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Effect of outer membrane permeability on chemotaxis in Escherichia coli

C Ingham1, M Buechner, J Adler

  • 1Department of Biochemistry, University of Wisconsin-Madison 53706.

Journal of Bacteriology
|July 1, 1990
PubMed

Insights

Escherichia coli outer membrane permeability, influenced by porins OmpF and OmpC, affects amino acid chemotaxis. Altering porin composition regulates bacterial sensory responses to environmental cues.

Area of Science:

  • Microbiology
  • Bacterial Physiology
  • Chemotaxis

Background:

  • The outer membrane of Gram-negative bacteria like Escherichia coli acts as a selective barrier.
  • Porins are key protein channels in the outer membrane regulating the passage of molecules.
  • Chemotaxis, the directed movement in response to chemical stimuli, is crucial for bacterial survival.

Purpose of the Study:

  • To investigate the role of major porins (OmpF and OmpC) in Escherichia coli's outer membrane permeability.
  • To determine how outer membrane permeability affects chemotaxis towards various compounds.
  • To explore the potential of chemotaxis as an in vivo assay for outer membrane permeability.

Main Methods:

  • Studied mutants in the major porin genes ompF and ompC of Escherichia coli.
  • Utilized spatial assays to measure chemotaxis towards amino acids (e.g., L-aspartate) and maltose.
  • Assessed methylation of methyl-accepting chemotaxis protein II as an indicator of chemotactic response.
  • Investigated the effect of LamB protein induction on taxis.

Main Results:

  • Both OmpF and OmpC porins facilitate amino acid passage for chemotaxis, with OmpF being more effective.
  • A double mutant lacking both OmpF and OmpC showed significantly reduced amino acid chemotaxis.
  • The maltoporin LamB enabled maltose taxis but not L-aspartate taxis, indicating selective permeability.
  • Salt taxis was less affected by porin mutations than amino acid taxis, suggesting alternative permeability pathways.

Conclusions:

  • Outer membrane porins play a critical role in mediating chemotaxis towards amino acids in E. coli.
  • Chemotaxis serves as a sensitive in vivo method to assess outer membrane permeability.
  • E. coli can modulate its chemotactic sensitivity by adjusting its outer membrane porin profile.

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