From EST to novel spider silk gene identification for production of spidroin-based biomaterials.

A cDNA library from a pool of all the seven silk glands from a tropical spider species was constructed. More than 1000 expressed sequence tag (EST) clones were created. Almost 65% of the EST clones were identified and around 50% were annotated. The cellular and functional distribution of the EST clones indicated high protein synthesis activity in spider silk glands. Novel clones with repetitive amino acid sequences, which is one of the most important characteristics of spider silk genes, were isolated. One of these clones, namely TuSp2 in current research, contains two almost identical fragments with one short C-terminal domain. Reverse transcription (RT) PCR and expression analysis showed that it is expressed in the tubuliform gland and involved in eggcase silk formation. Furthermore, its single repetitive domain can be induced to form various types of materials, including macroscopic fibers, transparent film and translucent hydrogel. This study implies promising potentials for future identification of novel spidroins and development of new spidroin-based biomaterials.