Independent regulation of synthesis of form I and form II ribulose bisphosphate carboxylase-oxygenase in Rhodopseudomonas sphaeroides.
Ribulose 1,5-bisphosphate carboxylase-oxygenase (RuBPC-O) activity was greatly enhanced when Rhodopseudomonas sphaeroides was grown in a mineral salts medium supplied with 1.5% CO2 in hydrogen. Analysis of cell extracts by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that cells growing on 1.5% CO2 in H2 specifically accumulated RuBPC-O polypeptides. Quantitative immunological determinations revealed that accumulation of form I and form II RuBPC-O closely correlates with the increase of specific activity. However, the two enzymes appeared to be derepressed at different levels. Upon transfer from heterotrophic to autotrophic (1.5% CO2) growth conditions, the intracellular form I RuBPC-O concentration was augmented 17-fold, whereas the form II RuBPC-O content increased only fourfold. As a result, the form I-form II ratio changed from 0.5 to about 2.0. Since this change in the RuBPC-O ratio occurred in the early stage of growth, it suggests that form I RuBPC-O is required for growth under drastic CO2 limitation. The difference in the extent of derepression of form I and form II RuBPC-O also indicates that the synthesis of each enzyme is regulated somewhat independently of the other.
Jouanneau
Y
Y
Tabita
F R
FR
D002245:Carbon Dioxide / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism; D007122:Immunoelectrophoresis; D008293:Malates / Q000378:metabolism; D012241:Rhodopseudomonas / Q000201:enzymology* / Q000235:genetics; D012273:Ribulose-Bisphosphate Carboxylase / Q000096:biosynthesis* / Q000276:immunology
D008293:Malates; D002245:Carbon Dioxide; D006859:Hydrogen; D012273:Ribulose-Bisphosphate Carboxylase