Download MendeleyVascular K ATP channel structural dynamics reveal regulatory mechanism by Mg-nucleotides.
Sung, M.W., Yang, Z., Driggers, C.M., Patton, B.L., Mostofian, B., Russo, J.D., Zuckerman, D.M., Shyng, S.L.(2021) Proc Natl Acad Sci U S A 118
- PubMed: 34711681
- DOI: https://doi.org/10.1073/pnas.2109441118
- Primary Citation of Related Structures:
7MIT, 7MJO, 7MJP, 7MJQ - PubMed Abstract:
Vascular tone is dependent on smooth muscle K ATP channels comprising pore-forming Kir6.1 and regulatory SUR2B subunits, in which mutations cause Cantú syndrome. Unique among K ATP isoforms, they lack spontaneous activity and require Mg-nucleotides for activation. Structural mechanisms underlying these properties are unknown. Here, we determined cryogenic electron microscopy structures of vascular K ATP channels bound to inhibitory ATP and glibenclamide, which differ informatively from similarly determined pancreatic K ATP channel isoform (Kir6.2/SUR1). Unlike SUR1, SUR2B subunits adopt distinct rotational "propeller" and "quatrefoil" geometries surrounding their Kir6.1 core. The glutamate/aspartate-rich linker connecting the two halves of the SUR-ABC core is observed in a quatrefoil-like conformation. Molecular dynamics simulations reveal MgADP-dependent dynamic tripartite interactions between this linker, SUR2B, and Kir6.1. The structures captured implicate a progression of intermediate states between MgADP-free inactivated, and MgADP-bound activated conformations wherein the glutamate/aspartate-rich linker participates as mobile autoinhibitory domain, suggesting a conformational pathway toward K ATP channel activation.
Organizational Affiliation:
Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health and Science University, Portland, OR 97239.
