Journal: Nat Struct Mol Biol / Year: 2018 Title: Structure of the mechanosensitive OSCA channels. Authors: Mingfeng Zhang / Dali Wang / Yunlu Kang / Jing-Xiang Wu / Fuqiang Yao / Chengfang Pan / Zhiqiang Yan / Chen Song / Lei Chen / Abstract: Mechanosensitive ion channels convert mechanical stimuli into a flow of ions. These channels are widely distributed from bacteria to higher plants and humans, and are involved in many crucial ...Mechanosensitive ion channels convert mechanical stimuli into a flow of ions. These channels are widely distributed from bacteria to higher plants and humans, and are involved in many crucial physiological processes. Here we show that two members of the OSCA protein family in Arabidopsis thaliana, namely AtOSCA1.1 and AtOSCA3.1, belong to a new class of mechanosensitive ion channels. We solve the structure of the AtOSCA1.1 channel at 3.5-Å resolution and AtOSCA3.1 at 4.8-Å resolution by cryo-electron microscopy. OSCA channels are symmetric dimers that are mediated by cytosolic inter-subunit interactions. Strikingly, they have structural similarity to the mammalian TMEM16 family proteins. Our structural analysis accompanied with electrophysiological studies identifies the ion permeation pathway within each subunit and suggests a conformational change model for activation.
History
Deposition
Dec 26, 2017
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Header (metadata) release
Sep 12, 2018
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Map release
Sep 12, 2018
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Update
Mar 27, 2024
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Current status
Mar 27, 2024
Processing site: PDBj / Status: Released
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Structure visualization
Movie
Surface view with section colored by density value
Film or detector model: GATAN K2 QUANTUM (4k x 4k) / Detector mode: COUNTING / Average electron dose: 50.0 e/Å2
Electron beam
Acceleration voltage: 300 kV / Electron source: FIELD EMISSION GUN
Electron optics
C2 aperture diameter: 100.0 µm / Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD / Cs: 2.7 mm
Experimental equipment
Model: Titan Krios / Image courtesy: FEI Company
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Image processing
Startup model
Type of model: OTHER Details: stochastic gradient descent (SGD) and branch-and-bound maximum likelihood optimization algorithms in cryosparc
Final reconstruction
Applied symmetry - Point group: C2 (2 fold cyclic) / Resolution.type: BY AUTHOR / Resolution: 4.8 Å / Resolution method: FSC 0.143 CUT-OFF / Software - Name: RELION / Number images used: 16322
Initial angle assignment
Type: OTHER / Software - Name: RELION / Details: maximum likely hood in relion
Final angle assignment
Type: OTHER / Software - Name: RELION Details: stochastic gradient descent (SGD) and branch-and-bound maximum likelihood optimization algorithms in cryosparc
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