Publications

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
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
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 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
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
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
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
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
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
bioleaching of pyrite by acidophilic thermophile acidianus brierleyi.	the kinetics of bioleaching of pyrite (fes(2)) by the acidophilic thermophilic bacterium acidianus brierleyi was studied in a well-mixed batch reactor. experiments were done at 65 degrees c and ph 1.5 on adsorption of a. brierleyi onto pyrite particles, liquid-phase oxidation of ferrous iron by a. brierleyi, and microbial leaching of pyrite. the adsorption of a. brierleyi was a fast process; equilibrium was attained within the first 30 min of exposure to pyrite. the adsorption equilibrium data w ...	1995	18623527
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
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
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
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