title: Southern analysis of BT-R1, the Manduca sexta gene encoding the receptor for the Cry1Ab toxin of Bacillus thuringiensis.
abstract: Various subspecies of the gram-positive bacterium Bacillus thuringiensis are known to produce a wide array of insecticidal crystal proteins (ICPs) upon sporulation. These ICPs act primarily on the brush border of midgut epithelial cells of susceptible larvae. Recently, a protein of 210 kDa, isolated from the midgut of Manduca sexta, has been demonstrated to bind the Cry1Ab toxin produced by B. thuringiensis subsp, berliner and is therefore postulated to be involved in mediating the toxicity of Cry1Ab. The cDNA encoding the 210 kDa protein, termed BT-R1 (Bacillus thuringiensis receptor-1), was recently cloned, and shows limited homology to the cadherin superfamily of proteins. Quite naturally, there is a great deal of interest in the characterization of BT-R1, the gene encoding the 210 kDa Cry1Ab binding protein. The studies presented here involve the use of various restriction fragments prepared from the cDNA encoding BT-R1 as probes of Southern blots bearing M. sexta genomic DNA cleaved with a variety of restriction endonucleases. These Southern blot data reveal that there are two discrete regions within the M. sexta genome which encode sequences homologous to BT-R1. On the basis of the signal intensities seen on Southern blots, it appears that only one of these genes encodes BT-R1, whereas the other is a closely related homologue.
authors.affiliation: Department of Molecular Biology, University of Wyoming, Laramie 82071, USA.
authors.forename: S E
authors.initials: SE
authors.lastname: Franklin
authors.forename: L
authors.initials: L
authors.lastname: Young
authors.forename: D
authors.initials: D
authors.lastname: Watson
authors.forename: A
authors.initials: A
authors.lastname: Cigan
authors.forename: T
authors.initials: T
authors.lastname: Meyer
authors.forename: L A
authors.initials: LA
authors.lastname: Bulla
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism*; D001427:Bacterial Toxins; D015139:Blotting, Southern; D002874:Chromosome Mapping; D015342:DNA Probes; D004731:Endotoxins / Q000378:metabolism*; D017344:Genes, Insect; D005819:Genetic Markers; D006460:Hemolysin Proteins; D019476:Insect Proteins; D007305:Insecticide Resistance; D018402:Manduca / Q000235:genetics*; D008957:Models, Genetic; D011110:Polymorphism, Genetic; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; C095416:Cry toxin receptors; D015342:DNA Probes; D004731:Endotoxins; D005819:Genetic Markers; D006460:Hemolysin Proteins; D019476:Insect Proteins; D011956:Receptors, Cell Surface; C030956:insecticidal crystal protein, Bacillus Thuringiensis