Alternate pathways of DNA replication: DNA polymerase I-dependent replication.
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.
D004256:DNA Polymerase I / Q000378:metabolism*; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D009154:Mutation; D010641:Phenotype; D013045:Species Specificity; D013489:Suppression, Genetic; D013696:Temperature; D014161:Transduction, Genetic
D004256:DNA Polymerase I; D004259:DNA-Directed DNA Polymerase