8iun | pdb_00008iun

Cryo-EM structure of the CRT-LESS RC-LH core complex from roseiflexus castenholzii

spinqualitylabelsall models 8iun, resolution 2.85Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 8iun is a 36 chain structure with sequence from Roseiflexus castenholzii. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 2.85Å Ligands: BGL, BPH, CA, CDL, HEC, LHG, LMT, MN, MQE, PEF, PGV, U4Z Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function A7NQE9_ROSCS Antenna complexes are light-harvesting systems, which transfer the excitation energy to the reaction centers.[ARBA:ARBA00002455] Publication Abstract from PubMed In wild-type phototrophic organisms, carotenoids (Crts) are primarily packed into specific pigment-protein complexes along with (Bacterio)chlorophylls and play important roles in the photosynthesis. Diphenylamine (DPA) inhibits carotenogenesis but not phototrophic growth of anoxygenic phototrophs and eliminates virtually all Crts from photocomplexes. To investigate the effect of Crts on assembly of the reaction center-light-harvesting (RC-LH) complex from the filamentous anoxygenic phototroph Roseiflexus (Rfl.) castenholzii, we generated carotenoidless (Crt-less) RC-LH complexes by growing cells in the presence of DPA. Here, we present cryo-EM structures of the Rfl. castenholzii native and Crt-less RC-LH complexes with resolutions of 2.86 A and 2.85 A, respectively. From the high-quality map obtained, several important but previously unresolved details in the Rfl. castenholzii RC-LH structure were determined unambiguously including the assignment and likely function of three small polypeptides, and the content and spatial arrangement of Crts with bacteriochlorophyll molecules. The overall structures of Crt-containing and Crt-less complexes are similar. However, structural comparisons showed that only five Crts remain in complexes from DPA-treated cells and that the subunit X (TMx) flanked on the N-terminal helix of the Cyt-subunit is missing. Based on these results, the function of Crts in the assembly of the Rfl. castenholzii RC-LH complex and the molecular mechanism of quinone exchange is discussed. These structural details provide a fresh look at the photosynthetic apparatus of an evolutionary ancient phototroph as well as new insights into the importance of Crts for proper assembly and functioning of the RC-LH complex. New insights on the photocomplex of Roseiflexus castenholzii revealed from comparisons of native and carotenoid-depleted complexes.,Qi CH, Wang GL, Wang FF, Xin Y, Zou MJ, Madigan MT, Wang-Otomo ZY, Ma F, Yu LJ J Biol Chem. 2023 Aug;299(8):105057. doi: 10.1016/j.jbc.2023.105057. Epub 2023 , Jul 17. PMID:37468106 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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