6M84

Crystal structure of cKir2.2 force open mutant in complex with PI(4,5)P2

Summary for 6M84

• Entry DOI: 10.2210/pdb6m84/pdb
• Descriptor: ATP-sensitive inward rectifier potassium channel 12, POTASSIUM ION, [(2R)-2-octanoyloxy-3-[oxidanyl-[(1R,2R,3S,4R,5R,6S)-2,3,6-tris(oxidanyl)-4,5-diphosphonooxy-cyclohexyl]oxy-phosphoryl]oxy-propyl] octanoate, ... (5 entities in total)
• Functional Keywords: metal transport, kir 2.2 force open mutant, complex
• Biological source: Gallus gallus (Chicken)
• Total number of polymer chains: 1
• Total formula weight: 40968.56

Authors

Lee, S.-J.,Ren, F.,Yuan, P.,Nichols, C.G. (deposition date: 2018-08-21, release date: 2019-09-04, Last modification date: 2024-10-30)

Primary citation

Zangerl-Plessl, E.M.,Lee, S.J.,Maksaev, G.,Bernsteiner, H.,Ren, F.,Yuan, P.,Stary-Weinzinger, A.,Nichols, C.G.
Atomistic basis of opening and conduction in mammalian inward rectifier potassium (Kir2.2) channels.
J.Gen.Physiol., 152:-, 2020

PubMed Abstract: Potassium ion conduction through open potassium channels is essential to control of membrane potentials in all cells. To elucidate the open conformation and hence the mechanism of K+ ion conduction in the classic inward rectifier Kir2.2, we introduced a negative charge (G178D) at the crossing point of the inner helix bundle, the location of ligand-dependent gating. This "forced open" mutation generated channels that were active even in the complete absence of phosphatidylinositol-4,5-bisphosphate (PIP2), an otherwise essential ligand for Kir channel opening. Crystal structures were obtained at a resolution of 3.6 Å without PIP2 bound, or 2.8 Å in complex with PIP2. The latter revealed a slight widening at the helix bundle crossing (HBC) through backbone movement. MD simulations showed that subsequent spontaneous wetting of the pore through the HBC gate region allowed K+ ion movement across the HBC and conduction through the channel. Further simulations reveal atomistic details of the opening process and highlight the role of pore-lining acidic residues in K+ conduction through Kir2 channels.

PubMed: 31744859
DOI: 10.1085/jgp.201912422

Experimental method

X-RAY DIFFRACTION (2.81 Å)