title: Macrodiolide formation by the thioesterase of a modular polyketide synthase.
abstract: Elaiophylin is an unusual C2 -symmetric antibiotic macrodiolide produced on a bacterial modular polyketide synthase assembly line. To probe the mechanism and selectivity of diolide formation, we sought to reconstitute ring formation in vitro by using a non-natural substrate. Incubation of recombinant elaiophylin thioesterase/cyclase with a synthetic pentaketide analogue of the presumed monomeric polyketide precursor of elaiophylin, specifically its N-acetylcysteamine thioester, produced a novel 16-membered C2 -symmetric macrodiolide. A linear dimeric thioester is an intermediate in ring formation, which indicates iterative use of the thioesterase active site in ligation and subsequent cyclization. Furthermore, the elaiophylin thioesterase acts on a mixture of pentaketide and tetraketide thioesters to give both the symmetric decaketide diolide and the novel asymmetric hybrid nonaketide diolide. Such thioesterases have potential as tools for the in vitro construction of novel diolides.
authors.affiliation: Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA (UK).
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Zhou
authors.forename: Patrícia
authors.initials: P
authors.lastname: Prediger
authors.forename: Luiz Carlos
authors.initials: LC
authors.lastname: Dias
authors.forename: Annabel C
authors.initials: AC
authors.lastname: Murphy
authors.forename: Peter F
authors.initials: PF
authors.lastname: Leadlay
mesh_terms: D000215:Acylation; D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000737:chemistry; D003500:Cyclization; D018942:Macrolides / Q000737:chemistry / Q000378:metabolism*; D048630:Polyketide Synthases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013869:Thiolester Hydrolases / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D018942:Macrolides; D011994:Recombinant Proteins; C033279:elaiophylin; D048630:Polyketide Synthases; D013869:Thiolester Hydrolases
keywords: biosynthesis; diolides; elaiophylin; polyketide synthase; thioesterase