Structural and quantum chemical basis for OCP-mediated quenching of phycobilisomes

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 p...

Full description

Saved in:
Bibliographic Details
Published in:Science advances 2024-04, Vol.10 (14), p.eadk7535-eadk7535
Main Authors: Sauer, Paul V, Cupellini, Lorenzo, Sutter, Markus, Bondanza, Mattia, Domínguez Martin, María Agustina, Kirst, Henning, Bína, David, Koh, Adrian Fujiet, Kotecha, Abhay, Greber, Basil J, Nogales, Eva, Polívka, Tomáš, Mennucci, Benedetta, Kerfeld, Cheryl A
Format: Article
Language:English
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary: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.
ISSN:2375-2548
2375-2548
DOI:10.1126/sciadv.adk7535