PMID:11985727

Citation	McLaggan, D, Jones, MA, Gouesbet, G, Levina, N, Lindey, S, Epstein, W and Booth, IR (2002) Analysis of the kefA2 mutation suggests that KefA is a cation-specific channel involved in osmotic adaptation in Escherichia coli.Mol. Microbiol. 43:521-36
Abstract	Mechanosensitive channels play an essential role in the regulation of turgor pressure in bacteria. In Escherichia coli, there are multiple mechanosensitive channels that have been characterized genetically: MscL, YggB and KefA. In this report, we describe the cloning of the kefA gene, the organization of the KefA protein and the phenotype of a missense mutation, kefA, which affects the KefA mechanosensitive channel. The altered function of the channel is manifest through increased sensitivity to K+ during growth at low osmolarity and complete inhibition of growth in media containing high K+ concentrations (0.6 M) in the presence of betaine or proline. Growth in high Na+ medium (0.6 M NaCl plus 20 mM K+) is normal. Analysis of the cytoplasmic pools shows that the mutant cannot regulate the K+ content of the cytoplasm when grown in high K+ medium. However, regulation of pools of amino acids is essentially normal and the mutant can accumulate high pools of proline during growth inhibition. The mutant shows increased sensitivity to acid hypo-osmotic shock (transition from neutral to acid pH combined with a reduction in osmolarity). The data are consistent with abnormal regulation of KefA in the presence of high K+ concentrations and either betaine or proline.
Links	PubMed
Keywords	Acids; Adaptation, Physiological; Bacterial Proteins; Cations; Escherichia coli; Escherichia coli Proteins; Genes, Bacterial; Glutamic Acid; Mutagenesis; Osmolar Concentration; Osmosis; Potassium; Potassium Channels; Proline; Trehalose; Water-Electrolyte Balance
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Species	Taxon ID	Strain	Gene (if known)	OMP	Phenotype	Details	Evidence	Notes
Escherichia coli		RQ2	kefA2	no growth	Growth	in medium containing high levels of K+ in the presence of betaine	Growth Curve	gain-of-fucntion mutation
Escherichia coli		RQ2	kefA2	no growth	Growth	in medium containing high levels of K+ in the presence of betaine	Growth Curve
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