Specifically adenylates L-threonine and, to a lesser extent, glycine and covalently loads both amino acids onto their corresponding peptidyl carrier domains. ATP + holo-[peptidyl-carrier protein] + L-threonine = AMP + diphosphate + L-threonyl-[peptidyl-carrier protein] ATP + glycine + holo-[peptidyl-carrier protein] = AMP + diphosphate + glycyl-[peptidyl-carrier protein] Siderophore biosynthesis; bacillibactin biosynthesis. Belongs to the ATP-dependent AMP-binding enzyme family. The phosphoserine observed at Ser-996 in PubMed:17218307 undoubtedly results from the secondary neutral loss of pantetheine from the phosphodiester linked cofactor.