Download MendeleyMolecular basis of beta-arrestin coupling to formoterol-bound beta1-adrenoceptor.
Lee, Y., Warne, T., Nehme, R., Pandey, S., Dwivedi-Agnihotri, H., Chaturvedi, M., Edwards, P.C., Garcia-Nafria, J., Leslie, A.G.W., Shukla, A.K., Tate, C.G.(2020) Nature 583: 862-866
- PubMed: 32555462
- DOI: https://doi.org/10.1038/s41586-020-2419-1
- Primary Citation of Related Structures:
6IBL, 6TKO - PubMed Abstract:
The β 1 -adrenoceptor (β 1 AR) is a G-protein-coupled receptor (GPCR) that couples 1 to the heterotrimeric G protein G s . G-protein-mediated signalling is terminated by phosphorylation of the C terminus of the receptor by GPCR kinases (GRKs) and by coupling of β-arrestin 1 (βarr1, also known as arrestin 2), which displaces G s and induces signalling through the MAP kinase pathway 2 . The ability of synthetic agonists to induce signalling preferentially through either G proteins or arrestins-known as biased agonism 3 -is important in drug development, because the therapeutic effect may arise from only one signalling cascade, whereas the other pathway may mediate undesirable side effects 4 . To understand the molecular basis for arrestin coupling, here we determined the cryo-electron microscopy structure of the β 1 AR-βarr1 complex in lipid nanodiscs bound to the biased agonist formoterol 5 , and the crystal structure of formoterol-bound β 1 AR coupled to the G-protein-mimetic nanobody 6 Nb80. βarr1 couples to β 1 AR in a manner distinct to that 7 of G s coupling to β 2 AR-the finger loop of βarr1 occupies a narrower cleft on the intracellular surface, and is closer to transmembrane helix H7 of the receptor when compared with the C-terminal α5 helix of G s . The conformation of the finger loop in βarr1 is different from that adopted by the finger loop of visual arrestin when it couples to rhodopsin 8 . β 1 AR coupled to βarr1 shows considerable differences in structure compared with β 1 AR coupled to Nb80, including an inward movement of extracellular loop 3 and the cytoplasmic ends of H5 and H6. We observe weakened interactions between formoterol and two serine residues in H5 at the orthosteric binding site of β 1 AR, and find that formoterol has a lower affinity for the β 1 AR-βarr1 complex than for the β 1 AR-G s complex. The structural differences between these complexes of β 1 AR provide a foundation for the design of small molecules that could bias signalling in the β-adrenoceptors.
Organizational Affiliation:
MRC Laboratory of Molecular Biology, Cambridge, UK.
