Two types of malonate decarboxylase are currently known, both of which form multienzyme complexes. The enzyme described here is a membrane-bound biotin-dependent, Na+-translocating enzyme . The other type is a biotin-independent cytosolic protein (cf. EC 4.1.1.88, biotin-independent malonate decarboxylase). As free malonate is chemically rather inert, it has to be activated prior to decarboxylation. Both enzymes achieve this by exchanging malonate with an acetyl group bound to an acyl-carrier protiein (ACP), to form malonyl-ACP and acetate, with subsequent decarboxylation regenerating the acetyl-bound form of the enzyme. The ACP subunit of both enzymes differs from that found in fatty-acid biosynthesis by having phosphopantethine attached to a serine side-chain as 2-(5-triphosphoribosyl)-3-dephospho-CoA rather than as phosphopantetheine 4'-phosphate. In the anaerobic bacterium Malonomonas rubra, the components of the multienzyme complex/enzymes involved in carrying out the reactions of this enzyme are as follows: MadA (EC 2.3.1.187, acetyl-S-ACP:malonate ACP transferase), MadB (EC 7.2.4.1, carboxybiotin decarboxylase), MadC/MadD (EC 2.1.3.10, malonyl-S-ACP:biotin-protein carboxyltransferase) and MadH (EC 6.2.1.35, acetate---[acyl-carrier protein] ligase). Two other components that are involved are MadE, the acyl-carrier protein and MadF, the biotin protein. The carboxy group is lost with retention of configuration .
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The enzyme appears in viruses and cellular organisms
reaction does not involve intermediate formation of malonyl-CoA but proceeds directly with free malonate. Catalytic mechanism involves exchange of the enzyme-bound acetyl residues by malonyl residues and subsequent decarboxylation releasing CO2 and regenerating the acetyl-enzyme. Biotin is involved in catalysis
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SYSTEMATIC NAME
IUBMB Comments
malonate carboxy-lyase (biotin-dependent)
Two types of malonate decarboxylase are currently known, both of which form multienzyme complexes. The enzyme described here is a membrane-bound biotin-dependent, Na+-translocating enzyme [6]. The other type is a biotin-independent cytosolic protein (cf. EC 4.1.1.88, biotin-independent malonate decarboxylase). As free malonate is chemically rather inert, it has to be activated prior to decarboxylation. Both enzymes achieve this by exchanging malonate with an acetyl group bound to an acyl-carrier protiein (ACP), to form malonyl-ACP and acetate, with subsequent decarboxylation regenerating the acetyl-bound form of the enzyme. The ACP subunit of both enzymes differs from that found in fatty-acid biosynthesis by having phosphopantethine attached to a serine side-chain as 2-(5-triphosphoribosyl)-3-dephospho-CoA rather than as phosphopantetheine 4'-phosphate. In the anaerobic bacterium Malonomonas rubra, the components of the multienzyme complex/enzymes involved in carrying out the reactions of this enzyme are as follows: MadA (EC 2.3.1.187, acetyl-S-ACP:malonate ACP transferase), MadB (EC 7.2.4.1, carboxybiotin decarboxylase), MadC/MadD (EC 2.1.3.10, malonyl-S-ACP:biotin-protein carboxyltransferase) and MadH (EC 6.2.1.35, acetate---[acyl-carrier protein] ligase). Two other components that are involved are MadE, the acyl-carrier protein and MadF, the biotin protein. The carboxy group is lost with retention of configuration [5].
subunit acetyl-S-acyl carrier protein: malonate acyl carrier protein-SH transferase catalyzes the transfer of acyl carrier protein from acetyl acyl carrier protein and malonate to yield malonyl acyl carrier protein and acetate. Malonate is thus activated on the enzyme by exchange for the catalytically important enzyme-bound acetyl thioester residues
subunit acetyl-S-acyl carrier protein: malonate acyl carrier protein-SH transferase catalyzes the transfer of acyl carrier protein from acetyl acyl carrier protein and malonate to yield malonyl acyl carrier protein and acetate. Malonate is thus activated on the enzyme by exchange for the catalytically important enzyme-bound acetyl thioester residues
the genes encoding components of the malonate decarboxylase enzyme system are located within a gene cluster of about 11 kb comprizing 14 genes that have been termed madYZGBAECDHKFLMN. MadA represents the acyl-carrier-protein-transferase component, MadB is the integral membrane-bound carboxybiotin protein decarboxylase, MadC and MadD are the two subunits of the carboxyltransferase, MadE is the acyl carrier protein and MadF is the biotin protein
the genes encoding components of the malonate decarboxylase enzyme system are located within a gene cluster of about 11 kb comprizing 14 genes that have been termed madYZGBAECDHKFLMN. MadA represents the acyl-carrier-protein-transferase component, MadB is the integral membrane-bound carboxybiotin protein decarboxylase, MadC and MadD are the two subunits of the carboxyltransferase, MadE is the acyl carrier protein and MadF is the biotin protein
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RENATURED/Commentary
ORGANISM
UNIPROT
LITERATURE
enzyme inhibited by thiocyanate or hydroxylamine, 50-65% of the original decarboxylase activity is restored by incubation of the extract with ATP in the presence of acetate, and the extent of reactivation increases after incubation with dithioerythritol. Reactivation is also obtained by chemical acetylation with acetic anhydride
Purification and characterization of a cytoplasmic enzyme component of the Na+-activated malonate decarboxylase system of Malonomonas rubra: acetyl-S-acyl carrier protein: malonate acyl carrier protein-SH transferase