Catalyzes the rate-limiting reaction in the biogenesis of long-chain fatty acids. Carries out three functions: biotin carboxyl carrier protein, biotin carboxylase and carboxyltransferase. acetyl-CoA + ATP + hydrogencarbonate = ADP + H(+) + malonyl-CoA + phosphate ATP + hydrogencarbonate + N(6)-biotinyl-L-lysyl-[protein] = ADP + H(+) + N(6)-carboxybiotinyl-L-lysyl-[protein] + phosphate Binds 2 manganese ions per subunit. By phosphorylation. Lipid metabolism; malonyl-CoA biosynthesis; malonyl-CoA from acetyl-CoA: step 1/1.