title: Fatty acid biosynthesis in Mycobacterium tuberculosis var. bovis Bacillus Calmette-Guérin. Purification and characterization of a novel fatty acid synthase, mycocerosic acid synthase, which elongates n-fatty acyl-CoA with methylmalonyl-CoA.
abstract: A crude extract from Mycobacterium tuberculosis var. bovis Bacillus Calmette-Guérin was previously shown to incorporate methylmalonyl-CoA into mycocerosic acids, exemplified by 2,4,6,8-tetramethyloctacosanoic acid, and malonyl-CoA into n-fatty acids (Rainwater D. L., and Kolattukudy, P. E. (1983) J. Biol. Chem. 258, 2979-2985). The presence of several fatty acid synthases with differences in substrate preference and product chain length was detected in the crude extract of M. tuberculosis var. bovis. Among them was a mycocerosic acid synthase which was purified to homogeneity using anion-exchange chromatography, gel filtration, affinity chromatography, and hydroxylapatite chromatography. This fatty acid synthase elongated long-chain fatty acyl-CoA primers using methylmalonyl-CoA and NADPH to produce multimethyl-branched mycocerosic acids. The enzyme was specific for methylmalonyl-CoA and would not incorporate malonyl-CoA into fatty acids. It elongated n-C6 to n-C20 CoA esters to generate primarily the corresponding tetramethyl-branched mycocerosic acids. Exogenous [1-14C]acyl-CoA and trideuteromethylmalonyl-CoA were incorporated into the multimethyl-branched fatty acids. Dodecyl sulfate electrophoresis showed that the enzyme had a molecular weight of 238,000, whereas gel filtration showed a native molecular weight of 490,000, indicating that the enzyme is composed of two monomers of identical molecular weight. The enzyme contained an acyl carrier protein-like segment as indicated by incorporation of [1-14C] pantothenate into the 238-kDa protein and production of 1 mol of taurine/mol of the monomer upon hydrolysis of performic acid-oxidized enzyme. It is concluded that the mycocerosic acid synthase is a multifunctional enzyme similar to the well-characterized multifunctional fatty acid synthases except for the substrate specificity.
mesh_terms: D000214:Acyl Coenzyme A / Q000031:analogs & derivatives* / Q000378:metabolism*; D000217:Acyltransferases / Q000302:isolation & purification* / Q000378:metabolism; D000596:Amino Acids / Q000032:analysis; D002250:Carbon Radioisotopes; D002849:Chromatography, Gas; D005227:Fatty Acids / Q000096:biosynthesis*; D007700:Kinetics; D008316:Malonyl Coenzyme A / Q000031:analogs & derivatives* / Q000378:metabolism; D008970:Molecular Weight; D009163:Mycobacterium bovis / Q000201:enzymology*; D013329:Structure-Activity Relationship
chemical_list: D000214:Acyl Coenzyme A; D000596:Amino Acids; D002250:Carbon Radioisotopes; D005227:Fatty Acids; C015357:methylmalonyl-coenzyme A; D008316:Malonyl Coenzyme A; D000217:Acyltransferases; C044110:mycocerosic acid synthase