May catalyze the condensation reaction of fatty acid synthesis by the addition to an acyl acceptor of two carbons from malonyl-ACP. acetyl-CoA + H(+) + malonyl-[ACP] = 3-oxobutanoyl-[ACP] + CO2 + CoA Lipid metabolism; fatty acid biosynthesis. Homodimer. Belongs to the thiolase-like superfamily. FabH family. Lacks the Asn-Xaa-Arg residues, which are typical of the ACP-binding site and are essential for the association between AcpP and FabH.