7OQ2

NaK S-DI mutant soaked in Na+

Summary for 7OQ2

• Entry DOI: 10.2210/pdb7oq2/pdb
• Related: 7OOR 7OOU 7OPH 7OQ1
• Descriptor: Potassium channel protein, (4S)-2-METHYL-2,4-PENTANEDIOL, SODIUM ION, ... (6 entities in total)
• Functional Keywords: ion channel, prokaryote, membrane protein, transport protein
• Biological source: Bacillus cereus (strain ATCC 14579 / DSM 31 / JCM 2152 / NBRC 15305 / NCIMB 9373 / NRRL B-3711)
• Total number of polymer chains: 2
• Total formula weight: 23807.48

Authors

Minniberger, S.,Plested, A.J.R. (deposition date: 2021-06-02, release date: 2022-06-22, Last modification date: 2024-02-07)

Primary citation

Minniberger, S.,Abdolvand, S.,Braunbeck, S.,Sun, H.,Plested, A.J.R.
Asymmetry and Ion Selectivity Properties of Bacterial Channel NaK Mutants Derived from Ionotropic Glutamate Receptors.
J.Mol.Biol., 435:167970-167970, 2023

PubMed Abstract: Ionotropic glutamate receptors are ligand-gated cation channels that play essential roles in the excitatory synaptic transmission throughout the central nervous system. A number of open-pore structures of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic-acid (AMPA)-type glutamate receptors became available recently by cryo-electron microscopy (cryo-EM). These structures provide valuable insights into the conformation of the selectivity filter (SF), the part of the ion channel that determines the ion selectivity. Nonetheless, due to the moderate resolution of the cryo-EM structures, detailed information such as ion occupancy of monovalent and divalent cations as well as positioning of the side-chains in the SF is still missing. Here, in an attempt to obtain high-resolution information about glutamate receptor SFs, we incorporated partial SF sequences of the AMPA and kainate receptors into the bacterial tetrameric cation channel NaK, which served as a structural scaffold. We determined a series of X-ray structures of NaK-CDI, NaK-SDI and NaK-SELM mutants at 1.42-2.10 Å resolution, showing distinct ion occupation of different monovalent cations. Molecular dynamics (MD) simulations of NaK-CDI indicated the channel to be conductive to monovalent cations, which agrees well with our electrophysiology recordings. Moreover, previously unobserved structural asymmetry of the SF was revealed by the X-ray structures and MD simulations, implying its importance in ion non-selectivity of tetrameric cation channels.

PubMed: 36682679
DOI: 10.1016/j.jmb.2023.167970

Experimental method

X-RAY DIFFRACTION (1.7 Å)