7d0j
From Proteopedia
Photosystem I-LHCI-LHCII of Chlamydomonas reinhardtii
Structural highlights
FunctionPSAA_CHLRE PsaA and PsaB bind P700, the primary electron donor of photosystem I (PSI), as well as the electron acceptors A0, A1 and FX. PSI is a plastocyanin/cytochrome c6-ferredoxin oxidoreductase, converting photonic excitation into a charge separation, which transfers an electron from the donor P700 chlorophyll pair to the spectroscopically characterized acceptors A0, A1, FX, FA and FB in turn. Oxidized P700 is reduced on the lumenal side of the thylakoid membrane by plastocyanin or cytochrome c6. Both potential cofactor branches in PSI seem to be active; however, electron transfer seems to proceed preferentially down the path including the phylloquinone bound by PsaA. Publication Abstract from PubMedPhotosystem I (PSI) and II (PSII) balance their light energy distribution absorbed by their light-harvesting complexes (LHCs) through state transition to maintain the maximum photosynthetic performance and to avoid photodamage. In state 2, a part of LHCII moves to PSI, forming a PSI-LHCI-LHCII supercomplex. The green alga Chlamydomonas reinhardtii exhibits state transition to a far larger extent than higher plants. Here we report the cryo-electron microscopy structure of a PSI-LHCI-LHCII supercomplex in state 2 from C. reinhardtii at 3.42 A resolution. The result reveals that the PSI-LHCI-LHCII of C. reinhardtii binds two LHCII trimers in addition to ten LHCI subunits. The PSI core subunits PsaO and PsaH, which were missed or not well-resolved in previous Cr-PSI-LHCI structures, are observed. The present results reveal the organization and assembly of PSI core subunits, LHCI and LHCII, pigment arrangement, and possible pathways of energy transfer from peripheral antennae to the PSI core. Structure of photosystem I-LHCI-LHCII from the green alga Chlamydomonas reinhardtii in State 2.,Huang Z, Shen L, Wang W, Mao Z, Yi X, Kuang T, Shen JR, Zhang X, Han G Nat Commun. 2021 Feb 17;12(1):1100. doi: 10.1038/s41467-021-21362-6. PMID:33597543[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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