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 itsN-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: Department of Biochemistry, University of Cambridge 80 Tennis Court Road, Cambridge CB2 1GA (UK) E-mail: pfl10@cam.ac.uk.
authors: Yongjun
authors: Y
authors: Zhou
authors: Institute of Chemistry, State University of Campinas UNICAMP, C.P. 6154, CEP 13084-971, Campinas SP (Brazil).
authors: Patrícia
authors: P
authors: Prediger
authors: Institute of Chemistry, State University of Campinas UNICAMP, C.P. 6154, CEP 13084-971, Campinas SP (Brazil).
authors: Luiz Carlos
authors: LC
authors: Dias
authors: Department of Biochemistry, University of Cambridge 80 Tennis Court Road, Cambridge CB2 1GA (UK) E-mail: pfl10@cam.ac.uk.
authors: Annabel C
authors: AC
authors: Murphy
authors: Department of Biochemistry, University of Cambridge 80 Tennis Court Road, Cambridge CB2 1GA (UK) E-mail: pfl10@cam.ac.uk.
authors: Peter F
authors: PF
authors: Leadlay
keywords: Biosynthese; Diolide; Elaiophylin; Polyketid-Synthase; Thioesterase