Acetylcholine Receptor Gating at Extracellular Transmembrane Domain Interface: the Cys-Loop and M2–M3 Linker
Acetylcholine receptor channel gating is a propagated conformational cascade that links changes in structure and function at the transmitter binding sites in the extracellular domain (ECD) with those at a “gate” in the transmembrane domain (TMD). We used Φ-value analysis to probe the relative timing...
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The Rockefeller University Press
2007
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| Online Access: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2151658/ |
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pubmed-21516582008-06-01 Acetylcholine Receptor Gating at Extracellular Transmembrane Domain Interface: the Cys-Loop and M2–M3 Linker Jha, Archana Cadugan, David J. Purohit, Prasad Auerbach, Anthony Articles Acetylcholine receptor channel gating is a propagated conformational cascade that links changes in structure and function at the transmitter binding sites in the extracellular domain (ECD) with those at a “gate” in the transmembrane domain (TMD). We used Φ-value analysis to probe the relative timing of the gating motions of α-subunit residues located near the ECD–TMD interface. Mutation of four of the seven amino acids in the M2–M3 linker (which connects the pore-lining M2 helix with the M3 helix), including three of the four residues in the core of the linker, changed the diliganded gating equilibrium constant (Keq) by up to 10,000-fold (P272 > I274 > A270 > G275). The average Φ-value for the whole linker was ∼0.64. One interpretation of this result is that the gating motions of the M2–M3 linker are approximately synchronous with those of much of M2 (∼0.64), but occur after those of the transmitter binding site region (∼0.93) and loops 2 and 7 (∼0.77). We also examined mutants of six cys-loop residues (V132, T133, H134, F135, P136, and F137). Mutation of V132, H134, and F135 changed Keq by 2800-, 10-, and 18-fold, respectively, and with an average Φ-value of 0.74, similar to those of other cys-loop residues. Even though V132 and I274 are close, the energetic coupling between I and V mutants of these positions was small (≤0.51 kcal mol−1). The M2–M3 linker appears to be the key moving part that couples gating motions at the base of the ECD with those in TMD. These interactions are distributed along an ∼16-Å border and involve about a dozen residues. The Rockefeller University Press 2007-12 /pmc/articles/PMC2151658/ /pubmed/18040057 http://dx.doi.org/10.1085/jgp.200709856 Text en Copyright © 2007, The Rockefeller University Press This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/). |
| repository_type |
Open Access Journal |
| institution_category |
Foreign Institution |
| institution |
US National Center for Biotechnology Information |
| building |
NCBI PubMed |
| collection |
Online Access |
| language |
English |
| format |
Online |
| author |
Jha, Archana Cadugan, David J. Purohit, Prasad Auerbach, Anthony |
| spellingShingle |
Jha, Archana Cadugan, David J. Purohit, Prasad Auerbach, Anthony Acetylcholine Receptor Gating at Extracellular Transmembrane Domain Interface: the Cys-Loop and M2–M3 Linker |
| author_facet |
Jha, Archana Cadugan, David J. Purohit, Prasad Auerbach, Anthony |
| author_sort |
Jha, Archana |
| title |
Acetylcholine Receptor Gating at Extracellular Transmembrane Domain Interface: the Cys-Loop and M2–M3 Linker |
| title_short |
Acetylcholine Receptor Gating at Extracellular Transmembrane Domain Interface: the Cys-Loop and M2–M3 Linker |
| title_full |
Acetylcholine Receptor Gating at Extracellular Transmembrane Domain Interface: the Cys-Loop and M2–M3 Linker |
| title_fullStr |
Acetylcholine Receptor Gating at Extracellular Transmembrane Domain Interface: the Cys-Loop and M2–M3 Linker |
| title_full_unstemmed |
Acetylcholine Receptor Gating at Extracellular Transmembrane Domain Interface: the Cys-Loop and M2–M3 Linker |
| title_sort |
acetylcholine receptor gating at extracellular transmembrane domain interface: the cys-loop and m2–m3 linker |
| description |
Acetylcholine receptor channel gating is a propagated conformational cascade that links changes in structure and function at the transmitter binding sites in the extracellular domain (ECD) with those at a “gate” in the transmembrane domain (TMD). We used Φ-value analysis to probe the relative timing of the gating motions of α-subunit residues located near the ECD–TMD interface. Mutation of four of the seven amino acids in the M2–M3 linker (which connects the pore-lining M2 helix with the M3 helix), including three of the four residues in the core of the linker, changed the diliganded gating equilibrium constant (Keq) by up to 10,000-fold (P272 > I274 > A270 > G275). The average Φ-value for the whole linker was ∼0.64. One interpretation of this result is that the gating motions of the M2–M3 linker are approximately synchronous with those of much of M2 (∼0.64), but occur after those of the transmitter binding site region (∼0.93) and loops 2 and 7 (∼0.77). We also examined mutants of six cys-loop residues (V132, T133, H134, F135, P136, and F137). Mutation of V132, H134, and F135 changed Keq by 2800-, 10-, and 18-fold, respectively, and with an average Φ-value of 0.74, similar to those of other cys-loop residues. Even though V132 and I274 are close, the energetic coupling between I and V mutants of these positions was small (≤0.51 kcal mol−1). The M2–M3 linker appears to be the key moving part that couples gating motions at the base of the ECD with those in TMD. These interactions are distributed along an ∼16-Å border and involve about a dozen residues. |
| publisher |
The Rockefeller University Press |
| publishDate |
2007 |
| url |
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2151658/ |
| _version_ |
1611424193789820928 |