Photolithoautotrophic growth and control of CO2 fixation in Rhodobacter sphaeroides and Rhodospirillum rubrum in the absence of ribulose bisphosphate carboxylase-oxygenase.
Rhodospirillum rubrum and Rhodobacter sphaeroides were shown to be capable of photolithoautotrophic growth in the absence of the reductive pentose phosphate (Calvin) cycle. Ribulose 1,5-bisphosphate carboxylase-oxygenase (RubisCO) deletion strains were incapable of photolithoautotrophic growth using hydrogen as an electron donor but were able to grow in the absence of organic carbon using less reduced inorganic electron donors, i.e., thiosulfate or sulfide. Wild-type R. rubrum grown in the presence of thiosulfate contained RubisCO levels that were 50-fold lower compared with those in cells growth with hydrogen as an electron donor without substantially influencing rates of photolithoautotrophic growth. These results suggest there are two independent CO2 fixation pathways that support photolithoautotrophic growth in purple nonsulfur photosynthetic bacteria, indicating that these organisms have developed sophisticated control mechanisms to regulate the flow of carbon from CO2 through these separate pathways.
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Department of Microbiology, Ohio State University, Columbus 43210-1192.
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D001426:Bacterial Proteins / Q000302:isolation & purification / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D017353:Gene Deletion; D007700:Kinetics; D008970:Molecular Weight; D012242:Rhodobacter sphaeroides / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D012247:Rhodospirillum rubrum / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism
D001426:Bacterial Proteins; D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase