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.

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.