Overlapping functions for recF and priA in cell viability and UV-inducible SOS expression are distinguished by dnaC809 in Escherichia coli K-12
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Published on: February 5, 2015
1Department of Molecular and Cell Biology, University of California, Berkeley 94720-3202, USA.
Abstract:
The recF and priA genes have roles in DNA repair and homologous recombination. Mutations in these genes also cause decreases in cell viability and alterations in UV-inducible sulAp-lacZ (SOS) expression. To find out if the two genes are in the same or different pathways for viability and SOS expression, the phenotypes of the double mutant strains were studied. The recF priA double mutant showed a lower viability and SOS expression level than either of the single mutants. In the case of cell viability, recF missense mutations decreased viability of a priA2::kan strain two to five-fold whereas recF null priA2::kan double mutants were not viable at all. dnaC809, a mutation that suppresses the UV-sensitive (UVs and Rec- phenotypes of priA2::kan, restored cell viability, but not UV-inducible SOS expression, to a priA recF strain. Since recF is epistatic with recO and recR (recOR) for UV resistance, recOR mutations were also tested with priA2::kan. No overlap was found between recOR and priA for viability and SOS expression. It is concluded that priA and recF have two different overlapping functions in viability and SOS expression that are distinguishable by the effects of dnaC809. The role of recF in a priA2::kan strain in cell viability is a new function for recF and unlike recF's other roles in DNA repair and recombination, is independent of recOR. A new role for priA in UV-inducible SOS expression in a recF mutant is also defined.
Insights
Investigating DNA repair genes recF and priA revealed distinct overlapping functions in cell viability and SOS expression. The priA gene plays a newly identified role in UV-inducible SOS expression within recF mutants.
Area of Science:
- Molecular Biology
- Genetics
- DNA Repair Mechanisms
Background:
- The recF and priA genes are crucial for DNA repair and homologous recombination.
- Mutations in recF and priA impact cell viability and UV-inducible SOS (Synthetic Optimal) expression.
- Understanding the pathway interactions of recF and priA is essential for elucidating DNA maintenance.
Purpose of the Study:
- To determine if recF and priA function in the same or different pathways concerning cell viability and SOS expression.
- To characterize the phenotypic interactions between recF and priA mutations.
- To identify novel roles for recF and priA in DNA repair pathways.
Main Methods:
- Construction and analysis of double mutant strains (recF priA).
- Phenotypic assessment of cell viability and UV-inducible SOS expression.
- Introduction of the dnaC809 suppressor mutation into priA recF strains.
- Testing recOR mutations in conjunction with priA2::kan for comparative analysis.
Main Results:
- The recF priA double mutant exhibited significantly lower viability and SOS expression compared to single mutants.
- The dnaC809 mutation restored cell viability but not UV-inducible SOS expression in priA recF strains.
- No overlap in function was observed between recOR and priA regarding viability and SOS expression.
Conclusions:
- PriA and recF possess distinct yet overlapping functions in cell viability and SOS expression, distinguishable by the dnaC809 mutation.
- A novel role for recF in priA2::kan strain viability, independent of recOR, was identified.
- A new function for priA in UV-inducible SOS expression within recF mutants was defined.
