Abstract
The mechanisms of plasmid-mediated enhancement of UV resistance (U function) and mutability (M function) had been studied. Isolation of inde-pendent mutants for each of these two functions clearly indicated that they were controlled by different genes. It was suggested that genes for these two functions were different from the gene for the plasmid-mediated DNA poly-merase described by MacPhee. We also proved that the function to enhance UV resistance was related to nicking activity of damaged DNA.
