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.
Original language | English |
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Pages (from-to) | 521-536 |
Number of pages | 15 |
Journal | Molecular Microbiology |
Volume | 43 |
Issue number | 2 |
DOIs | |
Publication status | Published - 2002 |
Keywords
- COMPATIBLE SOLUTE ACCUMULATION
- POTASSIUM-TRANSPORT LOCI
- MECHANOSENSITIVE CHANNEL
- SALMONELLA-TYPHIMURIUM
- ALKALINE-PHOSPHATASE
- CYTOPLASMIC MEMBRANE
- MULTIDRUG EFFLUX
- ION CHANNELS
- PROTEIN
- MSCL