Alternate pathways of DNA replication: DNA polymerase I-dependent replication

Proc Natl Acad Sci U S A. 1981 Nov;78(11):7024-7. doi: 10.1073/pnas.78.11.7024.


We have previously shown that some Escherichia coli [derivatives of strain HS432 (polA1, polB100, polC1026)] can replicate DNA at a restrictive temperature in the presence of a polCts mutation and that such revertants contain apparent DNA polymerase I activity. We demonstrate here that this strain of E. coli becomes temperature-resistant upon the introduction of a normal gene for DNA polymerase I or suppression of the polA1 nonsense mutation. Such temperature-resistant phenocopies become temperature-sensitive upon introduction of a temperature-sensitive DNA polymerase I gene. Our results confirm that DNA replication is DNA polymerase I-dependent in the temperature-resistant revertants, indicating that an alternative pathway of replication exists in E. coli. HS432 contains a transducible locus (which we term pcbA) that can support an alternate pathway in other E. coli strains, so the effect of suppression of polCts is a general one.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • DNA Polymerase I / metabolism*
  • DNA Replication*
  • DNA-Directed DNA Polymerase / metabolism*
  • Escherichia coli / enzymology*
  • Mutation
  • Phenotype
  • Species Specificity
  • Suppression, Genetic
  • Temperature
  • Transduction, Genetic


  • DNA Polymerase I
  • DNA-Directed DNA Polymerase