Inhibition of the proton-activated chloride channel PAC by PIP2
- Johns Hopkins Medicine, United States
- Van Andel Institute, United States
Abstract
Proton-Activated Chloride (PAC) channel is a ubiquitously expressed pH-sensing ion channel, encoded by PACC1 (TMEM206). PAC regulates endosomal acidification and macropinosome shrinkage by releasing chloride from the organelle lumens. It is also found at the cell surface, where it is activated under pathological conditions related to acidosis and contributes to acid-induced cell death. However, the pharmacology of the PAC channel is poorly understood. Here, we report that phosphatidylinositol (4,5)-bisphosphate (PIP2) potently inhibits PAC channel activity. We solved the cryo-electron microscopy structure of PAC with PIP2 at pH 4.0 and identified its putative binding site, which, surprisingly, locates on the extracellular side of the transmembrane domain (TMD). While the overall conformation resembles the previously resolved PAC structure in the desensitized state, the TMD undergoes remodeling upon PIP2-binding. Structural and electrophysiological analyses suggest that PIP2 inhibits the PAC channel by stabilizing the channel in a desensitized-like conformation. Our findings identify PIP2 as a new pharmacological tool for the PAC channel and lay the foundation for future drug discovery targeting this channel.
Data availability
The cryo-EM density map and atomic models have been deposited in the EMDB (Electron Microscopy Data Bank) and the Research Collaboratory for Structural Bioinformatics Protein Data Bank (RCS-PDB), respectively, under accession numbers EMD-28535 and PDB 8EQ4.
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Cryo-EM structure of PAC channel with PIP2Electron Microscopy Data Bank, EMD-28535.
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Cryo-EM structure of PAC channel with PIP2Electron Microscopy Data Bank, EMD-28964.
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Cryo-EM structure of PAC channel with PIP2Protein Data Bank, 8EQ4.
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Cryo-EM structure of PAC channel with PIP2Protein Data Bank,8FBL.
Article and author information
Author details
Funding
Boehringer Ingelheim Fonds (Graduate Student Fellowship)
- Ljubica Mihaljevic
National Institutes of Health (grant R35GM124824)
- Zhaozhu Qiu
National Institutes of Health (grant R01NS118014)
- Zhaozhu Qiu
National Institute of General Medical Sciences (T32 GM007445 Graduate Training Program)
- Ljubica Mihaljevic
American Heart Association (Postdoctoral Fellowship grant 20POST35120556)
- Zheng Ruan
National Institutes of Health (grant K99NS128258)
- Zheng Ruan
American Heart Association (Predoctoral Fellowship grant 18PRE34060025)
- James Osei-Owusu
National Institutes of Health (grant R01NS112363)
- Wei Lü
McKnight Foundation (McKnight Scholar Award)
- Zhaozhu Qiu
Alfred P. Sloan Foundation (Sloan Research Fellowship)
- Zhaozhu Qiu
Esther A. and Joseph Klingenstein Fund (Klingenstein-Simons Fellowship)
- Zhaozhu Qiu
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2023, Mihaljevic et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Inhibition of the proton-activated chloride channel PAC by PIP2
eLife 12:e83935.
https://doi.org/10.7554/eLife.83935
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