Structural highlights
Publication Abstract from PubMedWe have recently demonstrated that a common phenomenon in evolution of spider venom composition is the emergence of so-called modular toxins consisting of two domains, each corresponding to a "usual" single-domain toxin. In this article, we describe the structure of two domains that build up a modular toxin named spiderine or OtTx1a from the venom of Oxyopes takobius. Both domains were investigated by solution NMR in water and detergent micelles used to mimic membrane environment. The N-terminal spiderine domain OtTx1a-AMP (41 amino acid residues) contains no cysteines. It is disordered in aqueous solution but in micelles, it assumes a stable amphiphilic structure consisting of two alpha-helices separated by a flexible linker. On the contrary, the C-terminal domain OtTx1a-ICK (59 residues) is a disulfide-rich polypeptide reticulated by five S-S bridges. It presents a stable structure in water and its core is the inhibitor cystine knot (ICK) or knottin motif that is common among single-domain neurotoxins. OtTx1a-ICK structure is the first knottin with five disulfide bridges and it represents a good reference for the whole oxytoxin family. The affinity of both domains to membranes was measured with NMR using titration by liposome suspensions. In agreement with biological tests, OtTx1a-AMP was found to show high membrane affinity explaining its potent antimicrobial properties. Modular toxin from the lynx spider Oxyopes takobius: Structure of spiderine domains in solution and membrane-mimicking environment.,Nadezhdin KD, Romanovskaia DD, Sachkova MY, Oparin PB, Kovalchuk SI, Grishin EV, Arseniev AS, Vassilevski AA Protein Sci. 2017 Mar;26(3):611-616. doi: 10.1002/pro.3101. Epub 2017 Feb 12. PMID:27997708[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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