title: Targeted mutation at cytosine-containing pyrimidine dimers: studies of Escherichia coli B/r with acetophenone and 313-nm light.
abstract: We have tested the two-event model for UV mutagenesis producing class 2 suppressor mutations at glutamine tRNA genes in Escherichia coli. In the model used, the induction/indexing lesion is any type of pyrimidine dimer and the premutational photoproduct at the target site is a cytosine-containing dimer. Specific mutation-frequency responses were analyzed under conditions in which the ratio of thymine-thymine dimers to cytosine-containing dimers was modified by using 313-nm light and 0.0%, 0.1%, or 0.2% acetophenone. Changes observed in the production of class 2 suppressor mutations were consistent with the model and suggested that the G X C leads to A X T transitions responsible for class 2 suppressor mutations are targeted by cytosine-containing pyrimidine dimers at the mutational sites.
mesh_terms: D000098:Acetophenones / Q000633:toxicity*; D003596:Cytosine; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D008433:Mathematics; D008957:Models, Genetic; D009154:Mutation; D011740:Pyrimidine Dimers / Q000235:genetics* / Q000528:radiation effects; D013489:Suppression, Genetic / Q000187:drug effects / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D000098:Acetophenones; D011740:Pyrimidine Dimers; D003596:Cytosine; C038699:acetophenone