Suppression of dnaE nonsense mutations by pcbA1.
DNA polymerase III has been recognized as the required replication enzyme in Escherichia coli. The synthesis subunit of DNA polymerase III holoenzyme (alpha subunit) is encoded by the dnaE gene. We have reported that E. coli cells can survive and grow in the absence of a functional dnaE gene product if DNA polymerase I and the pcbA1 mutation are present. Existing mutations in the dnaE gene have been conditionally defective thermolabile mutations. We report here construction of nonsense mutations in the dnaE gene by use of a temperature-sensitive suppressor mutation to permit survival at the permissive temperature (32 degrees C). Introduction of the pcbA1 mutation eliminated the temperature-sensitive phenotype. We confirmed by immunoblotting the lack of detectable alpha subunit at 43 degrees C.
Maki
H
H
Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030.
Bryan
S K
SK
Horiuchi
T
T
Moses
R E
RE
D015153:Blotting, Western; D004256:DNA Polymerase I / Q000235:genetics*; D004258:DNA Polymerase III / Q000235:genetics*; D004250:DNA Topoisomerases, Type II / Q000235:genetics; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005798:Genes, Bacterial; D046911:Macromolecular Substances; D009154:Mutation / Q000528:radiation effects; D010957:Plasmids; D013489:Suppression, Genetic; D014466:Ultraviolet Rays
D046911:Macromolecular Substances; D004256:DNA Polymerase I; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase; D004250:DNA Topoisomerases, Type II