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Impact of mutS inactivation on foreign DNA acquisition by natural transformation in Pseudomonas stutzeri

Petra Meier1, Wilfried Wackernagel

  • 1Genetics, Department of Biology and Environmental Sciences, Carl von Ossietzky University of Oldenburg, Germany.

Journal of Bacteriology
|December 17, 2004
PubMed

Insights

Pseudomonas stutzeri MutS protein regulates DNA repair and genetic exchange. Downregulating MutS enhances foreign DNA acquisition, while upregulation enforces sexual isolation and affects recombination mechanisms.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • Prokaryotic mismatch repair involves MutS proteins recognizing DNA mismatches.
  • The mutS gene in Pseudomonas stutzeri ATCC 17587 was identified and characterized.

Purpose of the Study:

  • To investigate the role of the mutS gene in DNA repair, genetic exchange, and foreign DNA acquisition in P. stutzeri.
  • To understand the impact of MutS protein levels on sexual isolation and homology-facilitated illegitimate recombination (HFIR).

Main Methods:

  • Identification and characterization of the P. stutzeri mutS gene.
  • Construction and analysis of a mutS::aac mutant.
  • Transformation experiments using DNA fragments with nucleotide changes.
  • Complementation studies with E. coli and P. stutzeri mutants.
  • Analysis of foreign DNA acquisition and HFIR mechanisms.

Main Results:

  • A mutS::aac mutant exhibited significantly increased spontaneous mutability.
  • Mismatch repair efficiency was approximately 90% for transitions and transversions in wild-type P. stutzeri.
  • MutS deficiency partially alleviated sexual isolation, indicating a 14-16% contribution of mismatch repair.
  • Overexpression of mutS+ eliminated autogamic transformation and reduced heterogamic transformation.
  • MutS deficiency altered foreign DNA acquisition, increasing acquired DNA length and clustering HFIR events.

Conclusions:

  • MutS protein levels in P. stutzeri critically influence sexual isolation and foreign DNA acquisition.
  • Upregulation of MutS enforces sexual isolation, while downregulation increases foreign DNA uptake.
  • MutS plays a significant role in the mechanisms of homology-facilitated illegitimate recombination (HFIR).

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