Molecular and General Genetics MGG

, Volume 212, Issue 3, pp 393–404

Apparent gene conversion in an Escherichia coli rec+ strain is explained by multiple rounds of reciprocal crossing-over

  • Kenji Yamamoto
  • Hiroshi Yoshikura
  • Noriko Takahashi
  • Ichizo Kobayashi
Article

DOI: 10.1007/BF00330842

Cite this article as:
Yamamoto, K., Yoshikura, H., Takahashi, N. et al. Mol Gen Genet (1988) 212: 393. doi:10.1007/BF00330842

Summary

Gene conversion, the non-reciprocal transfer of sequence information between homologous DNA sequences, has been reported in lower eukaryotes, mammals and in Escherichia coli. In an E. coli rec+ strain, we established a plasmid carrying two different deleted neo genes (neoDL and neoDR) in an inverted orientation and then selected for homologous recombination events that had reconstructed an intact neo+ gene. We found some plasmids that had apparently experienced intramolecular gene conversion. Further evidence, however, suggests that they are products of multiple rounds of reciprocal crossing-over,apparently involving two plasmid molecules. First, most of the Neo+ clones contained multiple types of Neo+ plasmids, although the frequency of producing the neo+ clones was low. Second, all the neo+ clones also contained, as a minority, one particular form of dimer, which can be formed by reciprocal crossing-over between neoDL of one plasmid molecule and neoDR of another plasmid molecule. Third, in reconstruction experiments, we cloned and purified this dimer and transferred it back into the rec+ cells. The dimer gave rise to clones containing multiple types of neo+ recombinant monomers, including those apparent gene conversion types, and containing only few molecules of this dimer plasmid.

Key words

Homologous recombination recA recF Holliday structure Mismatch repair 
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Copyright information

© Springer-Verlag 1988

Authors and Affiliations

  • Kenji Yamamoto
    • 1
  • Hiroshi Yoshikura
    • 1
  • Noriko Takahashi
    • 2
  • Ichizo Kobayashi
    • 1
    • 2
  1. 1.Department of Bacteriology, Faculty of MedicineUniversity of TokyoTokyoJapan
  2. 2.Department of Infectious DiseasesNational Children's Medical Research CenterTokyoJapan
  3. 3.Department of Infectious DiseasesNational Children's Medical Research CenterTokyoJapan

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