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.