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The export of the DNA replication inhibitor Microcin B17 provides immunity for the host cell

M C Garrido1, M Herrero, R Kolter

  • 1Uuidad de Genetica Molecular, Hospital Ramón y Cajal, Madrid, Spain.

The EMBO Journal
|June 1, 1988
PubMed

Insights

Microcin B17 (MccB17) is an antibiotic that stops DNA replication. Immunity in producing strains involves genes mcbE, mcbF, and mcbG, with McbE and McbF likely acting as an export pump for MccB17.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • Microcin B17 (MccB17) is a peptide antibiotic inhibiting DNA replication in Enterobacteriaceae.
  • Microcin-producing bacteria possess inherent immunity to MccB17.
  • Genetic studies identified three genes (mcbE, mcbF, mcbG) mediating this immunity.

Purpose of the Study:

  • To elucidate the genetic basis and mechanisms of MccB17 immunity.
  • To identify the protein products of immunity genes mcbF and mcbG.
  • To understand the dual role of certain genes in both immunity and microcin production.

Main Methods:

  • Gene sequencing of mcbE, mcbF, and mcbG.
  • Identification of polypeptide products for mcbF and mcbG.
  • Functional analysis of individual gene contributions to immunity.

Main Results:

  • Polypeptide products for mcbF and mcbG were identified.
  • Immunity was found to be mediated by two distinct genetic mechanisms.
  • Genes mcbE and mcbF are implicated in both immunity and extracellular MccB17 production.

Conclusions:

  • A model proposing McbE and McbF as a cytoplasmic export pump for MccB17 is presented.
  • McbE is predicted to be an integral membrane protein, and McbF an ATP-binding transport protein.
  • This export system reconciles the dual functions of mcbE and mcbF in immunity and production.

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