Dissecting the mechanism of atlastin-mediated homotypic membrane fusion at the single-molecule level
Abstract Homotypic membrane fusion of the endoplasmic reticulum (ER) is mediated by dynamin-like GTPase atlastin (ATL). This fundamental process relies on GTP-dependent domain rearrangements in the N-terminal region of ATL (ATLcyto), including the GTPase domain and three-helix bundle (3HB). However,...
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| Format: | Article |
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Nature Portfolio
2024-03-01
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| Series: | Nature Communications |
| Online Access: | https://doi.org/10.1038/s41467-024-46919-z |
| _version_ | 1797247182757167104 |
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| author | Lijun Shi Chenguang Yang Mingyuan Zhang Kangning Li Keying Wang Li Jiao Ruming Liu Yunyun Wang Ming Li Yong Wang Lu Ma Shuxin Hu Xin Bian |
| author_facet | Lijun Shi Chenguang Yang Mingyuan Zhang Kangning Li Keying Wang Li Jiao Ruming Liu Yunyun Wang Ming Li Yong Wang Lu Ma Shuxin Hu Xin Bian |
| author_sort | Lijun Shi |
| collection | DOAJ |
| description | Abstract Homotypic membrane fusion of the endoplasmic reticulum (ER) is mediated by dynamin-like GTPase atlastin (ATL). This fundamental process relies on GTP-dependent domain rearrangements in the N-terminal region of ATL (ATLcyto), including the GTPase domain and three-helix bundle (3HB). However, its conformational dynamics during the GTPase cycle remain elusive. Here, we combine single-molecule FRET imaging and molecular dynamics simulations to address this conundrum. Different from the prevailing model, ATLcyto can form a loose crossover dimer upon GTP binding, which is tightened by GTP hydrolysis for membrane fusion. Furthermore, the α-helical motif between the 3HB and transmembrane domain, which is embedded in the surface of the lipid bilayer and self-associates in the crossover dimer, is required for ATL function. To recycle the proteins, Pi release, which disassembles the dimer, activates frequent relative movements between the GTPase domain and 3HB, and subsequent GDP dissociation alters the conformational preference of the ATLcyto monomer for entering the next reaction cycle. Finally, we found that two disease-causing mutations affect human ATL1 activity by destabilizing GTP binding-induced loose crossover dimer formation and the membrane-embedded helix, respectively. These results provide insights into ATL-mediated homotypic membrane fusion and the pathological mechanisms of related disease. |
| first_indexed | 2024-04-24T19:54:38Z |
| format | Article |
| id | doaj.art-278fc88fd06549c8ae6a71cf245b20bd |
| institution | Directory Open Access Journal |
| issn | 2041-1723 |
| language | English |
| last_indexed | 2024-04-24T19:54:38Z |
| publishDate | 2024-03-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Nature Communications |
| spelling | doaj.art-278fc88fd06549c8ae6a71cf245b20bd2024-03-24T12:25:04ZengNature PortfolioNature Communications2041-17232024-03-0115111410.1038/s41467-024-46919-zDissecting the mechanism of atlastin-mediated homotypic membrane fusion at the single-molecule levelLijun Shi0Chenguang Yang1Mingyuan Zhang2Kangning Li3Keying Wang4Li Jiao5Ruming Liu6Yunyun Wang7Ming Li8Yong Wang9Lu Ma10Shuxin Hu11Xin Bian12State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Frontiers Science Center for Cell Responses, Nankai UniversityNational Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of SciencesCollege of Life Sciences, Zhejiang UniversityState Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Frontiers Science Center for Cell Responses, Nankai UniversityCollege of Life Sciences, Zhejiang UniversityCollege of Life Sciences, Nankai UniversityCollege of Life Sciences, Nankai UniversityState Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Frontiers Science Center for Cell Responses, Nankai UniversityNational Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of SciencesCollege of Life Sciences, Zhejiang UniversityNational Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of SciencesNational Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of SciencesState Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Frontiers Science Center for Cell Responses, Nankai UniversityAbstract Homotypic membrane fusion of the endoplasmic reticulum (ER) is mediated by dynamin-like GTPase atlastin (ATL). This fundamental process relies on GTP-dependent domain rearrangements in the N-terminal region of ATL (ATLcyto), including the GTPase domain and three-helix bundle (3HB). However, its conformational dynamics during the GTPase cycle remain elusive. Here, we combine single-molecule FRET imaging and molecular dynamics simulations to address this conundrum. Different from the prevailing model, ATLcyto can form a loose crossover dimer upon GTP binding, which is tightened by GTP hydrolysis for membrane fusion. Furthermore, the α-helical motif between the 3HB and transmembrane domain, which is embedded in the surface of the lipid bilayer and self-associates in the crossover dimer, is required for ATL function. To recycle the proteins, Pi release, which disassembles the dimer, activates frequent relative movements between the GTPase domain and 3HB, and subsequent GDP dissociation alters the conformational preference of the ATLcyto monomer for entering the next reaction cycle. Finally, we found that two disease-causing mutations affect human ATL1 activity by destabilizing GTP binding-induced loose crossover dimer formation and the membrane-embedded helix, respectively. These results provide insights into ATL-mediated homotypic membrane fusion and the pathological mechanisms of related disease.https://doi.org/10.1038/s41467-024-46919-z |
| spellingShingle | Lijun Shi Chenguang Yang Mingyuan Zhang Kangning Li Keying Wang Li Jiao Ruming Liu Yunyun Wang Ming Li Yong Wang Lu Ma Shuxin Hu Xin Bian Dissecting the mechanism of atlastin-mediated homotypic membrane fusion at the single-molecule level Nature Communications |
| title | Dissecting the mechanism of atlastin-mediated homotypic membrane fusion at the single-molecule level |
| title_full | Dissecting the mechanism of atlastin-mediated homotypic membrane fusion at the single-molecule level |
| title_fullStr | Dissecting the mechanism of atlastin-mediated homotypic membrane fusion at the single-molecule level |
| title_full_unstemmed | Dissecting the mechanism of atlastin-mediated homotypic membrane fusion at the single-molecule level |
| title_short | Dissecting the mechanism of atlastin-mediated homotypic membrane fusion at the single-molecule level |
| title_sort | dissecting the mechanism of atlastin mediated homotypic membrane fusion at the single molecule level |
| url | https://doi.org/10.1038/s41467-024-46919-z |
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