Structural and quantum chemical basis for OCP-mediated quenching of phycobilisomes.
Date
2024-04-05ICR Author
Author
Sauer, PV
Cupellini, L
Sutter, M
Bondanza, M
Domínguez Martin, MA
Kirst, H
Bína, D
Koh, AF
Kotecha, A
Greber, BJ
Nogales, E
Polívka, T
Mennucci, B
Kerfeld, CA
Type
Journal Article
Metadata
Show full item recordAbstract
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.
Collections
Subject
Phycobilisomes
Bacterial Proteins
Canthaxanthin
Cryoelectron Microscopy
Cyanobacteria
Research team
Struct Biol DNA repair
Language
eng
Date accepted
2024-03-04
License start date
2024-04-05
Citation
Science Advances, 2024, 10 (14), pp. eadk7535 -
Publisher
AMER ASSOC ADVANCEMENT SCIENCE