A Steric “Ball-and-Chain” Mechanism for pH-Mediated Regulation of Gap Junction Channels
Summary: Gap junction channels (GJCs) mediate intercellular communication and are gated by numerous conditions such as pH. The electron cryomicroscopy (cryo-EM) structure of Cx26 GJC at physiological pH recapitulates previous GJC structures in lipid bilayers. At pH 6.4, we identify two conformationa...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2020-04-01
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| Series: | Cell Reports |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2211124720303600 |
| _version_ | 1819099716484333568 |
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| author | Ali K. Khan Maciej Jagielnicki William E. McIntire Michael D. Purdy Venkatasubramanian Dharmarajan Patrick R. Griffin Mark Yeager |
| author_facet | Ali K. Khan Maciej Jagielnicki William E. McIntire Michael D. Purdy Venkatasubramanian Dharmarajan Patrick R. Griffin Mark Yeager |
| author_sort | Ali K. Khan |
| collection | DOAJ |
| description | Summary: Gap junction channels (GJCs) mediate intercellular communication and are gated by numerous conditions such as pH. The electron cryomicroscopy (cryo-EM) structure of Cx26 GJC at physiological pH recapitulates previous GJC structures in lipid bilayers. At pH 6.4, we identify two conformational states, one resembling the open physiological-pH structure and a closed conformation that displays six threads of density, that join to form a pore-occluding density. Crosslinking and hydrogen-deuterium exchange mass spectrometry reveal closer association between the N-terminal (NT) domains and the cytoplasmic loops (CL) at acidic pH. Previous electrophysiologic studies suggest an association between NT residue N14 and H100 near M2, which may trigger the observed movement of M2 toward M1 in our cryo-EM maps, thereby accounting for additional NT-CL crosslinks at acidic pH. We propose that these pH-induced interactions and conformational changes result in extension, ordering, and association of the acetylated NT domains to form a hexameric “ball-and-chain” gating particle. : During tissue injury, acidic pH blocks gap junction channel intercellular communication. Khan et al. use cryo-EM and mass spectrometry to show that acidification causes extension, ordering, and association of the N-terminal domains to form a hexameric gating particle that sterically occludes the human Cx26 gap junction channel pore. Keywords: connexins, gap junction channels, pH gating, cryo-EM, mass spectrometry, hydrogen deuterium exchange, crosslinking, membrane proteins, protein structure, conformational changes |
| first_indexed | 2024-12-22T00:51:18Z |
| format | Article |
| id | doaj.art-d163253f30b04e81a04f624ad4d3420b |
| institution | Directory Open Access Journal |
| issn | 2211-1247 |
| language | English |
| last_indexed | 2024-12-22T00:51:18Z |
| publishDate | 2020-04-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Cell Reports |
| spelling | doaj.art-d163253f30b04e81a04f624ad4d3420b2022-12-21T18:44:25ZengElsevierCell Reports2211-12472020-04-01313A Steric “Ball-and-Chain” Mechanism for pH-Mediated Regulation of Gap Junction ChannelsAli K. Khan0Maciej Jagielnicki1William E. McIntire2Michael D. Purdy3Venkatasubramanian Dharmarajan4Patrick R. Griffin5Mark Yeager6Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USADepartment of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USADepartment of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USADepartment of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USADepartment of Molecular Medicine, The Scripps Research Institute, Scripps Florida, Jupiter, FL 33458, USADepartment of Molecular Medicine, The Scripps Research Institute, Scripps Florida, Jupiter, FL 33458, USADepartment of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Department of Medicine, Division of Cardiovascular Medicine, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Corresponding authorSummary: Gap junction channels (GJCs) mediate intercellular communication and are gated by numerous conditions such as pH. The electron cryomicroscopy (cryo-EM) structure of Cx26 GJC at physiological pH recapitulates previous GJC structures in lipid bilayers. At pH 6.4, we identify two conformational states, one resembling the open physiological-pH structure and a closed conformation that displays six threads of density, that join to form a pore-occluding density. Crosslinking and hydrogen-deuterium exchange mass spectrometry reveal closer association between the N-terminal (NT) domains and the cytoplasmic loops (CL) at acidic pH. Previous electrophysiologic studies suggest an association between NT residue N14 and H100 near M2, which may trigger the observed movement of M2 toward M1 in our cryo-EM maps, thereby accounting for additional NT-CL crosslinks at acidic pH. We propose that these pH-induced interactions and conformational changes result in extension, ordering, and association of the acetylated NT domains to form a hexameric “ball-and-chain” gating particle. : During tissue injury, acidic pH blocks gap junction channel intercellular communication. Khan et al. use cryo-EM and mass spectrometry to show that acidification causes extension, ordering, and association of the N-terminal domains to form a hexameric gating particle that sterically occludes the human Cx26 gap junction channel pore. Keywords: connexins, gap junction channels, pH gating, cryo-EM, mass spectrometry, hydrogen deuterium exchange, crosslinking, membrane proteins, protein structure, conformational changeshttp://www.sciencedirect.com/science/article/pii/S2211124720303600 |
| spellingShingle | Ali K. Khan Maciej Jagielnicki William E. McIntire Michael D. Purdy Venkatasubramanian Dharmarajan Patrick R. Griffin Mark Yeager A Steric “Ball-and-Chain” Mechanism for pH-Mediated Regulation of Gap Junction Channels Cell Reports |
| title | A Steric “Ball-and-Chain” Mechanism for pH-Mediated Regulation of Gap Junction Channels |
| title_full | A Steric “Ball-and-Chain” Mechanism for pH-Mediated Regulation of Gap Junction Channels |
| title_fullStr | A Steric “Ball-and-Chain” Mechanism for pH-Mediated Regulation of Gap Junction Channels |
| title_full_unstemmed | A Steric “Ball-and-Chain” Mechanism for pH-Mediated Regulation of Gap Junction Channels |
| title_short | A Steric “Ball-and-Chain” Mechanism for pH-Mediated Regulation of Gap Junction Channels |
| title_sort | steric ball and chain mechanism for ph mediated regulation of gap junction channels |
| url | http://www.sciencedirect.com/science/article/pii/S2211124720303600 |
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