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Regulation of synthesis of pyruvate carboxylase in the photosynthetic bacterium Rhodobacter capsulatus.
- Source :
-
Journal of bacteriology [J Bacteriol] 1997 Mar; Vol. 179 (5), pp. 1460-8. - Publication Year :
- 1997
-
Abstract
- The synthesis of pyruvate carboxylase (PC) was studied by using quantitative immunoblot analysis with an antibody raised against PC purified from Rhodobacter capsulatus and was found to vary 20-fold depending on the growth conditions. The PC content was high in cells grown on pyruvate or on carbon substrates metabolized via pyruvate (lactate, D-malate, glucose, or fructose) and low in cells grown on tricarboxylic acid (TCA) cycle intermediates or substrates metabolized without intermediate formation of pyruvate (acetate or glutamate). Under dark aerobic growth conditions with lactate as a carbon source, the PC content was approximately twofold higher than that found under light anaerobic growth conditions. The results of incubation experiments demonstrate that PC synthesis is induced by pyruvate and repressed by TCA cycle intermediates, with negative control dominating over positive control. The content of PC in R. capsulatus cells was also directly related to the growth rate in continuous cultures. The analysis of intracellular levels of pyruvate and TCA cycle intermediates in cells grown under different conditions demonstrated that the content of PC is directly proportional to the ratio between pyruvate and C4 dicarboxylates. These results suggest that the regulation of PC synthesis by oxygen and its direct correlation with growth rate may reflect effects on the balance of intracellular pyruvate and C4 dicarboxylates. Thus, this important enzyme is potentially regulated both allosterically and at the level of synthesis.
- Subjects :
- Aerobiosis
Amino Acid Sequence
Anaerobiosis
Chloramphenicol pharmacology
Citric Acid Cycle
Culture Media
Darkness
Dicarboxylic Acids metabolism
Enzyme Induction
Enzyme Repression
Fumarates metabolism
Lactic Acid metabolism
Lactic Acid pharmacology
Molecular Sequence Data
Protein Synthesis Inhibitors pharmacology
Pyruvate Carboxylase isolation & purification
Pyruvate Carboxylase metabolism
Pyruvic Acid metabolism
Pyruvic Acid pharmacology
Rhodobacter capsulatus growth & development
Pyruvate Carboxylase biosynthesis
Rhodobacter capsulatus enzymology
Subjects
Details
- Language :
- English
- ISSN :
- 0021-9193
- Volume :
- 179
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- Journal of bacteriology
- Publication Type :
- Academic Journal
- Accession number :
- 9045800
- Full Text :
- https://doi.org/10.1128/jb.179.5.1460-1468.1997