| structural and electronic factors in heterolytic cleavage: formation of the co(i) intermediate in the corrinoid/iron-sulfur protein from clostridium thermoaceticum. | we have completed the first direct structural characterization of an enzyme-bound four-coordinate co(i) intermediate, in this case for the corrinoid/iron-sulfur protein (c/fe-sp) from clostridium thermoaceticum. extended x-ray absorption fine structure and x-ray edge spectroscopy of the active co(i) state of the c/fe-sp indicates a four-coordinate (distorted) square-planar structure where the best fit gives average co-n(equatorial) distances of 1.87 +/- 0.01 a, corresponding to 4.2 +/- 0.3 ligan ... | 1995 | 7711048 |
| the reductive acetyl coenzyme a pathway: sequence and heterologous expression of active methyltetrahydrofolate:corrinoid/iron-sulfur protein methyltransferase from clostridium thermoaceticum. | the methyltransferase (metr) from clostridium thermoaceticum transfers the n5-methyl group of (6s)-methyltetrahydrofolate to the cobalt center of a corrinoid/iron-sulfur protein in the acetyl coenzyme a pathway. metr was purified to homogeneity and shown to lack metals. the acse gene encoding metr was sequenced and actively expressed in escherichia coli at a level of 9% of cell protein. regions in the sequence of metr and the e. coli cobalamin-dependent methionine synthase were found to share si ... | 1994 | 7928975 |
| the phylogeny of the genus clostridium: proposal of five new genera and eleven new species combinations. | the 16s rrna gene sequences of 34 named and unnamed clostridial strains were determined by pcr direct sequencing and were compared with more than 80 previously determined clostridial sequences and the previously published sequences of representative species of other low- g + c-content gram-positive genera, thereby providing an almost complete picture of the genealogical interrelationships of the clostridia. the results of our phylogenetic analysis corroborate and extend previous findings in show ... | 1994 | 7981107 |
| sequence and expression of the gene encoding the corrinoid/iron-sulfur protein from clostridium thermoaceticum and reconstitution of the recombinant protein to full activity. | the corrinoid/iron-sulfur protein (c/fe-sp) from clostridium thermoaceticum acts as a methyl group carrier in the anaerobic acetyl-coa pathway of co and co2 fixation. consisting of a small (approximately 33 kda) and a large (approximately 55 kda) subunit, the c/fe-sp contains 1 mol of cobalt in a corrinoid cofactor and 1 mol of [4fe-4s]2+/1+ cluster/mol of alpha beta dimer. cobalt is the site of methylation, and the [4fe-4s] center appears to serve an electron transfer function. the genes encodi ... | 1993 | 8449924 |
| isolation and characterization of the homoacetogenic thermophilic bacterium moorella glycerini sp. nov. | a thermophilic, anaerobic, spore-forming bacterium (strain jw/as-y6t) was isolated from a mixed sediment-water sample from a hot spring (calcite spring area) at yellowstone national park. the vegetative cells of this organism were straight rods, 0.4 to 0.6 by 3.0 to 6.5 microns. cells occurred singly and exhibited a slight tumbling motility. they formed round refractile endospores in terminal swollen sporangia. cells stained gram positive. the temperature range for growth at ph 6.8 was 43 to 65 ... | 1997 | 9336894 |
| carbonic anhydrase in acetobacterium woodii and other acetogenic bacteria. | acetobacterium woodii, acetohalobium arabaticum, clostridium formicoaceticum, and sporomusa silvacetica were found to contain carbonic anhydrase (ca). minimal to no ca activity was detected in moorella thermoautotrophica, moorella thermoacetica subsp. "pratumsolum," sporomusa termitida, and thermoanaerobacter kivui. of the acetogens tested, a. woodii had the highest ca specific activity, approximately 14 u mg of protein(-1), in extracts of either glucose- or h2-co2-cultivated cells. ca of a. woo ... | 1997 | 9371472 |
| role of the [4fe-4s] cluster in reductive activation of the cobalt center of the corrinoid iron-sulfur protein from clostridium thermoaceticum during acetate biosynthesis. | the corrinoid iron-sulfur protein (cfesp) from clostridium thermoaceticum functions as a methyl carrier in the wood-ljungdahl pathway of acetyl-coa synthesis. the small subunit (33 kda) contains cobalt in a corrinoid cofactor, and the large subunit (55 kda) contains a [4fe-4s] cluster. the cobalt center is methylated by methyltetrahydrofolate (ch3-h4folate) to form a methylcobalt intermediate and, subsequently, is demethylated by carbon monoxide dehydrogenase/acetyl-coa synthase (codh/acs). the ... | 1998 | 9548955 |
| bacterial selenocysteine synthase--structural and functional properties. | selenocysteine synthase from escherichia coli is a pyridoxal-5'-phosphate-containing enzyme which catalyses the conversion of seryl-trna(sec) into selenocysteyl-trna(sec). analysis of amino acid sequences indicated that selenocysteine synthase belongs to the alpha/gamma superfamily of pyridoxal-5'-phosphate-dependent enzymes. to identify the lysine residue carrying the prosthetic group, the genes coding for the selenocysteine synthases from moorella thermoacetica and desulfomicrobium baculatum w ... | 1998 | 9688279 |
| the role of an iron-sulfur cluster in an enzymatic methylation reaction. methylation of co dehydrogenase/acetyl-coa synthase by the methylated corrinoid iron-sulfur protein. | this paper focuses on how a methyl group is transferred from a methyl-cobalt(iii) species on one protein (the corrinoid iron-sulfur protein (cfesp)) to a nickel iron-sulfur cluster on another protein (carbon monoxide dehydrogenase/acetyl-coa synthase). this is an essential step in the wood-ljungdahl pathway of anaerobic co and co2 fixation. the results described here strongly indicate that transfer of methyl group to carbon monoxide dehydrogenase/acetyl-coa synthase occurs by an sn2 pathway. the ... | 1999 | 10206956 |
| the energy conserving methyltetrahydromethanopterin:coenzyme m methyltransferase complex from methanogenic archaea: function of the subunit mtrh. | in methanogenic archaea the transfer of the methyl group of n5-methyltetrahydromethanopterin to coenzyme m is coupled with energy conservation. the reaction is catalyzed by a membrane associated multienzyme complex composed of eight different subunits mtra-h. the 23 kda subunit mtra harbors a corrinoid prosthetic group which is methylated and demethylated in the catalytic cycle. we report here that the 34 kda subunit mtrh catalyzes the methylation reaction. mtrh was purified and shown to exhibit ... | 1999 | 10338124 |
| thermicanus aegyptius gen. nov., sp. nov., isolated from oxic soil, a fermentative microaerophile that grows commensally with the thermophilic acetogen moorella thermoacetica. | a thermophilic, fermentative microaerophile (et-5b) and a thermophilic acetogen (et-5a) were coisolated from oxic soil obtained from egypt. the 16s rrna gene sequence of et-5a was 99.8% similar to that of the classic acetogen moorella thermoacetica. further analyses confirmed that et-5a was a new strain of m. thermoacetica. for et-5b, the nearest 16s rrna gene sequence similarity value to known genera was approximately 88%. et-5b was found to be a motile rod with a genomic g+c content of 50.3 mo ... | 1999 | 10543831 |
| the crystal structure of n(10)-formyltetrahydrofolate synthetase from moorella thermoacetica. | the structure was solved at 2.5 a resolution using multiwavelength anomalous dispersion (mad) scattering by se-met residues. the subunit of n(10)-formyltetrahydrofolate synthetase is composed of three domains organized around three mixed beta-sheets. there are two cavities between adjacent domains. one of them was identified as the nucleotide binding site by homology modeling. the large domain contains a seven-stranded beta-sheet surrounded by helices on both sides. the second domain contains a ... | 2000 | 10747779 |
