engleski

Production of hybrid anthracycline(s) by heterologous expression of act-genes in S. rimosus

The aim of this study was to develop a system for generating novel hybrid polyketides in Streptomyces rimosus, the producer of OTC. The first steps in biosynthesis of aromatic polyketides, such as OTC, are catalyzed by the 'polyketide synthase' (PKS), which is responsible for the synthesis of the polyketide backbone. Each PKS is a multi-enzyme complex comprising ketosynthase-acyltransferase (KS/AT), acyl carrier protein (ACP) and chain length factor (CLF) subunits and (depending on the polyketide) other enzymes such as a ketoreductase (KR), cyclase (CYC) and aromatase (ARO). The genes encoding the OTC PKS are homologous to other aromatic PKS genes. A S. rimosus strain, deleted for KS/AT and CLF, was constructed and designated PZGLW2.0. This strain was blocked in the biosynthesis of OTC. Integrative plasmids, based on pSAM21 were prepared: a positive control (pPZG215) containing the OTC KS/AT and CLF, and three others encoding genes for the early reactions in the actinorhodin biosynthetic pathway2: pPZG217 (actI, actVII, actIV), pPZG218 (actI, actVII), pPZG219 (actI). Integration of pPZG215 into the chromosome of PZGLW2.0 restored OTC production. On the other hand, some transformants having pZGLW217 secreted about 500  g/ml of a purple hybrid anthracycline. Analysis of transformants and products will be presented. 1. T. Smokvina et al., Gene 94 (1990) 53-59 2. P. L. Bartel et al., J. Bacteriol. 172 (1990) 4816-4826

Streptomyces rimosus; polyketide; oxytetracycline; actinorhodin

nije evidentirano