This model represents the enzyme (also called D-alanine-D-alanyl carrier protein ligase) which activates D-alanine as an adenylate via the reaction D-ala + ATP -> D-ala-AMP + PPi, and further catalyzes the condensation of the amino acid adenylate with the D-alanyl carrier protein (D-ala-ACP). The D-alanine is then further transferred to teichoic acid in the biosynthesis of lipoteichoic acid (LTA) and wall teichoic acid (WTA) in gram positive bacteria, both polysacchatides. [Cell envelope, Biosynthesis and degradation of murein sacculus and peptidoglycan]