title: Interrogating the molecular basis for multiple macrolactone ring formation by the pikromycin polyketide synthase.
abstract: The pikromycin polyketide synthase (PKS) is unique in its ability to generate both 12 and 14 membered ring macrolactones. As such, dissection of the molecular basis for controlling metabolic diversity in this system remains an important objective for understanding modular PKS function and expanding chemical diversity. Here, we describe a series of experiments designed to probe the importance of the protein-protein interaction that occurs between the final two monomodules, PikAIII (module 5) and PikAIV (module 6), for the production of the 12 membered ring macrolactone 10-deoxymethynolide. The results obtained from these in vitro studies demonstrate that PikAIII and PikAIV generate the 12 membered ring macrocycle most efficiently when engaged in their native protein-protein interaction. Accordingly, the data are consistent with PikAIV adopting an alternative conformation that enables the terminal thioesterase domain to directly off-load the PikAIII-bound hexaketide intermediate for macrocyclization.
authors: University of Michigan Life Sciences Institute, Department of Medicinal Chemistry, 210 Washtenaw Avenue, Ann Arbor, MI 48109, USA.
authors: Jeffrey D
authors: JD
authors: Kittendorf
authors: Brian J
authors: BJ
authors: Beck
authors: Tonia J
authors: TJ
authors: Buchholz
authors: Wolfgang
authors: W
authors: Seufert
authors: David H
authors: DH
authors: Sherman
mesh_terms: D001483:Base Sequence; D020134:Catalytic Domain; D003500:Cyclization; D017931:DNA Primers; D004950:Esterases / Q000378:metabolism; D007783:Lactones / Q000737:chemistry*; D018942:Macrolides / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D048630:Polyketide Synthases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D007783:Lactones; D018942:Macrolides; D048630:Polyketide Synthases; D004950:Esterases; C003145:picromycin
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