is a small monomeric seven-iron protein with a thermal midpoint (t(m)) of 122 degrees c (ph 7). to gain insight into the basis of its thermostability, we have characterized unfolding reactions induced chemically and thermally at various phs. thermal unfolding of this ferredoxin, in the presence of various guanidine hydrochloride (guhcl) concentrations, yields a linear correlation between unfolding enthalpies (deltah[t(m)]) and t( ...	2001	11468351
ferredoxins from the archaeon acidianus ambivalens: overexpression and characterization of the non-zinc-containing ferredoxin fdb.	two ferredoxin genes, fda and fdb, from the extremely thermoacidophilic crenarchaeon acidianus ambivalens have been sequenced; the sequences share 86% similarity. whereas the deduced protein sequence of the ferredoxin fda clearly contains a zinc-binding motif, the corresponding sequence of the fdb is devoid of this motif. thus far, only the zinc-containing ferredoxin, fda, from a. ambivalens has been chemically and functionally characterized from its native source. using rt-pcr and northern blot ...	2001	11727834
an archaeal b-type cytochrome containing a nonfunctional carbonic anhydrase-like domain.	a new type of cytochrome b was isolated from the cytoplasmatic fraction of the archaeon acidianus ambivalens, which is the first soluble cytochrome found in this member of the thermoacidophilic order of the sulfolobales. the protein is a monomeric and monohemic cytochrome b with a molecular mass of 22 kda. visible spectroscopy of the as-purified protein shows a soret peak at 405 nm and a broad band at 625 nm, indicating the presence of a high-spin ferric heme. upon reduction, the soret band shif ...	2002	11941506
acidophiles of saline water at thermal vents of vulcano, italy.	dna was extracted from samples taken from close to acidic hydrothermal vents on shore of the aeolian island of vulcano (italy). rna gene sequences were amplified by pcr, cloned, and sequenced. a sequence with an origin in samples at 35 degrees and 45 degrees c corresponded to that of a novel acidithiobacillus species that was isolated from water close to the vents. novel, iron-oxidizing mesophilic acidophiles were isolated through enrichment cultures with ferrous iron but were not represented in ...	2002	12072955
acidianus ambivalens type-ii nadh dehydrogenase: genetic characterisation and identification of the flavin moiety as fmn.	the thermoacidophilic archaeon acidianus ambivalens contains a monomeric 47 kda type-ii nadh dehydrogenase (ndh), which contains a covalently bound flavin. in this work, by a combination of several methods, namely (31)p-nuclear magnetic resonance and fluorescence spectroscopies, it is proven that this enzyme contains covalent fmn, a novelty among this family of enzymes, which were so far thought to mainly have the flavin dinucleotide form. discrimination between several possible covalent flavin ...	2002	12417325
remarkable morphological diversity of viruses and virus-like particles in hot terrestrial environments.	electron microscopic studies of the viruses in two hot springs (85 degrees c, ph 1.5-2.0, and 75-93 degrees c, ph 6.5) in yellowstone national park revealed particles with twelve different morphotypes. this diversity encompassed known viruses of hyperthermophilic archaea, filamentous lipothrixviridae, rod-shaped rudiviridae, and spindle-shaped fuselloviridae, and novel morphotypes previously not observed in nature. two virus types resembled head-and-tail bacteriophages from the families siphovir ...	2002	12491107
characterization of a bifunctional archaeal acyl coenzyme a carboxylase.	acyl coenzyme a carboxylase (acyl-coa carboxylase) was purified from acidianus brierleyi. the purified enzyme showed a unique subunit structure (three subunits with apparent molecular masses of 62, 59, and 20 kda) and a molecular mass of approximately 540 kda, indicating an alpha(4)beta(4)gamma(4) subunit structure. the optimum temperature for the enzyme was 60 to 70 degrees c, and the optimum ph was around 6.4 to 6.9. interestingly, the purified enzyme also had propionyl-coa carboxylase activit ...	2003	12533469
[study on reclassification of extremely thermoacidophilic archaea strain s5].	the further study on thermoacidophilic archaea strain s5, with has been identified as sulfosphaerellus thermoacidophilum gen.nov.,sp.nov, has shown it was able to grow facultatively aerobically by means of two sulfur-metabolizing modes of chemolithotrophy which is the characteristic of acidianus. and the 16srrna gene of strain s5 was amplified, cloned and sequenced, a phylogenetic tree was constructed on the 16srrna gene sequences. the tree clearly indicated that strain s5 formed the same line ...	2001	12549077
