8to2

Bottom cylinder of high-resolution phycobilisome quenched by OCP (local refinement)

spinqualitylabelsall models 8to2, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 8to2 is a 29 chain structure with sequence from Synechocystis sp. PCC 6803. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 2Å Ligands: 45D, CYC Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Cyanobacteria use large antenna complexes called phycobilisomes (PBSs) for light harvesting. However, intense light triggers non-photochemical quenching, where the orange carotenoid protein (OCP) binds to PBS, dissipating excess energy as heat. The mechanism of efficiently transferring energy from phycocyanobilins in PBS to canthaxanthin in OCP remains insufficiently understood. Using cryo-electron microscopy, we unveiled the OCP-PBS complex structure at 1.6- to 2.1-angstrom resolution, showcasing its inherent flexibility. Using multiscale quantum chemistry, we disclosed the quenching mechanism. Identifying key protein residues, we clarified how canthaxanthin's transition dipole moment in its lowest-energy dark state becomes large enough for efficient energy transfer from phycocyanobilins. Our energy transfer model offers a detailed understanding of the atomic determinants of light harvesting regulation and antenna architecture in cyanobacteria. Structural and quantum chemical basis for OCP-mediated quenching of phycobilisomes.,Sauer PV, Cupellini L, Sutter M, Bondanza M, Dominguez Martin MA, Kirst H, Bina D, Koh AF, Kotecha A, Greber BJ, Nogales E, Polivka T, Mennucci B, Kerfeld CA Sci Adv. 2024 Apr 5;10(14):eadk7535. doi: 10.1126/sciadv.adk7535. Epub 2024 Apr , 5. PMID:38578996 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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