title: Further analysis of acyl-CoA-ACP-transacylases of mycobacterium smegmatis. Identification of a long chain alkyl malonyl-CoA-ACP-transacylase.
abstract: Homogenates were prepared from three sources, Mycobacterium smegmatis Saccharomyces cerevisiae and Escherichia coli and tested for docosyl malonyl-CoA-ACP transacylase activity, using ACP purified from E. coli strain B and [2R, 2S, 1, 3-14C2] docosyl malonyl-CoA synthesized chemically, as substrates. Only homogenates of M. semegmatis showed positive transacylase activity. Successive chromatographies on Sephadex G-150 and then on DEAE-Sephadex A-50 prove that neither the palmityl-CoA-ACP-transacylase nor the malonyl-CoA-ACP-transacylase of M. smegmatis are responsible for this activity. The question concerning the identity of the enzyme with one of the two entities exhibiting acetyl-CoA-ACP-transacylase activity, previously identified in homogenates of this microorganism (1973 this journal, 55, 1381-1394), remains open for further experimentation. The physiological significance of the presence of a long chain alkyl malonyl-CoA-ACP-transacylase in homogenates of M. smegmatis, a representative of the Actinomycetales, is discussed in relation to the mechanism of the biosynthesis of mycolic acids. Chromatography on Sephadex G-100 showed that the substrate of the enzyme, docosyl malonyl-CoA, exists, in 50 mu molar aqueous solution, mostly in an aggregated state. A factor has been identified in the homogenates, which in the presence of radioactive docosyl malonyl-CoA, leads to the formation of a radioactive material showing an apparent molecular weight less than 10000. The nature of this material is discussed.
mesh_terms: D000105:Acetyl Coenzyme A; D000123:Acetyltransferases / Q000378:metabolism; D000217:Acyltransferases / Q000302:isolation & purification* / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D002352:Carrier Proteins; D003065:Coenzyme A; D004926:Escherichia coli / Q000201:enzymology; D008314:Malonates; D009161:Mycobacterium / Q000201:enzymology*; D010169:Palmitic Acids; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D013045:Species Specificity
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D008314:Malonates; D010169:Palmitic Acids; D000105:Acetyl Coenzyme A; D000217:Acyltransferases; D000123:Acetyltransferases; D003065:Coenzyme A