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

DOI: 10.1038/s41467-018-06957-w DOI Help

Authors: Patricia S. Langan (Oak Ridge National Laboratory) , Venu Gopal Vandavasi (Oak Ridge National Laboratory) , Kevin L. Weiss (Oak Ridge National Laboratory) , Pavel V. Afonine (Lawrence Berkeley National Laboratory) , Kamel El Omari (University of Oxford) , Ramona Duman (Diamond Light Source) , Armin Wagner (Diamond Light Source) , Leighton Coates (Oak Ridge National Laboratory)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Communications , VOL 9

State: Published (Approved)
Published: October 2018
Diamond Proposal Number(s): 14493

Open Access Open Access

Abstract: 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.

Subject Areas: Biology and Bio-materials

Instruments: I23-Long wavelength MX

Added On: 05/11/2018 11:00


Discipline Tags:

Structural biology Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX) Long Wavelength Crystallography