7pnk | pdb_00007pnk
Unstacked compact Dunaliella PSII
Structural highlights
FunctionA0A1C8XRM6_DUNSA One of the components of the core complex of photosystem II (PSII). It binds chlorophyll and helps catalyze the primary light-induced photochemical processes of PSII. PSII is a light-driven water:plastoquinone oxidoreductase, using light energy to abstract electrons from H(2)O, generating O(2) and a proton gradient subsequently used for ATP formation.[HAMAP-Rule:MF_01495][RuleBase:RU004535] Publication Abstract from PubMedPhotosystem II (PSII) generates an oxidant whose redox potential is high enough to enable water oxidation , a substrate so abundant that it assures a practically unlimited electron source for life on earth . Our knowledge on the mechanism of water photooxidation was greatly advanced by high-resolution structures of prokaryotic PSII . Here, we show high-resolution cryogenic electron microscopy (cryo-EM) structures of eukaryotic PSII from the green alga Dunaliella salina at two distinct conformations. The conformers are also present in stacked PSII, exhibiting flexibility that may be relevant to the grana formation in chloroplasts of the green lineage. CP29, one of PSII associated light-harvesting antennae, plays a major role in distinguishing the two conformations of the supercomplex. We also show that the stacked PSII dimer, a form suggested to support the organisation of thylakoid membranes , can appear in many different orientations providing a flexible stacking mechanism for the arrangement of grana stacks in thylakoids. Our findings provide a structural basis for the heterogenous nature of the eukaryotic PSII on multiple levels. Structure of Dunaliella photosystem II reveals conformational flexibility of stacked and unstacked supercomplexes.,Caspy I, Fadeeva M, Mazor Y, Nelson N Elife. 2023 Feb 17;12:e81150. doi: 10.7554/eLife.81150. PMID:36799903[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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