This protein is a multifunctional enzyme, able to activate and polymerize the amino acids Ser and Asn as part of the synthesis of mycosubtilin. The Ser residue is further epimerized to the D-isomer form. The activation sites for these amino acids consist of individual domains. Binds 2 phosphopantetheines covalently. Belongs to the ATP-dependent AMP-binding enzyme family.