Molecular and General Genetics MGG

, Volume 218, Issue 2, pp 323–329

Mutagenic DNA repair genes on plasmids from the ‘pre-antibiotic era’

  • Steven G. Sedgwick
  • Susan M. Thomas
  • Victoria M. Hughes
  • David Lodwick
  • Peter Strike
Article

DOI: 10.1007/BF00331285

Cite this article as:
Sedgwick, S.G., Thomas, S.M., Hughes, V.M. et al. Molec Gen Genet (1989) 218: 323. doi:10.1007/BF00331285

Summary

Resistance transfer factors are natural conjugative plasmids encoding antibiotic resistance. Some also encode mutagenic DNA repair genes giving resistance to DNA damage and induced mutagenesis. It has been shown that antibiotic resistance has been acquired by recent transposition events; however, we show here that mutagenic repair genes existed much earlier on these types of plasmids. Conjugative plasmids from eight incompatibility groups from the Murray collection of ‘pre-antibiotic era’ enterobacteria were tested for complementation of mutagenic repair-deficient Escherichia coli umuC36. Although none of these plasmids carry transposon-encoded drug resistance genes, IncI1 and IncB plasmids were identified which restored ultraviolet resistance and induced mutability to umuC36 mutants. Furthermore they increased the UV resistance and induced mutability of wild-type E. coli, Klebsiella aerogenes and Citrobacter intermedius, thus showing that they could confer a general selective advantage to a variety of hosts. Like know mutagenic repair genes, complementation by these plasmid genes required the SOS response of the host cell. Nucleotide hybridisation showed that these plasmids harboured sequences similar to the impCAB locus, the mutagenic repair operon of modern-day IncI1 plasmids. The evolution of mutagenic repair genes is discussed.

Key words

Mutagenic DNA repairEvolutionMurray collectionimpCAB

Copyright information

© Springer-Verlag 1989

Authors and Affiliations

  • Steven G. Sedgwick
    • 1
  • Susan M. Thomas
    • 1
  • Victoria M. Hughes
    • 2
  • David Lodwick
    • 3
  • Peter Strike
    • 3
  1. 1.Genetics DivisionNational Institute for Medical ResearchLondonUK
  2. 2.Plasmid Section, National Collection of Type CulturesCentral Public Health LaboratoriesLondonUK
  3. 3.Genetics DepartmentUniversity of LiverpoolLiverpoolUK