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 more highly substituted tetracycline core compared to other 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 and found genes typically associated with tetracycline biosynthesis as well as a wide variety of tailoring enzymes. Through expression of the extended minimal PKS in a heterologous host, Streptomyces CH999, we are able to confirm the production of a decaketide backbone consistent with a tetracycline biosynthesis. We also confirmed a downstream oxygenase confirming the utilization of tetracycline intermediate 6-methylpretetramid. 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.

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