title: Novel molecular and mechanical properties of egg case silk from wasp spider, Argiope bruennichi.
abstract: Araneoid spiders use specialized abdominal glands to produce up to seven different protein-based silks/glues that have various mechanical properties. To date, the fibroin sequences encoding egg case fibers have not been fully determined. To gain further understanding of a recently reported spider silk protein gene family, several novel strategies were utilized in this study to isolate two full-length cDNAs of egg case silk proteins, cylindrical silk protein 1 (CySp1, 9.1 kb) and cylindrical silk protein 2 (CySp2, 9.8 kb), from the wasp spider, Argiope bruennichi. Northern blotting analysis demonstrated that CySp1 and CySp2 are selectively expressed in the cylindrical glands. The amino acid composition of raw egg case silk was closely consistent with the deduced amino acid composition based on the sequences of CySp1 and CySp2, which supports the assertion that CySp1 and CySp2 represent two major components of egg case silk. CySp1 and CySp2 are primarily composed of remarkable homogeneous assemble repeats that are 180 residues in length and consist of several complex subrepeats, and they contain highly homologous C-termini and markedly different N-termini. Our results suggest a possible link between CySp1 and CySp2. In addition, comparisons of stress/strain curves for dragline and egg case silk from Argiope bruennichi showed obvious differences in ultimate strength and extensibility, and similarities in toughness.
authors.affiliation: Department of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda 386-8567, Japan.
authors.forename: Ai-Chun
authors.initials: AC
authors.lastname: Zhao
authors.forename: Tian-Fu
authors.initials: TF
authors.lastname: Zhao
authors.forename: Koichi
authors.initials: K
authors.lastname: Nakagaki
authors.forename: Yuan-Song
authors.initials: YS
authors.lastname: Zhang
authors.forename: Yang-Hu
authors.initials: YH
authors.lastname: Sima
authors.forename: Yun-Gen
authors.initials: YG
authors.lastname: Miao
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Shiomi
authors.forename: Zenta
authors.initials: Z
authors.lastname: Kajiura
authors.forename: Yoko
authors.initials: Y
authors.lastname: Nagata
authors.forename: Masayuki
authors.initials: M
authors.lastname: Takadera
authors.forename: Masao
authors.initials: M
authors.lastname: Nakagaki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D005260:Female; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010063:Ovum / Q000378:metabolism; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D047011:Silk / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013112:Spiders / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D018076:DNA, Complementary; D019476:Insect Proteins; D047011:Silk