ATP-linked citrate lyase activity in the green sulfur bacterium Chlorobium limicola forma thiosulfatophilum

Ivanovsky, R. N.; Sintsov, N. V.; Kondratieva, E. N.

doi:10.1007/bf00406165

Cited by 86 publications

(43 citation statements)

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“…In bacteria, however, ATP-citrate lyase has been found only in organisms which employ the RTCA cycle to assimilate CO 2 into cell material. ATP-citrate lyases have now been identified in several groups of prokaryotes (proteobacteria, green sulfur bacteria, and thermophilic Knallgas bacteria) (14,25,27), in sulfur-dependent archaea (3), and in the eukaryotic green alga Chlamydomonas reinhardtii (5). It is apparent ( Fig.…”

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“…One complete turn of this cycle yields one molecule of oxaloacetate from four molecules of CO 2 , or in a variation from the original scheme, two CO 2 molecules can form a molecule of acetate. Confirmation of this scheme, however, was not provided until a citrate lyase activity was detected in crude extracts of Chlorobium limicola (14). In contrast to prokaryotic citrate lyases obtained from bacteria growing anaerobically on citrate, the C. limicola enzyme was found to be both ATP and coenzyme A (CoA) dependent, and until its discovery in C. limicola, ATP-dependent citrate lyase enzymes had been identified only in eukaryotes, being found in all animal tissues (30), some oleaginous yeasts and molds (11,18), plants (9), and green algae (5).…”

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The reductive tricarboxylic acid cycle of carbon dioxide assimilation: initial studies and purification of ATP-citrate lyase from the green sulfur bacterium Chlorobium tepidum

Wahlund

Tabita

1997

J Bacteriol

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Carbon dioxide is fixed largely by the reductive tricarboxylic acid (RTCA) cycle in green sulfur bacteria. One of the key enzymes, ATP-citrate lyase, was purified to apparent homogeneity from the moderately thermophilic green sulfur bacterium Chlorobium tepidum. The molecular weight of the native enzyme was about 550,000, and the preponderance of evidence indicated that the protein is composed of identical subunits (M r of Х135,000) which degraded to two major proteins with M r s of Х65,000 and Х42,000. Western immunoblots and in vitro phosphorylation experiments indicated that these two species could have been the result of proteolysis by an endogenous protease, similar to what has been observed with mammalian, yeast, and mold ATP-citrate lyase. In addition to apparent structural similarities, the catalytic properties of C. tepidum ATP-citrate lyase showed marked similarities to the eukaryotic enzyme, with significant differences from other prokaryotic ATP-citrate lyases, including the enzyme from the closely related organism Chlorobium limicola. Phosphorylation of C. tepidum ATP-citrate lyase occurred, presumably on a histidine residue at the active site, similar to the case for the mammalian enzyme. In contrast to the situation observed for other prokaryotic ATP-citrate lyase enzymes, the C. tepidum enzyme was not able to replace ATP and GTP for activity or use Cu 2؉ to replace Mg 2؉ for enzyme activity. Given the apparent structural and catalytic similarities of the enzyme from C. tepidum and its eukaryotic counterpart, the C. tepidum system should serve as an excellent model for studies of the enzymology and regulation of this protein.

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The reductive tricarboxylic acid cycle of carbon dioxide assimilation: initial studies and purification of ATP-citrate lyase from the green sulfur bacterium Chlorobium tepidum

Wahlund

Tabita

1997

J Bacteriol

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“…2-Oxoglutarate:ferredoxin oxidoreductase catalyzes the carboxylation of succinyl-CoA to 2-oxoglutarate, ATP citrate lyase the ATP-dependent cleavage of citrate to acetylCoA and oxaloacetate, and fumarate reductase the reduction of fumarate forming succinate. The presence of these enzyme activities in autotrophically grown bacteria and archaea is indicative of a functioning reductive TCA cycle (5,28,46,48,49). However, activity of ATP citrate lyase has also been identified in heterotrophic and facultative autotrophic organisms: i.e., the sulfate reducers Desulfobacter postgatei and Desulfobacter hydrogenophilus, respectively (37, 48).…”

