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Daring to be different: colicin N finds another way

Karen S Jakes1

  • 1Department of Physiology and Biophysics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA.

Molecular Microbiology
|March 5, 2014
PubMed

Insights

Colicin N uniquely binds to lipopolysaccharide (LPS) instead of a protein receptor. This finding clarifies how this toxic protein enters Escherichia coli, differing from other colicins.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Colicins are protein toxins from Escherichia coli that kill other E. coli cells.
  • Most colicins use outer membrane proteins as receptors and translocators for cell entry.
  • Colicin N was previously thought to use OmpF as both receptor and translocator.

Purpose of the Study:

  • To elucidate the unique mechanism of Colicin N uptake and toxicity in Escherichia coli.
  • To identify the specific receptor and entry pathway for Colicin N.

Main Methods:

  • Genetic screens to identify genes essential for Colicin N killing.
  • Biochemical analysis of Colicin N's receptor-binding domain.
  • Investigation of lipopolysaccharide (LPS) synthesis requirements for Colicin N activity.

Main Results:

  • Colicin N's receptor-binding domain interacts with lipopolysaccharide (LPS), not the OmpF protein.
  • Minimal LPS length is necessary for Colicin N binding, explaining genetic screen results.
  • Colicin N utilizes LPS as its primary receptor, a novel mechanism among known colicins.

Conclusions:

  • Colicin N employs a distinct mechanism of cell entry by binding to LPS.
  • This discovery challenges the established understanding of colicin-receptor interactions.
  • The findings provide new insights into the diversity of bacterial toxin mechanisms.

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