Abstract
Serotonin (or 5-hydroxytryptamine, 5-HT) is an important neurotransmitter that activates 12 different G protein-coupled receptors (GPCRs) through selective coupling of Gs, Gi, or Gq proteins. The structural basis for G protein subtype selectivity by these GPCRs remains elusive. Here, we report the structures of the serotonin receptors 5-HT4, 5-HT6, and 5-HT7 with Gs, and 5-HT4 with Gi1. The structures reveal that transmembrane helices TM5 and TM6 alternate lengths as a macro-switch to determine receptor's selectivity for Gs and Gi, respectively. We find that the macro-switch by the TM5-TM6 length is shared by class A GPCR-G protein structures. Furthermore, we discover specific residues within TM5 and TM6 that function as micro-switches to form specific interactions with Gs or Gi. Together, these results present a common mechanism of Gs versus Gi protein coupling selectivity or promiscuity by class A GPCRs and extend the basis of ligand recognition at serotonin receptors.
Original language | English |
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Pages (from-to) | 2681-2695.e6 |
Number of pages | 22 |
Journal | Molecular cell |
Volume | 82 |
Issue number | 14 |
Early online date | 16 Jun 2022 |
DOIs | |
Publication status | Published - 21 Jul 2022 |
Bibliographical note
Funding Information:The cryo-EM data were collected at the Center of Cryo-Electron Microscopy, Shanghai Institute of Materia Medica, and at the Center of Cryo-Electron Microscopy, Zhejiang University. Cryo-EM data collection for the 5-HT 4 -G s complex was carried out at Shuimu BioSciences Ltd. The authors thank all staff at Shuimu BioSciences Ltd. for their technical support. This work was partially supported by the National Key R&D Programs of China ( 2018YFA0507002 ), the Shanghai Municipal Science and Technology Major Project ( 2019SHZDZX02 ), the CAS Strategic Priority Research Program ( XDB37030103 ) to H.E.X.; the National Key Basic Research Program of China ( 2019YFA0508800 ), the National Natural Science Foundation of China ( 81922071 ), the Zhejiang Province Natural Science Fund for Excellent Young Scholars ( LR19H310001 ), Key R & D Projects of Zhejiang Province ( 2021C03039 ) to Y.Z.; the National Natural Science Foundation of China ( 31770796 ) and National Science and Technology Major Project ( 2018ZX09711002-002-002 ) to Y.J.; the EU Horizon 2020, Innovative Training Network SAFER ( 765657 ) to I.A.S.; the Lundbeck Foundation ( R163-2013-16327 ) and Novo Nordisk Foundation ( NNF18OC0031226 ) to D.E.G. and K.H. We thank Albert J. Kooistra and Gáspár Pándy-Szekeres for structure annotation, and Henrik Daver for scripts to calculate G protein insertion angles. Cartoons in graphical abstract, Figure 1 A, and Figure 6L were created with BioRender.com .
Publisher Copyright:
© 2022 Elsevier Inc.
Funding
The cryo-EM data were collected at the Center of Cryo-Electron Microscopy, Shanghai Institute of Materia Medica, and at the Center of Cryo-Electron Microscopy, Zhejiang University. Cryo-EM data collection for the 5-HT 4 -G s complex was carried out at Shuimu BioSciences Ltd. The authors thank all staff at Shuimu BioSciences Ltd. for their technical support. This work was partially supported by the National Key R&D Programs of China ( 2018YFA0507002 ), the Shanghai Municipal Science and Technology Major Project ( 2019SHZDZX02 ), the CAS Strategic Priority Research Program ( XDB37030103 ) to H.E.X.; the National Key Basic Research Program of China ( 2019YFA0508800 ), the National Natural Science Foundation of China ( 81922071 ), the Zhejiang Province Natural Science Fund for Excellent Young Scholars ( LR19H310001 ), Key R & D Projects of Zhejiang Province ( 2021C03039 ) to Y.Z.; the National Natural Science Foundation of China ( 31770796 ) and National Science and Technology Major Project ( 2018ZX09711002-002-002 ) to Y.J.; the EU Horizon 2020, Innovative Training Network SAFER ( 765657 ) to I.A.S.; the Lundbeck Foundation ( R163-2013-16327 ) and Novo Nordisk Foundation ( NNF18OC0031226 ) to D.E.G. and K.H. We thank Albert J. Kooistra and Gáspár Pándy-Szekeres for structure annotation, and Henrik Daver for scripts to calculate G protein insertion angles. Cartoons in graphical abstract, Figure 1 A, and Figure 6L were created with BioRender.com .
Funders | Funder number |
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Key R & D Projects of Zhejiang Province | 2021C03039, 31770796 |
Zhejiang Province Natural Science Fund for Excellent Young Scholars | LR19H310001 |
National Natural Science Foundation of China | 81922071 |
National Natural Science Foundation of China | |
Chinese Academy of Sciences | XDB37030103 |
Chinese Academy of Sciences | |
Science and Technology Commission of Shanghai Municipality | 2019SHZDZX02 |
Science and Technology Commission of Shanghai Municipality | |
Lundbeckfonden | R163-2013-16327 |
Lundbeckfonden | |
Horizon 2020 | 765657 |
Horizon 2020 | |
Novo Nordisk Fonden | NNF18OC0031226 |
Novo Nordisk Fonden | |
National Key Research and Development Program of China | 2018YFA0507002, 2019YFA0508800 |
National Key Research and Development Program of China | |
National Major Science and Technology Projects of China | 2018ZX09711002-002-002 |
National Major Science and Technology Projects of China |
Keywords
- 5-HT
- 5-HT receptor
- cryo-EM structure
- G protein selectivity
- GPCR
- ligand selectivity
- serotonin receptor
- signaling complex