Molecular basis of force-from-lipids gating in the mechanosensitive channel MscS

  1. Bharat Reddy
  2. Navid Bavi
  3. Allen Lu
  4. Yeonwoo Park
  5. Eduardo Perozo  Is a corresponding author
  1. The University of Chicago, United States

Abstract

Prokaryotic mechanosensitive (MS) channels open by sensing the physical state of the membrane. As such, lipid-protein interactions represent the defining molecular process underlying mechanotransduction. Here, we describe cryo-electron microscopy (cryo-EM) structures of the E. coli small-conductance mechanosensitive channel (MscS) in nanodiscs (ND). They reveal a novel membrane-anchoring fold that plays a significant role in channel activation and establish a new location for the lipid bilayer, shifted ~14 Å from previous consensus placements. Two types of lipid densities are explicitly observed. A phospholipid that 'hooks' the top of each TM2-TM3 hairpin and likely plays a role in force sensing, and a bundle of acyl chains occluding the permeation path above the L105 cuff. These observations reshape our understanding of force-from-lipids gating in MscS and highlight the key role of allosteric interactions between TM segments and phospholipids bound to key dynamic components of the channel.

Data availability

EM maps and atomic models have been deposited at the Electron Microscopy Data Bank (accession numbers EMD-20508, EMD-20510, EMD-20509, and EMD-20148) and the Protein Data Back (entry codes 6PWN, 6PWP and 6PWO).

The following data sets were generated
    1. Reddy BG
    2. Perozo E
    (2019) MscS Nanodisc
    Electron Microscopy Data Bank, EMD-20510.
    1. Reddy BG
    2. Perozo E
    (2019) MscS DDM
    Electron Microscopy Data Bank, EMD-20509.

Article and author information

Author details

  1. Bharat Reddy

    Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Navid Bavi

    Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Allen Lu

    Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, United States
    Competing interests
    The authors declare that no competing interests exist.
  4. Yeonwoo Park

    Department of Ecology and Evolution, The University of Chicago, Chicago, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Eduardo Perozo

    Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, United States
    For correspondence
    eperozo@uchicago.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-7132-2793

Funding

National Institute of General Medical Sciences (R01GM131191)

  • Eduardo Perozo

National Institute of General Medical Sciences (U54GM087519)

  • Eduardo Perozo

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

© 2019, Reddy 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.

Metrics

  • 5,514
    views
  • 949
    downloads
  • 100
    citations

Views, downloads and citations are aggregated across all versions of this paper published by eLife.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Bharat Reddy
  2. Navid Bavi
  3. Allen Lu
  4. Yeonwoo Park
  5. Eduardo Perozo
(2019)
Molecular basis of force-from-lipids gating in the mechanosensitive channel MscS
eLife 8:e50486.
https://doi.org/10.7554/eLife.50486

Share this article

https://doi.org/10.7554/eLife.50486

Further reading

    1. Biochemistry and Chemical Biology
    2. Structural Biology and Molecular Biophysics
    Assmaa Elsheikh, Camden M Driggers ... Show-Ling Shyng
    Research Article

    Pancreatic KATP channel trafficking defects underlie congenital hyperinsulinism (CHI) cases unresponsive to the KATP channel opener diazoxide, the mainstay medical therapy for CHI. Current clinically used KATP channel inhibitors have been shown to act as pharmacochaperones and restore surface expression of trafficking mutants; however, their therapeutic utility for KATP trafficking-impaired CHI is hindered by high affinity binding, which limits functional recovery of rescued channels. Recent structural studies of KATP channels employing cryo-electron microscopy (cryoEM) have revealed a promiscuous pocket where several known KATP pharmacochaperones bind. The structural knowledge provides a framework for discovering KATP channel pharmacochaperones with desired reversible inhibitory effects to permit functional recovery of rescued channels. Using an AI-based virtual screening technology AtomNet followed by functional validation, we identified a novel compound, termed Aekatperone, which exhibits chaperoning effects on KATP channel trafficking mutations. Aekatperone reversibly inhibits KATP channel activity with a half-maximal inhibitory concentration (IC50) ~9 μM. Mutant channels rescued to the cell surface by Aekatperone showed functional recovery upon washout of the compound. CryoEM structure of KATP bound to Aekatperone revealed distinct binding features compared to known high affinity inhibitor pharmacochaperones. Our findings unveil a KATP pharmacochaperone enabling functional recovery of rescued channels as a promising therapeutic for CHI caused by KATP trafficking defects.

    1. Biochemistry and Chemical Biology
    2. Structural Biology and Molecular Biophysics
    Andrew P Latham, Longchen Zhu ... Bin Zhang
    Research Article

    The phase separation of intrinsically disordered proteins is emerging as an important mechanism for cellular organization. However, efforts to connect protein sequences to the physical properties of condensates, that is, the molecular grammar, are hampered by a lack of effective approaches for probing high-resolution structural details. Using a combination of multiscale simulations and fluorescence lifetime imaging microscopy experiments, we systematically explored a series of systems consisting of diblock elastin-like polypeptides (ELPs). The simulations succeeded in reproducing the variation of condensate stability upon amino acid substitution and revealed different microenvironments within a single condensate, which we verified with environmentally sensitive fluorophores. The interspersion of hydrophilic and hydrophobic residues and a lack of secondary structure formation result in an interfacial environment, which explains both the strong correlation between ELP condensate stability and interfacial hydrophobicity scales, as well as the prevalence of protein-water hydrogen bonds. Our study uncovers new mechanisms for condensate stability and organization that may be broadly applicable.