THE REGULATION OF METHYLMALONYL-CoA FORMATION PATHW AYS IN REFAMYCIN SV-PRODUCING AMYCOLATOPSIS MEDITERRANEl U32
力复霉素前体甲基丙二酰CoA合成途径的研究

( 2R)-Methylmalonyl-CoA, carbon precursor for rifamycin SV could be synthesized through at least three enzymatic systems from intermediates of TCA cycle and other pathways, they are methylmalonyl-CoA transcarboxylase, propionyl-CoA carboxylase, MCM and MCR. By comparing the time course of enzymatic activity with that of rifamycin synthesis and the Km values of the enzymes showed that MCM was the mainenzyme responsible for the methylmalonyl-CoA formation in A.mediterranei U32.The contribution of various systems was subject to regulation of environmental factors. The addition of propionate into medium makes the methylmalony-CoA transcarboxylase become the main enzyme responsible for the methylmalonyl-CoA formation.In addition, the regulatory characteristics of the key enzymes in various pathways were studied.