|Entry||Database: EMDB / ID: 9700|
|Title||Cryo-EM map of Chlamydomonas reinhardtii PSI-LHCI supercomplex at 6.9A resolution|
|Map data||C. reinhardtii PSI-LHCI supercomplex|
|Sample||Supercomplex of photosystem I core with ten bound LHCA subunits.:|
|Source||Chlamydomonas reinhardtii (plant)|
|Method||single particle reconstruction / cryo EM / 6.9 Å resolution|
|Authors||Burton-Smith RN / Kubota-Kawai H / Murata K|
|Citation||Journal: J. Biol. Chem. / Year: 2019|
Title: Ten antenna proteins are associated with the core in the supramolecular organization of the photosystem I supercomplex in .
Authors: Hisako Kubota-Kawai / Raymond N Burton-Smith / Ryutaro Tokutsu / Chihong Song / Seiji Akimoto / Makio Yokono / Yoshifumi Ueno / Eunchul Kim / Akimasa Watanabe / Kazuyoshi Murata / Jun Minagawa
Abstract: Photosystem I (PSI) is a large pigment-protein complex mediating light-driven charge separation and generating a highly negative redox potential, which is eventually utilized to produce organic ...Photosystem I (PSI) is a large pigment-protein complex mediating light-driven charge separation and generating a highly negative redox potential, which is eventually utilized to produce organic matter. In plants and algae, PSI possesses outer antennae, termed light-harvesting complex I (LHCI), which increase the energy flux to the reaction center. The number of outer antennae for PSI in the green alga is known to be larger than that of land plants. However, their exact number and location remain to be elucidated. Here, applying a newly established sample purification procedure, we isolated a highly pure PSI-LHCI supercomplex containing all nine LHCA gene products under state 1 conditions. Single-particle cryo-EM revealed the 3D structure of this supercomplex at 6.9 Å resolution, in which the densities near the PsaF and PsaJ subunits were assigned to two layers of LHCI belts containing eight LHCIs, whereas the densities between the PsaG and PsaH subunits on the opposite side of the LHCI belt were assigned to two extra LHCIs. Using single-particle cryo-EM, we also determined the 2D projection map of the mutant, which confirmed the assignment of LHCA2 and LHCA9 to the densities between PsaG and PsaH. Spectroscopic measurements of the PSI-LHCI supercomplex suggested that the bound LHCA2 and LHCA9 proteins have the ability to increase the light-harvesting energy for PSI. We conclude that the PSI in has a larger and more distinct outer-antenna organization and higher light-harvesting capability than that in land plants.
|Date||Deposition: Nov 2, 2018 / Header (metadata) release: Feb 27, 2019 / Map release: Feb 27, 2019 / Last update: Feb 27, 2019|
|Structure viewer||EM map: |
Downloads & links
|File||emd_9700.map.gz (map file in CCP4 format, 67109 KB)|
|Projections & slices|
Images are generated by Spider.
|Voxel size||X=Y=Z: 1.992 Å|
CCP4 map header:
-Entire Supercomplex of photosystem I core with ten bound LHCA subunits.
|Entire||Name: Supercomplex of photosystem I core with ten bound LHCA subunits.|
Number of components: 1
-Component #1: protein, Supercomplex of photosystem I core with ten bound LHCA s...
|Protein||Name: Supercomplex of photosystem I core with ten bound LHCA subunits.|
Recombinant expression: No
|Mass||Theoretical: 800 kDa|
|Source||Species: Chlamydomonas reinhardtii (plant) / Strain: 137c|
|Specimen||Specimen state: particle / Method: cryo EM|
|Sample solution||pH: 7.5|
|Vitrification||Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Humidity: 95 %|
-Electron microscopy imaging
|Imaging||Microscope: JEOL 2200FS|
|Electron gun||Electron source: FIELD EMISSION GUN / Accelerating voltage: 200 kV / Electron dose: 2 e/Å2 / Illumination mode: FLOOD BEAM|
|Lens||Imaging mode: BRIGHT FIELD|
|Specimen Holder||Model: OTHER|
|Camera||Detector: DIRECT ELECTRON DE-20 (5k x 3k)|
|Processing||Method: single particle reconstruction / Applied symmetry: C1 (asymmetric) / Number of projections: 10835|
|3D reconstruction||Software: RELION / Resolution: 6.9 Å / Resolution method: FSC 0.143 CUT-OFF|
-Atomic model buiding
|Modeling #1||Refinement protocol: rigid body / Target criteria: Correlation coefficient / Refinement space: REAL|
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