Functions of malonate decarboxylase subunits from Pseudomonas putida

Malonate decarboxylase from Pseudomonasputida is composed of five subunits, alpha, beta, gamma, delta, and epsilon. Two subunits, delta and epsilon, have been identified as an acyl-carrier protein (ACP) and malonyl-CoA:ACP transacylase, respectively. Functions of the other three subunits have not been identified, because recombinant subunits expressed in Escherichia coi formed inclusion bodies. To resolve this problem, we used a coexpression system with GroEL/ES from E. coli, and obtained active recombinant subunits. Enzymatic analysis of the purified recombinant subunits showed that the alpha subunit was an acetyl-S-ACP:malonate ACP transferase and that the betagamma-subunit complex was a malonyl-S-ACP decarboxylase.