The multifactorial influences of RpoS, Mlc and cAMP on ptsG expression under glucose-limited and anaerobic conditions

Shona Seeto, Lucinda Notley-McRobb, Thomas Ferenci*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

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-α-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.

Original languageEnglish
Pages (from-to)211-215
Number of pages5
JournalResearch in Microbiology
Volume155
Issue number3
DOIs
Publication statusPublished - Apr 2004
Externally publishedYes

Keywords

  • cAMP
  • Chemostat populations
  • Glucose limitation
  • Glucose transport
  • mlc mutation
  • rpoS

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