Structure of the vasopressin hormone–V2 receptor–β-arrestin1 ternary complex

Abstract

Arrestins interact with G protein–coupled receptors (GPCRs) to stop G protein activation and to initiate key signaling pathways. Recent structural studies shed light on the molecular mechanisms involved in GPCR-arrestin coupling, but whether this process is conserved among GPCRs is poorly understood. Here, we report the cryo–electron microscopy active structure of the wild-type arginine-vasopressin V2 receptor (V2R) in complex with β-arrestin1. It reveals an atypical position of β-arrestin1 compared to previously described GPCR-arrestin assemblies, associated with an original V2R/β-arrestin1 interface involving all receptor intracellular loops. Phosphorylated sites of the V2R carboxyl terminus are clearly identified and interact extensively with the β-arrestin1 N-lobe, in agreement with structural data obtained with chimeric or synthetic systems. Overall, these findings highlight a notable structural variability among GPCR-arrestin signaling complexes.

Structural details of a Class B GPCR-arrestin complex revealed by genetically encoded crosslinkers in living cells

“…Our crosslinking data show that this segment of PTH1R comes close to the positively charged region at the distal edge of the arrestin N-domain (“N-edge”), comprised of the 160-loop and the loop between β-strands IV and V. This arrangement is compatible with the available GPCR-arrestin structures, since the proximal GPCR C-tail is pushed away from the central crest of arrestin by the presence of the 7TM domain, so that this negatively charged region is optimally positioned to interact with the N-edge. This holds true also for the V 2 R. Although in the structure of arr2 bound to the V 2 Rpp the proximal phosphorylation lies close to the finger loop, the resolved segment of the receptor C-tail in the full-length V 2 R-arr2 structure 25 guides the proximal cluster to the arrestin N-edge, in line with our crosslinking results with the full-length V 2 R (Supplementary Fig. 18c ) and with our PTH1R-arr2 model.…”

“…Only a few structures of GPCR-arrestin complexes have been solved so far: rhodopsin-arr1 fusion 18 – 20 , and arr2 in complex with neurotensin receptor type 1 (NTS 1 R) 21 , 22 , chimeric muscarinic acetylcholine receptor M2 (M 2 R) 23 , and beta-1–adrenergic receptor (β 1 -AR) 24 fused to the highly phosphorylated tail of the vasopressin V2 receptor (V 2 R-phosphopeptide, V 2 Rpp). Recently, the structures of the complexes of the full-length V 2 R 25 and the serotonin receptor 2B 26 with arr2 have been published. In all cases, the phosphorylated receptor tail binds to the arrestin N-domain, whereas the 7-transmembrane (7TM) domain holds the arrestin central crest.…”

A key GPCR phosphorylation motif discovered in arrestin2•CCR5 phosphopeptide complexes

“…Remarkably, the N-terminal V2Rpp residues pT347 and pS350 form contacts with observable electron density to the arrestin2 finger loop and nearby residues (Figure 5A). However, these two phosphoresidues do not form visible interactions with arrestin2 in fulllength receptor complexes such as the M2R-V2Rpp chimera•arrestin2 (PDB: 6U1N), the β1AR-V2Rpp chimera•arrestin2 (PDB: 6TKO) (Figure 5A) and the recently solved V2R•arrestin2 structures 16 . Rather in these complexes, only the phosphosites beyond V2R residue 356 coordinate with the arrestin2 N-domain in an identical manner as in the V2Rpp and CCR5 6P complex structures.…”

“…Rather in these complexes, only the phosphosites beyond V2R residue 356 coordinate with the arrestin2 N-domain in an identical manner as in the V2Rpp and CCR5 6P complex structures. This is presumably due to steric constraints imposed by the direct binding of the receptor core to the arrestin2 finger loop [14][15][16] . An inspection of the β1AR-V2Rpp chimera•arrestin2 structure (Figure 5A) shows that a flexible linker of about 15 residues connects the receptor helix 8 and the phosphorylation motif recognized by the arrestin2 Ndomain.…”

“…The molecular details of the specificity of GPCR-arrestin interactions and the causes for the different functional outcomes of varying phosphorylation patterns are still poorly understood. Previously solved full-length GPCR•arrestin complex structures comprise a rhodopsin-arrestin1 fusion complex 12 , a fusion complex of the engineered constitutively active arrestin2 with the truncated 5HT 2B serotonin receptor 13 , an arrestin2 complex with a chimera of the M2 muscarinic receptor (M2R) and the vasopressin 2 receptor C-terminal phosphopeptide (V2Rpp) 14 , a β1AR-V2Rpp chimera•arrestin2 complex 15 , as well as native V2R•arrestin2 16 and NTR1•arrestin2 17,18 complexes. Of these, the rhodopsin fusion, the M2R-V2Rpp and β1AR-V2Rpp chimera, as well as the truncated 5HT 2B serotonin receptor fusion complexes show similar orientations of the arrestin.…”