Ultraviolet-Sensitive Mutator mutU4 of Escherichia coli Inviable with polA

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Abstract
Attempts to transduce the ultraviolet-sensitive mutator lesion mutU4 into strains deficient in deoxyribonucleic acid polymerase I ( polA ) were unsuccessful. Mutator recombinants were found when the polA recipient had first been reverted to Pol + by selection for resistance to methyl methanesulfonate. The inviability of the mutU4 polA double mutant was demonstrated by a reduction in the absolute number of transductants when the recipient was polA as compared with Pol + , and selection was made for markers very close to mutU4 . Double mutants containing mutU4 and polA4 , which determines a cold-sensitive polymerase, were unable to grow at 24 C, the nonpermissive temperature.