title: New insight into the mechanism underlying fibroin secretion in silkworm, Bombyx mori.
abstract: In order to investigate the role of different parts of the fibroin heavy chain (H-chain) in the secretion of fibroin in the silk gland of the silkworm (Bombyx mori) in vivo, two enhanced green fluorescent protein (EGFP)/H-chain fusion genes with deduced protein sequences containing an identical N-terminal region and different C-terminal regions of the H-chain were introduced into the B. mori genome using a piggyBac-mediated germline transformation. EGFP fluorescence and molecular analysis showed the products of two different EGFP/H-chain fusion proteins were secreted into the posterior silk gland lumen and aggregated in the middle silk gland and spun into cocoons. The results revealed that only the non-repetitive N terminus of the H-chain is essential for secretion of the H-chain into the posterior silk gland lumen. In addition, our results also indicated that the most likely post-translational modification of the H-chain is at the C-terminal domain. Here, our results not only provide a theoretical basis for the genetic modification of silk fiber as a functional biomaterial but also are of great significance to establishing a new silk gland bioreactor to mass-produce exogenous proteins in an active form.
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Key Laboratory for Sericulture Functional Genomics and Biotechnology of the Agricultural Ministry, Southwest University, Chongqing, China.
authors.forename: Dingpei
authors.initials: D
authors.lastname: Long
authors.forename: Weijian
authors.initials: W
authors.lastname: Lu
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Qing
authors.initials: Q
authors.lastname: Guo
authors.forename: Zhonghuai
authors.initials: Z
authors.lastname: Xiang
authors.forename: Aichun
authors.initials: A
authors.lastname: Zhao
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D012831:Bombyx / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D005349:Fibroins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017344:Genes, Insect; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007814:Larva / Q000254:growth & development / Q000502:physiology; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
chemical_list: D011993:Recombinant Fusion Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D005349:Fibroins
keywords: EGFP/H-chain fusion protein; fibroin secretion mechanism; piggyBac; silk; transgenic silkworm