title: Analysis of Streptomyces avermitilis genes required for avermectin biosynthesis utilizing a novel integration vector.
abstract: An integration vector for gene analysis in Streptomyces has been constructed. This vector replicates in Escherichia coli, and integrates into Streptomyces by homologous recombination between a cloned fragment and the genome. To overcome methylation-specific restriction barriers, an E. coli mutant triply defective in DNA methylation was constructed as a source for the integration plasmids. The frequency of integration of pVE616 derivatives into the Streptomyces avermitilis genome was proportional to the size of the cloned DNA. Derivatives of pVE616, containing fragments from pVE650, a plasmid with a 24-kb insert of S. avermitilis DNA, were used in complementation analyses of seven S. avermitilis mutants defective in glycosylation of avermectin (Av). Three complementation groups, located in a 7-kb region, were identified. Derivatives of pVE616, containing fragments from the 18-kb of DNA adjacent to the glycosylation region, were integrated into an Av producer. Av produced from the integrants was substantially reduced, indicating that the 18 kb also encodes gene products which are involved in Av biosynthesis.
authors.affiliation: Merck Sharp and Dohme Research Laboratories, Rahway, NJ 07065.
authors.forename: D J
authors.initials: DJ
authors.lastname: MacNeil
authors.forename: K M
authors.initials: KM
authors.lastname: Gewain
authors.forename: C L
authors.initials: CL
authors.lastname: Ruby
authors.forename: G
authors.initials: G
authors.lastname: Dezeny
authors.forename: P H
authors.initials: PH
authors.lastname: Gibbons
authors.forename: T
authors.initials: T
authors.lastname: MacNeil
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000235:genetics; D005816:Genetic Complementation Test; D005822:Genetic Vectors; D006031:Glycosylation; D007559:Ivermectin / Q000031:analogs & derivatives* / Q000378:metabolism; D008745:Methylation; D008969:Molecular Sequence Data; D010957:Plasmids; D015183:Restriction Mapping; D013302:Streptomyces / Q000235:genetics* / Q000378:metabolism; D014169:Transformation, Bacterial
chemical_list: D004269:DNA, Bacterial; D007559:Ivermectin; C019264:avermectin