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Hyperrecombination in Streptococcus pneumoniae depends on an atypical mutY homologue

M M Samrakandi1, F Pasta

  • 1Laboratoire de Microbiologie et Génétique Moléculaires, Université Paul Sabatier, Toulouse, France.

Journal of Bacteriology
|June 15, 2000
PubMed

Insights

The pneumococcal mutY gene disruption prevents hyperrecombination and reduces AT-to-CG mutations. This study identifies a novel DNA repair mechanism involving adenine glycosylase in Streptococcus pneumoniae.

Area of Science:

  • Molecular Biology
  • Genetics
  • Microbiology

Background:

  • The mutation ami36 causes hyperrecombination by converting A/G mispairs to CG pairs.
  • This process depends on DNA polymerase I, but the specific correcting function remained unidentified.

Purpose of the Study:

  • To identify the DNA repair mechanism responsible for the ami36 mutation's effects.
  • To investigate the role of the pneumococcal mutY homologue in DNA repair and mutation.

Main Methods:

  • Genome sequence analysis to identify the mutY homologue.
  • Gene disruption experiments to assess the effect on hyperrecombination and mutation.
  • Complementation assays in Escherichia coli.

Main Results:

  • Disruption of the pneumococcal mutY homologue abolished ami36-induced hyperrecombination.
  • The disruption resulted in a mutator phenotype, specifically increasing AT-to-CG transversions.
  • The pneumococcal MutY protein lacks conserved cysteines for a [4Fe-4S](2+) cluster but complements E. coli mutY strains.

Conclusions:

  • The pneumococcal MutY protein is crucial for repairing A/G mispairs and preventing AT-to-CG transversions.
  • The absence of conserved cysteines suggests a unique structural or functional adaptation in pneumococcal MutY.
  • This finding reveals a novel DNA repair pathway in Streptococcus pneumoniae.

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