Unraveling the spider web silk droplets proteopeptides content and functional characterization of web toxins

Abstract

Orb-weaving spiders have evolved the ability to synthesize adhesive threads to enhance the efficiency of their chemical arsenal for catching, paralyzing and/or killing prey. These adhesive threads are present in the capture spiral of the orb-webs, coated by a viscous solution that covers the entire silk fibers in the shape of droplets, which contain many vesicles under suspension, entrapping a solution containing proteins, peptides and low molecular mass compounds. Different omics approaches combining gas and liquid chromatography coupled to mass spectrometry (GC-MS; LC-ESI-MS/MS) have identified toxic compounds in the capture spiral, indicating the involvement of these toxins in prey capture by web. Once these toxins were identified in the web, our previous data demonstrated that they are structurally similar to toxins isolated from spider and scorpion venoms, and even to Conus venoms. Many studies have shown that spider venoms contain proteins and peptides with insecticidal properties that can act on neuronal ion channels and receptors in vertebrates and invertebrates. Taking into account these studies and the presence of toxins in the web silk, the current study aims to evaluate the toxicity potential of the crude web silk extract, as well as purified toxin-like peptides, in the insect nervous system. For this purpose, will be use assays two-electrode voltage clamp (TEVC) electrophysiology and whole-cell patch-clamp electrophysiology to evaluate toxin activities against a wide range of ion channels. In addition, will be perform MALDI-Imaging analysis of the web silk droplets in order to investigate the toxin content trapped by the extracellular lipid vesicles suspended within the aqueous interior of these droplets on the web silk. The outcomes of this study will include: (i) a better understanding of the chemical and ecological interaction of these compounds in the insect-prey capture by Nephila sp. spider webs; (ii) possibility application of newly discovered ion channel toxins as pharmacological tools or as leads for development of selective insecticides.