Regulation of anaerobic carbon monoxide oxidation activity in Rhodocyclus gelatinosus

Champine, J

doi:10.1016/0378-1097(87)90340-5

Cited by 3 publications

(4 citation statements)

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“…2 verified that CO-dependent H 2 production is indeed coupled to ATP formation. This observation also confirmed the earlier findings by Champine and Uffen (6). Similarly, in the methanogenic bacterium Methanosarcina barkeri, CO oxidation to CO 2 and H 2 is coupled to the phosphorylation of ADP to ATP, even though the physiological function of its CODH is to mediate CO 2 formation from the carboxyl group of acetate during methanogenesis (5), a reaction that is not detected in photosynthetic bacteria (14).…”

Section: Discussionsupporting

confidence: 91%

“…However, the growth media used in the above studies were often supplemented with complex carboncontaining nutrients such as Trypticase, yeast extract, and sodium acetate, which complicates the conclusion that CO could serve as the sole carbon and energy source. Nonetheless, new ATP synthesis was indeed detected in R. gelatinosus strain 1 in darkness when CO was added as the carbon substrate along with Trypticase (6). This finding provided the first direct evidence in a photosynthetic bacterium that the CO-to-H 2 pathway is linked to ATP production.…”

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confidence: 62%

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Energy Generation from the CO Oxidation-Hydrogen Production Pathway in Rubrivivax gelatinosus

Maness

Huang

Smolinski

et al. 2005

Appl Environ Microbiol

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When incubated in the presence of CO gas, Rubrivivax gelatinosus CBS induces a CO oxidation-H 2 production pathway according to the stoichiometry CO ؉ H 2 O 3 CO 2 ؉ H 2 . Once induced, this pathway proceeds equally well in both light and darkness. When light is not present, CO can serve as the sole carbon source, supporting cell growth anaerobically with a cell doubling time of nearly 2 days. This observation suggests that the CO oxidation reaction yields energy. Indeed, new ATP synthesis was detected in darkness following CO additions to the gas phase of the culture, in contrast to the case for a control that received an inert gas such as argon. When the CO-to-H 2 activity was determined in the presence of the electron transport uncoupler carbonylcyanide m-chlorophenylhydrazone (CCCP), the rate of H 2 production from CO oxidation was enhanced nearly 40% compared to that of the control. Upon the addition of the ATP synthase inhibitor N,N-dicyclohexylcarbodiimide (DCCD), we observed an inhibition of H 2 production from CO oxidation which could be reversed upon the addition of CCCP. Collectively, these data strongly suggest that the CO-to-H 2 reaction yields ATP driven by a transmembrane proton gradient, but the detailed mechanism of this reaction is not yet known. These findings encourage additional research aimed at long-term H 2 production from gas streams containing CO.Hydrogen is a clean fuel that addresses the issues of energy security and energy independence while preserving a pristine environment. Biomass gasification generates a gas stream enriched in CO and H 2 (synthesis gas). Many microbes have been reported to metabolize CO according to the equation CO ϩ H 2 O 7 H 2 ϩ CO 2 (4, 7, 9, 25). The biological CO-to-H 2 pathway is therefore ideal if it is used following biomass gasification to convert the CO component in the synthesis gas into additional H 2 . One such candidate is the purple nonsulfur photosynthetic bacterium Rubrivivax gelatinosus CBS, which was isolated from its natural environment with the ability to metabolize CO, yielding H 2 (16). The CO oxidation pathway in R. gelatinosus CBS consists of at least two enzymatic steps: CO dehydrogenase (CODH) catalyzes the oxidation of CO, and hydrogenase mediates the reduction of protons, yielding H 2 (17), similar to their counterparts in Rhodospirillum rubrum (8,11). Earlier findings documented that both R. gelatinosus strain 1 and R. rubrum can grow in darkness by using CO as their carbon substrate (14, 24). However, the growth media used in the above studies were often supplemented with complex carboncontaining nutrients such as Trypticase, yeast extract, and sodium acetate, which complicates the conclusion that CO could serve as the sole carbon and energy source. Nonetheless, new ATP synthesis was indeed detected in R. gelatinosus strain 1 in darkness when CO was added as the carbon substrate along with Trypticase (6). This finding provided the first direct evidence in a photosynthetic bacterium that the CO-to-H 2 pathway is linked to ATP product...

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Section: Discussionsupporting

confidence: 91%

mentioning

confidence: 62%

Energy Generation from the CO Oxidation-Hydrogen Production Pathway in Rubrivivax gelatinosus

Maness

Huang

Smolinski

et al. 2005

Appl Environ Microbiol

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“…Rhodocyclus gelatinosus (formerly Rhodopseudomonas gelatinosa; [55]) is able to grow anaerobically in the dark with CO as sole carbon and energy source [122,123] and CO oxidation can also occur in the light [124]. In Rs.…”

Section: Co Metabolismmentioning

confidence: 99%

Biochemical genetics revisited: the use of mutants to study carbon and nitrogen metabolism in the photosynthetic bacteria

