Loss of Ultraviolet Light Protection and Enhanced Ultraviolet Light-induced Mutability in Pseudomonas aeruginosa Carrying Mutant R Plasmids

Abstract

Two mutants of the R plasmid pMG2, selected on the basis of loss of enhanced UV-induced mutability, no longer protected a wild type, a uvr rec+ type mutant, or a polA type mutant of P. aeruginosa against the lethal effects of UV. For 1 of the R plasmid mutants tested, pPL2, a plasmid-determined DNA polymerase was no longer detected. The properties of these mutants indicate that a plasmid gene function responsible for enhanced UV-induced mutability also confers UV-protection on the host cells. A plasmid-determined DNA polymerase plays a major role in producting these effects. The effects of sodium arsenite on plasmid UV-protection and enhanced UV-induced mutability in strain TRPF showed that a recA-dependent, arsenite-sensitive repair pathway is present in P. aeruginosa.