| anaerobic thermophilic fermentation for acetic acid production from milk permeate. | fermentation of milk permeate to produce acetic acid under anaerobic thermophilic conditions (approximately 60 degrees c) was studied. although none of the known thermophilic acetogenic bacteria can ferment lactose, it has been found that one strain can use galactose and two strains can use lactate. moorella thermoautotrophica dsm 7417 and m. thermoacetica dsm 2955 were able to convert lactate to acetate at thermophilic temperatures with a yield of approximately 0.93 g g(-1). among the strains s ... | 2000 | 10784299 |
| cation binding and thermostability of fthfs monovalent cation binding sites and thermostability of n10-formyltetrahydrofolate synthetase from moorella thermoacetica. | formyltetrahydrofolate synthetase (fthfs) from the thermophilic homoacetogen, moorella thermoacetica, has an optimum temperature for activity of 55-60 degrees c and requires monovalent cations for both optimal activity and stabilization of tetrameric structure at higher temperatures. the crystal structures of complexes of fthfs with cesium and potassium ions were examined and monovalent cation binding positions identified. unexpectedly, nh(4)(+) and k(+), both of which are strongly activating io ... | 2000 | 11087401 |
| acetic acid production from lactose by an anaerobic thermophilic coculture immobilized in a fibrous-bed bioreactor. | an anaerobic thermophilic coculture consisting of a heterofermentative bacterium (clostridium thermolacticum) and a homoacetogen (moorella thermoautotrophica) was developed for acetic acid production from lactose and milk permeate. the fermentation kinetics with free cells in conventional fermentors and immobilized cells in a recycle batch fibrous-bed bioreactor were studied. the optimal conditions for the cocultured fermentation were found to be 58 degrees c and ph 6.4. in the free-cell ferment ... | 2000 | 11101328 |
| novel strains of moorella thermoacetica form unusually heat-resistant spores. | two strains of moorella thermoacetica, jw/b-2 and jw/db-4, isolated as contaminants from autoclaved media for chemolithoautotrophic growth containing 0.1% (wt/vol) yeast extract, formed unusually heat-resistant spores. spores of the two strains required heat activation at 100 degrees c of more than 2 min and up to 90 min for maximal percentage of germination. kinetic analysis indicated the presence of two distinct subpopulations of heat-resistant spores. the decimal reduction time (d10-time=time ... | 2000 | 11131023 |
| five-gene cluster in clostridium thermoaceticum consisting of two divergent operons encoding rubredoxin oxidoreductase- rubredoxin and rubrerythrin-type a flavoprotein- high-molecular-weight rubredoxin. | a five-gene cluster encoding four nonheme iron proteins and a flavoprotein from the thermophilic anaerobic bacterium clostridium thermoaceticum (moorella thermoacetica) was cloned and sequenced. based on analysis of deduced amino acid sequences, the genes were identified as rub (rubredoxin), rbo (rubredoxin oxidoreductase), rbr (rubrerythrin), fpra (type a flavoprotein), and a gene referred to as hrb (high-molecular-weight rubredoxin). northern blot analysis demonstrated that the five-gene clust ... | 2001 | 11160086 |
| polyamines of the thermophilic eubacteria belonging to the genera thermosipho, thermaerobacter and caldicellulosiruptor. | cellular polyamines of four new thermophiles located in three early branched eubacterial clades, were investigated for the chemotaxonomic significance of polyamine distribution profiles. the thermophilic anaerobic thermosipho japonicus, belonging to the order thermotogales, contained norspermidine, norspermine and thermospermine in addition to spermidine and spermine. the polyamine profile was identical to the polyamine composition of thermotoga, fervidobacterium and petrotoga species of the ord ... | 2001 | 11327112 |
| characterization of a three-component vanillate o-demethylase from moorella thermoacetica. | the moorella thermoacetica aromatic o-demethylase was characterized as an inducible three-component system with similarity to the methanogenic methanol, methylamine, and methanethiol methyltransferases and to the o-demethylase system from acetobacterium dehalogenans. mtvb catalyzes methyl transfer from a phenylmethylether to the cobalt center of mtvc, a corrinoid protein. mtva catalyzes transmethylation from mtvc to tetrahydrofolate, forming methyltetrahydrofolate. cobalamin can substitute for m ... | 2001 | 11344134 |
| separation of a phenol carboxylating organism from a two-member, strict anaerobic co-culture. | in a culture converting phenol to benzoic acid under anaerobic conditions and previously described as being constituted of only a clostridium-like strain 6, another bacterium (strain 7) was observed. each organism was enriched by centrifugation on a percoll gradient. strain 6 was purified by dilution and plating. strain 7 did not grow on solid media, but a strain 7 culture, cleared of strain 6, was obtained by subculturing in the presence of ampicillin and by dilution. in fresh medium, phenol wa ... | 2001 | 11400726 |
| isolation and characterization of a soluble nadph-dependent fe(iii) reductase from geobacter sulfurreducens. | nadph is an intermediate in the oxidation of organic compounds coupled to fe(iii) reduction in geobacter species, but fe(iii) reduction with nadph as the electron donor has not been studied in these organisms. crude extracts of geobacter sulfurreducens catalyzed the nadph-dependent reduction of fe(iii)-nitrilotriacetic acid (nta). the responsible enzyme, which was recovered in the soluble protein fraction, was purified to apparent homogeneity in a four-step procedure. its specific activity for f ... | 2001 | 11443080 |
| acetyl coenzyme a synthesis from unnatural methylated corrinoids: requirement for "base-off" coordination at cobalt. | | 2001 | 11456791 |
| tolerance and metabolic response of acetogenic bacteria toward oxygen. | the acetogens sporomusa silvacetica, moorella thermoacetica, clostridium magnum, acetobacterium woodii, and thermoanaerobacter kivui (i) grew in both semisolid and liquid cultivation media containing o(2) and (ii) consumed small amounts of o(2). low concentrations of o(2) caused a lag phase in growth but did not alter the ability of these acetogens to synthesize acetate via the acetyl coenzyme a pathway. cell extracts of s. silvacetica, m. thermoacetica, and c. magnum contained peroxidase and na ... | 2002 | 11823254 |
| gelria glutamica gen. nov., sp. nov., a thermophilic, obligately syntrophic, glutamate-degrading anaerobe. | a novel anaerobic, gram-positive, thermophilic, spore-forming, obligately syntrophic, glutamate-degrading bacterium, strain tgo(t), was isolated from a propionate-oxidizing methanogenic enrichment culture. the axenic culture was obtained by growing the bacterium on pyruvate. cells were rod-shaped and non-motile. the optimal temperature for growth was 50-55 degrees c and growth occurred between 37 and 60 degrees c. the ph range for growth was 5.5-8 with optimum growth at ph 7. in pure culture, st ... | 2002 | 11931148 |
| stopped-flow kinetics of methyl group transfer between the corrinoid-iron-sulfur protein and acetyl-coenzyme a synthase from clostridium thermoaceticum. | kinetics of methyl group transfer between the ni-fe-s-containing acetyl-coa synthase (acs) and the corrinoid protein (cofesp) from clostridium thermoaceticum were investigated using the stopped-flow method at 390 nm. rates of the reaction ch(3)-co(3+)fesp + acs(red) <==> co(1+)fesp + ch(3)-acs(ox) in both forward and reverse directions were determined using various protein and reductant concentrations. ti(3+)citrate, dithionite, and co were used to reductively activate acs (forming acs(red)). th ... | 2002 | 12033855 |
