title: Mutation of a novel ABC transporter gene is responsible for the failure to incorporate uric acid in the epidermis of ok mutants of the silkworm, Bombyx mori.
abstract: ok mutants of the silkworm, Bombyx mori, exhibit highly translucent larval skin resulting from the inability to incorporate uric acid into the epidermal cells. Here we report the identification of a gene responsible for the ok mutation using positional cloning and RNAi experiments. In two independent ok mutant strains, we found a 49-bp deletion and a 233-bp duplication, respectively, in mRNAs of a novel gene, Bm-ok, which encodes a half-type ABC transporter, each of which results in translation of a truncated protein in each mutant. Although the Bm-ok sequence was homologous to well-known transporter genes, white, scarlet, and brown in Drosophila, the discovery of novel orthologs in the genomes of lepidopteran, hymenopteran, and hemipteran insects identifies it as a member of a new distinct subfamily of transporters. Embryonic RNAi of Bm-ok demonstrated that repression of Bm-ok causes a translucent phenotype in the first-instar silkworm larva. We discuss the possibility that Bm-ok forms a heterodimer with another half-type ABC transporter, Bmwh3, and acts as a uric acid transporter in the silkworm epidermis.
authors.affiliation: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Lingyan
authors.initials: L
authors.lastname: Wang
authors.forename: Takashi
authors.initials: T
authors.lastname: Kiuchi
authors.forename: Tsuguru
authors.initials: T
authors.lastname: Fujii
authors.forename: Takaaki
authors.initials: T
authors.lastname: Daimon
authors.forename: Muwang
authors.initials: M
authors.lastname: Li
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Banno
authors.forename: Shingo
authors.initials: S
authors.lastname: Kikuta
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kikawada
authors.forename: Susumu
authors.initials: S
authors.lastname: Katsuma
authors.forename: Toru
authors.initials: T
authors.lastname: Shimada
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D012831:Bombyx / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D004817:Epidermis / Q000201:enzymology / Q000378:metabolism; D005260:Female; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism*; D007313:Insecta / Q000145:classification / Q000201:enzymology / Q000235:genetics; D008297:Male; D009154:Mutation; D010802:Phylogeny; D014527:Uric Acid / Q000378:metabolism*
chemical_list: D018528:ATP-Binding Cassette Transporters; D019476:Insect Proteins; D014527:Uric Acid