Characterization of full-length tubuliform spidroin gene from Araneus ventricosus

Orb-web spiders produce at least seven different protein-based silk that exhibit different mechanical properties. Egg case silk is spun by tubuliform glands and used to form the outer shell of egg case. To date, only two complete cDNA sequences have been reported for tubuliform spidroin (TuSp, also known as CySp for cylindrical spidroin). Here, we report the complete genomic DNA sequence for a tubuliform spidroin (TuSp1) gene from orb-web weaving spider species Araneus ventricosus, which was obtained by using a long distance PCR approach. The primary component of Araneus ventricosus TuSp1 gene contains a single large exon (5763 bp) and encodes 1921 amino acid residues dominated by 9 tandem repeats flanked by conserved non-repetitive N- and C-terminal domains. These repeats (each 176-155 amino acids long) found in Araneus ventricosus TuSp1 are highly conserved (>96% identical at amino acid level).