| crystal structure of an mrna-binding fragment of moorella thermoacetica elongation factor selb. | selb is an elongation factor needed for the co-translational incorporation of selenocysteine. selenocysteine is coded by a uga stop codon in combination with a specific downstream mrna hairpin. in bacteria, the c-terminal part of selb recognizes this hairpin, while the n-terminal part binds gtp and trna in analogy with elongation factor tu (ef-tu). we present the crystal structure of a c-terminal fragment of selb (selb-c) from moorella thermoacetica at 2.12 a resolution, solved by a combination ... | 2002 | 12145214 |
| preparation of a crystallizable mrna-binding fragment of moorella thermoacetica elongation factor selb. | selb is a bacterial elongation factor required for the decoding of a uga stop codon together with a specific mrna hairpin to selenocysteine. in attempts to crystallize moorella thermoacetica selb, a proteolysis process occurred and crystals of a proteolytic fragment were observed. the crystals, which appeared after a year, contained a c-terminal 30 kda fragment containing the mrna-binding domain. this fragment was reproduced through recloning. crystals diffracting to 2.7 a were obtained. | 2002 | 12351842 |
| a ni-fe-cu center in a bifunctional carbon monoxide dehydrogenase/acetyl-coa synthase. | a metallocofactor containing iron, sulfur, copper, and nickel has been discovered in the enzyme carbon monoxide dehydrogenase/acetyl-coa (coenzyme a) synthase from moorella thermoacetica (f. clostridium thermoaceticum). our structure at 2.2 angstrom resolution reveals that the cofactor responsible for the assembly of acetyl-coa contains a [fe4s4] cubane bridged to a copper-nickel binuclear site. the presence of these three metals together in one cluster was unanticipated and suggests a newly dis ... | 2002 | 12386327 |
| influence of nitrate on oxalate- and glyoxylate-dependent growth and acetogenesis by moorella thermoacetica. | oxalate and glyoxylate supported growth and acetate synthesis by moorella thermoacetica in the presence of nitrate under basal (without yeast extract) culture conditions. in oxalate cultures, acetate formation occurred concomitant with growth and nitrate was reduced in the stationary phase. growth in the presence of [(14)c]bicarbonate or [(14)c]oxalate showed that co(2) reduction to acetate and biomass or oxalate oxidation to co(2) was not affected by nitrate. however, cells engaged in oxalate-d ... | 2002 | 12420166 |
| reduction and methyl transfer kinetics of the alpha subunit from acetyl coenzyme a synthase. | stopped-flow was used to evaluate the methylation and reduction kinetics of the isolated alpha subunit of acetyl-coenzyme a synthase from moorella thermoacetica. this catalytically active subunit contains a novel ni-x-fe4s4 cluster and a putative unidentified n = 2 redox site called d. the d-site must be reduced for a methyl group to transfer from a corrinoid-iron-sulfur protein, a key step in the catalytic synthesis of acetyl-coa. the fe4s4 component of this cluster is also redox active, raisin ... | 2003 | 12517128 |
| functional copper at the acetyl-coa synthase active site. | the bifunctional co dehydrogenase/acetyl-coa synthase (codh/acs) plays a central role in the wood-ljungdahl pathway of autotrophic co(2) fixation. a recent structure of the moorella thermoacetica enzyme revealed that the acs active site contains a [4fe-4s] cluster bridged to a binuclear cu-ni site. here, biochemical and x-ray absorption spectroscopic (xas) evidence is presented that the copper ion at the m. thermoacetica acs active site is essential. depletion of copper correlates with reduction ... | 2003 | 12589021 |
| the tungsten-containing formate dehydrogenase from methylobacterium extorquens am1: purification and properties. | nad-dependent formate dehydrogenase (fdh1) was isolated from the alpha-proteobacterium methylobacterium extorquens am1 under oxic conditions. the enzyme was found to be a heterodimer of two subunits (alpha1beta1) of 107 and 61 kda, respectively. the purified enzyme contained per mol enzyme approximately 5 mol nonheme iron and acid-labile sulfur, 0.6 mol noncovalently bound fmn, and approximately 1.8 mol tungsten. the genes encoding the two subunits of fdh1 were identified on the m. extorquens am ... | 2003 | 12605683 |
| a novel cellulolytic, anaerobic, and thermophilic bacterium, moorella sp. strain f21. | a cellulolytic and thermophilic anaerobe was isolated from soil. this bacterium made a halo on a roll-tube culture containing avicel. analysis of the pcr-based 16s rrna gene sequence showed that the bacterium was closely related to moorella thermoacetica. scanning electron microscopy showed the bacterium is a rod and has no protuberant structure on the surface of cells growing on cellulose, suggesting that this strain is a non-cellulosomal cellulolytic bacterium. carboxymethyl cellulase and xyla ... | 2003 | 12619693 |
| ni-zn-[fe4-s4] and ni-ni-[fe4-s4] clusters in closed and open subunits of acetyl-coa synthase/carbon monoxide dehydrogenase. | the crystal structure of the tetrameric alpha2beta2 acetyl-coenzyme a synthase/carbon monoxide dehydrogenase from moorella thermoacetica has been solved at 1.9 a resolution. surprisingly, the two alpha subunits display different (open and closed) conformations. furthermore, x-ray data collected from crystals near the absorption edges of several metal ions indicate that the closed form contains one zn and one ni at its active site metal cluster (a-cluster) in the alpha subunit, whereas the open f ... | 2003 | 12627225 |
| a flavodiiron protein and high molecular weight rubredoxin from moorella thermoacetica with nitric oxide reductase activity. | a five-gene "oxidative stress protection" cluster has recently been described from the strictly anaerobic, acetogenic bacterium, moorella thermoacetica [das, a., et al. (2001) j. bacteriol. 183, 1560-1567]. within this cluster are two cotranscribed genes, fpra (for a-type flavoprotein) and hrb (for high molecular weight rubredoxin) whose encoded proteins have no known functions. here we show that fpra and hrb are expressed in m. thermoacetica under normal anaerobic growth conditions and report c ... | 2003 | 12627946 |
| methanol utilization by a novel thermophilic homoacetogenic bacterium, moorella mulderi sp. nov., isolated from a bioreactor. | a thermophilic, anaerobic, spore-forming bacterium (strain tms) was isolated from a thermophilic bioreactor operated at 65 degrees c with methanol as the energy source. cells were gram-positive straight rods, 0.4-0.6 microm x 2-8 microm, growing as single cells or in pairs. the temperature range for growth was 40-70 degrees c with an optimum at 65 degrees c. growth was observed from ph 5.5 to 8.5, and the optimum ph was around 7. the salinity range for growth was 0-45 g nacl l(-1 )with an optimu ... | 2003 | 12637975 |
| nitrite as an energy-conserving electron sink for the acetogenic bacterium moorella thermoacetica. | nitrite served as an energy-conserving electron acceptor for the acetogenic bacterium moorella thermoacetica. growth occurred in an undefined (0.1% yeast extract) medium containing 20 m m glyoxylate and 5 m m nitrite and was essentially equivalent to that observed in the absence of nitrite. in the presence of nitrite, acetate (the normal product of glyoxylate-derived acetogenesis) was not detected during growth. instead, growth was coupled to nitrite dissimilation to ammonium, and acetogenesis w ... | 2003 | 12732959 |
