Mechanosensitive channel YnaI has lipid-bound extended sensor paddles
Wenxin Hu1, Zhiming Wang1, Hongjin Zheng2
1Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, School of Medicine, Aurora, USA.
Communications Biology
|May 21, 2021
Summary
Researchers studied the structure of YnaI, a bacterial mechanosensitive channel (MS) homolog. The findings highlight the crucial role of pocket lipids in the function of these essential membrane proteins.
Area of Science:
- Structural Biology
- Biophysics
- Microbiology
Background:
- Bacterial mechanosensitive channels (MS) are crucial for cell survival under osmotic stress.
- Studies on MscS from Escherichia coli (E. coli) have elucidated general MS channel mechanisms.
- Controversies exist regarding the role of lipids in MscS channel gating, necessitating studies on homologs.
Purpose of the Study:
- To determine the structure of YnaI, a close homolog of MscS in E. coli.
- To investigate the role of lipids in the function of bacterial mechanosensitive channels.
- To provide insights into the gating mechanism of MscS-like channels.
Main Methods:
- Cryo-electron microscopy (cryo-EM) at 3.3 Å resolution.
- Structural analysis of the YnaI channel in its non-conducting state.
- Biochemical experiments and mutagenesis studies.
Main Results:
- The structure of YnaI revealed an intact membrane sensor paddle domain stabilized by key residues (H43, Q46, Y50, K93).
- Lipid densities were observed in pockets between sensor paddles, interacting with residues Q100 and R120.
- These lipids, potentially enriched in cardiolipin and phosphatidylserine, are suggested to be functionally important.
Conclusions:
- The structure of YnaI provides a high-resolution view of a bacterial mechanosensitive channel homolog.
- Pocket lipids interacting with specific residues are proposed to be functionally critical for channel gating.
- This study supports the importance of membrane lipids in the regulation of mechanosensitive channel activity.
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