autotrophic co2 fixation pathways in archaea (crenarchaeota).	representative autotrophic and thermophilic archaeal species of different families of crenarchaeota were examined for key enzymes of the known autotrophic co(2) fixation pathways. pyrobaculum islandicum ( thermoproteaceae) contained key enzymes of the reductive citric acid cycle. this finding is consistent with the operation of this pathway in the related thermoproteus neutrophilus. pyrodictium abyssi and pyrodictium occultum ( pyrodictiaceae) contained ribulose 1,5-bisphosphate carboxylase, whi ...	2003	12610721
the isolation and use of iron-oxidizing, moderately thermophilic acidophiles from the collie coal mine for the generation of ferric iron leaching solution.	moderately thermophilic, iron-oxidizing acidophiles were enriched from coal collected from an open-cut mine in collie, western australia. iron-oxidizers were enriched in fluidized-bed reactors (fbr) at 60 degrees c and 70 degrees c; and iron-oxidation rates were determined. ferrous iron oxidation by the microbiota in the original coal material was inhibited above 63;c. in addition to four iron-oxidizers, closely related to sulfobacillus spp that had been earlier isolated from the 60 degrees c fb ...	2003	12664157
purification and properties of the sulfur oxygenase/reductase from the acidothermophilic archaeon, acidianus strain s5.	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 (s(o)) to sulfite, thiosulfate, and sulfide. the optimal ph and temperature were 5.0 and 70 degrees c, respectivel ...	2003	12664265
genus-specific protein binding to the large clusters of dna repeats (short regularly spaced repeats) present in sulfolobus genomes.	short regularly spaced repeats (srsrs) occur in multiple large clusters in archaeal chromosomes and as smaller clusters in some archaeal conjugative plasmids and bacterial chromosomes. the sequence, size, and spacing of the repeats are generally constant within a cluster but vary between clusters. for the crenarchaeon sulfolobus solfataricus p2, the repeats in the genome fall mainly into two closely related sequence families that are arranged in seven clusters containing a total of 441 repeats w ...	2003	12670964
ftir spectroscopic characterization of the cytochrome aa3 from acidianus ambivalens: evidence for the involvement of acidic residues in redox coupled proton translocation.	the aa(3)-type quinol oxidase from acidianus ambivalens is a divergent member of the heme-copper oxidases superfamily, namely, concerning the putative channels for intraprotein proton conduction. in this study, we used electrochemically induced ftir difference spectroscopy to identify residues involved in redox-coupled protonation changes. in the spectral region characteristic for the nu(c=o) mode from protonated aspartic or glutamic acid side chains, a number of prominent features can be observ ...	2003	12755620
protein-protein, protein-rna and protein-lipid interactions of signal-recognition particle components in the hyperthermoacidophilic archaeon acidianus ambivalens.	the signal-recognition particle (srp) of one of the most acidophilic and hyperthermophilic archaeal cells, acidianus ambivalens, and its putative receptor component, ftsy (prokaryotic srp receptor), were investigated in detail. a. ambivalens ffh (fifty-four-homologous protein) was shown to be a soluble protein with strong affinity to membranes. in its membrane-residing form, ffh was extracted from plasma membranes with chaotropic agents like urea, but not with agents diminishing electrostatic in ...	2003	12775213
membrane-bound hydrogenase and sulfur reductase of the hyperthermophilic and acidophilic archaeon acidianus ambivalens.	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 lo ...	2003	12949162
afv1, a novel virus infecting hyperthermophilic archaea of the genus acidianus.	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. ...	2003	14592760
occurrence, biochemistry and possible biotechnological application of the 3-hydroxypropionate cycle.	the 3-hydroxypropionate cycle, a pathway for autotrophic carbon dioxide fixation, is reviewed with special emphasis on the biochemistry of co2 fixing enzymes in acidianus brierleyi, a thermophilic and acidophilic archeon. in the 3-hydroxypropionate cycle, two enzymes, acetyl-coa carboxylase and propionyl-coa carboxylase, catalyze co2 fixation. it has been shown in a. brierleyi, and subsequently in metallosphaera sedula, that acetyl-coa carboxylase is promiscuous, acting equally well on acetyl-co ...	2004	14997352
