Abstract
In plants, hyperosmolality stimuli triggers opening of the osmosensitive channels, leading to a rapid downstream signaling cascade initiated by cytosolic calcium concentration elevation. Members of the OSCA family in Arabidopsis thaliana, identified as the hyperosmolality-gated calcium-permeable channels, have been suggested to play a key role during the initial phase of hyperosmotic stress response. Here, we report the atomic structure of Arabidopsis OSCA1.2 determined by single-particle cryo-electron microscopy. It contains 11 transmembrane helices and forms a homodimer. It is in an inactivated state, and the pore-lining residues are clearly identified. Its cytosolic domain contains a RNA recognition motif and two unique long helices. The linker between these two helices forms an anchor in the lipid bilayer and may be essential to osmosensing. The structure of AtOSCA1.2 serves as a platform for the study of the mechanism underlying osmotic stress responses and mechanosensing.
Highlights
In plants, hyperosmolality stimuli triggers opening of the osmosensitive channels, leading to a rapid downstream signaling cascade initiated by cytosolic calcium concentration elevation
Via genetic screens and functional analysis, the osmosensitive Ca2+ permeable cation channel proteins were identified in Arabidopsis by two independent groups, which was named CSC1 and OSCA1, respectively[17,24]
We present the structure of OSCA1.2 from Arabidopsis thaliana (AtOSCA1.2) determined by single-particle cryo-electron microscopy with a nominal resolution of 3.68 Å for the overall structure
Summary
Hyperosmolality stimuli triggers opening of the osmosensitive channels, leading to a rapid downstream signaling cascade initiated by cytosolic calcium concentration elevation. Members of the OSCA family in Arabidopsis thaliana, identified as the hyperosmolality-gated calcium-permeable channels, have been suggested to play a key role during the initial phase of hyperosmotic stress response. We report the atomic structure of Arabidopsis OSCA1.2 determined by single-particle cryo-electron microscopy It contains 11 transmembrane helices and forms a homodimer. We present the structure of OSCA1.2 from Arabidopsis thaliana (AtOSCA1.2) determined by single-particle cryo-electron microscopy (cryo-EM) with a nominal resolution of 3.68 Å for the overall structure. This structure serves as a framework for understanding OSCA-mediated osmosensing and calcium flux in plants at a molecular level
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