Biosynthesis of the antifungal polyketide antibiotic soraphen A in Sorangium cellulosum and Streptomyces lividans

The derivatization of soraphen by combinatorial biosynthesis has been a longstanding goal of the Natural Product Genetics group at Ciba Geigy - Novartis - Syngenta. We have cloned and characterized the soraphen A biosynthetic gene cluster of Sorangium cellulosum So ce26. To facilitate the genetic manipulation of So ce26, a central regulator of gliding motility was identified and its encoding gene disrupted to create a nonswarming strain. Despite this improvement, engineering of soraphen biosynthesis remained elusive in So ce26. Thus, the genes for the soraphen polyketide synthase, the post-polyketide tailoring steps, and methoxymalonate biosynthesis were introduced into Streptomyces lividans. Production of soraphen A in this genetically tractable strain also required provision of benzoyl-CoA by feeding benzoate or cinnamate.