the sulphur oxygenase reductase from acidianus ambivalens is a multimeric protein containing a low-potential mononuclear non-haem iron centre.	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 appr ...	2004	15030315
acidianus tengchongensis sp. nov., a new species of acidothermophilic archaeon isolated from an acidothermal spring.	a new thermoacidophilic, obligately chemolithotrophic, facultatively aerobic archaeon acidianus s5(t), was isolated from a tengchong acidothermal spring in southwestern china. it is a gram-negative, nonmotile, irregular coccoid organism with a cell diameter of 1.2 microm. the optimal ph and temperature for growth are 2.5 and 70 degrees c, respectively. under anaerobic conditions, the organism reduces elemental sulfur with molecular hydrogen, producing hydrogen sulfide. under aerobic conditions, ...	2004	15057486
active site structure of the aa3 quinol oxidase of acidianus ambivalens.	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 ...	2004	15100046
dissimilatory oxidation and reduction of elemental sulfur in thermophilic archaea.	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 ...	2004	15168612
coupling of the pathway of sulphur oxidation to dioxygen reduction: characterization of a novel membrane-bound thiosulphate:quinone oxidoreductase.	thiosulphate is one of the products of the initial step of the elemental sulphur oxidation pathway in the thermoacidophilic archaeon acidianus ambivalens. a novel thiosulphate:quinone oxidoreductase (tqo) activity was found in the membrane extracts of aerobically grown cells of this organism. the enzyme was purified 21-fold from the solubilized membrane fraction. the tqo oxidized thiosulphate with tetrathionate as product and ferricyanide or decyl ubiquinone (dq) as electron acceptors. the maxim ...	2004	15306018
theoretical identification of proton channels in the quinol oxidase aa3 from acidianus ambivalens.	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 ...	2004	15377522
studies on the degradation pathway of iron-sulfur centers during unfolding of a hyperstable ferredoxin: cluster dissociation, iron release and protein stability.	the ferredoxin from the thermoacidophile acidianus ambivalens is a representative of the archaeal family of di-cluster [3fe-4s][4fe-4s] ferredoxins. previous studies have shown that these ferredoxins are intrinsically very stable and led to the suggestion that upon protein unfolding the iron-sulfur clusters degraded via linear three-iron sulfur center species, with 610 and 520 nm absorption bands, resembling those observed in purple aconitase. in this work, a kinetic and spectroscopic investigat ...	2004	15578277
key role of cysteine residues in catalysis and subcellular localization of sulfur oxygenase-reductase of acidianus tengchongensis.	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 mutage ...	2005	15691910
the sulfur oxygenase reductase from acidianus ambivalens is an icosatetramer as shown by crystallization and patterson analysis.	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-crysta ...	2004	15698962
a rieske ferredoxin typifying a subtype within rieske proteins: spectroscopic, biochemical and stability studies.	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 f ...	2005	15710385
diversity of thermophilic and non-thermophilic crenarchaeota at 80 degrees c.	a hot spring in the solfataric field of pisciarelli (naples-italy) was analysed for archaeal diversity. total dna was extracted from the environment, archaeal 16s rrna genes were amplified with archaea specific primers, and a clone library consisting of 201 clones was established. the clones were grouped in 10 different groups each representing a specific band pattern using restriction fragment length polymorphism (rflp). members of all 10 groups were sequenced and phylogenetically analyzed. sur ...	2005	15727822
a novel rudivirus, arv1, of the hyperthermophilic archaeal genus acidianus.	virus arv1, the first member of the family rudiviridae infecting hyperthermophilic archaea of the genus acidianus, was isolated from a hot spring in pozzuoli, italy. the rod-shaped virions, 610 +/- 50 nm long and 22 +/- 3 nm wide, are non-enveloped and carry a helical nucleoprotein core, with three tail fibers protruding at each end which appear to be involved in adsorption onto the host cell surface. the virions contain two protein components, a major one of 14.4 kda, which is glycosylated and ...	2005	15866073
