Isolation and partial characterization of bacteriophage T5 mutants deficient in the ability to induce deoxynucleoside...

Two mutants of bacteriophage T5 deficient in the ability to induce wild-type levels of deoxynucleoside monophosphate kinase were isolated and partially characterized. Both mutations were demonstrated to be in a structural gene for the kinase. One of the mutants, designated dnk 10, induces no detectable levels of dCMP, dGMP, or dTMP kinase activity. Because the mutant can successfully infect nonpermissive cells, phage-induced deoxynucleoside monophosphate kinase appears to be an unessential function for phage production. DNA synthesis in dnk 10-infected cells, however, is reduced to 30% of that observed in wild-type-infected cells; phage production is reduced by a comparable amount. The dnk mutation has been mapped and located on the "C" region of the T5 genetic map, 6.3 map units from the C1 locus.