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Properties of a cytochrome c-enriched light particulate fraction isolated from the photosynthetic bacterium Rhodopseudomonas spheroides.

ABSTRACT: Differential centrifugation of suspensions of French-press-disrupted Rhodopseudomonas spheroides yielded a light particulate fraction that was different in many properties from the bulk membrane fraction. It was enriched in cytochrome c and had a low cytochrome b content. When prepared from photosynthetically grown cells this fraction had a very low specific bacteriochlorophyll content. The cytochrome c of the light particles differed in absorption maxima at 77K from cytochrome c2 attached to membranes; there was pronounced splitting of the alpha-band, as is found in cytochrome c2 free in solution. Potentiometric titration at A552--A540 showed the presence of two components that fitted an n = 1 titration; one component had a midpoint redox potential of +345mV, like cytochrome c2 in solution, and the second had E0' at pH 7.0 of +110 mV, and they were present in a ratio of approx. 2:3. Difference spectroscopy at 77K showed that the spectra of the two components were very similar. More of a CO-binding component was present in particles from photosynthetically grown cells. Light membranes purified by centrifugation on gradients of 5--60% (w/w) sucrose retained the two c cytochromes; they contained no detectable succinate-cytochrome c reductase or bacteriochlorophyll and very little ubiquinone, but they contained NADH-cytochrome c reductase and some phosphate. Electrophoresis on sodium dodecyl sulphate/polyacrylamide gels showed that the light membranes of aerobically and photosynthetically grown cells were very similar and differed greatly from other membrane fractions of R. spheroides.

SUBMITTER: Barrett J

PROVIDER: S-EPMC1185906 | biostudies-other | 1978 Jul

REPOSITORIES: biostudies-other

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Microbial community in microbial fuel cell (MFC) medium and effluent enriched with purple photosynthetic bacterium (Rhodopseudomonas sp.).

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Functional genomic analysis of three nitrogenase isozymes in the photosynthetic bacterium Rhodopseudomonas palustris

2005-11-10 | GSE3030 | GEO

Functional genomic analysis of three nitrogenase isozymes in the photosynthetic bacterium Rhodopseudomonas palustris.

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Functional genomic analysis of three nitrogenase isozymes in the photosynthetic bacterium Rhodopseudomonas palustris

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2010-06-30 | E-GEOD-3030 | biostudies-arrayexpress

Draft Whole-Genome Sequence of the Purple Nonsulfur Photosynthetic Bacterium <i>Rhodopseudomonas rutila</i> R1.

Project description:Rhodopseudomonas species are purple nonsulfur bacteria found in many environments and known for their diverse metabolic capabilities. Here, we report the genome sequence of Rhodopseudomonas rutila type strain R1 and a whole-genome nucleotide comparison of related Rhodopseudomonas palustris species, suggesting the necessity for future reevaluation of the Rhodopseudomonas species differentiation.

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Lipid biosynthesis in synchronized cultures of the photosynthetic bacterium Rhodopseudomonas sphaeroides.

Project description:Lipid biosynthesis has been studied in photosynthetic cultures of Rhodopseudomonas sphaeroides that had been synchronized by stationary-phase cycling or by a centrifugation selection procedure. Synchrony index values in the range 0.70-0.80 were obtained for the first cell cycle with both synchronization methods. The major membrane lipids phosphatidylethanolamine and phosphatidylglycerol were accumulated discontinuously during the cell cycle, their mass doubling immediately before cell division. This accumulation of lipid corresponded to peaks in incorporation of radioactivity from either [1-14C]acetate or [2-3H]glycerol into individual acyl lipids as measured in individual portions of bacteria. For phosphatidylglycerol an additional peak of incorporation of radioactivity from [2-3H]glycerol was found midway through the cell cycle. In spite of their rather similar endogenous fatty acid compositions, the individual phosphoacylglycerols showed distinctive patterns of incorporation of radioactivity from [1-14C]acetate into their acyl moieties. The discontinuous synthesis of acyl lipids observed in cultures of Rhodopseudomonas sphaeroides synchronized by either stationary-phase cycling or centrifugation selection procedures contrasted with the accumulation of chlorophyll-protein complexes whose amounts were found to increase throughout the cell cycle. The implications of these findings for the control of lipid synthesis in bacterial photosynthetic membranes are discussed.

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Ferrochelatase of Rhodopseudomonas spheroides.

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