National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM43949
United States
Howard Hughes Medical Institute (HHMI)
United States
Citation
Journal: Nature / Year: 2017 Title: Structural basis for gating the high-conductance Ca-activated K channel. Authors: Richard K Hite / Xiao Tao / Roderick MacKinnon / Abstract: The precise control of an ion channel gate by environmental stimuli is crucial for the fulfilment of its biological role. The gate in Slo1 K channels is regulated by two separate stimuli, ...The precise control of an ion channel gate by environmental stimuli is crucial for the fulfilment of its biological role. The gate in Slo1 K channels is regulated by two separate stimuli, intracellular Ca concentration and membrane voltage. Slo1 is thus central to understanding the relationship between intracellular Ca and membrane excitability. Here we present the Slo1 structure from Aplysia californica in the absence of Ca and compare it with the Ca-bound channel. We show that Ca binding at two unique binding sites per subunit stabilizes an expanded conformation of the Ca sensor gating ring. These conformational changes are propagated from the gating ring to the pore through covalent linkers and through protein interfaces formed between the gating ring and the voltage sensors. The gating ring and the voltage sensors are directly connected through these interfaces, which allow membrane voltage to regulate gating of the pore by influencing the Ca sensors.
Average exposure time: 0.3 sec. / Electron dose: 1.4 e/Å2 / Detector mode: SUPER-RESOLUTION / Film or detector model: GATAN K2 SUMMIT (4k x 4k) / Num. of grids imaged: 1 / Num. of real images: 4000
EM imaging optics
Energyfilter name: GIF / Energyfilter upper: 15 eV / Energyfilter lower: -15 eV Spherical aberration corrector: FEI Cs corrector on Titan Krios
Image scans
Sampling size: 5 µm / Width: 7420 / Height: 7676 / Movie frames/image: 50 / Used frames/image: 1-50
Resolution: 3.8 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 60000 / Symmetry type: POINT
Atomic model building
B value: 160 / Protocol: AB INITIO MODEL / Space: RECIPROCAL
Refinement
Resolution: 3.8→147 Å / Cor.coef. Fo:Fc: 0.889 / SU B: 86.753 / SU ML: 1.047 Stereochemistry target values: MAXIMUM LIKELIHOOD WITH PHASES Details: HYDROGENS HAVE BEEN ADDED IN THE RIDING POSITIONS
Rfactor
Num. reflection
% reflection
Rwork
0.3848
-
-
obs
0.3848
26401
100 %
Solvent computation
Ion probe radii: 0.8 Å / Shrinkage radii: 0.8 Å / VDW probe radii: 1.2 Å / Solvent model: MASK