8FB9

LH2-LH3 antenna in anti parallel configuration embedded in a nanodisc

Summary for 8FB9

• Entry DOI: 10.2210/pdb8fb9/pdb
• EMDB information: 28962
• Descriptor: Light-harvesting protein B800-820 alpha chain, Light-harvesting protein B800-820 beta chain, Light-harvesting protein B-800/850 alpha chain, ... (6 entities in total)
• Functional Keywords: antenna, membrane protein, nanodisc, bacteriochlorophyll, photosynthesis
• Biological source: Magnetospirillum molischianum; More
• Total number of polymer chains: 32
• Total formula weight: 230540.93

Authors

Toporik, H.,Harris, D.,Schlau-Cohen, G.S.,Mazor, Y. (deposition date: 2022-11-29, release date: 2023-07-19, Last modification date: 2024-06-19)

Primary citation

Wang, D.,Fiebig, O.C.,Harris, D.,Toporik, H.,Ji, Y.,Chuang, C.,Nairat, M.,Tong, A.L.,Ogren, J.I.,Hart, S.M.,Cao, J.,Sturgis, J.N.,Mazor, Y.,Schlau-Cohen, G.S.
Elucidating interprotein energy transfer dynamics within the antenna network from purple bacteria.
Proc.Natl.Acad.Sci.USA, 120:e2220477120-e2220477120, 2023

PubMed Abstract: In photosynthesis, absorbed light energy transfers through a network of antenna proteins with near-unity quantum efficiency to reach the reaction center, which initiates the downstream biochemical reactions. While the energy transfer dynamics within individual antenna proteins have been extensively studied over the past decades, the dynamics between the proteins are poorly understood due to the heterogeneous organization of the network. Previously reported timescales averaged over such heterogeneity, obscuring individual interprotein energy transfer steps. Here, we isolated and interrogated interprotein energy transfer by embedding two variants of the primary antenna protein from purple bacteria, light-harvesting complex 2 (LH2), together into a near-native membrane disc, known as a nanodisc. We integrated ultrafast transient absorption spectroscopy, quantum dynamics simulations, and cryogenic electron microscopy to determine interprotein energy transfer timescales. By varying the diameter of the nanodiscs, we replicated a range of distances between the proteins. The closest distance possible between neighboring LH2, which is the most common in native membranes, is 25 Å and resulted in a timescale of 5.7 ps. Larger distances of 28 to 31 Å resulted in timescales of 10 to 14 ps. Corresponding simulations showed that the fast energy transfer steps between closely spaced LH2 increase transport distances by ∼15%. Overall, our results introduce a framework for well-controlled studies of interprotein energy transfer dynamics and suggest that protein pairs serve as the primary pathway for the efficient transport of solar energy.

PubMed: 37399405
DOI: 10.1073/pnas.2220477120

Experimental method

ELECTRON MICROSCOPY (6.4 Å)