Molecular cloning and analysis of the full-length aciniform spidroin gene from Araneus ventricosus

Orb-web spiders produce more than seven different protein-based silks/glues by specialized abdominal glands for different uses. Prey-wrapping silk is secreted by aciniform glands for wrapping prey and forming the inner layer of egg case, and is almost twice as tough as other silks because of high strength and extensibility. So far, only two complete gene sequences have been obtained for aciniform spidroins (AcSp1). Here we describe the AcSp1 full-length gene sequence from the spider species Araneus ventricosus, using a long-distance PCR (LD-PCR) approach. The full-length AcSp1 gene is a single enormous exon of 10,338 bp in size, and the predicted protein sequence is 3445 amino acids long and consists of a conserved nonrepetitive N-terminal domain, a central predominantly repetitive region composed of fifteen repeat units, and a conserved nonrepetitive C-terminal domain.