Characterization of Egg Case Silk and Spider Silk Gene Transcription in Black Widow Spiders

摘要

Spiders are able to spin a variety of silk types for various purposes, each with their own unique properties. The mechanical properties of spider silk out-perform the mechanical properties of many man-made materials we use today, including tensile steel, KevlarTM, and nylon. To further understand the proteins the silks are made of and how they are synthesized in the silk glands, transcriptional and proteomic analysis was conducted. Transcriptional regulation of silk genes was investigated to determine how and why several silk proteins are transcribed into mRNA products together in the same gland. The tubuliform gland is one of the major contributors of egg case silk production. The mRNA of major ampullate spidroins 1 and 2 (MaSp1, MaSp2) and tubuliform spidroin 1 (TuSp1) is found in the tubuliform glands, but not all are translated into proteins for egg case silk purposes. To understand why not all of the transcribed mRNA products are not being translated into proteins, the promoter sequences of MaSp1, MaSp2, and TuSp1 were aligned and found to contain an E-Box site. Several constructs containing the cDNA of the promoter sequences and cDNA of bHLH transcription factors were built to test transcriptional regulation of MaSp1, MaSp2, and TuSp1. Proteomic analysis of egg case silk and the tubuliform glands was also conducted to identify further proteins synthesized in the tubuliform glands and to determine which of these proteins are ultimately incorporated into the egg case silk fibers by MS/MS analysis. Multiple silk proteins were identified within the tubuliform glands and incorporated into the egg case fibers, suggesting silks are composite fibers of multiple spidroins.