CoA + R-COO- + ATP –> R-COSCoA + AMP + PPi
Closely related acyl carrier protein (ACP) ligases act in the same way since ACP shares the same phosphopantetheine prosthetic group, and a few CoA ligases are capable of using ACP as an alternative substrate. It is possible that a small number of the genes we are studying encode carboxy-ACP ligases. Also, one subset of the Arabidopsis AMP-binding proteins contains enzymes that activate carboxyl groups for conjugation to amino acids. The genes encoding these functions will not be studied under this grant. More broadly, the CoA ligases are related to firefly luciferase and to activation domains of proteins involved in non-ribosomal peptide synthesis. Crystal structures for luciferases and the PheA domain of gramicidin S synthetase are available, and these have been used as the basis for modeling the structures of several plant AAEs.