Fig. 5.

Genetic interactions of ygbT and DNA damage sensitivity of the ygbT deletion strain. (A) Chromosomal positions of ygbT (green arrow), rec (purple arrows), ruv (yellow arrows), and other gene (red arrows) deletions used as donors (marked with Cm^R) or recipients (marked with Kan^R) in eSGA experiments. csdA and rpoS donor deletions (blue arrows) located close to the rec and ygbT genes served as controls for effects of proximity on recombination. The numbers indicate the gene coordinates on the E. coli chromosome (in minutes). OriT is the F origin of transfer in Hfr Cavalli (12.2 minutes). (B) Validation of ygbT-rec and ygbT-ruv synthetic genetic interactions. rec (Panel I), ruv (Panel II), and control (csdA and rpoS, Panel III) Hfr Cavalli donor deletion strains were crossed with the indicated F^- recipient deletion strains (deleted for ruv, ygbT, or various genes flanking ruv and ygbT), followed by selection on plates containing chloramphenicol and kanamycin. (C) Serial cell dilution assay showing growth inhibition of ygbT-ruvABC double mutants and their single mutants by MMC (0.15 μM). Growth is classified as sensitive to MMC (+) or not sensitive compared with wild-type (−). Also shown are the effects of complementing ΔygbT with pBAD vectors expressing wild-type or inactive mutant YgbT. (D) Effects of the indicated doses of UV irradiation on the survival of ygbT-ruvABC double mutants and their single mutants. The values plotted are averages from three independent experiments.