| inactivation of acetyl-coa synthase/carbon monoxide dehydrogenase by copper. | two recent crystal structures of acetyl-coa synthase (acs) from moorella thermoacetica exhibited different metal contents and geometries at their active site, called the a-cluster. this led to the proposal of two catalytic mechanisms, one ni-based, the other cu-based. acs was studied with respect to synthase activity, methyl group transfer activity, metal content, and epr spectroscopy. our results indicate that cu is not required for catalysis and that it inactivates acs by binding to the proxim ... | 2003 | 12889960 |
| improvement of acetate production from lactose by growing clostridium thermolacticum in mixed batch culture. | the objective of this study was to increase the acetate production by clostridium thermolacticum growing on lactose, available as a renewable resource in the milk and whey permeate from the cheese industry. | 2003 | 12969297 |
| highly selective electrocatalytic conversion of co2 to co at -0.57 v (nhe) by carbon monoxide dehydrogenase from moorella thermoacetica. | we found that codh is a fascinating enzyme for the electrochemical conversion of co2 to co. it could reduce co2 to co at -0.57 v vs nhe with approximately 100% current efficiency in 0.1 m phosphate buffer (ph 6.3). nature's unique structure of c-cluster in codh would be responsible for the low overpotential and the selective and fast conversion of co2. the turnover number per c-cluster is 700 h-1, and the ph optimum is 6.3. | 2003 | 14640627 |
| infrared studies of carbon monoxide binding to carbon monoxide dehydrogenase/acetyl-coa synthase from moorella thermoacetica. | carbon monoxide dehydrogenase/acetyl-coa synthase (codh/acs) is a bifunctional enzyme that catalyzes the reversible reduction of carbon dioxide into carbon monoxide and the coupled synthesis of acetyl-coa from the carbon monoxide produced. exposure of codh/acs from moorella thermoacetica to carbon monoxide gives rise to several infrared bands in the 2100-1900 cm(-1) spectral region that are attributed to the formation of metal-coordinated carbon monoxide species. infrared bands attributable to m ... | 2003 | 14674756 |
| a functional ni-ni-[4fe-4s] cluster in the monomeric acetyl-coa synthase from carboxydothermus hydrogenoformans. | in anaerobic microorganisms employing the acetyl-coa pathway, acetyl-coa synthase (acs) and co dehydrogenase (codh) form a complex (acs/codh) that catalyzes the synthesis of acetyl-coa from co, a methyl group, and coa. previously, a [4fe-4s] cubane bridged to a copper-nickel binuclear site (active site cluster a of the acs component) was identified in the acs(mt)/codh(mt) from moorella thermoacetica whereas another study revealed a nickel-nickel site in the open form of acs(mt), and a zink-nicke ... | 2004 | 14699043 |
| oxalate metabolism by the acetogenic bacterium moorella thermoacetica. | whole-cell and cell-extract experiments were performed to study the mechanism of oxalate metabolism in the acetogenic bacterium moorella thermoacetica. in short-term, whole-cell assays, oxalate consumption was low unless cell suspensions were supplemented with co(2), kno(3), or na(2)s(2)o(3). cell extracts catalyzed the oxalate-dependent reduction of benzyl viologen. oxalate consumption occurred concomitant to benzyl viologen reduction; when benzyl viologen was omitted, oxalate was not appreciab ... | 2004 | 14769464 |
| autocatalytic activation of acetyl-coa synthase. | acetyl-coa synthase (acs identical with acs/codh identical with codh/acs) from moorella thermoacetica catalyzes the synthesis of acetyl-coa from co, coa, and a methyl group of a corrinoid-iron-sulfur protein (cofesp). a time lag prior to the onset of acetyl-coa production, varying from 4 to 20 min, was observed in assay solutions lacking the low-potential electron-transfer agent methyl viologen (mv). no lag was observed when mv was included in the assay. the length of the lag depended on the con ... | 2004 | 15015040 |
| evidence that nini acetyl-coa synthase is active and that the cuni enzyme is not. | the bifunctional co dehydrogenase/acetyl-coa synthase (codh/acs) plays a central role in the wood-ljungdahl pathway of autotrophic co(2) fixation. one structure of the moorella thermoacetica enzyme revealed that the active site of acs (the a-cluster) consists of a [4fe-4s] cluster bridged to a binuclear cuni center with cu at the proximal metal site (m(p)) and ni at the distal metal site (m(d)). in another structure of the same enzyme, ni or zn was present at m(p). on the basis of a positive cor ... | 2004 | 15049702 |
| carbon monoxide induced decomposition of the active site [ni-4fe-5s] cluster of co dehydrogenase. | during the past two years, crystal structures of cu- and mo-containing carbon monoxide dehydrogenases (codhs) and ni- and fe-containing codhs have been reported. the active site of codhs from anaerobic bacteria (cluster c) is composed of ni, fe, and s for which crystallographic studies of the enzymes from carboxydothermus hydrogenoformans, rhodospirillum rubrum, and moorella thermoaceticarevealed structural similarities in the overall protein fold but showed substantial differences in the essent ... | 2004 | 15113209 |
| evidence for a proton transfer network and a required persulfide-bond-forming cysteine residue in ni-containing carbon monoxide dehydrogenases. | carbon monoxide dehydrogenase from moorella thermoacetica catalyzes the reversible oxidation of co to co(2) at a nickel-iron-sulfur active site called the c-cluster. mutants of a proposed proton transfer pathway and of a cysteine residue recently found to form a persulfide bond with the c-cluster were characterized. four semiconserved histidine residues were individually mutated to alanine. his116 and his122 were essential to catalysis, while his113 and his119 attenuated catalysis but were not e ... | 2004 | 15134447 |
| crystallographic evidence for a co/co(2) tunnel gating mechanism in the bifunctional carbon monoxide dehydrogenase/acetyl coenzyme a synthase from moorella thermoacetica. | acetyl coenzyme a synthase (acs) acts in concert with carbon monoxide dehydrogenase (codh) to catalyze the formation of acetyl-coenzyme a from co(2)-derived co and ch(3)(+) molecules. recent crystal structures have shown that the three globular domains constituting the acs subunit may be arranged in either a closed or an open conformation. a long hydrophobic tunnel network allows diffusion of co between the codh and the acs active sites in the closed form, but it is blocked in the open form. on ... | 2004 | 15221479 |
| spectroscopic and computational insights into the geometric and electronic properties of the a-cluster of acetyl-coenzyme a synthase. | for the last two decades, the bifunctional enzyme acetyl-coenzyme a synthase/carbon monoxide dehydrogenase (acs/codh) from moorella thermoacetica has been the subject of considerable research aimed at elucidating the geometric and electronic properties of the a-cluster, which serves as the active site for acs catalysis. while the recent success in obtaining high-resolution x-ray structures of this enzyme solved many of the mysteries regarding the number, identities, and coordination environments ... | 2004 | 15221480 |
| physiology of the thermophilic acetogen moorella thermoacetica. | moorella thermoacetica (originally isolated as clostridium thermoaceticum) has served as the primary acetogenic bacterium for the resolution of the acetyl coenzyme a (acetyl-coa) or wood-ljungdahl pathway, a metabolic pathway that (i) autotrophically assimilates co2 and (ii) is centrally important to the turnover of carbon in many habitats. the purpose of this article is to highlight the diverse physiological features of this model acetogen and to examine some of the consequences of its metaboli ... | 2004 | 15249059 |
