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Publication Abstract from PubMed

Because it controls the majority of polyketide stereocenters, the ketoreductase (KR) is a central target in engineering polyketide synthases (PKSs). To elucidate the mechanisms of stereocontrol, the structure of KR from the first module of the tylosin PKS was determined. A comparison with a recently solved erythromycin KR that operates on the same substrate explains why their products have opposite alpha-substituent chiralities. The structure reveals how polyketides are guided into the active site by key residues in different KR types. There are four types of reductase-competent KRs, each capable of fixing a unique combination of alpha-substituent and beta-hydroxyl group chiralities, as well as two types of reductase-incompetent KRs that control alpha-substituent chirality alone. A protocol to assign how a module will enforce substituent chirality based on its sequence is presented.

A tylosin ketoreductase reveals how chirality is determined in polyketides.,Keatinge-Clay AT Chem Biol. 2007 Aug;14(8):898-908. PMID:17719489^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.