Cryo-EM structure of the rhodopsin-Gαi-βγ complex reveals binding of the rhodopsin C-terminal tail to the Gβ subunit
- Paul Scherrer Institute, Switzerland
- University of Basel, Switzerland
- Hoffmann-La Roche Ltd, Switzerland
Abstract
One of the largest membrane protein families in eukaryotes are G protein-coupled receptors (GPCRs). GPCRs modulate cell physiology by activating diverse intracellular transducers, prominently heterotrimeric G proteins. The recent surge in structural data has expanded our understanding of GPCR-mediated signal transduction. However, many aspects, including the existence of transient interactions, remain elusive. We present the cryo-EM structure of the light-sensitive GPCR rhodopsin in complex with heterotrimeric Gi. Our density map reveals the receptor C-terminal tail bound to the Gβ subunit of the G protein, providing a structural foundation for the role of the C-terminal tail in GPCR signaling, and of Gβ as scaffold for recruiting Gα subunits and G protein-receptor kinases. By comparing available complexes, we found a small set of common anchoring points that are G protein-subtype specific. Taken together, our structure and analysis provide new structural basis for the molecular events of the GPCR signaling pathway.
Data availability
The cryo-EM density map of the rhodopsin-Gi complex bound to Fab16 has been deposited in the EM Data Bank (accession code EMD-4598), and the related structure coordinates have been deposited in the Protein Data Bank (accession code 6QNO). The crystal structure of Fab16 has been deposited in the Protein Data Bank (accession code 6QNK). Source data for Figure 3 is provided in Suppl. Table 3.
-
Rhodopsin-Gi protein complexElectron Microscopy Data Bank, EMD-4598.
-
Antibody FAB fragment targeting Gi protein heterotrimerProtein Data Bank, 6QNK.
-
Crystal structure of the rhodopsin-mini-Go complexProtein Data Bank, 6FUF.
Article and author information
Author details
Nicholas MI Taylor
Funding
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (310030_153145)
- Gebhard Schertler
Swiss Nanoscience Institute (A13.12 NanoGhip)
- Gebhard Schertler
National Centres of Competence in Research (TransCure)
- Henning Stahlberg
Holcim Stiftung
- Jacopo Marino
ETH Zurich
- Tilman Flock
University of Cambridge
- Tilman Flock
Roche
- Shoji Maeda
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (160805)
- Xavier Deupi
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (310030B_173335)
- Gebhard Schertler
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2019, Tsai 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
-
- 5,288
- views
-
- 906
- downloads
-
- 59
- 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)
Cryo-EM structure of the rhodopsin-Gαi-βγ complex reveals binding of the rhodopsin C-terminal tail to the Gβ subunit
eLife 8:e46041.
https://doi.org/10.7554/eLife.46041
Further reading
-
- Biochemistry and Chemical Biology
- Structural Biology and Molecular Biophysics
African trypanosomes are the causative agents of neglected tropical diseases affecting both humans and livestock. Disease control is highly challenging due to an increasing number of drug treatment failures. African trypanosomes are extracellular, blood-borne parasites that mainly rely on glycolysis for their energy metabolism within the mammalian host. Trypanosomal glycolytic enzymes are therefore of interest for the development of trypanocidal drugs. Here, we report the serendipitous discovery of a camelid single-domain antibody (sdAb aka Nanobody) that selectively inhibits the enzymatic activity of trypanosomatid (but not host) pyruvate kinases through an allosteric mechanism. By combining enzyme kinetics, biophysics, structural biology, and transgenic parasite survival assays, we provide a proof-of-principle that the sdAb-mediated enzyme inhibition negatively impacts parasite fitness and growth.
-
- Biochemistry and Chemical Biology
N 6,2’-O-dimethyladenosine (m6Am) is a modified nucleotide located at the first transcribed position in mRNA and snRNA that is essential for diverse physiological processes. m6Am mapping methods assume each gene uses a single start nucleotide. However, gene transcription usually involves multiple start sites, generating numerous 5’ isoforms. Thus, gene-level annotations cannot capture the diversity of m6Am modification in the transcriptome. Here, we describe CROWN-seq, which simultaneously identifies transcription-start nucleotides and quantifies m6Am stoichiometry for each 5’ isoform that initiates with adenosine. Using CROWN-seq, we map the m6Am landscape in nine human cell lines. Our findings reveal that m6Am is nearly always a high stoichiometry modification, with only a small subset of cellular mRNAs showing lower m6Am stoichiometry. We find that m6Am is associated with increased transcript expression and provide evidence that m6Am may be linked to transcription initiation associated with specific promoter sequences and initiation mechanisms. These data suggest a potential new function for m6Am in influencing transcription.
