@article{4f8c984c4a3444dea760f4294f7b27ca,
title = "Structure of a dimeric photosystem II complex from a cyanobacterium acclimated to far-red light",
abstract = "Photosystem II (PSII) is the water-splitting enzyme central to oxygenic photosynthesis. To drive water oxidation, light is harvested by accessory pigments, mostly chlorophyll (Chl) a molecules, which absorb visible light (400–700 nm). Some cyanobacteria facultatively acclimate to shaded environments by altering their photosynthetic machinery to additionally absorb far-red light (FRL, 700–800 nm), a process termed far-red light photoacclimation or FaRLiP. During far-red light photoacclimation, FRL-PSII is assembled with FRL-specific isoforms of the subunits PsbA, PsbB, PsbC, PsbD, and PsbH, and some Chl-binding sites contain Chls d or f instead of the usual Chl a. The structure of an apo-FRL-PSII monomer lacking the FRL-specific PsbH subunit has previously been determined, but visualization of the dimeric complex has remained elusive. Here, we report the cryo-EM structure of a dimeric FRL–PSII complex. The site assignments for Chls d and f are consistent with those assigned in the previous apo-FRL-PSII monomeric structure. All sites that bind Chl d or Chl f at high occupancy exhibit a FRL-specific interaction of the formyl moiety of the Chl d or Chl f with the protein environment, which in some cases involves a phenylalanine sidechain. The structure retains the FRL-specific PsbH2 subunit, which appears to alter the energetic landscape of FRL-PSII, redirecting energy transfer from the phycobiliprotein complex to a Chl f molecule bound by PsbB2 that acts as a bridge for energy transfer to the electron transfer chain. Collectively, these observations extend our previous understanding of the structure-function relationship that allows PSII to function using lower energy FRL.",
keywords = "chlorophyll, cofactor assignment, cryo-EM, cyanobacteria, electron transfer, energy transfer, far-red light photoacclimation, photosynthesis, photosystem II, PsbH",
author = "Gisriel, {Christopher J.} and Gaozhong Shen and Flesher, {David A.} and Vasily Kurashov and Golbeck, {John H.} and Brudvig, {Gary W.} and Muhamed Amin and Bryant, {Donald A.}",
note = "Funding Information: We acknowledge the Yale CryoEM Resource that is funded in part by NIH grant S10OD023603 , Dr Kaifeng Zhou for sample screening, and Dr Shenping Wu for high-resolution data collection. We acknowledge the Office of the Dean at the Yale School of Medicine and Office of the Provost at Yale University for funding of the Yale CryoEM Resource. We also acknowledge the Yale Center for Research Computing for use of the computing infrastructure. We thank Dr Tatiana N. Laremore in the Proteomics and Mass Spectrometry Core Facility of the Huck Institutes for the Life Sciences at The Pennsylvania State University for performing the tryptic peptide mass fingerprinting by HPLC/MS-MS spectrometry. Funding Information: Research reported in this publication was supported in part by the National Institute of General Medical Sciences of the National Institutes of Health under Award Number K99GM140174 to C. J. G. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This work was also supported by National Science Foundation grant MCB-1613022 to D. A. B. and J. H. G. and by Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences grant DE-FG02-05ER15646 to G. W. B. D. A. F. was supported by the Predoctoral Program in Biophysics NIH T32 GM008283. Funding Information: We acknowledge the Yale CryoEM Resource that is funded in part by NIH grant S10OD023603, Dr Kaifeng Zhou for sample screening, and Dr Shenping Wu for high-resolution data collection. We acknowledge the Office of the Dean at the Yale School of Medicine and Office of the Provost at Yale University for funding of the Yale CryoEM Resource. We also acknowledge the Yale Center for Research Computing for use of the computing infrastructure. We thank Dr Tatiana N. Laremore in the Proteomics and Mass Spectrometry Core Facility of the Huck Institutes for the Life Sciences at The Pennsylvania State University for performing the tryptic peptide mass fingerprinting by HPLC/MS-MS spectrometry. C. J. G. G. S. and D. A. F. data curation; C. J. G. G. S. D. A. F. V. K. and M. A. formal analysis; C. J. G. D. A. F. J. H. G. G. W. B. and D. A. B. funding acquisition; C. J. G. J. H. G. G. W. B. and D. A. B. project administration; C. J. G. J. H. G. G. W. B. and D. A. B. supervision; C. J. G. G. W. B. and D. A. B. validation; C. J. G. G. S. D. A. F. and V. K. visualization; C. J. G. writing–original draft; C. J. G. G. S. D. A. F. V. K. J. H. G. G. W. B. M. A. and D. A. B. writing–review and editing; G. W. B. and D. A. B. resources; M. A. methodology; M. A. software; D. A. B. conceptualization. Research reported in this publication was supported in part by the National Institute of General Medical Sciences of the National Institutes of Health under Award Number K99GM140174 to C. J. G. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This work was also supported by National Science Foundation grant MCB-1613022 to D. A. B. and J. H. G. and by Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences grant DE-FG02-05ER15646 to G. W. B. D. A. F. was supported by the Predoctoral Program in Biophysics NIH T32 GM008283. Publisher Copyright: {\textcopyright} 2022 The Authors",
year = "2023",
month = jan,
doi = "10.1016/j.jbc.2022.102815",
language = "English",
volume = "299",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC",
number = "1",
}