This enzyme, along with EC 184.108.40.206, [acyl-carrier-protein] S-acetyltransferase, is essential for the initiation of fatty-acid biosynthesis in bacteria. This enzyme also provides the malonyl groups for polyketide biosynthesis . The product of the reaction, malonyl-ACP, is an elongation substrate in fatty-acid biosynthesis. In Mycobacterium tuberculosis, holo-ACP (the product of EC 220.127.116.11, holo-[acyl-carrier-protein] synthase) is the preferred substrate . This enzyme also forms part of the multienzyme complexes EC 18.104.22.168 (biotin-independent malonate decarboxylase) and EC 22.214.171.124 (biotin-dependent malonate decarboxylase). Malonylation of ACP is immediately followed by decarboxylation within the malonate-decarboxylase complex to yield acetyl-ACP, the catalytically active species of the decarboxylase . In the enzyme from Klebsiella pneumoniae, methylmalonyl-CoA can also act as a substrate but acetyl-CoA cannot  whereas the enzyme from Pseudomonas putida can use both as substrates . The ACP subunit found in fatty-acid biosynthesis contains a pantetheine-4'-phosphate prosthetic group; that from malonate decarboxylase also contains pantetheine-4'-phosphate but in the form of a 2′-(5-triphosphoribosyl)-3′-dephospho-CoA prosthetic group.