PMID:15059634
| Citation |
Seeto, S, Notley-McRobb, L and Ferenci, T (2004) The multifactorial influences of RpoS, Mlc and cAMP on ptsG expression under glucose-limited and anaerobic conditions. Res. Microbiol. 155:211-5 |
|---|---|
| Abstract |
The ptsG gene encodes the high-affinity glucose receptor component of the PEP:glucose phosphotransferase system. PtsG is the major glucose transporter in Escherichia coli under glucose-excess conditions but its regulation under glucose limitation or anaerobiosis is poorly defined. Using a ptsG-lacZ transcriptional fusion, ptsG expression was found to peak with low (micromolar) external glucose levels in glucose-limited chemostats, so PtsG is primed to contribute to glucose scavenging under hunger response conditions. This regulatory pattern was confirmed using methyl- alpha-glucoside transport assays of PtsG-dependent transport. The regulation of ptsG by cAMP contributed to the optimal expression with micromolar glucose but ptsG was actually repressed to levels below that in glucose-excess batch cultures at very slow growth rates and submicromolar glucose concentrations. RpoS contributed to repression of ptsG in slow-growing bacteria but not under glucose-excess conditions. Also, Mlc increasingly contributed to the repression of ptsG at residual glucose concentrations too low to saturate PtsG. A similar pattern of ptsG regulation was observed in anaerobic cultures with either glucose-excess or glucose-limiting situations. |
| Links |
PubMed Online version:10.1016/j.resmic.2003.11.011 |
| Keywords |
Anaerobiosis; Bacterial Proteins/metabolism; Biological Transport; Bioreactors; Cyclic AMP/metabolism; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins; Gene Expression Regulation, Bacterial/physiology; Glucose/metabolism; Methylglucosides/metabolism; Monosaccharide Transport Proteins/metabolism; Phosphoenolpyruvate Sugar Phosphotransferase System/biosynthesis; Phosphoenolpyruvate Sugar Phosphotransferase System/genetics; Repressor Proteins/metabolism; Sigma Factor/metabolism |
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