@article{126588ee98bb4190aed188c5e8163233,
title = "Structural and functional analyses of photosystem II in the marine diatom Phaeodactylum tricornutum",
abstract = "A descendant of the red algal lineage, diatoms are unicellular eukaryotic algae characterized by thylakoid membranes that lack the spatial differentiation of stroma and grana stacks found in green algae and higher plants. While the photophysiology of diatoms has been studied extensively, very little is known about the spatial organization of the multimeric photosynthetic protein complexes within their thylakoid membranes. Here, using cryo-electron tomography, proteomics, and biophysical analyses, we elucidate the macromolecular composition, architecture, and spatial distribution of photosystem II complexes in diatom thylakoid membranes. Structural analyses reveal 2 distinct photosystem II populations: loose clusters of complexes associated with antenna proteins and compact 2D crystalline arrays of dimeric cores. Biophysical measurements reveal only 1 photosystem II functional absorption cross section, suggesting that only the former population is photosynthetically active. The tomographic data indicate that the arrays of photosystem II cores are physically separated from those associated with antenna proteins. We hypothesize that the islands of photosystem cores are repair stations, where photodamaged proteins can be replaced. Our results strongly imply convergent evolution between the red and the green photosynthetic lineages toward spatial segregation of dynamic, functional microdomains of photosystem II supercomplexes.",
keywords = "Cryo-electron tomography, Diatom, Functional absorption analysis, Photosystem II, Thylakoid membranes",
author = "Orly Levitan and Muyuan Chen and Xuyuan Kuang and Cheong, {Kuan Yu} and Jennifer Jiang and Melissa Banal and Nikhita Nambiar and Gorbunov, {Maxim Y.} and Ludtke, {Steven J.} and Falkowski, {Paul G.} and Wei Dai",
note = "Funding Information: Ehud Zelzion and Dana Price of the Rutgers Genome Cooperative for support with bioinformatic and phylogenetic analyses. Tomographic data acquisition at Purdue University was supported by the National Institute of Health Midwest Consortium for High Resolution Cryo-electron Microscopy (U24 GM116789-01A1). This research was supported by grants from National Funding Information: Tilt series of thylakoid membrane were collected at Rutgers Cryo-Electron Microscopy and Cryo-Electron Tomography Core Facility and the Cryo-Electron Microscopy Facility at Purdue University. We thank Jason Kaelber at Rutgers Cryo-Electron Microscopy and Cryo-Electron Tomography Core Facility for technical support in data collection. Focused ion beam milling of plunge frozen diatom cells was carried out at Thermo Fisher Scientific Factory at Brno, Czechia. We thank Jakub Kuba and Radovan Spurn? for their support in milling and imaging of frozen lamellae. We would like to acknowledge Haiyan Zheng and Caifeng Zhao at the Biological Mass Spectrometry Facility at Robert Wood Johnson Medical School for conducting the quantitative mass spectrometry analysis. We also thank Ehud Zelzion and Dana Price of the Rutgers Genome Cooperative for support with bioinformatic and phylogenetic analyses. Tomographic data acquisition at Purdue University was supported by the National Institute of Health Midwest Consortium for High Resolution Cryo-electron Microscopy (U24 GM116789-01A1). This research was supported by grants from National Science Foundation EAGER award 1558128 to O.L. and P.G.F. and from National Institute of Health (R01GM080139 and P01GM121203 to S.J.L.). Partial funding for this study came from the Rutgers Busch Biomedical Research Grant to W.D. and Bennett L. Smith Endowment to P.G.F. X.K. was partially supported by the China Scholarship Council (File 201606375128). Funding Information: Science Foundation EAGER award 1558128 to O.L. and P.G.F. and from National Institute of Health (R01GM080139 and P01GM121203 to S.J.L.). Partial funding for this study came from the Rutgers Busch Biomedical Research Grant to W.D. and Bennett L. Smith Endowment to P.G.F. X.K. was partially supported by the China Scholarship Council (File 201606375128). Publisher Copyright: {\textcopyright} 2019 National Academy of Sciences. All rights reserved.",
year = "2019",
month = aug,
day = "27",
doi = "10.1073/pnas.1906726116",
language = "English (US)",
volume = "116",
pages = "17316--17322",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
publisher = "National Academy of Sciences",
number = "35",
}