2 GENES ENCODING URACIL PHOSPHORIBOSYLTRANSFERASE ARE PRESENT IN BACILLUS-SUBTILIS

Uracil phosphoribosyltransferase (UPRTase) catalyzes the key reaction in the salvage of uracil in many microorganisms. Surprisingly, two gen es encoding UPRTase activity were cloned from Bacillus subtilis by com plementation of an Escherichia coli mutant. The genes were sequenced, and the putative amino acid sequences,were deduced. One gene showed a high level of homology to UPRTases from other organisms, whereas the o ther gene with a low level of homology to other UPRTases turned out to be the pyrR gene-the repressor of the pyr operon. The role of these g enes in uracil metabolism was established by an analysis of the phenot ypes of upp and pyrR mutants.