Authors
Hackney, C. M., Koch, T. L., Ryding, N. L., Rogalski, A., Chase, K., Giglio, M. L., Espino, S. S., Acyatan, Z. G., Watkins, M., Olivera, B. M., Safavi-Hemami, H., Teilum, K., Ellgaard, L.
Abstract
Marine cone snails produce a diverse array of bioactive peptides, known as conotoxins, in their venom. Given their high target potency and specificity, conotoxins are attractive compounds for the development of precision research tools and pharmacological agents. Here, we provide the first experimental characterization of a conotoxin from the MKAVA superfamily, conkazal-M1, from Conus magus. Using NMR spectroscopy, we show that conkazal-M1 adopts a fold characteristic of the Kazal-type protease inhibitor family, featuring a Glu residue at the inhibitory P1 position. Recombinantly expressed conkazal-M1 inhibits the proteolytic activity of Subtilisin A with an apparent Ki of 1.1 M. In addition, conkazal-M1 partially inhibits calcium transients in mouse sensory neurons, suggesting a potential role in modulating ion-channel activity as seen for many other toxins. The dual function of conkazal-M1 in protease inhibition and neuroactivity is analogous to the dual function of several toxins harboring a Kunitz-type fold. The well-conserved sequence of the MKAVAs indicates an evolutionary trajectory where these proteins face an adaptive conflict when mutations that enhance one activity compromise the other. Collectively, this work provides new structural and functional insight into a previously uncharacterized toxin superfamily in cone snails and expands our knowledge about the toxin arsenal available to venomous animals.
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bioRxiv
The authors list and abstract were imported from bioRxiv on 07 Nov 2025.
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