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Publication Abstract from PubMed

Polyketides are a class of biologically active microbial and plant-derived metabolites that possess a high degree of structural and functional diversity and include many human therapeutics, among them anti-infective and anti-cancer drugs, growth promoters and anti-parasitic agents. The macrolide antibiotics, characterized by a glycoside-linked macrolactone, constitute an important class of polyketides, including erythromycin and the natural ketolide anti-infective agent pikromycin. Here we describe new mechanistic details of macrolactone ring formation catalyzed by the pikromycin polyketide synthase thioesterase domain from Streptomyces venezuelae. A pentaketide phosphonate mimic of the final pikromycin linear chain-elongation intermediate was synthesized and shown to be an active site affinity label. The crystal structures of the affinity-labeled enzyme and of a 12-membered-ring macrolactone product complex suggest a mechanism for cyclization in which a hydrophilic barrier in the enzyme and structural restraints of the substrate induce a curled conformation to direct macrolactone ring formation.

Structural basis for macrolactonization by the pikromycin thioesterase.,Akey DL, Kittendorf JD, Giraldes JW, Fecik RA, Sherman DH, Smith JL Nat Chem Biol. 2006 Oct;2(10):537-42. Epub 2006 Sep 10. PMID:16969372^[1]

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