Identification of a sensory neuron Cav2.3 inhibitor within a new superfamily of macro-conotoxins

Hackney, C. M.; Florez Salcedo, P.; Mueller, E.; Kjelgaard, L. D.; Watkins, M.; Zachariassen, L. G.; McArthur, J. R.; Adams, D. J.; Kristensen, A. S.; Olivera, B.; Finol-Urdaneta, R. K.; Safavi, H.; Morth, J. P.; Ellgaard, L.

doi:10.1101/2022.07.04.498665

bioRxiv · 10.1101/2022.07.04.498665

Identification of a sensory neuron Cav2.3 inhibitor within a new superfamily of macro-conotoxins

Hackney, C. M.·Florez Salcedo, P.·Mueller, E.·Kjelgaard, L. D.·Watkins, M.·Zachariassen, L. G.·McArthur, J. R.·Adams, D. J.·Kristensen, A. S.·Olivera, B.·Finol-Urdaneta, R. K.·Safavi, H.·Morth, J. P.·Ellgaard, L.

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Abstract

Animal venom peptides represent valuable compounds for biomedical exploration. The venoms of marine cone snails constitute a particularly rich source of peptide toxins, known as conotoxins. Here, we identify the sequence of an unusually large conotoxin, Mu8.1, that defines a new class of conotoxins evolutionarily related to the well-known con-ikot-ikots and two additional conotoxin classes not previously described. The crystal structure of recombinant Mu8.1 displays a saposin-like fold and shows structural similarity with con-ikot-ikot. Functional studies demonstrate that Mu8.1 curtails calcium influx in defined classes of murine somatosensory dorsal root ganglion (DRG) neurons. When tested on a variety of voltage-gated ion channels, Mu8.1 preferentially inhibited the R-type (Cav2.3) calcium channel. Ca2+ signals from Mu8.1-sensitive DRG neurons were also inhibited by SNX-482, a known spider peptide modulator of Cav2.3 and voltage-gated K+ (Kv4) channels. Our findings highlight the potential of Mu8.1 as a molecular tool to identify and study neuronal subclasses expressing Cav2.3. Importantly, this multidisciplinary study demonstrates the feasibility of large, disulfide-rich venom-component investigation, an endeavor that will lead to the discovery of novel structures and functions in the previously underexplored group of macro-conotoxins.

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Hackney, C. M., Florez Salcedo, P., Mueller, E., Kjelgaard, L. D., Watkins, M., Zachariassen, L. G., McArthur, J. R., Adams, D. J., Kristensen, A. S., Olivera, B., Finol-Urdaneta, R. K., Safavi, H., Morth, J. P., Ellgaard, L.. 2022-07-04. Identification of a sensory neuron Cav2.3 inhibitor within a new superfamily of macro-conotoxins. https://doi.org/10.1101/2022.07.04.498665

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