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Molecular asymmetry of a photosynthetic supercomplex from green sulfur bacteria

Puskar, Ryan and Du Truong, Chloe and Swain, Kyle and Chowdhury, Saborni and Chan, Ka-Yi and Li, Shan and Cheng, Kai-Wen and Wang, Ting Yu and Poh, Yu-Ping and Mazor, Yuval and Liu, Haijun and Chou, Tsui-Fen and Nannenga, Brent L. and Chiu, Po-Lin (2022) Molecular asymmetry of a photosynthetic supercomplex from green sulfur bacteria. Nature Communications, 13 . Art. No. 5824. ISSN 2041-1723. PMCID PMC9529944. doi:10.1038/s41467-022-33505-4.

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The photochemical reaction center (RC) features a dimeric architecture for charge separation across the membrane. In green sulfur bacteria (GSB), the trimeric Fenna-Matthews-Olson (FMO) complex mediates the transfer of light energy from the chlorosome antenna complex to the RC. Here we determine the structure of the photosynthetic supercomplex from the GSB Chlorobaculum tepidum using single-particle cryogenic electron microscopy (cryo-EM) and identify the cytochrome c subunit (PscC), two accessory protein subunits (PscE and PscF), a second FMO trimeric complex, and a linker pigment between FMO and the RC core. The protein subunits that are assembled with the symmetric RC core generate an asymmetric photosynthetic supercomplex. One linker bacteriochlorophyll (BChl) is located in one of the two FMO-PscA interfaces, leading to differential efficiencies of the two energy transfer branches. The two FMO trimeric complexes establish two different binding interfaces with the RC cytoplasmic surface, driven by the associated accessory subunits. This structure of the GSB photosynthetic supercomplex provides mechanistic insight into the light excitation energy transfer routes and a possible evolutionary transition intermediate of the bacterial photosynthetic supercomplex from the primitive homodimeric RC.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle
Li, Shan0000-0002-0829-1821
Cheng, Kai-Wen0000-0001-9888-9773
Poh, Yu-Ping0000-0001-6709-2147
Mazor, Yuval0000-0001-5072-0928
Liu, Haijun0000-0003-0537-0302
Chou, Tsui-Fen0000-0003-2410-2186
Nannenga, Brent L.0000-0001-6859-3429
Chiu, Po-Lin0000-0001-8608-7650
Additional Information:We thank Chihiro Azai, Patricia Baker, and Hila Toporik for advising us on the procedure for culture growth. We very much appreciate Robert Blankenship and Kevin Redding for fruitful scientific discussion. We thank Dewight Williams and David Lowry for the EM assistance in the Eyring Materials Center (EMC) at Arizona State University (ASU). We acknowledge using the Titan Krios TEM at the EMC and the funding for the instrumentation by NSF MRI 1531991. A portion of this research was supported by NIH grant U24GM129547 and performed at the Pacific Northwest Center for Cryo-EM (PNCC) at Oregon Health & Science University (OHSU), Portland, OR, and accessed through EMSL (grid.436923.9), a DOE Office of Science User Facility sponsored by the Office of Biological and Environmental Research (PNCC proposal number: 160074). We thank Omar Davulcu for the EM assistance at the PNCC site. We acknowledge the funding support by Army Research Office (ARO) (W911NF2010321) to P.-L.C., the support by the DOE, Office of Basic Energy Sciences, Photosynthetic Systems Program (DE-FG02-07ER15902) to H.L., and the GPU device support by the NVIDIA GPU Grant Program to P.-L.C. We especially thank John C.H. Spence for initiating the idea for the quantum biology project, and we missed the days discussing sciences and making discoveries together.
Funding AgencyGrant Number
Army Research Office (ARO)W911NF2010321
Department of Energy (DOE)DE-FG02-07ER15902
PubMed Central ID:PMC9529944
Record Number:CaltechAUTHORS:20221019-343672700.6
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117493
Deposited By: Research Services Depository
Deposited On:27 Oct 2022 22:37
Last Modified:28 Oct 2022 00:09

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