Expression of the Pseudomonas putida OCT plasmid alkane degradation pathway is modulated by two different global control signals: evidence from continuous cultures.
Expression of the genes of the alkane degradation pathway encoded in the Pseudomonas putida OCT plasmid are subject to negative and dominant global control depending on the carbon source used and on the physiological status of the cell. We investigated the signals responsible for this control in chemostat cultures under conditions of nutrient or oxygen limitation. Our results show that this global control is not related to the growth rate and responds to two different signals. One signal is the concentration of the carbon source that generates the repressing effect (true catabolite repression control). The second signal is influenced by the level of expression of the cytochome o ubiquinol oxidase, which in turn depends on factors such as oxygen availability or the carbon source used. Since under carbon limitation conditions the first signal is relieved but the second signal is not, we propose that modulation mediated by the cytochrome o ubiquinol oxidase is not classical catabolite repression control but rather a more general physiological control mechanism. The two signals have an additive, but independent, effect, inhibiting induction of the alkane degradation pathway.
Dinamarca
M Alejandro
MA
Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Campus de la Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
Aranda-Olmedo
Isabel
I
Puyet
Antonio
A
Rojo
Fernando
F
D000473:Alkanes / Q000378:metabolism* / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002244:Carbon / Q000378:metabolism; D003470:Culture Media; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D010100:Oxygen / Q000494:pharmacology; D010957:Plasmids / Q000235:genetics*; D011401:Promoter Regions, Genetic; D016958:Pseudomonas putida / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D015398:Signal Transduction; D019802:Succinic Acid / Q000378:metabolism
D000473:Alkanes; D001426:Bacterial Proteins; D003470:Culture Media; D002244:Carbon; D019802:Succinic Acid; C038862:cytochrome o oxidase; D003576:Electron Transport Complex IV; D010100:Oxygen