The French Muscular Dystrophy Telethon (AFM-Telethon)
23207
France
The French Muscular Dystrophy Telethon (AFM-Telethon)
23210
France
Citation
Journal: Sci Adv / Year: 2022 Title: Cryo-electron microscopy unveils unique structural features of the human Kir2.1 channel. Authors: Carlos A H Fernandes / Dania Zuniga / Charline Fagnen / Valérie Kugler / Rosa Scala / Gérard Péhau-Arnaudet / Renaud Wagner / David Perahia / Saïd Bendahhou / Catherine Vénien-Bryan / Abstract: We present the first structure of the human Kir2.1 channel containing both transmembrane domain (TMD) and cytoplasmic domain (CTD). Kir2.1 channels are strongly inward-rectifying potassium channels ...We present the first structure of the human Kir2.1 channel containing both transmembrane domain (TMD) and cytoplasmic domain (CTD). Kir2.1 channels are strongly inward-rectifying potassium channels that play a key role in maintaining resting membrane potential. Their gating is modulated by phosphatidylinositol 4,5-bisphosphate (PIP). Genetically inherited defects in Kir2.1 channels are responsible for several rare human diseases, including Andersen's syndrome. The structural analysis (cryo-electron microscopy), surface plasmon resonance, and electrophysiological experiments revealed a well-connected network of interactions between the PIP-binding site and the G-loop through residues R312 and H221. In addition, molecular dynamics simulations and normal mode analysis showed the intrinsic tendency of the CTD to tether to the TMD and a movement of the secondary anionic binding site to the membrane even without PIP. Our results revealed structural features unique to human Kir2.1 and provided insights into the connection between G-loop and gating and the pathological mechanisms associated with this channel.
For structural fitting, it was used dock-in-map (available at PHENIX) that uses both SSM and convolution-based shape searches to find a part of a map that is similar to a model. An initial in silico homology model of human Kir2.1 was generated using I-TASSER using the crystal structure of chicken Kir2.2 channel (PDB ID 3JYC) as a template. For building and refinement of the atomic model, the transmembrane domain (TMD, 55-184 region) of this in silico model was placed into the final sharpened cryo-EM map using the Dock in Map tool available in PHENIX. For the cytoplasmic domain (CTD; 188-367 region), the crystal structure of the CTD from mice Kir2.1 channel (PDB ID 1U4F) was placed into the final cryo-EM map using the same approach. Once the models were placed in the electron density, the loops that connect the two domains (185-187 region) and a N-terminal loop (41-54 region) absent in the in silico model were manually built using Coot.
Refinement
Space: REAL / Protocol: OTHER / Overall B value: 404.73 / Target criteria: Correlation coefficient
Output model
PDB-7zdz: Cryo-EM structure of the human inward-rectifier potassium 2.1 channel (Kir2.1)
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