Willison¹

1993

FEMS Microbiology Letters

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The biochemical genetics approach is defined as the use of mutants, in comparative studies with the wild‐type, to obtain information about biochemical and physiological processes in complex metabolic systems. This approach has been used extensively, for example in studies on the bioenergetics of the photosynthetic bacteria, but has been applied less frequently to studies of intermediary carbon and nitrogen metabolism in phototrophic organisms. Several important processes in photosynthetic bacteria—the regulation of nitrogenase synthesis and activity, the control of intracellular redox balance during photoheterotrophic growth, and chemotaxis—have been shown to involve metabolism. However, current understanding of carbon and nitrogen metabolism in these organisms is insufficient to allow a complete understanding of these phenomena. The purpose of the present review is to give an overview of carbon and nitrogen metabolism in the photosynthetic bacteria, with particular emphasis on work carried out with mutants, and to indicate areas in which the biochemical genetics approach could be applied successfully. In particular, it will be argued that, in the case of Rhodobacter capsulatus and Rb. sphaeroides, two species which are fast‐growing, possess a versatile metabolism, and have been extensively studied genetically, it should be possible to obtain a complete, integrated description of carbon and nitrogen metabolism, and to undertake a qualitative and quantitative analysis of the flow of carbon and reducing equivalents during photoheterotrophic growth. This would require a systematic biochemical genetic study employing techniques such as HPLC, NMR, and mass spectrometry, which are briefly discussed. The review is concerned mainly with Rb. capsulatus and Rb. sphaeroides, since most studies with mutants have been carried out with these organisms. However, where possible, a comparison is made with other species of purple non‐sulphur bacteria and with purple and green sulphur bacteria, and recent literature relevant to these organisms has been cited.

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“…CODH in these organisms, however, is constitutively expressed and is generally involved in acetate metabolism. CODH in R. rubrum and R. gelatinosus is specifically CO induced (9,14) and appears to have no function in acetate metabolism (10).…”

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confidence: 99%

Characterization of the region encoding the CO-induced hydrogenase of Rhodospirillum rubrum

et al. 1996

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In the photosynthetic bacterium Rhodospirillum rubrum, the presence of carbon monoxide (CO) induces expression of several proteins. These include carbon monoxide dehydrogenase (CODH) and a CO-tolerant hydrogenase. Together these enzymes catalyze the following conversion: CO ؉ H 2 O 3 CO 2 ؉ H 2 . This system enables R. rubrum to grow in the dark on CO as the sole energy source. Expression of this system has been shown previously to be regulated at the transcriptional level by CO. We have now identified the remainder of the CO-regulated genes encoded in a contiguous region of the R. rubrum genome. These genes, cooMKLXU, apparently encode proteins related to the function of the CO-induced hydrogenase. As seen before with the gene for the large subunit of the CO-induced hydrogenase (cooH), most of the proteins predicted by these additional genes show significant sequence similarity to subunits of Escherichia coli hydrogenase 3. In addition, all of the newly identified coo gene products show similarity to subunits of NADH-quinone oxidoreductase (energyconserving NADH dehydrogenase I) from various eukaryotic and prokaryotic organisms. We have found that dicyclohexylcarbodiimide, an inhibitor of mitochondrial NADH dehydrogenase I (also called complex I), inhibits the CO-induced hydrogenase as well. We also show that expression of the cooMKLXUH operon is regulated by CO and the transcriptional activator CooA in a manner similar to that of the cooFSCTJ operon that encodes the subunits of CODH and related proteins.In the presence of carbon monoxide (CO), Rhodospirillum rubrum induces synthesis of a CO-oxidizing system. This system catalyzes the net reaction CO ϩ H 2 O 3 CO 2 ϩ H 2 . The reaction is carried out by two enzymes: CO dehydrogenase (CODH) and a CO-tolerant hydrogenase. CODH is a wellcharacterized nickel-iron enzyme (10) that carries out the oxidation of CO to CO 2 , producing two reducing equivalents. Hydrogenase then consumes these reducing equivalents by the reduction of two protons to H 2 (9, 17). Intermediate electron carriers (including the ferredoxin-like small subunit of CODH [17]) may also be involved in the reaction.The hydrogenase is tightly membrane bound and has yet to be purified, although the sequence of its large subunit (CooH) and several of its properties have been described previously (22). A wide variety of hydrogenases from other organisms, however, have been purified and characterized. These hydrogenases have been found to fall into three distinct categories: Fe-only, Ni-Fe, and Ni-Fe-Se enzymes (for reviews, see references 1, 4, and 56). The CO-induced hydrogenase from R. rubrum apparently belongs to the Ni-Fe class, on the basis of its protein sequence and the requirement of Ni for activity (22).There seem to be two CO-regulated transcripts in R. rubrum. The first, cooFSCTJ, encodes CODH and related proteins (27,29,43) and has been shown to be regulated by the product of the cooA gene (43). CooA appears to bind to a specific region of DNA upstream of the cooF promoter in a CO-dependent m...

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Regulation of anaerobic carbon monoxide oxidation activity in Rhodocyclus gelatinosus

Cited by 3 publications

References 8 publications

Energy Generation from the CO Oxidation-Hydrogen Production Pathway in Rubrivivax gelatinosus

Energy Generation from the CO Oxidation-Hydrogen Production Pathway in Rubrivivax gelatinosus

Biochemical genetics revisited: the use of mutants to study carbon and nitrogen metabolism in the photosynthetic bacteria

Characterization of the region encoding the CO-induced hydrogenase of Rhodospirillum rubrum

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