structure and genome organization of afv2, a novel archaeal lipothrixvirus with unusual terminal and core structures.	a novel filamentous virus, afv2, from the hyperthermophilic archaeal genus acidianus shows structural similarity to lipothrixviruses but differs from them in its unusual terminal and core structures. the double-stranded dna genome contains 31,787 bp and carries eight open reading frames homologous to those of other lipothrixviruses, a single trna(lys) gene containing a 12-bp archaeal intron, and a 1,008-bp repeat-rich region near the center of the genome.	2005	15901711
prokaryotic sulfur oxidation.	recent biochemical and genomic data differentiate the sulfur oxidation pathway of archaea from those of bacteria. from these data it is evident that members of the alphaproteobacteria harbor the complete sulfur-oxidizing sox enzyme system, whereas members of the beta and gamma subclass and the chlorobiaceae contain sox gene clusters that lack the genes encoding sulfur dehydrogenase. this indicates a different pathway for oxidation of sulfur to sulfate. acidophilic bacteria oxidize sulfur by a sy ...	2005	15939347
identification of core active site residues of the sulfur oxygenase reductase from acidianus ambivalens by site-directed mutagenesis.	the sulfur oxygenase reductase (sor) is the initial enzyme in the sulfur oxidation pathway of acidianus ambivalens. the sor is composed of 308 aa residues, three of which are cysteines, and contains a mononuclear non-heme iron site. mutations of the suspected iron-binding residues h86, h90 and e114 to alanine resulted in inactive enzyme with no iron incorporated, whereas an e114d mutant showed 1% of wild type activity. the mutation of c31 to alanine and serine caused inactivity of the enzyme, ho ...	2005	15970399
viral diversity in hot springs of pozzuoli, italy, and characterization of a unique archaeal virus, acidianus bottle-shaped virus, from a new family, the ampullaviridae.	virus-like particles with five different morphotypes were observed in an enriched environmental sample from a hot, acidic spring (87 to 93 degrees c, ph 1.5) in pozzuoli, italy. the morphotypes included rigid rods, flexible filaments, and novel, exceptional forms. particles of each type were isolated, and they were shown to represent viable virions of five novel viruses which infect members of the hyperthermophilic archaeal genus acidianus. one of these, named the acidianus bottle-shaped virus, ...	2005	16014951
virology: independent virus development outside a host.	viruses are thought to be functionally inactive once they are outside and independent of their host cell. here we describe an exceptional property of a newly discovered virus that infects a hyperthermophilic archaeon growing in acidic hot springs: the lemon-shaped viral particle develops a very long tail at each of its pointed ends after being released from its host cell. the process occurs only at the temperature of the host's habitat (75-90 degrees c) and it does not require the presence of th ...	2005	16121167
structure and coordination of cub in the acidianus ambivalens aa3 quinol oxidase heme-copper center.	the coordination environment of the cu(b) center of the quinol oxidase from acidianus ambivalens, a type b heme-copper oxygen reductase, was investigated by fourier transform (ft) ir and extended x-ray absorption fine structure (exafs) spectroscopy. the comparative structural chemistry of dinuclear fe-cu sites of the different types of oxygen reductases is of great interest. fully reduced a. ambivalens quinol oxidase binds co at the heme a (3) center, with nu(co)=1,973 cm(-1). on photolysis, the ...	2005	16163550
midpoint potentials of hemes a and a3 in the quinol oxidase from acidianus ambivalens are inverted.	the aa3 type b oxygen reductase from the thermophilic archaeon acidianus ambivalens (qo) was immobilized on silver electrodes and studied by potential-dependent surface-enhanced resonance raman (serr) spectroscopy. the immobilized enzyme retains the native structure at the level of the heme pockets and exhibits reversible electrochemistry. from the potential dependence of specific spectral marker bands, the midpoint potentials of hemes a and a3 were unambiguously determined for the first time, b ...	2005	16190720
crystallisation and preliminary structure determination of a nadh: quinone oxidoreductase from the extremophile acidianus ambivalens.	nadh:quinone oxidoreductases (ndhs), constitute one of the electron entry points into membrane-bound respiratory chains, oxidising nadh and reducing quinones. type-ii ndhs (ndh-2) are functionally unable to translocate protons and are typically constituted by a single approximately 50 kda subunit lacking iron-sulfur clusters and containing one flavin as the sole redox centre. no three dimensional crystal structure is yet available for ndhs. we describe the crystallisation and preliminary structu ...	2006	16303338
