In-Depth Proteome Analysis of Black Widow Dragline Spider Silk

Spider silk in Lactrodectus hesperus (black widow spider) species is renowned for its tensile strength, toughness and elasticity. These properties allow spider silk to outperform some of the best man-made materials such as Kevlar. Despite 6-7 different fiber types, our lab focuses mainly on Major Ampullate (MA) silk. In particular, we are involved in studying the structural proteins (spidroins), which are the molecules that comprise a vast amount of the silk. Previous proteome analysis of dragline silk has revealed approximately 48 proteins - most are uncharacterized. We hypothesize that our proteome analysis of dragline silk will provide a more comprehensive list of proteins, further revealing unknown proteins that are constituents of dragline silk. In order to discover new proteins, we dissolved dragline silk from black widow spiders with urea to denature the proteins. Proteins were further unfolded using reducing agent, followed by alkylation of cysteine sidechain groups. Following these steps, the proteins were digested with trypsin and the peptides separated using nano high performance liquid chromatography. Peptides were subject to MS and MS/MS analysis using an Orbitrap Fusion mass spectrometer. Spectra were analyzed using Proteome Discover 2.1 software. From our experiment we have generated a new list of proteins that more accurately depicts proteins within dragline silk