Identification of mutations that alter the gating of the Escherichia coli mechanosensitive channel protein, MscK

Chan Li, Michelle D. Edwards, Hochterl Jeong, John Roth, Ian R. Booth

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Mechanosensitive channels allow bacteria to survive rapid increases in turgor pressure. Substantial questions remain as to how these channels sense and respond to mechanical stress. Here we describe a set of mutants with alterations in their MscK channel protein. The mutants were detected fortuitously by their enhanced ability to modify the accumulation of quinolinic acid. Some amino acid changes lie in the putative pore region of MscK, but others affect sequences that lie amino-terminal to the domain aligning with MscS. We demonstrate that the alterations in MscK cause the channel to open more frequently in the absence of excessive mechanical stress. This is manifested in changes in sensitivity to external K+ by cells expressing the mutant proteins. Single-channel analysis highlighted a range of gating behaviours: activation at lower pressures than the wild type, inability to achieve the fully open state or a modified requirement for K+. Thus, the dominant uptake phenotype of these mutants may result from a defect in their ability to regulate the gating of MscK. The locations of the substituted residues suggest that the overall gating mechanism of MscK is comparable to that of MscS, but with subtleties introduced by the additional protein sequences in MscK.

Original languageEnglish (US)
Pages (from-to)560-574
Number of pages15
JournalMolecular Microbiology
Volume64
Issue number2
DOIs
StatePublished - Apr 2007

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Mechanical Stress
Escherichia coli
Quinolinic Acid
Pressure
Mutation
Mutant Proteins
Proteins
Bacteria
Phenotype
Amino Acids

ASJC Scopus subject areas

  • Molecular Biology
  • Microbiology

Cite this

Identification of mutations that alter the gating of the Escherichia coli mechanosensitive channel protein, MscK. / Li, Chan; Edwards, Michelle D.; Jeong, Hochterl; Roth, John; Booth, Ian R.

In: Molecular Microbiology, Vol. 64, No. 2, 04.2007, p. 560-574.

Research output: Contribution to journalArticle

Li, Chan ; Edwards, Michelle D. ; Jeong, Hochterl ; Roth, John ; Booth, Ian R. / Identification of mutations that alter the gating of the Escherichia coli mechanosensitive channel protein, MscK. In: Molecular Microbiology. 2007 ; Vol. 64, No. 2. pp. 560-574.
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