coal depyritization by the thermophilic archaeon metallosphaera sedula.	the kinetics of pyrite oxidation by metallosphaera sedula were investigated with mineral pyrite and two coals with moderate (pittsburgh no. 8) and high (new brunswick, canada) pyritic sulfur content. m. sedula oxidized mineral pyrite at a greater rate than did another thermophile, acidianus brierleyi, or a mesophile, thiobacillus ferrooxidans. maximum rates of coal depyritization were also greater with m. sedula, although the magnitude of biological stimulation above abiotic rates was notably le ...	1993	16349006
production of recombinant and tagged proteins in the hyperthermophilic archaeon sulfolobus solfataricus.	many systems are available for the production of recombinant proteins in bacterial and eukaryotic model organisms, which allow us to study proteins in their native hosts and to identify protein-protein interaction partners. in contrast, only a few transformation systems have been developed for archaea, and no system for high-level gene expression existed for hyperthermophilic organisms. recently, a virus-based shuttle vector with a reporter gene was developed for the crenarchaeote sulfolobus sol ...	2006	16391031
x-ray structure of a self-compartmentalizing sulfur cycle metalloenzyme.	numerous microorganisms oxidize sulfur for energy conservation and contribute to the global biogeochemical sulfur cycle. we have determined the 1.7 angstrom-resolution structure of the sulfur oxygenase reductase from the thermoacidophilic archaeon acidianus ambivalens, which catalyzes an oxygen-dependent disproportionation of elemental sulfur. twenty-four monomers form a large hollow sphere enclosing a positively charged nanocompartment. apolar channels provide access for linear sulfur species. ...	2006	16484493
novel thermostable y-family polymerases: applications for the pcr amplification of damaged or ancient dnas.	for many years, taq polymerase has served as the stalwart enzyme in the pcr amplification of dna. however, a major limitation of taq is its inability to amplify damaged dna, thereby restricting its usefulness in forensic applications. in contrast, y-family dna polymerases, such as dpo4 from sulfolobus solfataricus, can traverse a wide variety of dna lesions. here, we report the identification and characterization of five novel thermostable dpo4-like enzymes from acidianus infernus, sulfolobus sh ...	2006	16488882
rapid specific detection and quantification of bacteria and archaea involved in mineral sulfide bioleaching using real-time pcr.	a sybrgreen real-time pcr assay was developed to detect and quantify both total and selected 16s rdna species of bacteria and archaea involved in the bioleaching of metals from sulfide ores. a set of specific and universal primers based on 16s rdna sequences was designed and validated for specific detection and quantification of dna isolated from representative strains of acidianus brierleyi, sulfolobus sp., sulfobacillus thermosulfidooxidans, sulfobacillus acidophilus, acidithiobacillus caldus, ...	2006	16508994
structural and genomic properties of the hyperthermophilic archaeal virus atv with an extracellular stage of the reproductive cycle.	a novel virus, atv, of the hyperthermophilic archaeal genus acidianus has the unique property of undergoing a major morphological development outside of, and independently of, the host cell. virions are extruded from host cells as lemon-shaped tail-less particles, after which they develop long tails at each pointed end, at temperatures close to that of the natural habitat, 85 degrees c. the extracellularly developed tails constitute tubes, which terminate in an anchor-like structure that is not ...	2006	16677670
archaeal diversity in two thermophilic chalcopyrite bioleaching reactors.	this study used a culture-independent molecular approach to investigate the archaeal community composition of thermophilic bioleaching reactors. two culture samples, mtc-a and mtc-b, grown with different concentrations of chalcopyrite (cufes2), a copper sulfidic ore, at a temperature of 78 degrees c and ph 1.6 were studied. phylogenetic analysis of the 16s rrna genes revealed that both cultures consisted of archaea belonging to the sulfolobales. the 16s rrna gene clone library of mtc-a grown wit ...	2006	17014503