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Evidence for Autotrophic CO ₂ Fixation via the Reductive Tricarboxylic Acid Cycle by Members of the ε Subdivision of Proteobacteria

et al. 2005

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Based on 16S rRNA gene surveys, bacteria of the subdivision of proteobacteria have been identified to be important members of microbial communities in a variety of environments, and quite a few have been demonstrated to grow autotrophically. However, no information exists on what pathway of autotrophic carbon fixation these bacteria might use. In this study, Thiomicrospira denitrificans and Candidatus Arcobacter sulfidicus, two chemolithoautotrophic sulfur oxidizers of the subdivision of proteobacteria, were examined for activities of the key enzymes of the known autotrophic CO 2 fixation pathways. Both organisms contained activities of the key enzymes of the reductive tricarboxylic acid cycle, ATP citrate lyase, 2-oxoglutarate: ferredoxin oxidoreductase, and pyruvate:ferredoxin oxidoreductase. Furthermore, no activities of key enzymes of other CO 2 fixation pathways, such as the Calvin cycle, the reductive acetyl coenzyme A pathway, and the 3-hydroxypropionate cycle, could be detected. In addition to the key enzymes, the activities of the other enzymes involved in the reductive tricarboxylic acid cycle could be measured. Sections of the genes encoding the ␣-and ␤-subunits of ATP citrate lyase could be amplified from both organisms. These findings represent the first direct evidence for the operation of the reductive tricarboxylic acid cycle for autotrophic CO 2 fixation in -proteobacteria. Since -proteobacteria closely related to these two organisms are important in many habitats, such as hydrothermal vents, oxic-sulfidic interfaces, or oilfields, these results suggest that autotrophic CO 2 fixation via the reductive tricarboxylic acid cycle might be more important than previously considered.Almost all major groups of prokaryotes include representatives that are able to grow autotrophically (33). These organisms play an essential role in ecosystems by providing a continuous supply of organic carbon for heterotrophs. The Calvin-Benson-Bassham cycle (Calvin cycle) represents the most important extant autotrophic carbon fixation pathway (43, 50). Despite its global significance, it is restricted to organisms with high-energy yield from a chemotrophic or phototrophic lifestyle. Microorganisms present in extreme environments, e.g., high temperature or anaerobic or acidic conditions, generally utilize different CO 2 fixation pathways (17, 33). At present, there are three alternative pathways known: the reductive tricarboxylic acid (TCA) cycle, the reductive acetyl coenzyme A (CoA) pathway, and the 3-hydroxypropionate cycle (4, 33).It has been proposed that the first autotrophic pathway was akin to either the reductive TCA cycle or the reductive acetylCoA pathway (11,17,35,45,58). The reductive TCA cycle has the characteristics of an autocatalytic cycle and leads to a complex cyclic reaction network from which other anabolic pathways could have evolved (11, 58): e.g., the oxidative TCA cycle (8,45). Based upon biochemical and isotopic analyses, the reductive TCA cycle appears to operate in phylogenetically diverse aut...

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“…The threonine pathway could be excluded, and the results are in accord with a mechanism for the formation of 2-oxobutyrate from acetyl coenzyme A and pyruvate via citramalate.The green sulfur bacteria are obligately anaerobic and phototrophic and fix CO2 by a reductive tricarboxylic acid cycle (6,7,9,13 Spectrophotometric determination of total branched-chain 2-oxoacids was carried out as described earlier (18). The individual oxoacids were separated as the trimethylsilyl (TMS) derivatives (11) by gas-liquid chromatography on a column containing 10% OV-17 (Supelco) in Gaschrom Q in a Perkin-Elmer 3920 gas chromatograph equipped with a hydrogen flame ionization detector.…”

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“…The green sulfur bacteria are obligately anaerobic and phototrophic and fix CO2 by a reductive tricarboxylic acid cycle (6,7,9,13). They are only very distantly related to other phototrophic bacteria (20).…”

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Mechanism of biosynthesis of 2-oxo-3-methylvalerate in Chlorobium vibrioforme

