Defects in the error prevention oxidized guanine system potentiate stationary-phase mutagenesis in Bacillus subtilis.
Previous studies showed that a Bacillus subtilis strain deficient in mismatch repair (MMR; encoded by the mutSL operon) promoted the production of stationary-phase-induced mutations. However, overexpression of the mutSL operon did not completely suppress this process, suggesting that additional DNA repair mechanisms are involved in the generation of stationary-phase-associated mutants in this bacterium. In agreement with this hypothesis, the results presented in this work revealed that starved B. subtilis cells lacking a functional error prevention GO (8-oxo-G) system (composed of YtkD, MutM, and YfhQ) had a dramatic propensity to increase the number of stationary-phase-induced revertants. These results strongly suggest that the occurrence of mutations is exacerbated by reactive oxygen species in nondividing cells of B. subtilis having an inactive GO system. Interestingly, overexpression of the MMR system significantly diminished the accumulation of mutations in cells deficient in the GO repair system during stationary phase. These results suggest that the MMR system plays a general role in correcting base mispairing induced by oxidative stress during stationary phase. Thus, the absence or depression of both the MMR and GO systems contributes to the production of stationary-phase mutants in B. subtilis. In conclusion, our results support the idea that oxidative stress is a mechanism that generates genetic diversity in starved cells of B. subtilis, promoting stationary-phase-induced mutagenesis in this soil microorganism.
Vidales
Luz E
LE
Department of Biology, University of Guanajuato, P.O. Box 187, Guanajuato, Gto. 36050 MEXICO.
Cárdenas
Lluvia C
LC
Robleto
Eduardo
E
Yasbin
Ronald E
RE
Pedraza-Reyes
Mario
M
D001412:Bacillus subtilis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D053843:DNA Mismatch Repair; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism; D006147:Guanine / Q000378:metabolism*; D016296:Mutagenesis; D009154:Mutation; D009876:Operon; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism
D001426:Bacterial Proteins; D017382:Reactive Oxygen Species; D006147:Guanine; D045643:DNA Repair Enzymes