acidianus manzaensis sp. nov., a novel thermoacidophilic archaeon growing autotrophically by the oxidation of h2 with the reduction of fe3+.	a novel thermoacidophilic iron-reducing archaeon, strain na-1, was isolated from a hot fumarole in manza, japan. strain na-1 could grow autotrophically using h2 or s0 as an electron donor and fe3+ as an electron acceptor, and also could grow heterotrophically using some organic compounds. fe3+ and o2 served as electron acceptors for growth. however, s0, no3-, no2-, so4(2-), mn4+, fumarate, and fe2o3 did not serve as electron acceptors. the ranges of growth temperature and ph were 60-90 degrees c ...	2006	17066338
crystal structure of afv3-109, a highly conserved protein from crenarchaeal viruses.	the extraordinary morphologies of viruses infecting hyperthermophilic archaea clearly distinguish them from bacterial and eukaryotic viruses. moreover, their genomes code for proteins that to a large extend have no related sequences in the extent databases. however, a small pool of genes is shared by overlapping subsets of these viruses, and the most conserved gene, exemplified by the orf109 of the acidianus filamentous virus 3, afv3, is present on genomes of members of three viral familes, the ...	2007	17241456
ferrous iron- and sulfur-induced genes in sulfolobus metallicus.	genes of sulfolobus metallicus that appeared to be upregulated in relation to growth on either ferrous iron or sulfur were identified using subtractive hybridization of cdnas. the genes upregulated during growth on ferrous iron were found in a cluster, and most were predicted to encode membrane proteins. quantitative reverse transcription-pcr of cdna showed upregulation of most of these genes during growth on ferrous iron and pyrite compared to results during growth on sulfur. the highest expres ...	2007	17322327
genome of the acidianus bottle-shaped virus and insights into the replication and packaging mechanisms.	the acidianus bottle-shaped virus, abv, infects strains of the hyperthermophilic archaeal genus acidianus and is morphologically distinct from all other known viruses. its genome consists of linear double-stranded dna, containing 23,814 bp with a g+c content of 35%, and it exhibits a 590-bp inverted terminal repeat. of the 57 predicted orfs, only three produced significant matches in public sequence databases with genes encoding a glycosyltransferase, a thymidylate kinase and a protein-primed dn ...	2007	17412384
studies of the molten globule state of ferredoxin: structural characterization and implications on protein folding and iron-sulfur center assembly.	the biological insertion of iron-sulfur clusters (fe-s) involves the interaction of (metallo) chaperons with a partly folded target polypeptide. in this respect, the study of nonnative protein conformations in iron-sulfur proteins is relevant for the understanding of the folding process and cofactor assembly. we have investigated the formation of a molten globule state in the [3fe4s][4fe4s] ferredoxin from the thermophilic archaeon acidianus ambivalens (aafd), which also contains a structural zi ...	2007	17510960
acidianus sulfidivorans sp. nov., an extremely acidophilic, thermophilic archaeon isolated from a solfatara on lihir island, papua new guinea, and emendation of the genus description.	a novel, extremely thermoacidophilic, obligately chemolithotrophic archaeon (strain jp7(t)) was isolated from a solfatara on lihir island, papua new guinea. cells of this organism were non-motile, gram-negative staining, irregular-shaped cocci, 0.5-1.5 microm in size, that grew aerobically by oxidation of sulfur, fe(2+) or mineral sulfides. cells grew anaerobically using fe(3+) as a terminal electron acceptor and h(2)s as an electron donor but did not oxidize hydrogen with elemental sulfur as el ...	2007	17625168
a spectroscopic study of the temperature induced modifications on ferredoxin folding and iron-sulfur moieties.	thermal perturbation of the dicluster ferredoxin from acidianus ambivalens was investigated employing a toolbox of spectroscopic methods. ftir and visible cd were used for assessing changes of the secondary structure and coarse alterations of the [3fe4s] and [4fe4s] cluster moieties, respectively. fine details of the disassembly of the metal centers were revealed by paramagnetic nmr and resonance raman spectroscopy. overall, thermally induced unfolding of aafd is initiated with the loss of -heli ...	2007	17696500
structure of the acidianus filamentous virus 3 and comparative genomics of related archaeal lipothrixviruses.	four novel filamentous viruses with double-stranded dna genomes, namely, acidianus filamentous virus 3 (afv3), afv6, afv7, and afv8, have been characterized from the hyperthermophilic archaeal genus acidianus, and they are assigned to the betalipothrixvirus genus of the family lipothrixviridae. the structures of the approximately 2-mum-long virions are similar, and one of them, afv3, was studied in detail. it consists of a cylindrical envelope containing globular subunits arranged in a helical f ...	2008	17942536
