title: Elucidation of gephyronic acid biosynthetic pathway revealed unexpected SAM-dependent methylations.
abstract: Gephyronic acid, a cytostatic polyketide produced by the myxobacterium Cystobacter violaceus Cb vi76, exhibits potent and selective eukaryotic protein synthesis inhibition. Next-generation sequencing of the C. violaceus genome revealed five type I polyketide synthases and post-PKS tailoring enzymes including an O-methyltransferase and a cytochrome P450 monooxygenase. Seven methyltransferase (MT) domains embedded within the PKS subunits were found to install the methyl branches throughout the gephyronic acid skeleton. A rare loading domain from the GNAT superfamily also contains an embedded MT domain that catalyzes the in situ production of an isobutyryl starter unit. Phylogenetic analysis identified new motifs that distinguish MT domains located in PKS pathways with in cis acyltransferase (AT) domains from MT domains located in PKS pathways with trans AT enzymes. The identification of the gene cluster sets the stage for the generation of a heterologous expression system, which will allow further investigation of selective eukaryotic protein synthesis inhibitors through the generation of gephyronic acid analogues.
authors.affiliation: Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana, United States.
authors.forename: Jeanette
authors.initials: J
authors.lastname: Young
authors.forename: D Cole
authors.initials: DC
authors.lastname: Stevens
authors.forename: Rory
authors.initials: R
authors.lastname: Carmichael
authors.forename: John
authors.initials: J
authors.lastname: Tan
authors.forename: Shwan
authors.initials: S
authors.lastname: Rachid
authors.forename: Christopher N
authors.initials: CN
authors.lastname: Boddy
authors.forename: Rolf
authors.initials: R
authors.lastname: Müller
authors.forename: Richard E
authors.initials: RE
authors.lastname: Taylor
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D053898:Biosynthetic Pathways / Q000235:genetics; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004926:Escherichia coli / Q000254:growth & development; D005229:Fatty Acids, Monounsaturated / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D015394:Molecular Structure; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D005810:Multigene Family; D009231:Myxococcales / Q000737:chemistry* / Q000235:genetics; D010802:Phylogeny; D048630:Polyketide Synthases / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012436:S-Adenosylmethionine / Q000378:metabolism*; D017421:Sequence Analysis
chemical_list: D005229:Fatty Acids, Monounsaturated; D009097:Multienzyme Complexes; C092168:gephyronic acid; D048630:Polyketide Synthases; D012436:S-Adenosylmethionine; D003577:Cytochrome P-450 Enzyme System; D008780:Methyltransferases; D000217:Acyltransferases