title: A type I/type III polyketide synthase hybrid biosynthetic pathway for the structurally unique ansa compound kendomycin.
abstract: Kendomycin is a bioactive polyketide that is produced by various Streptomyces strains. It displays strong antibiotic activities against a wide range of bacteria and exhibits remarkable cytotoxic effects on the growth of several human cancer cell lines. In this study we cloned the corresponding biosynthetic locus from the producer Streptomyces violaceoruber (strain 3844-33C). Our analysis shows that a mixed type I/type III polyketide synthase pathway is responsible for the formation of the fully carbogenic macrocyclic scaffold of kendomycin, which is unprecedented among all of the ansa compounds that have been isolated so far. Heterologous expression of a gene set in Streptomyces coelicolor shows that 3,5-dihydroxybenzoic acid is an intermediate in the starter unit biosynthesis that is initiated by the type III polyketide synthase. The identification of the kendomycin biosynthetic gene cluster sets the stage to study a novel chain termination mechanism by a type I PKS that leads to carbocycle formation and provides the starting material for the heterologous expression of the entire pathway, and the production of novel derivatives by genetic engineering.
authors.affiliation: Universität des Saarlandes, Institut für Pharmazeutische Biotechnologie, Im Stadtwald, 66123 Saarbrücken, Germany.
authors.forename: Silke C
authors.initials: SC
authors.lastname: Wenzel
authors.forename: Helge B
authors.initials: HB
authors.lastname: Bode
authors.forename: Irene
authors.initials: I
authors.lastname: Kochems
authors.forename: Rolf
authors.initials: R
authors.lastname: Müller
mesh_terms: D000217:Acyltransferases / Q000378:metabolism*; D001483:Base Sequence; D024881:Drug Resistance, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D015723:Gene Library; D020868:Gene Silencing; D062385:Hydroxybenzoates / Q000378:metabolism; D005810:Multigene Family / Q000235:genetics; D048630:Polyketide Synthases / Q000378:metabolism*; D012118:Resorcinols; D017828:Rifabutin / Q000031:analogs & derivatives* / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D062385:Hydroxybenzoates; D012118:Resorcinols; C485395:kendomycin; D017828:Rifabutin; C076950:alpha-resorcylic acid; D048630:Polyketide Synthases; D000217:Acyltransferases; C020141:flavanone synthetase