Abstract
We have described the pcbA1 mutation which enables E. coli cells to replicate DNA in the absence of a functional dnaE gene product if DNA polymerase I (the polA gene product) is present. The pcbA1 mutation phenotypically suppresses multiple dnaEts and dnaEam alleles. The pcbA1 / PolI replication pathway differs from normal in sensitivity to certain DNA-damaging agents such as methylmethane sulfonate (MMS) and a lack of damage-directed mutagenesis. We report here cloning of the pcbA1 gene in a multicopy plasmid. The pcbA1 mutation is detected only in cis; therefore, cloning necessitated gene eviction. The pcbA1 gene lies closely- linked to gyrB. We have demonstrated the physical presence of DNA polymerase I in the replicating holoenzyme complex by immunoblotting using dnaEam strains. We conclude that E. coli has two alternate replisome structures: REP-A, in which DNA polymerase I is the functional synthetic subunit; and REP-E, in which the α-subunit, product of the dnaE gene, is functional. To investigate further the role of individual DNA polymerases in replication, we have isolated the polB gene on multicopy plasmids.
Original language | English (US) |
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Pages (from-to) | 249-254 |
Number of pages | 6 |
Journal | BBA - Gene Structure and Expression |
Volume | 951 |
Issue number | 2-3 |
DOIs | |
State | Published - Dec 20 1988 |
Keywords
- (E. coli)
- DNA polymerase I
- DNA replication pathway
- pcbA1 cloning
- polB
ASJC Scopus subject areas
- Structural Biology
- Biophysics
- Biochemistry
- Genetics