RESUMEN
Recently, recombinant Streptomyces venezuelae has been established as a heterologous host for microbial production of flavanones and stilbenes, a class of plant-specific polyketides. In the present work, we expanded the applicability of the S. venezuelae system to the production of more diverse plant polyketides including flavones and flavonols. A plasmid with the synthetic codon-optimized flavone synthase I gene from Petroselium crispum was introduced to S. venezuelae DHS2001 bearing a deletion of the native pikromycin polyketide synthase gene, and the resulting strain generated flavones from exogenously fed flavanones. In addition, a recombinant S. venezuelae mutant expressing a codon-optimized flavanone 3beta-hydroxylase gene from Citrus siensis and a flavonol synthase gene from Citrus unshius also successfully produced flavonols.
Asunto(s)
Flavonas/biosíntesis , Flavonoles/biosíntesis , Microbiología Industrial/métodos , Streptomyces/metabolismo , Apiaceae/enzimología , Apiaceae/genética , Citrus/enzimología , Expresión Génica , Genes de Plantas/genética , Ingeniería Genética , Oxigenasas de Función Mixta/genética , Streptomyces/genéticaRESUMEN
Phenylpropanoids, including flavonoids and stilbenes, are plant secondary metabolites with potential pharmacological and nutraceutical properties. To expand the applicability of Streptomyces venezuelae as a heterologous host to plant polyketide production, flavonoid and stilbene biosynthetic genes were expressed in an engineered strain of S. venezuelae DHS2001 bearing a deletion of native pikromycin polyketide synthase gene. A plasmid expressing the 4-coumarate/cinnamate:coenzyme A ligase from Streptomyces coelicolor (ScCCL) and the chalcone synthase from Arabidopsis thaliana (atCHS) under the control of a single ermE* promoter was constructed and introduced into S. venezuelae DHS2001. The resulting strain produced racemic naringenin and pinocembrin from 4-coumaric acid and cinnamic acid, respectively. Placement of an additional ermE* promoter upstream of the codon-optimized atCHS (atCHS(op)) gene significantly increased the yield of both flavanones. Expression of codon-optimized chalcone isomerase gene from Medicago sativa, together with ScCCL and atCHS(op) genes led to production of (2S)-flavanones, but the yield was reduced. On the other hand, a recombinant strain harboring the ScCCL and codon-optimized stilbene synthase gene from Arachis hypogaea generated stilbenes such as resveratrol and pinosylvin. This is the first report on the heterologous expression of plant phenylpropanoid biosynthetic pathways in Streptomyces genus.