title: A specific role of the Saccharopolyspora erythraea thioesterase II gene in the function of modular polyketide synthases.
abstract: Bacterial modular polyketide synthase (PKS) genes are commonly associated with another gene that encodes a thioesterase II (TEII) believed to remove aberrantly loaded substrates from the PKS. Co-expression of the Saccharopolyspora erythraea ery-ORF5 TEII and eryA genes encoding 6-deoxyerythronolide B synthase (DEBS) in Streptomyces hosts eliminated or significantly lowered production of 8,8'-deoxyoleandolide [15-nor-6-deoxyerythronolide B (15-nor-6dEB)], which arises from an acetate instead of a propionate starter unit. Disruption of the TEII gene in an industrial Sac. erythraea strain caused a notable amount of 15-norerythromycins to be produced by utilization of an acetate instead of a propionate starter unit and also resulted in moderately lowered production of erythromycin compared with the amount produced by the parental strain. A similar behaviour of the TEII gene was observed in Escherichia coli strains that produce 6dEB and 15-methyl-6dEB. Direct biochemical analysis showed that the ery-ORF5 TEII enzyme favours hydrolysis of acetyl groups bound to the loading acyl carrier protein domain (ACP(L)) of DEBS. These results point to a clear role of the TEII enzyme, i.e. removal of a specific type of acyl group from the ACP(L) domain of the DEBS1 loading module.
authors.affiliation: Kosan Biosciences, Hayward, CA 94545, USA.
authors.forename: Zhihao
authors.initials: Z
authors.lastname: Hu
authors.affiliation: Department of Chemical Engineering, Chemistry and Biochemistry, Stanford University, Stanford, CA 94305, USA.
authors.forename: Blaine A
authors.initials: BA
authors.lastname: Pfeifer
authors.affiliation: Department of Chemical Engineering, Chemistry and Biochemistry, Stanford University, Stanford, CA 94305, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Chao
authors.affiliation: Kosan Biosciences, Hayward, CA 94545, USA.
authors.forename: Sumati
authors.initials: S
authors.lastname: Murli
authors.affiliation: Kosan Biosciences, Hayward, CA 94545, USA.
authors.forename: Jim
authors.initials: J
authors.lastname: Kealey
authors.affiliation: Kosan Biosciences, Hayward, CA 94545, USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Carney
authors.affiliation: Kosan Biosciences, Hayward, CA 94545, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Ashley
authors.affiliation: Department of Chemical Engineering, Chemistry and Biochemistry, Stanford University, Stanford, CA 94305, USA.
authors.forename: Chaitan
authors.initials: C
authors.lastname: Khosla
authors.affiliation: Kosan Biosciences, Hayward, CA 94545, USA.
authors.forename: C Richard
authors.initials: CR
authors.lastname: Hutchinson
mesh_terms: D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D004917:Erythromycin / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000737:chemistry; D064429:Fatty Acid Synthases / Q000235:genetics*; D015870:Gene Expression; D005798:Genes, Bacterial; D008956:Models, Chemical; D009097:Multienzyme Complexes / Q000235:genetics* / Q000378:metabolism*; D016930:Saccharopolyspora / Q000201:enzymology* / Q000235:genetics*; D013302:Streptomyces / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D013869:Thiolester Hydrolases / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial; D009097:Multienzyme Complexes; C034277:6-deoxyerythronolide B; D004917:Erythromycin; D064429:Fatty Acid Synthases; D013869:Thiolester Hydrolases; C022738:thioesterase II