Abstract
We show here that membrane-tethered toxins facilitate the biophysical study of the roles of toxin residues in K+ channel blockade to reveal two blocking mechanisms in the K+ channel pore. The structure of the sea anemone type I (SAK1) toxin HmK is determined by NMR. T-HmK residues are scanned by point mutation to map the toxin surface, and seven residues are identified to be critical to occlusion of the KcsA channel pore. T-HmK-Lys22 is shown to interact with K+ ions traversing the KcsA pore from the cytoplasm conferring voltage dependence on the toxin off rate, a classic mechanism that we observe as well with HmK in solution and for Kv1.3 channels. In contrast, two related SAK1 toxins, Hui1 and ShK, block KcsA and Kv1.3, respectively, via an arginine rather than the canonical lysine, when tethered and as free peptides.
Original language | English |
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Article number | eaaz3439 |
Journal | Science advances |
Volume | 6 |
Issue number | 10 |
DOIs | |
State | Published - Mar 2020 |
Bibliographical note
Publisher Copyright:© 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).
Funding
Funding: We are grateful for grant support from the NIH (GM111716 to S.A.N.G.) and the United States-Israel Binational Science Foundation (BSF 2013185 and 2017243) to S.A.N.G. and J.H.C.
Funders | Funder number |
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National Institutes of Health | |
National Institute of General Medical Sciences | R01GM111716 |
United States-Israel Binational Science Foundation | 2017243, BSF 2013185 |