@article{22750,
  abstract     = {Robust oxygenic photosynthesis requires the efficient assembly and repair of the multi-subunit oxygen-evolving photosystem II (PSII) complex. Previous cryogenic electron microscopy (cryo-EM) structures of PSII assembly/disassembly intermediates have relied on the analysis of deletion mutants or removal of PSII subunits in vitro. Here we report the cryo-EM structures of naturally occurring dimeric PSII intermediates from the cyanobacterium Thermosynechococcus vestitus at a resolution of about 2.2 Å. These intermediates contain inactive dimers lacking the oxygen-evolving complex (OEC) and semi-active dimers with the OEC present in one of the two monomers. Our structural data provide a mechanism for how assembly and disassembly of the Mn4CaO5 cluster is coordinated with the binding and release of the extrinsic proteins: restructuring of the C-terminal tail of D1 subunit during assembly or disassembly of the Mn cluster triggers conformational changes in D2, CP47 and CP43 to drive the binding/release of the extrinsic proteins. A combination of structural and mass spectrometry data also suggests that the inactive PSII complexes may include damaged complexes containing oxidized D1-His332, a monodentate ligand to one of the Mn ions of the OEC.},
  author       = {Zhao, Ziyu and Vercellino, Irene and Whitelegge, Julian P. and Maghlaoui, Karim and Białek, Wojciech and Nixon, Peter J. and Sazanov, Leonid A},
  issn         = {2041-1723},
  journal      = {Nature Communications},
  publisher    = {Springer Nature},
  title        = {{Cryo-EM structures of naturally occurring dimeric photosystem II complexes lacking the Mn4CaO5 cluster}},
  doi          = {10.1038/s41467-026-75324-x},
  volume       = {17},
  year         = {2026},
}