Structure of the mechanosensitive OSCA channels
Mingfeng Zhang1,2,3, Dali Wang4, Yunlu Kang1
1State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, Peking University, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Beijing, China.
Nature Structural & Molecular Biology
|September 8, 2018
Summary
Two mechanosensitive ion channels, AtOSCA1.1 and AtOSCA3.1, from Arabidopsis thaliana represent a new class of channels. Structural and electrophysiological studies reveal their dimeric nature and ion pathway, suggesting an activation mechanism.
Area of Science:
- Plant Biology
- Molecular Biology
- Biophysics
Background:
- Mechanosensitive ion channels are vital cellular components that transduce mechanical forces into electrical signals.
- These channels are essential for numerous physiological processes across diverse organisms, including plants and humans.
Purpose of the Study:
- To characterize the structure and function of two Arabidopsis thaliana OSCA family proteins, AtOSCA1.1 and AtOSCA3.1.
- To determine if these proteins represent a novel class of mechanosensitive ion channels.
Main Methods:
- Cryo-electron microscopy was used to solve the structures of AtOSCA1.1 and AtOSCA3.1 at high resolution.
- Electrophysiological studies were performed to investigate channel activity and ion permeation.
Main Results:
- AtOSCA1.1 and AtOSCA3.1 were identified as a new class of mechanosensitive ion channels.
- The cryo-EM structures revealed symmetric dimeric assemblies with cytosolic inter-subunit interactions.
- Structural similarity was observed between OSCA channels and mammalian TMEM16 family proteins.
- The ion permeation pathway was identified within each subunit, and a model for conformational changes during activation was proposed.
Conclusions:
- OSCA proteins form a distinct class of mechanosensitive ion channels with unique structural features.
- The findings provide insights into the molecular mechanisms underlying mechanotransduction in plants.
- The structural similarity to TMEM16 proteins suggests potential conserved functions or evolutionary relationships.
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