title: Production of Bombyx mori silk fibroin incorporated with unnatural amino acids.
abstract: Silk fibroin incorporated with unnatural amino acids was produced by in vivo feeding of p-chloro-, p-bromo-, and p-azido-substituted analogues of L-phenylalanine (Phe) to transgenic silkworms (Bombyx mori) that expressed a mutant of phenylalanyl-tRNA synthetase with expanded substrate recognition capabilities in silk glands. Cutting down the content of Phe in the diet was effective for increasing the incorporation of Phe analogues but simultaneously caused a decrease of fibroin production. The azide groups incorporated in fibroin were active as chemical handles for click chemistry in both the solubilized and the solid (fibrous) states. The azides survived degumming in the boiling alkaline solution that is required for complete removal of the sericin layer, demonstrating that AzPhe-incorporated silk fibroin could be a versatile platform to produce "clickable" silk materials in various forms. This study indicates the huge potential of UAA mutagenesis as a novel methodology to alter the characteristics of B. mori silk.
authors.affiliation: Silk Materials Research Unit, Genetically Modified Organisms Research Center, National Institute of Agrobiological Sciences (NIAS) , Tsukuba, Ibaraki 305-8634, Japan.
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Teramoto
authors.forename: Katsura
authors.initials: K
authors.lastname: Kojima
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D001386:Azides / Q000737:chemistry; D012831:Bombyx / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D061565:Cycloaddition Reaction; D005349:Fibroins / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D007814:Larva / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D008969:Molecular Sequence Data; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D021122:Protein Subunits / Q000096:biosynthesis / Q000302:isolation & purification
chemical_list: D001386:Azides; D021122:Protein Subunits; D010649:Phenylalanine; D005349:Fibroins