Characterization of a cysteine-rich protein specifically expressed in the silk gland of caddisfly Stenopsyche marmorata (Trichoptera; Stenopsychidae)

• Published in: Bioscience, biotechnology, and biochemistry biotechnology, and biochemistry, 2010-01, Vol.74 (1), p.108-112
• Main Authors: Wang, Y., Shinshu Univ., Ueda, Nagano (Japan). Faculty of Textile Science and Technology, Wang, H, Zhao, T, Nakagaki, M
• Format: Article
• Language: English
• Subjects: Adhesion; adhesive protein; Adhesives; ADHESIVIDAD; ADHESIVITE; Amino Acid Sequence; Amino acids; Animals; Biological and medical sciences; caddisfly; Cements; Cloning, Molecular; Cysteine; cysteine-rich; DNA, Complementary - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation; GLANDE SERICIGENE; GLANDULAS SERIGENAS; http://www.fao.org/aos/agrovoc#c_34337; http://www.fao.org/aos/agrovoc#c_4204; http://www.fao.org/aos/agrovoc#c_6259; http://www.fao.org/aos/agrovoc#c_7409; http://www.fao.org/aos/agrovoc#c_7903; Hydroxyl groups; Insect Proteins - chemistry; Insect Proteins - genetics; Insect Proteins - metabolism; Insecta - anatomy & histology; Insecta - genetics; Insecta - metabolism; LARVAE; LARVAS; LARVE; Microscopy; Molecular Sequence Data; PROTEINAS; PROTEINE; PROTEINS; Silk; Silk - metabolism; SILK GLANDS; Stenopsyche marmorata; Stenopsychidae; STICKINESS; TRICHOPTERA
• ISSN: 0916-8451; 1347-6947
• DOI: 10.1271/bbb.90606

A novel protein, Smsp-72k, was found to be selectively expressed in the silk gland of aquatic larvae of the Stenopsychid caddisfly (Stenopsyche marmorata). The protein was characterized by an abundance of cysteine (13.97%) and charged residues (47.21%). Amino acids with hydroxyl side-chains accounted for an additional 10% of the Smsp-72k protein, with serine at 4.4% and threonine at 5.6%. A cysteine-rich repetitive sequence is common to many potential and known underwater adhesive/cement proteins and cell-cell adhesion molecules. We hypothesized that Smsp-72k is an adhesive/cement protein that increases the adhesiveness of the silk fiber of S. marmorata. The hydroxyl groups of Smsp-72k might form a link with the heavy chain fibroin of S. marmorata, removing the weak boundary-water layer and allowing the spreading of the silk protein onto the surface of the substratum during the process of adhesion.