This family consists of several bacterial malonate decarboxylase gamma subunit proteins. Malonate decarboxylase of Klebsiella pneumoniae consists of four different subunits and catalyses the conversion of malonate plus H+ to acetate and CO2. The catalysis proceeds via acetyl and malonyl thioester residues with the phosphribosyl-dephospho-CoA prosthetic group of the acyl carrier protein (ACP) subunit. MdcD and E together probably function as malonyl-S-ACP decarboxylase [1].

1: Sequence of a gene cluster from Klebsiella pneumoniae encoding malonate decarboxylase and expression of the enzyme in Escherichia coli. Hoenke S, Schmid M, Dimroth P; Eur J Biochem 1997;246:530-538. PMID:9208947