(2S,3R)-3-methyl-L-phenylalanine + holo-[peptidyl-carrier protein] + ATP = (3R)-3-methyl-L-phenylalanyl-[peptidyl carrier-protein] + AMP + diphosphate
(2s,3r)-3-methyl-l-phenylalanine + holo-[peptidyl-carrier protein] + atp = (3r)-3-methyl-l-phenylalanyl-[peptidyl carrier-protein] + amp + diphosphate