| effect of sodium sulfide on ni-containing carbon monoxide dehydrogenases. | the structure of the active-site c-cluster in co dehydrogenase from carboxydothermus hydrogenoformans includes a mu(2)-sulfide ion bridged to the ni and unique fe, whereas the same cluster in enzymes from rhodospirillum rubrum (codh(rr)) and moorella thermoacetica (codh(mt)) lack this ion. this difference was investigated by exploring the effects of sodium sulfide on activity and spectral properties. sulfide partially inhibited the co oxidation activity of codh(rr) and generated a lag prior to s ... | 2004 | 15264843 |
| ethanol production from h2 and co2 by a newly isolated thermophilic bacterium, moorella sp. huc22-1. | the thermophilic bacterium, moorella sp. huc22-1, newly isolated from a mud sample, produced ethanol from h(2) and co(2) during growth at 55 degrees c. in batch cultures in serum bottles, 1.5 mm ethanol was produced from 270 mm h(2) and 130 mm co(2) after 156 h, whereas less than 1 mm ethanol was produced from 23 mm fructose after 33 h. alcohol dehydrogenase and acetaldehyde dehydrogenase activities were higher in cells grown with h(2) and co(2) than those grown with fructose. the nadh/nad(+) an ... | 2004 | 15604806 |
| physiology of the thermophilic acetogen moorella thermoacetica. | moorella thermoacetica (originally isolated as clostridium thermoaceticum) has served as the primary acetogenic bacterium for the resolution of the acetyl coenzyme a (acetyl-coa) or wood-lijungdahl pathway, a metabolic pathway that (i) autotrophically assimilates co2 and (ii) is centrally important to the turnover of carbon in many habitats. the purpose of this article is to highlight the diverse physiological features of this model acetogen and to examine some of the consequences of its metabol ... | 2004 | 15630808 |
| cytochrome bd oxidase, oxidative stress, and dioxygen tolerance of the strictly anaerobic bacterium moorella thermoacetica. | the gram-positive, thermophilic, acetogenic bacterium moorella thermoacetica can reduce co2 to acetate via the wood-ljungdahl (acetyl coenzyme a synthesis) pathway. this report demonstrates that, despite its classification as a strict anaerobe, m. thermoacetica contains a membrane-bound cytochrome bd oxidase that can catalyze reduction of low levels of dioxygen. whole-cell suspensions of m. thermoacetica had significant endogenous o2 uptake activity, and this activity was increased in the presen ... | 2005 | 15743950 |
| the tunnel of acetyl-coenzyme a synthase/carbon monoxide dehydrogenase regulates delivery of co to the active site. | the effect of [co] on acetyl-coa synthesis activity of the isolated alpha subunit of acetyl-coenzyme a synthase/carbon monoxide dehydrogenase from moorella thermoacetica was determined. in contrast to the complete alpha(2)beta(2) enzyme where multiple co molecules exhibit strong cooperative inhibition, alpha was weakly inhibited, apparently by a single co with k(i) = 1.5 +/- 0.5 mm; other parameters include k(cat) = 11 +/- 1 min(-)(1) and k(m) = 30 +/- 10 microm. the alpha subunit lacked the pre ... | 2005 | 15839681 |
| x-ray crystal structures of moorella thermoacetica fpra. novel diiron site structure and mechanistic insights into a scavenging nitric oxide reductase. | several members of a widespread class of bacterial and archaeal metalloflavoproteins, called fpra, likely function as scavenging nitric oxide reductases (s-nors). however, the only published x-ray crystal structure of an fpra is for a protein characterized as a rubredoxin:dioxygen oxidoreductase (roo) from desulfovibrio gigas. therefore, the crystal structure of moorella thermoacetica fpra, which has been established to function as an s-nor, was solved in three different states: as isolated, red ... | 2005 | 15850383 |
| acetate production from lactose by clostridium thermolacticum and hydrogen-scavenging microorganisms in continuous culture--effect of hydrogen partial pressure. | the effect of the addition of hydrogen-consuming microorganisms on the metabolism of clostridium thermolacticum was studied. by growing this bacterium in continuous culture at 58 degrees c, on 29 mmol lactose l(-1) (10 gl(-1)) in the feed, with the h2-consuming microorganisms methanothermobacter thermoautotrophicus and moorella thermoautotrophica, the volumetric productivity of acetate was increased up to 3.9 mmol l(-1)h(-1) at a dilution rate of 0.058 h(-1). this was about three times higher th ... | 2005 | 15992956 |
| acetate and ethanol production from h2 and co2 by moorella sp. using a repeated batch culture. | the growth inhibition of moorella sp. huc22-1 by undissociated acetic acid was analyzed using a non-competitive inhibition model coupled with a ph inhibition model. in the cells grown on h2 and co2, the inhibition constant, k(p) of the undissociated acetic acid was 6.2 mm (164 mm as the total acetate at ph 6.2, pka = 4.795, 55 degrees c), which was 1.5-fold higher than that obtained in cells grown on fructose. when a ph-controlled batch culture was performed using a fermentor at ph 6.2 with h2 a ... | 2005 | 16233785 |
| enrichment and detection of microorganisms involved in direct and indirect methanogenesis from methanol in an anaerobic thermophilic bioreactor. | to gain insight into the microorganisms involved in direct and indirect methane formation from methanol in a laboratory-scale thermophilic (55 degrees c) methanogenic bioreactor, reactor sludge was disrupted and serial dilutions were incubated in specific growth media containing methanol and possible intermediates of methanol degradation as substrates. with methanol, growth was observed up to a dilution of 10(8). however, when methanothermobacter thermoautotrophicus strain z245 was added for h2 ... | 2005 | 16328652 |
| phenotypic and genotypic characterization of some moorella sp. strains isolated from canned foods. | six anaerobic thermophilic strains isolated from various spoiled cans including fish soups and cooked meats were characterized using a polyphasic approach. these strains were closely related to moorella thermoacetica or moorella thermoautotrophica species. except the spacer region between the 16s and the 23s rrna genes, which exhibited two pcr profiles distinguishing both species, the genotypic and phylogenetic analyses grouped these isolates, the type strains, and all sequences of moorella ther ... | 2006 | 16458469 |
| crystallization and preliminary x-ray analysis of the mrna-binding domain of elongation factor selb in complex with rna. | in bacteria, the selenocysteine-specific elongation factor selb is necessary for incorporation of selenocysteine, the 21st amino acid, into proteins by the ribosome. selb binds to an mrna hairpin formed by the selenocysteine-insertion sequence (secis) and delivers selenocysteyl-trna (sec-trnasec) at the ribosomal a site. the minimum fragment (residues 512-634) of moorella thermoacetica selb (selb-m) required for mrna binding has been overexpressed and purified. the complex of selb-m with 23 nucl ... | 2005 | 16511023 |
| isolation, crystallization and preliminary x-ray analysis of a methanol-induced corrinoid protein from moorella thermoacetica. | a corrinoid protein was induced and overexpressed in methanol-grown cells of the thermophilic anaerobic bacterium moorella thermoacetica. the protein was purified from cytosolic extracts. after screening for crystallization conditions and optimization, crystals were obtained that diffracted strongly on a rotating-anode x-ray source. a diffraction data set was collected and processed including reflections to 1.9 a resolution. reflections were indexed in a primitive orthorhombic cell with unit-cel ... | 2005 | 16511090 |
