(613e) Investigating the Biosynthesis of a Tetracycline Analog with Antitumor Properties

Tetracyclines are an important group of natural products that are synthesized by different Streptomyces species by way of a type II polyketide biosynthetic pathway. These compounds have played an important role in treating bacterial infections since their discovery in 1948. More recently, several semisynthetic analogs of tetracycline have been shown to have antitumor properties, which has sparked interest in their development as a possible cancer therapy. We have obtained a strain which has been identified as producing a novel tetracycline compound SF2575. This compound has a much more complicated structure than many naturally derived tetracyclines such as chlorotetracycline and oxytetracycline, and has also been shown to have potent antitumor activity. Due to the complexity of the molecule, biosynthetic methods likely provide the most tractable path to producing and manipulating this compound. To this end, we have sequenced the previously unidentified gene cluster responsible for the production of this compound. Through expression of the minimal PKS in a heterologous host, Streptomyces CH999, we were able to confirm the production of a decaketide backbone consistant with a tetracycline biosynthesis. We plan to use this new sequence information to systematically investigate the role of individual proteins in the biosynthetic pathway towards the goal of engineering this pathway to produce novel compounds.