Fig 6. GTAs confer survival to DNA damage.

(A) Survival of a recipient strain bearing the vanillate-inducible restriction enzyme I-SceI and an I-SceI site on the chromosome co-incubated with either a GTA producer (P_xyl-gafYZ) or a GTA non-producer control (P_xyl-empty). Vanillate was added to induce double-strand breaks in the recipient strain and xylose was added to induce the xylose promoter in the donors. Survival of the recipient strains was assayed after the indicated times with 10-fold serial dilutions on plates containing chloramphenicol with no vanillate (− van) to quantify all recipient cells and chloramphenicol with vanillate (+ van) to quantify all recipient cells that have lost the lethality of I-SceI expression. Outcome of sequencing the region harboring the I-SceI site in individual survivors is shown at the bottom. (B) Wild-type and various mutants were grown in PYE for 48 h and then exposed to a range of zeocin concentrations (0–90 μg/mL) for 24 h. Survival was enumerated with 10-fold serial dilutions. (C) Susceptibilities of different strains to the DNA-damaging agents MMC (0.5 mg/mL), HU (300 mg/mL), EMS (100 mg/mL), 2 control antibiotics cephalexin (6 mg/mL), and vancomycin (100 mg/mL). All cells tested were in stationary phase when plated except when indicated for MMC exp., where cells were in exponential phase. (D) Radius of inhibition of different strains to DNA-damaging agents and 2 control antibiotics. Radii are normalized to the WT mean radius for the drug (n = 3, error bars indicate SD). All cells tested were in stationary phase when plated except when indicated for MMC exp, where cells were in exponential phase. * = p-value <0.05 between indicated data and wild type. Data are available in S1 Data. GTA, gene transfer agent.