title: Influence of uvrB and pKM101 on the spectrum of spontaneous, UV- and gamma-ray-induced base substitutions that revert hisG46 in Salmonella typhimurium.
abstract: Oligonucleotide probes were used to identify base substitutions in 1089 revertants of hisG46 in Salmonella typhimurium that arose spontaneously or following irradiation with UV- or gamma-rays. The hisG46 allele, carrying a mutant CCC codon (Pro) in place of the wild-type codon CTC (Leu69) reverted via 6 distinguishable mutational events--C to T transitions at codon sites 1 or 2, C to A or C to G transversions at codon site 1, C to A at codon site 2, and an extragenic suppressor mutation. The distribution of hisG46 revertants differed among treatments and was influenced by the DNA-repair capacity of the bacteria. Plasmid pKM101 enhanced the frequencies of both spontaneous and induced mutations; transversion events were enhanced more efficiently by pKM101 than were transition events. Compared to Uvr+ bacteria, Uvr- bacteria had higher frequencies of spontaneous and induced mutations; transition mutations were enhanced more efficiently than were transversion mutations. The influence of DNA-repair activities on the mutational spectra provides some insights on the origins of spontaneous and UV-induced mutations.
authors.affiliation: Department of Cancer Biology, Harvard School of Public Health, Boston, MA 02115.
authors.forename: E
authors.initials: E
authors.lastname: Eisenstadt
authors.forename: J K
authors.initials: JK
authors.lastname: Miller
authors.forename: L S
authors.initials: LS
authors.lastname: Kahng
authors.forename: W M
authors.initials: WM
authors.lastname: Barnes
mesh_terms: D004249:DNA Damage; D004260:DNA Repair; D005720:Gamma Rays; D006639:Histidine / Q000235:genetics; D009154:Mutation / Q000528:radiation effects*; D012486:Salmonella typhimurium / Q000235:genetics* / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D006639:Histidine