Roles of YqjH and YqjW, Homologs of the Escherichia coli UmuC/DinB or Y Superfamily of DNA Polymerases, in Stationary-Phase Mutagenesis and UV-Induced Mutagenesis of Bacillus subtilis

Abstract

ABSTRACT YqjH and YqjW are Bacillus subtilis homologs of the UmuC/DinB or Y superfamily of DNA polymerases that are involved in SOS-induced mutagenesis in Escherichia coli . While the functions of YqjH and YqjW in B . subtilis are still unclear, the comparisons of protein structures demonstrate that YqjH has 36% identity to E . coli DNA polymerase IV (DinB protein), and YqjW has 26% identity to E . coli DNA polymerase V (UmuC protein). In this report, we demonstrate that both YqjH and the products of the yqjW operon are involved in UV-induced mutagenesis in this bacterium. Furthermore, resistance to UV-induced damage is significantly reduced in cells lacking a functional YqjH protein. Analysis of stationary-phase mutagenesis indicates that absences of YqjH, but not that of YqjW, decreases the ability of B . subtilis to generate revertants at the hisC952 allele via this system. These data suggest a role for YqjH in the generation of at least some types of stationary-phase-induced mutagenesis.