9ygz

Cryo-EM structure of active mutant human green cone opsin (E129Q) in complex with chimeric G protein (miniGist)

spinqualitylabelsall models 9ygz, resolution 3.04Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9ygz is a 5 chain structure with sequence from Homo sapiens and Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3.04Å Ligands: RET Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed We describe a straightforward method for purifying and optimizing human green cone opsin (GCO), which we then used for biophysical and structural studies of a GCO mutant, GCO(E129Q). Our results show that in dark-state GCO, residue E129 enables long-wavelength light absorption, presumably by acting as the counterion for the protonated retinal Schiff base. Notably, the Schiff base pKa in dark-state GCO(E129Q) appears to be markedly lower (pKa approximately 4) than in the rhodopsin equivalent, Rho(E113Q) (pKa approximately 7), indicating distinct electrostatic environments at the retinal attachment site. Functional studies show that light-activated GCO(E129Q) decays more slowly and activates more G-protein than wild-type GCO (GCO(WT)). To identify the basis for these differences, we determined the structure of active GCO(E129Q) bound to a G-protein. We first developed a streamlined workflow to identify conditions that enhance GCO(E129Q) binding to G-proteins. This approach involved screening GCO(E129) binding to Galpha-CT resin (beads bearing tethered Galpha C-terminal peptides), followed by small-scale pull-down assays using 1D4 antibody beads to detect co-purification of GCO(E129) with a Venus-tagged mini-G-protein. Using the optimized conditions, we determined a 3.0-A cryo-EM structure of the GCO(E129)-G-protein complex. Comparison with rhodopsin and our recent 3.0-A structure of GCO(WT) reveals that the active-state architectures are largely similar, with several intriguing differences. Together, these results establish a generalizable, streamlined approach for biophysical and structural analysis of cone opsins and provide new mechanistic insight into the activation and signaling properties of GCO. Biophysical and structural analysis of human green cone opsin.,Yao W, Fay JF, Farrens DL Biophys J. 2026 May 19;125(10):2448-2462. doi: 10.1016/j.bpj.2026.03.029. Epub , 2026 Mar 14. PMID:41832604 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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