| spectroscopic studies of the corrinoid/iron-sulfur protein from moorella thermoacetica. | methyl transfer reactions are important in a number of biochemical pathways. an important class of methyltransferases uses the cobalt cofactor cobalamin, which receives a methyl group from an appropriate methyl donor protein to form an intermediate organometallic methyl-co bond that subsequently is cleaved by a methyl acceptor. control of the axial ligation state of cobalamin influences both the mode (i.e., homolytic vs heterolytic) and the rate of co-c bond cleavage. here we have studied the ax ... | 2006 | 16608335 |
| novel thermophilic sulfate-reducing bacteria from a geothermally active underground mine in japan. | thermophilic sulfate-reducing bacteria were enriched from samples obtained from a geothermal underground mine in japan. the enrichment cultures contained bacteria affiliated with the genera desulfotomaculum, thermanaeromonas, thermincola, thermovenabulum, moorella, "natronoanaerobium," and clostridium. two novel thermophilic sulfate-reducing strains, rl50jiii and rl80jiv, affiliated with the genera desulfotomaculum and thermanaeromonas, respectively, were isolated. | 2006 | 16672530 |
| epr spectroscopic and computational characterization of the hydroxyethylidene-thiamine pyrophosphate radical intermediate of pyruvate:ferredoxin oxidoreductase. | the radical intermediate of pyruvate:ferredoxin oxidoreductase (pfor) from moorella thermoacetica was characterized using electron paramagnetic resonance (epr) spectroscopy at x-band and d-band microwave frequencies. epr spectra, obtained with various combinations of isotopically labeled substrate (pyruvate) and coenzyme (thiamine pyrophosphate (tpp)), were analyzed by spectral simulations. parameters obtained from the simulations were compared with those predicted from electronic structure calc ... | 2006 | 16752902 |
| mössbauer and epr study of recombinant acetyl-coa synthase from moorella thermoacetica. | mössbauer and epr spectroscopies were used to study the electronic structure of the a-cluster from recombinant acetyl-coa synthase (the alpha subunit of the alpha2beta2 acetyl-coa synthase/co dehydrogenase). once activated with ni, these subunits have properties mimicking those associated with the alpha2beta2 tetramer, including structural heterogeneities. the fe4s4 portion of the a-cluster in oxidized, methylated, and acetylated states was in the 2+ core oxidation state. upon reduction with dit ... | 2006 | 16834342 |
| theoretical study of the reduction of nitric oxide in an a-type flavoprotein. | the mechanism for the reduction of nitric oxide to nitrous oxide and water in an a-type flavoprotein (fpra) in moorella thermoacetica, which has been proposed to be a scavenging type of nitric oxide reductase, has been investigated using density functional theory (b3lyp). a dinitrosyl complex, [{feno}(7)](2), has previously been proposed to be a key intermediate in the no reduction catalyzed by fpra. the electrons and protons involved in the reduction were suggested to "super-reduce" the dinitro ... | 2007 | 16957917 |
| methanol utilizing desulfotomaculum species utilizes hydrogen in a methanol-fed sulfate-reducing bioreactor. | a sulfate-reducing bacterium, strain ww1, was isolated from a thermophilic bioreactor operated at 65 degrees c with methanol as sole energy source in the presence of sulfate. growth of strain ww1 on methanol or acetate was inhibited at a sulfide concentration of 200 mg l(-1), while on h2/co2, no apparent inhibition occurred up to a concentration of 500 mg l(-1). when strain ww1 was co-cultured under the same conditions with the methanol-utilizing, non-sulfate-reducing bacteria, thermotoga lettin ... | 2007 | 17028873 |
| characterization of a corrinoid protein involved in the c1 metabolism of strict anaerobic bacterium moorella thermoacetica. | the strict anaerobic, thermophilic bacterium moorella thermoacetica metabolizes c1 compounds for example co(2)/h(2), co, formate, and methanol into acetate via the wood/ljungdahl pathway. some of the key steps in this pathway include the metabolism of the c1 compounds into the methyl group of methylenetetrahydrofolate (mthf) and the transfer of the methyl group from mthf to the methyl group of acetyl-coa catalyzed by methyltransferase, corrinoid protein and co dehydrogenase/acetyl coa synthase. ... | 2007 | 17211893 |
| characterization of enzymes involved in the ethanol production of moorella sp. huc22-1. | since the thermophilic bacterium moorella sp. huc22-1 produces 120 mm acetate and 5.2 mm ethanol from h(2)-co(2), several candidate genes, which were predicted to code for three alcohol dehydrogenases (adha, b, c) and one acetaldehyde dehydrogenase (aldh), were cloned from huc22-1. the cloned genes were subcloned into a his-tagged expression vector and expressed in escherichia coli. recombinant adha and b were both dependent on nadp(h) but independent of nad(h), and their reduction activities fr ... | 2007 | 17318639 |
| structural insight into a molecular switch in tandem winged-helix motifs from elongation factor selb. | elongation factor selb is responsible for co-translational incorporation of selenocysteine (sec) into proteins. the uga stop codon is recoded as a sec codon in the presence of a downstream mrna hairpin. in prokaryotes, in addition to the ef-tu-like n-terminal domains, a c-terminal extension containing four tandem winged-helix motifs (wh1-4) recognizes the mrna hairpin. the 2.3-a resolution crystal structure of the escherichia coli wh3/4 domains bound to mrna with mutagenesis data reveal that the ... | 2007 | 17537456 |
| na+-pyrophosphatase: a novel primary sodium pump. | membrane-bound pyrophosphatase (ppase) is commonly believed to couple pyrophosphate (ppi) hydrolysis to h+ transport across the membrane. here, we demonstrate that two newly isolated bacterial membrane ppases from the mesophile methanosarcina mazei (mm-ppase) and the moderate thermophile moorella thermoacetica and a previously described ppase from the hyperthermophilic bacterium thermotoga maritima catalyze na+ rather than h+ transport into escherichia coli inner membrane vesicles (imv). when as ... | 2007 | 17605473 |
| a cbs domain-containing pyrophosphatase of moorella thermoacetica is regulated by adenine nucleotides. | cbs (cystathionine beta-synthase) domains are found in proteins from all kingdoms of life, and point mutations in these domains are responsible for a variety of hereditary diseases in humans; however, the functions of cbs domains are not well understood. in the present study, we cloned, expressed in escherichia coli, and characterized a family ii ppase (inorganic pyrophosphatase) from moorella thermoacetica (mtcbs-ppase) that has a pair of tandem 60-amino-acid cbs domains within its n-terminal d ... | 2007 | 17714078 |
| conformational switches in winged-helix domains 1 and 2 of bacterial translation elongation factor selb. | the crystal structure of the first two winged-helix motifs of translation elongation factor selb from moorella thermoacetica has been determined at 1.1 a resolution. compared with the previous structure of the two domains in conjunction with winged-helix modules 3 and 4, the first winged-helix domain underwent a substantial conformational change during which the alpha-helical and beta-sheet portions of the element opened up like a shell. this conformational rearrangement was elicited by a change ... | 2007 | 17881825 |
| the three-dimensional structure of the moorella thermoacetica selenocysteine insertion sequence rna hairpin and its interaction with the elongation factor selb. | incorporation of the amino acid selenocysteine into a growing protein chain involves the interaction between a hairpin in the mrna termed the selenocysteine insertion sequence (secis) and the special elongation factor selb. here we present the structure of the secis from the thermophilic organism moorella thermoacetica (secis-mt) determined using nuclear magnetic resonance (nmr) spectroscopy. the secis-mt hairpin structure contains a pentaloop with the first and fourth nucleotides of the loop fo ... | 2007 | 17901155 |
