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Allosteric conformational change of a cyclic nucleotide-gated ion channel revealed by DEER spectroscopy.
Proc Natl Acad Sci U S A. 2020 05 19; 117(20):10839-10847.PN

Abstract

Cyclic nucleotide-gated (CNG) ion channels are essential components of mammalian visual and olfactory signal transduction. CNG channels open upon direct binding of cyclic nucleotides (cAMP and/or cGMP), but the allosteric mechanism by which this occurs is incompletely understood. Here, we employed double electron-electron resonance (DEER) spectroscopy to measure intersubunit distance distributions in SthK, a bacterial CNG channel from Spirochaeta thermophila Spin labels were introduced into the SthK C-linker, a domain that is essential for coupling cyclic nucleotide binding to channel opening. DEER revealed an agonist-dependent conformational change in which residues of the B'-helix displayed outward movement with respect to the symmetry axis of the channel in the presence of the full agonist cAMP, but not with the partial agonist cGMP. This conformational rearrangement was observed both in detergent-solubilized SthK and in channels reconstituted into lipid nanodiscs. In addition to outward movement of the B'-helix, DEER-constrained Rosetta structural models suggest that channel activation involves upward translation of the cytoplasmic domain and formation of state-dependent interactions between the C-linker and the transmembrane domain. Our results demonstrate a previously unrecognized structural transition in a CNG channel and suggest key interactions that may be responsible for allosteric gating in these channels.

Authors+Show Affiliations

Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195. Department of Chemistry, University of Washington, Seattle, WA 98195.Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195.Department of Biochemistry, University of Washington, Seattle, WA 98195.Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195; zagotta@uw.edu stst@uw.edu.Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195; zagotta@uw.edu stst@uw.edu. Department of Chemistry, University of Washington, Seattle, WA 98195.

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

32358188

Citation

Evans, Eric G B., et al. "Allosteric Conformational Change of a Cyclic Nucleotide-gated Ion Channel Revealed By DEER Spectroscopy." Proceedings of the National Academy of Sciences of the United States of America, vol. 117, no. 20, 2020, pp. 10839-10847.
Evans EGB, Morgan JLW, DiMaio F, et al. Allosteric conformational change of a cyclic nucleotide-gated ion channel revealed by DEER spectroscopy. Proc Natl Acad Sci USA. 2020;117(20):10839-10847.
Evans, E. G. B., Morgan, J. L. W., DiMaio, F., Zagotta, W. N., & Stoll, S. (2020). Allosteric conformational change of a cyclic nucleotide-gated ion channel revealed by DEER spectroscopy. Proceedings of the National Academy of Sciences of the United States of America, 117(20), 10839-10847. https://doi.org/10.1073/pnas.1916375117
Evans EGB, et al. Allosteric Conformational Change of a Cyclic Nucleotide-gated Ion Channel Revealed By DEER Spectroscopy. Proc Natl Acad Sci USA. 2020 05 19;117(20):10839-10847. PubMed PMID: 32358188.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Allosteric conformational change of a cyclic nucleotide-gated ion channel revealed by DEER spectroscopy. AU - Evans,Eric G B, AU - Morgan,Jacob L W, AU - DiMaio,Frank, AU - Zagotta,William N, AU - Stoll,Stefan, Y1 - 2020/05/01/ PY - 2020/11/01/pmc-release PY - 2020/5/3/pubmed PY - 2020/5/3/medline PY - 2020/5/3/entrez KW - DEER KW - EPR KW - allostery KW - cyclic nucleotide KW - ion channel SP - 10839 EP - 10847 JF - Proceedings of the National Academy of Sciences of the United States of America JO - Proc. Natl. Acad. Sci. U.S.A. VL - 117 IS - 20 N2 - Cyclic nucleotide-gated (CNG) ion channels are essential components of mammalian visual and olfactory signal transduction. CNG channels open upon direct binding of cyclic nucleotides (cAMP and/or cGMP), but the allosteric mechanism by which this occurs is incompletely understood. Here, we employed double electron-electron resonance (DEER) spectroscopy to measure intersubunit distance distributions in SthK, a bacterial CNG channel from Spirochaeta thermophila Spin labels were introduced into the SthK C-linker, a domain that is essential for coupling cyclic nucleotide binding to channel opening. DEER revealed an agonist-dependent conformational change in which residues of the B'-helix displayed outward movement with respect to the symmetry axis of the channel in the presence of the full agonist cAMP, but not with the partial agonist cGMP. This conformational rearrangement was observed both in detergent-solubilized SthK and in channels reconstituted into lipid nanodiscs. In addition to outward movement of the B'-helix, DEER-constrained Rosetta structural models suggest that channel activation involves upward translation of the cytoplasmic domain and formation of state-dependent interactions between the C-linker and the transmembrane domain. Our results demonstrate a previously unrecognized structural transition in a CNG channel and suggest key interactions that may be responsible for allosteric gating in these channels. SN - 1091-6490 UR - https://www.unboundmedicine.com/medline/citation/32358188/Allosteric_conformational_change_of_a_cyclic_nucleotide-gated_ion_channel_revealed_by_DEER_spectroscopy L2 - http://www.pnas.org/cgi/pmidlookup?view=long&pmid=32358188 DB - PRIME DP - Unbound Medicine ER -
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