Molecular and General Genetics MGG

, Volume 210, Issue 2, pp 369–372

Mismatch repair during pneumococcal transformation of small deletions produced by site-directed mutagenesis

  • A. M. Gasc
  • P. Garcia
  • D. Baty
  • A. M. Sicard
Short Communications

Summary

The genetic behaviour of short non-homologous regions has been studied during transformation of Streptococcus pneumoniae. Amethopterin-resistant mutants belonging to the amiA locus were used for these investigations. Five mutants deleted for 1–5 bp were obtained by oligonucleotide-direcrted mutagenesis. Their efficiency of transformation was measured using recipient strains either able to excise and repair mismatched bases (Hex+) or Hex- derivatives. Deletions or insertions of 1 and 2 bp are fully recognized by the Hex system, and are efficiently repaired whereas 3-bp deletions or insertions are only partially excised and repaired. The efficiency of repair is inversely related to the size of the non-homology. Markers with 5-bp deletions or insertions are poorly repaired and thus transform at very high frequency: similar results are obtained in reciprocal crosses. It is proposed that 1-or 2-bp deletions or insertions are included in the heteroduplex structure as transition mutations. The Hex system would detect only small deviations from the normal DNA structure.

Key words

Oligomer mutagenesis Mismatch repair Recombination Heteroduplex DNA 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Copyright information

© Springer-Verlag 1987

Authors and Affiliations

  • A. M. Gasc
    • 1
  • P. Garcia
    • 1
  • D. Baty
    • 2
  • A. M. Sicard
    • 1
  1. 1.Centre de Recherche de Biochimie et Génétique Cellulaires CNRSToulouse CedexFrance
  2. 2.Centre de Biochimie et Biologie Moléculaire CNRSMarseilleFrance
  3. 3.Centro de Investigaciones Biológicas(CSIC)MadridSpain

Personalised recommendations