| towards understanding selenocysteine incorporation into bacterial proteins. | in bacteria, uga stop codons can be recoded to direct the incorporation of selenocysteine into proteins on the ribosome. recoding requires a selenocysteine incorporation sequence (secis) downstream of the uga codon, a specialized translation factor selb, and the non-canonical sec-trnasec, which is formed from ser-trnasec by selenocysteine synthase, sela, using selenophosphate as selenium donor. here we describe a rapid-kinetics approach to study the mechanism of selenocysteine insertion into pro ... | 2007 | 17937620 |
| (per)chlorate reduction by the thermophilic bacterium moorella perchloratireducens sp. nov., isolated from underground gas storage. | a thermophilic bacterium, strain an10, was isolated from underground gas storage with methanol as a substrate and perchlorate as an electron acceptor. cells were gram-positive straight rods, 0.4 to 0.6 mum in diameter and 2 to 8 mum in length, growing as single cells or in pairs. spores were terminal with a bulged sporangium. the temperature range for growth was 40 to 70 degrees c, with an optimum at 55 to 60 degrees c. the ph optimum was around 7. the salinity range for growth was between 0 and ... | 2008 | 17981952 |
| molecular switch in tandem winged-helix motifs of elongation factor selb. | elongation factor selb is responsible for cotranslational incorporation of the 21(st) amino acid selenocysteine (sec) into proteins. uga stop codon is recoded as a sec codon in presence of a downstream mrna hairpin. prokaryotic selb has ef-tu-like n-terminal domains and a c-terminal extension containing four tandem winged-helix motifs (wh1-4). the c-terminal extension recognizes the mrna hairpin. crystal structures of the escherichia coli wh3/4 domains and wh1-4 domains from moorella thermoaceti ... | 2007 | 18029744 |
| degradation of glyoxylate and glycolate with atp synthesis by a thermophilic anaerobic bacterium, moorella sp. strain huc22-1. | the thermophilic homoacetogenic bacterium moorella sp. strain huc22-1 ferments glyoxylate to acetate roughly according to the reaction 2 glyoxylate --> acetate + 2 co(2). a batch culture with glyoxylate and yeast extract yielded 11.7 g per mol of cells per substrate, which was much higher than that obtained with h(2) plus co(2). crude extracts of glyoxylate-grown cells catalyzed the adp- and nadp-dependent condensation of glyoxylate and acetyl coenzyme a (acetyl-coa) to pyruvate and co(2) and co ... | 2008 | 18083850 |
| xenon in and at the end of the tunnel of bifunctional carbon monoxide dehydrogenase/acetyl-coa synthase. | a fascinating feature of some bifunctional enzymes is the presence of an internal channel or tunnel to connect the multiple active sites. a channel can allow for a reaction intermediate generated at one active site to be used as a substrate at a second active site, without the need for the intermediate to leave the safety of the protein matrix. one such bifunctional enzyme is carbon monoxide dehydrogenase/acetyl-coa synthase from moorella thermoacetica (mtcodh/acs). a key player in the global ca ... | 2008 | 18293927 |
| crystallization and preliminary x-ray analysis of rsbs from moorella thermoacetica at 2.5 a resolution. | the thermophilic bacterium moorella thermoacetica possesses an rsb operon that is related to the genetic locus common to many gram-positive bacteria that regulates the activity of the stress-responsive sigma factor sigma(b). one of the gene products of this operon is rsbs, a single stas-domain protein that is a component of higher order assemblies in bacillus subtilis known as 'stressosomes'. it is expected that similar complexes are found in m. thermoacetica, but in this instance regulating the ... | 2008 | 18323607 |
| two proteins with diaphorase activity from clostridium thermocellum and moorella thermoacetica. | two high-molecular-weight rubredoxin genes (hrb) from clostridium thermocellum and moorella thermoacetica were expressed in escherichia coli and their translated products (hrb) were characterized. m. thermoacetica hrb showed strong diaphorase activity. in contrast, c. thermocellum hrb, containing neither fmn nor fad in the molecule, showed flavin reductase activity with moderate diaphorase activity. both enzymes were optimally active at about 50 degrees c. | 2008 | 18323661 |
| tunnel mutagenesis and ni-dependent reduction and methylation of the alpha subunit of acetyl coenzyme a synthase/carbon monoxide dehydrogenase. | two isolated alpha subunit mutants (a110c and a222l) of the alpha(2)beta(2) acetyl coenzyme a synthase (acs)/carbon monoxide dehydrogenase (codh) from moorella thermoacetica were designed to block the co-migrating tunnel in the alpha subunit, allowing comparison with equivalent mutants in acs/codh. after ni activation, both mutants exhibited electron paramagnetic resonance spectra indicating that the a-cluster was properly assembled. acs activities were similar to those of the wild-type recombin ... | 2008 | 18365259 |
| the complete genome sequence of moorella thermoacetica (f. clostridium thermoaceticum). | this paper describes the genome sequence of moorella thermoacetica (f. clostridium thermoaceticum), which is the model acetogenic bacterium that has been widely used for elucidating the wood-ljungdahl pathway of co and co(2) fixation. this pathway, which is also known as the reductive acetyl-coa pathway, allows acetogenic (often called homoacetogenic) bacteria to convert glucose stoichiometrically into 3 mol of acetate and to grow autotrophically using h(2) and co as electron donors and co(2) as ... | 2008 | 18631365 |
| syntrophic growth on formate: a new microbial niche in anoxic environments. | anaerobic syntrophic associations of fermentative bacteria and methanogenic archaea operate at the thermodynamic limits of life. the interspecies transfer of electrons from formate or hydrogen as a substrate for the methanogens is key. contrary requirements of syntrophs and methanogens for growth-sustaining product and substrate concentrations keep the formate and hydrogen concentrations low and within a narrow range. since formate is a direct substrate for methanogens, a niche for microorganism ... | 2008 | 18708519 |
| atypical one-carbon metabolism of an acetogenic and hydrogenogenic moorella thermoacetica strain. | a thermophilic spore-forming bacterium (strain amp) was isolated from a thermophilic methanogenic bioreactor that was fed with cobalt-deprived synthetic medium containing methanol as substrate. 16s rrna gene analysis revealed that strain amp was closely related to the acetogenic bacterium moorella thermoacetica dsm 521(t) (98.3% sequence similarity). dna-dna hybridization showed 75.2 +/- 4.7% similarity to m. thermoacetica dsm 521(t), suggesting that strain amp is a m. thermoacetica strain. stra ... | 2009 | 18854977 |
| [characterization of bacterial diversity in the shengli-s12 oil reservoir by culture-dependent and culture-independent methods]. | examining bacterial diversity in an oil reservoir of shengli oil field by both culture-independent molecular technique and enrichment method. | 2008 | 18956759 |
| crystallographic snapshots of cyanide- and water-bound c-clusters from bifunctional carbon monoxide dehydrogenase/acetyl-coa synthase. | nickel-containing carbon monoxide dehydrogenases (codhs) reversibly catalyze the oxidation of carbon monoxide to carbon dioxide and are of vital importance in the global carbon cycle. the unusual catalytic codh c-cluster has been crystallographically characterized as either a nife(4)s(4) or a nife(4)s(5) metal center, the latter containing a fifth, additional sulfide that bridges ni and a unique fe site. to determine whether this bridging sulfide is catalytically relevant and to further explore ... | 2009 | 19583207 |
