MUTANT-GENES OF GRAMICIDIN-S SYNTHETASE-1 DEFECTIVE IN PHENYLALANINE RACEMIZATION HAVE THE SAME SEQUENCE AS THE WILD GENE

Mutant grs1 genes were cloned and sequenced from the Bacillus brevis N agano BI-4, C-3, E-1, and E-2 strains, which produce defective gramici din S synthetase 1 (GS1), lacking racemase activity. Surprisingly, the se mutant genes had entirely the same sequence as that of the wild typ e gene. These mutant strains also produce defective gramicidin S synth etase 2 (GS2), lacking 4'-phosphopantetheine, a prosthetic group of th is enzyme. The participation of this group in phenylalanine racemizati on is suggested.