The glutamine-utilizing site of Bacillus subtilis glutamine phosphoribosylpyrophosphate amidotransferase.

Abstract

Reaction of Bacillus subtilis glutamine phosphoribosylpyrophosphate amidotransferase with 6-diazo-5oxo-L-norleucine resulted in complete loss of its ability to catalyze glutamine-dependent phosphoribosylamine formation and its glutaminase activity, whereas its ability to catalyze ammonia-dependent phosphoribosylamine formation and to hydrolyze phosphoribosylpyrophosphate was increased.The site of reaction with 6-diazo-5-oxo-~-norleucine was the NHz-terminal cysteine residue.The NH,-terminal sequence of the B. subtilis enzyme was homologous with that of the corresponding amidotransferase from Escherichia coli, for which the NHz-terminal cysteine is also essential for glutamine utilization (Tso, J.