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Escherichia coli peptidase A, B, or N can process translation inhibitor microcin C

Teymur Kazakov1, Gaston H Vondenhoff, Kirill A Datsenko

  • 1Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia.

Journal of Bacteriology
|January 29, 2008
PubMed

Insights

Microcin C (McC) is processed by Escherichia coli peptidases PepA, PepB, or PepN, inhibiting bacterial growth. The slowest step in this microcin C processing is the removal of its initial methionine residue.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Microcin C (McC) is a heptapeptide-nucleotide antibiotic that inhibits bacterial growth by targeting aspartyl-tRNA synthetase.
  • McC's mechanism involves cellular processing to release an active inhibitor, but the specific enzymes responsible and the rate-limiting steps were not fully elucidated.

Purpose of the Study:

  • To identify the specific Escherichia coli peptidases involved in processing microcin C.
  • To determine the rate-limiting step in microcin C processing.

Main Methods:

  • Surveyed Escherichia coli strains with disrupted peptidase genes (PepA, PepB, PepN).
  • Assessed the processing efficiency of microcin C in vitro.
  • Investigated the initial step of microcin C processing, focusing on deformylation.

Main Results:

  • Any of three broad-specificity oligopeptidases—PepA, PepB, or PepN—can effectively process microcin C in vivo.
  • The rate-limiting step for microcin C processing in vitro is the deformylation of the N-terminal methionine residue.

Conclusions:

  • Escherichia coli utilizes multiple non-specific peptidases (PepA, PepB, PepN) for microcin C processing, highlighting functional redundancy.
  • Deformylation of the initial methionine is the key slow step in microcin C activation, offering a potential target for antimicrobial strategies.

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