Abstract
The sodium potassium ion channel (NaK) is a nonselective ion channel that conducts both sodium and potassium across the cellular membrane. A new crystallographic structure of NaK reveals conformational differences in the residues that make up the selectivity filter between the four subunits that form the ion channel and the inner helix of the ion channel. The crystallographic structure also identifies a side-entry, ion-conduction pathway for Na+ permeation that is unique to NaK. NMR studies and molecular dynamics simulations confirmed the dynamical nature of the top part of the selectivity filter and the inner helix in NaK as also observed in the crystal structure. Taken together, these results indicate that the structural plasticity of the selectivity filter combined with the dynamics of the inner helix of NaK are vital for the efficient conduction of different ions through the non-selective ion channel of NaK.
Original language | English |
---|---|
Pages (from-to) | 421-430 |
Number of pages | 10 |
Journal | IUCrJ |
Volume | 8 |
DOIs | |
State | Published - May 1 2021 |
Funding
Research at ORNL’s Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy. The Office of Biological and Environmental Research supported research at Oak Ridge National Laboratory’s Center for Structural Molecular Biology (CSMB), using facilities supported by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy. Results shown in this report are derived from work performed at Argonne National Laboratory (ANL), Structural Biology Center at the Advanced Photon Source. ANL is operated by UChicago Argonne, LLC, for the US Department of Energy, Office of Biological and Environmental Research (contract No. DE-AC02-06CH11357). HS, BLdG and WK thank the German Research Foundation (DFG) through FOR 2518 DynIon for financial support (P3 and P5 projects). KH is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy-EXC 2008-390540038-UniSysCat. This research used resources at the Second Target Station, which is a DOE Office of Science User Facilities Construction Project at Oak Ridge National Laboratory. LC acknowledges support by the NIH (grant No. R01-GM071939).
Keywords
- X-ray crystallography
- ion channels
- membrane proteins
- molecular dynamics
- solid-state NMR