Journal: Nature / Year: 2022 Title: Structures of a phycobilisome in light-harvesting and photoprotected states. Authors: María Agustina Domínguez-Martín / Paul V Sauer / Henning Kirst / Markus Sutter / David Bína / Basil J Greber / Eva Nogales / Tomáš Polívka / Cheryl A Kerfeld / Abstract: Phycobilisome (PBS) structures are elaborate antennae in cyanobacteria and red algae. These large protein complexes capture incident sunlight and transfer the energy through a network of embedded ...Phycobilisome (PBS) structures are elaborate antennae in cyanobacteria and red algae. These large protein complexes capture incident sunlight and transfer the energy through a network of embedded pigment molecules called bilins to the photosynthetic reaction centres. However, light harvesting must also be balanced against the risks of photodamage. A known mode of photoprotection is mediated by orange carotenoid protein (OCP), which binds to PBS when light intensities are high to mediate photoprotective, non-photochemical quenching. Here we use cryogenic electron microscopy to solve four structures of the 6.2 MDa PBS, with and without OCP bound, from the model cyanobacterium Synechocystis sp. PCC 6803. The structures contain a previously undescribed linker protein that binds to the membrane-facing side of PBS. For the unquenched PBS, the structures also reveal three different conformational states of the antenna, two previously unknown. The conformational states result from positional switching of two of the rods and may constitute a new mode of regulation of light harvesting. Only one of the three PBS conformations can bind to OCP, which suggests that not every PBS is equally susceptible to non-photochemical quenching. In the OCP-PBS complex, quenching is achieved through the binding of four 34 kDa OCPs organized as two dimers. The complex reveals the structure of the active form of OCP, in which an approximately 60 Å displacement of its regulatory carboxy terminal domain occurs. Finally, by combining our structure with spectroscopic properties, we elucidate energy transfer pathways within PBS in both the quenched and light-harvesting states. Collectively, our results provide detailed insights into the biophysical underpinnings of the control of cyanobacterial light harvesting. The data also have implications for bioengineering PBS regulation in natural and artificial light-harvesting systems.
Model: Quantifoil R2/1 / Material: COPPER / Mesh: 300 / Support film - Material: GOLD / Support film - topology: HOLEY / Details: Streptavidin affinity grid, home made
Vitrification
Cryogen name: ETHANE-PROPANE / Instrument: FEI VITROBOT MARK IV / Details: Manual blotting.
-
Electron microscopy
Microscope
TFS KRIOS
Image recording
Film or detector model: GATAN K3 (6k x 4k) / Average electron dose: 50.0 e/Å2
Electron beam
Acceleration voltage: 300 kV / Electron source: FIELD EMISSION GUN
Electron optics
Illumination mode: OTHER / Imaging mode: BRIGHT FIELD
Sample stage
Cooling holder cryogen: NITROGEN
Experimental equipment
Model: Titan Krios / Image courtesy: FEI Company
+
Image processing
Details
Streptavidin lattice was subtracted after movie alignment.
Startup model
Type of model: OTHER / Details: Ab initio model
Final reconstruction
Resolution.type: BY AUTHOR / Resolution: 2.7 Å / Resolution method: FSC 0.143 CUT-OFF / Software - Name: cryoSPARC (ver. 3.1) / Number images used: 135701
Initial angle assignment
Type: MAXIMUM LIKELIHOOD / Software - Name: cryoSPARC
Final angle assignment
Type: MAXIMUM LIKELIHOOD / Software - Name: cryoSPARC
+
About Yorodumi
-
News
-
Feb 9, 2022. New format data for meta-information of EMDB entries
New format data for meta-information of EMDB entries
Version 3 of the EMDB header file is now the official format.
The previous official version 1.9 will be removed from the archive.
In the structure databanks used in Yorodumi, some data are registered as the other names, "COVID-19 virus" and "2019-nCoV". Here are the details of the virus and the list of structure data.
Jan 31, 2019. EMDB accession codes are about to change! (news from PDBe EMDB page)
EMDB accession codes are about to change! (news from PDBe EMDB page)
The allocation of 4 digits for EMDB accession codes will soon come to an end. Whilst these codes will remain in use, new EMDB accession codes will include an additional digit and will expand incrementally as the available range of codes is exhausted. The current 4-digit format prefixed with “EMD-” (i.e. EMD-XXXX) will advance to a 5-digit format (i.e. EMD-XXXXX), and so on. It is currently estimated that the 4-digit codes will be depleted around Spring 2019, at which point the 5-digit format will come into force.
The EM Navigator/Yorodumi systems omit the EMD- prefix.
Related info.:Q: What is EMD? / ID/Accession-code notation in Yorodumi/EM Navigator
Yorodumi is a browser for structure data from EMDB, PDB, SASBDB, etc.
This page is also the successor to EM Navigator detail page, and also detail information page/front-end page for Omokage search.
The word "yorodu" (or yorozu) is an old Japanese word meaning "ten thousand". "mi" (miru) is to see.
Related info.:EMDB / PDB / SASBDB / Comparison of 3 databanks / Yorodumi Search / Aug 31, 2016. New EM Navigator & Yorodumi / Yorodumi Papers / Jmol/JSmol / Function and homology information / Changes in new EM Navigator and Yorodumi