title: Analysis of a 108-kb region of the Saccharopolyspora spinosa genome covering the obscurin polyketide synthase locus.
abstract: A 108-kb genomic DNA region of Saccharopolyspora spinosa NRRL 18395, producer of the agriculturally important insecticidal antibiotics spinosyns, has been cloned, sequenced and analyzed to reveal clustered genes encoding a type I polyketide synthase (PKS) complex. The genes for the PKS are flanked by genes encoding homologs of enzymes that are involved in the urea cycle, valine, leucine and isoleucine biosynthesis and energy metabolism. While the disruption of the PKS genes by insertional inactivation was not expected to abolish the production of spinosyns, no differences were found in the antibacterial, antifungal, or insecticidal activities either of the parental and the knockout mutant strains under the growth conditions tested. Deduction of the most likely structure of the polyketide core of the cryptic metabolite, termed obscurin, from the predicted modules and domains of the PKS suggests the formation of a highly unsaturated substituted C22 carboxylic acid that might undergo further processing after its release from the PKS.
authors.affiliation: Syngenta Biotechnology Inc., 3054 Cornwallis Road, Research Triangle Park, NC 27709, USA.
authors.forename: Ross
authors.initials: R
authors.lastname: Zirkle
authors.forename: Todd A
authors.initials: TA
authors.lastname: Black
authors.forename: Joern
authors.initials: J
authors.lastname: Gorlach
authors.forename: James M
authors.initials: JM
authors.lastname: Ligon
authors.forename: István
authors.initials: I
authors.lastname: Molnár
mesh_terms: D003001:Cloning, Molecular; D017124:Conserved Sequence / Q000235:genetics; D016680:Genome, Bacterial; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics*; D009124:Muscle Proteins / Q000737:chemistry / Q000235:genetics; D016930:Saccharopolyspora / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D009097:Multienzyme Complexes; D009124:Muscle Proteins