Crystal structure of jumping spider rhodopsin-1 as a light sensitive GPCR

Abstract

Light-sensitive G protein-coupled receptors (GPCRs)—rhodopsins—absorb photons to isomerize their covalently bound retinal, triggering conformational changes that result in downstream signaling cascades. Monostable rhodopsins release retinal upon isomerization as opposed to the retinal in bistable rhodopsins that “reisomerize” upon absorption of a second photon. Understanding the mechanistic differences between these light-sensitive GPCRs has been hindered by the scarcity of recombinant models of the latter. Here, we reveal the high-resolution crystal structure of a recombinant bistable rhodopsin, jumping spider rhodopsin-1, bound to the inverse agonist 9-cis retinal. We observe a water-mediated network around the ligand hinting toward the basis of their bistable nature. In contrast to bovine rhodopsin (monostable), the transmembrane bundle of jumping spider rhodopsin-1 as well that of the bistable squid rhodopsin adopts a more “activation-ready” conformation often observed in other nonphotosensitive class A GPCRs. These similarities suggest the role of jumping spider rhodopsin-1 as a potential model system in the study of the structure–function relationship of both photosensitive and nonphotosensitive class A GPCRs.

Spectral tuning mediated by helix III in butterfly long wavelength-sensitive visual opsins revealed by heterologous action spectroscopy

“…A previous mutational study [16] and the crystal structure of bovine rhodopsin (1 U19) [28] suggested that interactions of the hydroxyl-bearing three amino acids in helices IV and VI with the chromophore tune the absorption spectrum of primate LWS opsins. In the crystal structure of the jumping spider rhodopsin-1 (6I9K) [29], which is a Gq-coupled visual opsin similar to PxRh1 and PxRh3, the alpha carbons of all seven amino acid residues that differ between the PxRh1 and PxRh3 helix IIIs, including those at positions 116 and 120, appear to be located on the side of helix III distal from the chromophore retinal (Additional file 3: Figure S3). This suggests a unique indirect interaction with retinal through other amino acid residue(s).…”

The C-terminus and Third Cytoplasmic Loop Cooperatively Activate Mouse Melanopsin Phototransduction

“…extended 5 th and 6 th transmembrane helices/3 rd cytoplasmic loop, positively charged cytoplasmic loops, and C-terminus contacting G-protein) for their selectivity, we propose that similar features are shared amongst rhabdomeric-type visual pigments. Of the available resolved protein structures of GPCRs, two are of rhabdomeric visual pigments: two squid rhodopsin structures and jumping spider rhodopsin (47, 48, 62). Similar structural features are observed in melanopsin’s predicted structure and the structures of the resolved rhabdomeric-type visual pigments.…”

Immobilization of arrestin-3 on different biosensor platforms for evaluating GPCR binding

“…As a model GPCR we selected Jumping Spider Rhodopsin-1 (JSR1), a light-sensitive bistable class A GPCR, which has recently been shown to be highly thermostable in its wild-type form in vitro 26 and is an interesting target for the development of optogenetic tools. 26,27 In fact, as other rhodopsins, JSR1 is easily activated by illumination without the addition of ligands. Moreover, invertebrate rhodopsins are known to be able to bind arrestin in a phosphorylation-independent way upon illumination.…”

“…Moreover, invertebrate rhodopsins are known to be able to bind arrestin in a phosphorylation-independent way upon illumination. 28 Finally, the high resolution crystal structure of JSR1 (PDB ID 6I9K) 26 shows Fig. 1 Schematic representation of possible interactions between DDMstabilized JSR1 and immobilized Arr3.…”