Long-term effect of mutagenic DNA repair on accumulation of mutations in Pseudomonas syringae B86-17.
Forty replicate lineages of Pseudomonas syringae B86-17 cells expressing the rulAB mutagenic DNA repair (MDR) determinant or the rulB::Km MDR-deficient mutant GWS242 were passaged through single-cell bottlenecks (60 cycles), with a UV radiation (UVR) exposure given to half of the lineages at the beginning of each cycle. After every 10th bottleneck cycle, single-colony isolates from all 80 lineages were subjected to 39 phenotypic screens, with newly arising mutations detected in 60 and 0% of UVR-exposed or non-UVR-exposed B86-17 lineages, respectively, by the 60th cycle. Cellular fitness, measured as growth rate in a minimal medium, of UVR-exposed lineages of both B86-17 and GWS242 after 60 cycles was not significantly different from that of the ancestral strains. Although UVR exposure and MDR activity increased the occurrence of mutations in cells, a significant reduction in overall fitness was not observed.
Zhang
Shouan
S
National Center for Agricultural Utilization Research, USDA Agricultural Research Service, Peoria, Illinois, USA.
Sundin
George W
GW
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003470:Culture Media; D004260:DNA Repair; D009154:Mutation; D044224:Pseudomonas syringae / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects*; D011836:Radiation Tolerance; D014466:Ultraviolet Rays
D001426:Bacterial Proteins; D003470:Culture Media; C102287:RulA protein, Pseudomonas syringae; C102288:RulB protein, Pseudomonas syringae