1988

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The biosynthesis of 2-oxo-3-methylvalerate in Chlorobium vibrioforme was investigated by '3C nuclear magnetic resonance spectroscopy of the oxoacid formed from "3C-labeled acetate by washed suspensions. The threonine pathway could be excluded, and the results are in accord with a mechanism for the formation of 2-oxobutyrate from acetyl coenzyme A and pyruvate via citramalate.The green sulfur bacteria are obligately anaerobic and phototrophic and fix CO2 by a reductive tricarboxylic acid cycle (6,7,9,13 Spectrophotometric determination of total branched-chain 2-oxoacids was carried out as described earlier (18). The individual oxoacids were separated as the trimethylsilyl (TMS) derivatives (11) by gas-liquid chromatography on a column containing 10% OV-17 (Supelco) in Gaschrom Q in a Perkin-Elmer 3920 gas chromatograph equipped with a hydrogen flame ionization detector. The carrier gas was N2, and the column temperature was 100°C. The TMS derivative of malonic acid was used as the internal standard. The 2-oxoisocaproate derivative gave double signals due to isomerization, and the one for C-2 overlapped with the C-2 signal of 2-oxo-3-methylvalerate. The value for the latter therefore had to be determined by calculation from the peak ratios (12).The distribution of 13C in the oxoacids was determined by NMR spectroscopy of the 2,4-dinitrophenylhydrazones, which were isolated in the crystalline state from the supernatant fluid. 13C NMR spectra were obtained on a JEOL FX60 spectrometer operating at 15.0 MHz. The 2,4-dinitrophenylhydrazones (approximately 25 mg) were dissolved in 1.5 ml of tetradeuteromethanol, and TMS was used as the internal standard. The number of pulses accumulated was 36,000, the pulse width was 8 jxs, and the pulse delay was 1.8 s.Chemical shifts of the oxoacid carbons relative to TMS were determined with the derivatives of standard (unlabeled) oxoacids, the assignments being based on off-resonance experiments (Table 1).The 2-oxoisocaproate derivative gave two signals for each C atom. That for C-2 overlapped the C-2 peak of 2-oxo-3-methylvalerate. The value for the latter had therefore to be calculated from the peak ratios as determined on standards.The aromatic signal at 123.8 ppm was used as a reference atom (C1) in the calculation of relative signal strengths. The expression K/Ki refers to the signal strength of carbon atom j using carbon atom i as the reference in the oxoacid derivatives formed from unlabeled CO2 and acetate. The expressions Mj and Mi denote the signal intensities corresponding to carbon atoms j and i, respectively, in the oxoacid derivatives formed from 13C-enriched substrates.The proportions of branched-chain 2-oxoacids formed by C. vibrioforme were determined by gas-liquid chromatography prior to the 13C labeling experiments. The dominant oxoacid was 2-oxoisocaproate, present at about twice the concentration of 2-oxo-3-methylvalerate. Increased light intensity or the presence of acetate slightly stimulated oxoacid formation but had no effect on the ratio of acids formed. A...

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ATP-linked citrate lyase activity in the green sulfur bacterium Chlorobium limicola forma thiosulfatophilum

Cited by 86 publications

References 9 publications

The reductive tricarboxylic acid cycle of carbon dioxide assimilation: initial studies and purification of ATP-citrate lyase from the green sulfur bacterium Chlorobium tepidum

The reductive tricarboxylic acid cycle of carbon dioxide assimilation: initial studies and purification of ATP-citrate lyase from the green sulfur bacterium Chlorobium tepidum

Evidence for Autotrophic CO ₂ Fixation via the Reductive Tricarboxylic Acid Cycle by Members of the ε Subdivision of Proteobacteria

Mechanism of biosynthesis of 2-oxo-3-methylvalerate in Chlorobium vibrioforme

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ATP-linked citrate lyase activity in the green sulfur bacterium Chlorobium limicola forma thiosulfatophilum

Cited by 86 publications

References 9 publications

The reductive tricarboxylic acid cycle of carbon dioxide assimilation: initial studies and purification of ATP-citrate lyase from the green sulfur bacterium Chlorobium tepidum

The reductive tricarboxylic acid cycle of carbon dioxide assimilation: initial studies and purification of ATP-citrate lyase from the green sulfur bacterium Chlorobium tepidum

Evidence for Autotrophic CO 2 Fixation via the Reductive Tricarboxylic Acid Cycle by Members of the ε Subdivision of Proteobacteria

Mechanism of biosynthesis of 2-oxo-3-methylvalerate in Chlorobium vibrioforme

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Evidence for Autotrophic CO ₂ Fixation via the Reductive Tricarboxylic Acid Cycle by Members of the ε Subdivision of Proteobacteria