crystallographic analysis of the intact metal centres [3fe-4s](1+/0) and [4fe-4s](2+/1+) in a zn(2+) -containing ferredoxin.	detailed structural models of di-cluster seven-iron ferredoxins constitute a valuable resource for folding and stability studies relating the metal cofactors' role in protein stability. the here reported, hemihedric twinned crystal structure at 2.0 a resolution from acidianus ambivalens ferredoxin, shows an integral 103 residues, physiologically relevant native form composed by a n-terminal extension comprising a his/asp zn(2+) site and the ferredoxin (betaalphabeta)(2) core, which harbours inta ...	2008	18258200
the dihydrolipoamide dehydrogenase from the crenarchaeon acidianus ambivalens.	a dihydrolipoamide dehydrogenase (dldh) was purified and characterized for the first time from a crenarchaeon, acidianus ambivalens. the holoenzyme consists of two identical subunits with a molecular mass of 45.4 kda per monomer. it contains fad as a prosthetic group and uses nad+ as the preferential substrate, but can also reduce nadp+. the michaelis-menten constants of the forward (nad+ reduction) and reverse (nadh oxidation) reactions were km (dihydrolipoamide)=0.70 mm, km (nad+)=0.71 mm, km ...	2008	18312361
crystal structure studies on sulfur oxygenase reductase from acidianus tengchongensis.	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 path ...	2008	18329378
cell cycle characteristics of crenarchaeota: unity among diversity.	the hyperthermophilic archaea acidianus hospitalis, aeropyrum pernix, pyrobaculum aerophilum, pyrobaculum calidifontis, and sulfolobus tokodaii representing three different orders in the phylum crenarchaeota were analyzed by flow cytometry and combined phase-contrast and epifluorescence microscopy. the overall organization of the cell cycle was found to be similar in all species, with a short prereplicative period and a dominant postreplicative period that accounted for 64 to 77% of the generati ...	2008	18502873
on the relative contribution of ionic interactions over iron-sulfur clusters to ferredoxin stability.	metal centres play an important structural role in maintaining the native conformation of a protein. here we use biophysical methods to investigate what is the relative contribution of iron-sulfur clusters in respect to ionic interactions in a thermophilic di-cluster ferredoxin model. changes in protonation affect both the stability and the conformational dynamics of the protein fold. in the ph 5.5-8 interval, the protein has a high melting temperature (t(m) approximately 120 degrees c), which d ...	2008	18534203
comparative architecture of octahedral protein cages. i. indexed enclosing forms.	the architectural elements of four protein cages (bacterio ferritin, human mitochondrial ferritin, sulfur oxygenase reductase and small heat-shock protein) are compared top-to-bottom. the starting points are polyhedra with octahedral symmetry 432 enclosing the cage and delimiting the central cavity, respectively, which have vertices at points of a species-dependent cubic form lattice. the approach is extended from the whole cage to axial-symmetric clusters down to polyhedral forms of single mono ...	2008	18560166
comparative architecture of octahedral protein cages. ii. interplay between structural elements.	in paper i [janner (2008). acta cryst. a64, 494-502], the enclosing forms of the monomers of four octahedral holoenzymes (bacterio and mitochondrial ferritins, small heat-shock protein and sulfur oxygenase reductase) were derived, with vertices at points of a cubic lattice and indexed accordingly. the correspondence between vertices and neighboring residues allows a sequential ordering of the vertices within the polyline defined by the c(alpha) atoms of the primary structure. the alignment of th ...	2008	18560167
viruses in acidic geothermal environments of the kamchatka peninsula.	screening for viruses in samples taken from acidic hot springs of kamchatka (russia) revealed a collection of morphotypes, including linear, spherical and complex fusiform shapes, which show partial similarity to those found in acidic geothermal environments in other geographical locations. one of the viruses, acidianus filamentous virus 9, afv9, was isolated and its structure and genome were studied in detail.	2008	18565736