7PBW

Cryo-EM structure of light harvesting complex 2 from Rba. sphaeroides.

This is a non-PDB format compatible entry.

Summary for 7PBW

• Entry DOI: 10.2210/pdb7pbw/pdb
• EMDB information: 13307
• Descriptor: Light-harvesting protein B-800/850 alpha chain, Light-harvesting protein B-800/850 beta chain, BACTERIOCHLOROPHYLL A, ... (7 entities in total)
• Functional Keywords: photosynthesis, purple bacteria, light harvesting complex 2, lh2, membrane protein, cryo-em.
• Biological source: Cereibacter sphaeroides 2.4.1; More
• Total number of polymer chains: 18
• Total formula weight: 130744.25

Authors

Qian, P.,Swainsbury, D.J.K.,Croll, T.I.,Castro-Hartmann, P.,Sader, K.,Divitini, G.,Hunter, C.N. (deposition date: 2021-08-02, release date: 2021-11-24, Last modification date: 2024-11-20)

Primary citation

Qian, P.,Swainsbury, D.J.K.,Croll, T.I.,Castro-Hartmann, P.,Divitini, G.,Sader, K.,Hunter, C.N.
Cryo-EM Structure of the Rhodobacter sphaeroides Light-Harvesting 2 Complex at 2.1 angstrom.
Biochemistry, 60:3302-3314, 2021

PubMed Abstract: Light-harvesting 2 (LH2) antenna complexes augment the collection of solar energy in many phototrophic bacteria. Despite its frequent role as a model for such complexes, there has been no three-dimensional (3D) structure available for the LH2 from the purple phototroph . We used cryo-electron microscopy (cryo-EM) to determine the 2.1 Å resolution structure of this LH2 antenna, which is a cylindrical assembly of nine αβ heterodimer subunits, each of which binds three bacteriochlorophyll (BChl) molecules and one carotenoid. The high resolution of this structure reveals all of the interpigment and pigment-protein interactions that promote the assembly and energy-transfer properties of this complex. Near the cytoplasmic face of the complex there is a ring of nine BChls, which absorb maximally at 800 nm and are designated as B800; each B800 is coordinated by the N-terminal carboxymethionine of LH2-α, part of a network of interactions with nearby residues on both LH2-α and LH2-β and with the carotenoid. Nine carotenoids, which are spheroidene in the strain we analyzed, snake through the complex, traversing the membrane and interacting with a ring of 18 BChls situated toward the periplasmic side of the complex. Hydrogen bonds with C-terminal aromatic residues modify the absorption of these pigments, which are red-shifted to 850 nm. Overlaps between the macrocycles of the B850 BChls ensure rapid transfer of excitation energy around this ring of pigments, which act as the donors of energy to neighboring LH2 and reaction center light-harvesting 1 (RC-LH1) complexes.

PubMed: 34699186
DOI: 10.1021/acs.biochem.1c00576

Experimental method

ELECTRON MICROSCOPY (2.1 Å)