Although numerous spider fibroins have been reported, no known silk coating peptides have been discovered. We provide the first biochemical evidence for a spider coating peptide, called SCP-2, found on gumfooted lines, scaffolding joints and egg cases. The presence of this spider coating peptide on the fibers is supported by MS/MS analysis. Using quantitative real-time PCR analysis, we also demonstrate that SCP-2 has a flagelliform-restricted mRNA pattern of expression. Molecular modeling of the SCP-2 amino acid sequence predicts it adopts an alpha-helical structure that is amphipathic in nature. SCP-2, which can be extracted from fibers using water, is hypothesized to influence the mechanical properties of the silk fibers as well as serve a protective function for the threads. Based upon the restricted pattern of expression of SCP-2, our findings reveal novel insight regarding the glandular function of the flagelliform gland in . cob weaving spiders, suggesting it produces aqueous coating materials that are deposited on a wide range of different silk types. In addition, in an attempt to advance our understanding regarding silk gene transcription, our lab has developed the first antibody against the bHLH factor SGSF. SGSF has been implicated as a potential transcriptional regulator of silk gene transcription in spiders. Development of the anti-SGSF antibody was accomplished via the overexpression and purification of a fusion protein in bacteria, which consisted of the C-terminal region of SGSF fused to thioredoxin. Purified SGSF fusion proteins were injected into rabbits and the polyclonal antiserum was collected and tested by western blot analysis to determine the specificity of the immunological reagent. Western blot analyses revealed the anti-SGSF antiserum was capable of recognizing bacterially expressed SGSF in an efficient manner. Collectively, these studies lay the groundwork for future investigations involving the use of the antibody to determine the role of SGSF in silk transcription.

Belonging to the diverse order Araneae, the black widow spider Latrodectus 4 hesperus produces high-performance silks with a broad range ofbiological functions and mechanical properties. The cob weaver spider spins different fibers by using seven specialized glands located in its abdomen. Egg case silk originates from the tubuliforrn gland and to date, no proteins that participate in the assembly process of egg case silk proteins have been identified. The goal of this project was the expression, purification, and characterization of such protein products. De novo sequencing of peptides from in-solution tryptic digestion of black widow spider dragline silk, the most studied type of silk, identified a novel cysteine-rich nonfibroin- like peptide that we named cysteine-rich component or CRC- 1. Further analysis of a large pool of nucleic acid sequences deposited in our custom eDNA database revealed 4 additional sequences with similarities to each other at the amino acid level called CRC-2, CRC-3, CRC-4, and CRC-5, suggesting a new family of proteins. Specifically, Q-PCR analysis revealed that the CRC-5 mRNAs were predominantly expressed in the tubuliform and aggregate glands. Since the aggregate gland manufactures a more complex aqueous solution compared to the tubuliforrn gland, we focused these studies on the tubuliform gland and resultant egg case fibers. Westem blot analysis using a cross-reactive polyclonal anti-CRC-1 antiserum conoborated the presence of CRC-5 in the tubulifmm gland and egg case silk, supporting the colocalization ofTuSpl, a tubuliform gland-specific protein, and CRC-5. Thus, we have demonstrated that these two proteins are present within tubuliform silks. In vitro studies suggested that recombinant CRC-5 displayed enzymatic activity similar to a sulfhydryl oxidase. Collectively, our findings provide new insights into novel proteins that have a potential role in the silk assembly and extrusion pathway of egg case silk fibers.