Mapping of the gene specifying DNA polymerase III of Bacillus subtilis

polC, the gene specifying the structure of the replication-specific DNA polymerase III of B. subtilis, was mapped by exploiting azp-12, a mutation conferring resistance to azopyrimidine which determines a mutant, azopyrimidine-resistant enzyme. azp-12 was located in the area of the pyrA locus and is between spcB1 and recA1. azp-12 was linked by transformation to four other mutations which influence the in vitro behaviour of DNA polymerase III--polC25, polC26, mut-1(ts), and DNAF133; the close linkage of these five mutations strongly suggests that they are alleles of the same gene.