Identification of four major hornet silk genes with a complex of alanine-rich and serine-rich sequences in Vespa simillima xanthoptera Cameron.
Hornet silk, a fibrous protein in the cocoon produced by the larva of the vespa, is composed of four major proteins. In this study, we constructed silk-gland cDNA libraries from larvae of the hornet Vespa simillima xanthoptera Cameron and deduced the full amino acid sequences of the four hornet silk proteins, which were named Vssilk 1-4 in increasing order of molecular size. Portions of the amino acid sequences of the four proteins were confirmed by Matrix-assisted laser desorption/ionization-time of flight/mass spectrometry (MALDI-TOF/MS) and N-terminal protein sequencing. The primary sequences of the four Vssilk proteins (1-4) were highly divergent, but the four proteins had some common properties: (i) the amino acid compositions of all four proteins were similar to each other in that the well-defined and characteristic repetitive patterns present in most of the known silk proteins were absent; and (ii) the characteristics of the amino acid sequences of the four proteins were also similar in that Ser-rich structures such as sericin were localized at both ends of the chains and Ala-rich structures such as fibroin were found in the center. These characteristic primary structures might be responsible for the coexisting alpha-helix and beta-sheet conformations that make up the unique secondary structure of hornet silk proteins in the native state. Because heptad repeat sequences of hydrophobic residue are present in the Ala-rich region, we believe that the Ala-rich region of hornet silk predominantly forms a coiled coil with an alpha-helix conformation.
Sezutsu
Hideki
H
National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8634, Japan.
Kajiwara
Hideyuki
H
Kojima
Katsura
K
Mita
Kazuei
K
Tamura
Toshiki
T
Tamada
Yasushi
Y
Kameda
Tsunenori
T
D000409:Alanine / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D018076:DNA, Complementary / Q000235:genetics; D017344:Genes, Insect; D019476:Insect Proteins / Q000737:chemistry* / Q000235:genetics*; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D020539:Sequence Analysis, Protein; D012694:Serine / Q000737:chemistry; D047011:Silk / Q000737:chemistry* / Q000235:genetics*; D014863:Wasps / Q000235:genetics*
D018076:DNA, Complementary; D019476:Insect Proteins; D047011:Silk; D012694:Serine; D000409:Alanine