| novel domain arrangement in the crystal structure of a truncated acetyl-coa synthase from moorella thermoacetica. | ni-dependent acetyl-coa synthase (acs) and co dehydrogenase (codh) constitute the central enzyme complex of the wood-ljungdahl pathway of acetyl-coa formation. the crystal structure of a recombinant bacterial acs lacking the n-terminal domain that interacts with codh shows a large reorganization of the remaining two globular domains, producing a narrow cleft of suitable size, shape, and nature to bind coa. sequence comparisons with homologous archaeal enzymes that naturally lack the n-terminal d ... | 2009 | 19650626 |
| methanol utilization in defined mixed cultures of thermophilic anaerobes in the presence of sulfate. | we studied thermophilic sulfate reduction with methanol as electron donor in continuous cultures. mixed cultures of selected microorganisms were used, representing different methanol degrading pathways followed by various trophic groups of microorganisms. our results show that direct competition for methanol between a homoacetogen, moorella thermoautotrophica, and a sulfate reducer, desulfotomaculum kuznetsovii, is in favour of the sulfate reducer due to its affinity for methanol. methanogenesis ... | 2004 | 19712297 |
| thermostable cyanuric acid hydrolase from moorella thermoacetica atcc 39073. | cyanuric acid, a metabolic intermediate in the degradation of many s-triazine compounds, is further metabolized by cyanuric acid hydrolase. cyanuric acid also accumulates in swimming pools due to the breakdown of the sanitizing agents di- and trichloroisocyanuric acid. structurally stable cyanuric acid hydrolases are being considered for usage in pool water remediation. in this study, cyanuric acid hydrolase from the thermophile moorella thermoacetica atcc 39073 was cloned, expressed in escheric ... | 2009 | 19767460 |
| nucleotide- and substrate-induced conformational transitions in the cbs domain-containing pyrophosphatase of moorella thermoacetica. | in contrast to all other known pyrophosphatases, moorella thermoacetica pyrophosphatase (mtcbs-ppase) contains nucleotide-binding cbs domains and is thus strongly regulated by adenine nucleotides. stopped-flow measurements using a fluorescent amp analogue, 2'(3')-o-(n-methylanthranoyl)-amp (mant-amp), reveal that nucleotide binding to mtcbs-ppase involves a three-step increase in mant-amp fluorescence with relaxation times from 0.01 to 100 s, implying conformational changes in the complex. this ... | 2010 | 20038140 |
| selenium controls transcription of paralogous formate dehydrogenase genes in the termite gut acetogen, treponema primitia. | summary the termite gut spirochete, treponema primitia, is a co(2)-reductive acetogen that is phylogenetically distinct from other distantly related and more extensively studied acetogens such as moorella thermoacetica. research on t. primitia has revealed details about the role of spirochetes in co(2)-reductive acetogenesis, a process important to the mutualism occurring between termites and their gut microbial communities. here, a locus of the t. primitia genome containing wood-ljungdahl pathw ... | 2010 | 20236167 |
| pcr detection of thermophilic spore-forming bacteria involved in canned food spoilage. | thermophilic bacteria that form highly heat-resistant spores constitute an important group of spoilage bacteria of low-acid canned food. a pcr assay was developed in order to rapidly trace these bacteria. three pcr primer pairs were designed from rrna gene sequences. these primers were evaluated for the specificity and the sensitivity of detection. two primer pairs allowed detection at the species level of geobacillus stearothermophilus and moorella thermoacetica/thermoautrophica. the other pair ... | 2010 | 20397018 |
| typical methanogenic inhibitors can considerably alter bacterial populations and affect the interaction between fatty acid degraders and homoacetogens. | the effects of two typical methanogenic inhibitors [2-bromoethanesulfonate (bes) and chloroform (chcl(3))] on the bacterial populations were investigated using molecular ecological techniques. terminal restriction fragment length polymorphism analyses (t-rflp) in combination with clone library showed that both the toxicants not only inhibited methanogenic activity but also considerably altered the bacterial community structure. species of low % g + c gram-positive bacteria (clostridiales), high ... | 2010 | 20559824 |
| clostridium ljungdahlii represents a microbial production platform based on syngas. | clostridium ljungdahlii is an anaerobic homoacetogen, able to ferment sugars, other organic compounds, or co(2)/h(2) and synthesis gas (co/h(2)). the latter feature makes it an interesting microbe for the biotech industry, as important bulk chemicals and proteins can be produced at the expense of co(2), thus combining industrial needs with sustained reduction of co and co(2) in the atmosphere. sequencing the complete genome of c. ljungdahlii revealed that it comprises 4,630,065 bp and is one of ... | 2010 | 20616070 |
| infrared and epr spectroscopic characterization of a ni(i) species formed by photolysis of a catalytically competent ni(i)-co intermediate in the acetyl-coa synthase reaction. | acetyl-coa synthase (acs) catalyzes the synthesis of acetyl-coa from co, coenzyme a (coa), and a methyl group from the ch(3)-co(3+) site in the corrinoid iron-sulfur protein (cfesp). these are the key steps in the wood-ljungdahl pathway of anaerobic co and co(2) fixation. the active site of acs is the a-cluster, which is an unusual nickel-iron-sulfur cluster. there is significant evidence for the catalytic intermediacy of a co-bound paramagnetic ni species, with an electronic configuration of [f ... | 2010 | 20669901 |
| formate-driven growth coupled with h(2) production. | although a common reaction in anaerobic environments, the conversion of formate and water to bicarbonate and h(2) (with a change in gibbs free energy of δg° = +1.3 kj mol(-1)) has not been considered energetic enough to support growth of microorganisms. recently, experimental evidence for growth on formate was reported for syntrophic communities of moorella sp. strain amp and a hydrogen-consuming methanothermobacter species and of desulfovibrio sp. strain g11 and methanobrevibacter arboriphilus ... | 2010 | 20844539 |
| identification and characterization of oxalate oxidoreductase, a novel thiamine pyrophosphate-dependent 2-oxoacid oxidoreductase that enables anaerobic growth on oxalate. | moorella thermoacetica is an anaerobic acetogen, a class of bacteria that is found in the soil, the animal gastrointestinal tract, and the rumen. this organism engages the wood-ljungdahl pathway of anaerobic co(2) fixation for heterotrophic or autotrophic growth. this paper describes a novel enzyme, oxalate oxidoreductase (oor), that enables m. thermoacetica to grow on oxalate, which is produced in soil and is a common component of kidney stones. exposure to oxalate leads to the induction of thr ... | 2010 | 20956531 |
| mutational analysis of residues in the regulatory cbs domains of moorella thermoacetica pyrophosphatase corresponding to disease-related residues of human proteins. | mtcbs-ppase [cbs (cystathionine β-synthase) domain-containing pyrophosphatase from moorella thermoacetica] contains a pair of cbs domains that strongly bind adenine nucleotides, thereby regulating enzyme activity. eight residues associated with the cbs domains of mtcbs-ppase were screened to explore possible associations with regulation of enzyme activity. the majority of the substitutions (v99a, r168a, y169a, y169f, y188a and h189a) enhanced the catalytic activity of mtcbs-ppase, two substituti ... | 2011 | 21067517 |