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Anomalous X-ray diffraction studies of ion transport in K(+) channels

Potassium ion channels utilize a highly selective filter to rapidly transport K(+) ions across cellular membranes. This selectivity filter is composed of four binding sites which display almost equal electron density in crystal structures with high potassium ion concentrations. This electron density...

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Autores principales: Langan, Patricia S., Vandavasi, Venu Gopal, Weiss, Kevin L., Afonine, Pavel V., el Omari, Kamel, Duman, Ramona, Wagner, Armin, Coates, Leighton
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6208422/
https://www.ncbi.nlm.nih.gov/pubmed/30382100
http://dx.doi.org/10.1038/s41467-018-06957-w
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author Langan, Patricia S.
Vandavasi, Venu Gopal
Weiss, Kevin L.
Afonine, Pavel V.
el Omari, Kamel
Duman, Ramona
Wagner, Armin
Coates, Leighton
author_facet Langan, Patricia S.
Vandavasi, Venu Gopal
Weiss, Kevin L.
Afonine, Pavel V.
el Omari, Kamel
Duman, Ramona
Wagner, Armin
Coates, Leighton
author_sort Langan, Patricia S.
collection PubMed
description Potassium ion channels utilize a highly selective filter to rapidly transport K(+) ions across cellular membranes. This selectivity filter is composed of four binding sites which display almost equal electron density in crystal structures with high potassium ion concentrations. This electron density can be interpreted to reflect a superposition of alternating potassium ion and water occupied states or as adjacent potassium ions. Here, we use single wavelength anomalous dispersion (SAD) X-ray diffraction data collected near the potassium absorption edge to show experimentally that all ion binding sites within the selectivity filter are fully occupied by K(+) ions. These data support the hypothesis that potassium ion transport occurs by direct Coulomb knock-on, and provide an example of solving the phase problem by K-SAD.
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spelling pubmed-62084222018-10-31 Anomalous X-ray diffraction studies of ion transport in K(+) channels Langan, Patricia S. Vandavasi, Venu Gopal Weiss, Kevin L. Afonine, Pavel V. el Omari, Kamel Duman, Ramona Wagner, Armin Coates, Leighton Nat Commun Article Potassium ion channels utilize a highly selective filter to rapidly transport K(+) ions across cellular membranes. This selectivity filter is composed of four binding sites which display almost equal electron density in crystal structures with high potassium ion concentrations. This electron density can be interpreted to reflect a superposition of alternating potassium ion and water occupied states or as adjacent potassium ions. Here, we use single wavelength anomalous dispersion (SAD) X-ray diffraction data collected near the potassium absorption edge to show experimentally that all ion binding sites within the selectivity filter are fully occupied by K(+) ions. These data support the hypothesis that potassium ion transport occurs by direct Coulomb knock-on, and provide an example of solving the phase problem by K-SAD. Nature Publishing Group UK 2018-10-31 /pmc/articles/PMC6208422/ /pubmed/30382100 http://dx.doi.org/10.1038/s41467-018-06957-w Text en © The Author(s) 2018 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Langan, Patricia S.
Vandavasi, Venu Gopal
Weiss, Kevin L.
Afonine, Pavel V.
el Omari, Kamel
Duman, Ramona
Wagner, Armin
Coates, Leighton
Anomalous X-ray diffraction studies of ion transport in K(+) channels
title Anomalous X-ray diffraction studies of ion transport in K(+) channels
title_full Anomalous X-ray diffraction studies of ion transport in K(+) channels
title_fullStr Anomalous X-ray diffraction studies of ion transport in K(+) channels
title_full_unstemmed Anomalous X-ray diffraction studies of ion transport in K(+) channels
title_short Anomalous X-ray diffraction studies of ion transport in K(+) channels
title_sort anomalous x-ray diffraction studies of ion transport in k(+) channels
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6208422/
https://www.ncbi.nlm.nih.gov/pubmed/30382100
http://dx.doi.org/10.1038/s41467-018-06957-w
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