Involvement of recF , recO , and recR Genes in UV-Radiation Mutagenesis of Escherichia coli

Abstract

ABSTRACT The recF , recO , and recR genes were originally identified as those affecting the RecF pathway of recombination in Escherichia coli cells. Several lines of evidence suggest that the recF , recO , and recR genes function at the same step of recombination and postreplication repair. In this work, we report that null mutations in recF , recO , or recR greatly reduce UV-radiation mutagenesis (UVM) in an assay for reversion from a Trp − ( trpE65 ) to a Trp + phenotypes. Introduction of the defective lexA51 mutation [ lexA51 (Def)] and/or UmuD′ into recF , recO , and recR mutants failed to restore normal UVM in the mutants. On the other hand, the presence of recA2020 , a suppressor mutation for recF , recO , and recR mutations, restored normal UVM in recF , recO , and recR mutants. These results indicate an involvement of the recF , recO , and recR genes and their products in UVM, possibly by affecting the third role of RecA in UVM.