title: Acyltransferase mediated polyketide release from a fungal megasynthase.
abstract: LovF is a highly reducing polyketide synthase (HR-PKS) from the filamentous fungus Aspergillus terreus. LovF synthesizes the alpha-S-methylbutyrate side chain that is subsequently transferred to monacolin J to yield the cholesterol-lowering natural product lovastatin. In the report, we expressed the full length LovF and reconstituted the megasynthase activities in vitro. We confirmed the diketide product of LovF is offloaded from the LovF ACP domain by the dissociated acyltransferase LovD. This represents the first example of acyltransferase-mediated release of polyketide products from fungal PKSs. We determined LovD primarily interacts with the ACP domain of LovF and the protein-protein interactions lead to highly efficient transfer of the diketide product. The catalytic efficiency is enhanced nearly 1 x 10(6)-fold when LovF was used as the acyl carrier instead of N-acetylcysteamine. Reconstitution and characterization of the LovF offloading mechanism provide new insights into the functions of fungal HR-PKS.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, California 90095, USA.
authors.forename: Xinkai
authors.initials: X
authors.lastname: Xie
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Meehan
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.forename: Pieter C
authors.initials: PC
authors.lastname: Dorrestein
authors.forename: Yi
authors.initials: Y
authors.lastname: Tang
mesh_terms: D000217:Acyltransferases / Q000737:chemistry / Q000378:metabolism*; D001230:Aspergillus / Q000201:enzymology* / Q000235:genetics; D005656:Fungal Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D048630:Polyketide Synthases / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification
chemical_list: D005656:Fungal Proteins; D009097:Multienzyme Complexes; D011994:Recombinant Proteins; D048630:Polyketide Synthases; D000217:Acyltransferases