9K3Q

Cryo-EM structure of the Rhodospirillum rubrum RC-LH1 complex

Summary for 9K3Q

• Entry DOI: 10.2210/pdb9k3q/pdb
• EMDB information: 62025
• Descriptor: Light-harvesting protein B-870 beta chain, UBIQUINONE-10, Light-harvesting protein B-870 alpha chain, ... (10 entities in total)
• Functional Keywords: reaction centre light-harvesting 1, photosynthesis
• Biological source: Rhodospirillum rubrum; More
• Total number of polymer chains: 35
• Total formula weight: 300811.64

Authors

Liu, Z.K.,Wang, P.,Liu, L.N. (deposition date: 2024-10-19, release date: 2024-12-04, Last modification date: 2026-06-17)

Primary citation

Christianson, B.,Liu, Z.,Zhang, Y.,Wang, C.,Gardner, A.M.,Zhang, Y.Z.,Wang, P.,Liu, L.N.
Characterization of the Structure and Function of the Photosynthetic RC-LH1 Core Supercomplex From Rhodospirillum rubrum.
Physiol.Plantarum, 177:e70275-e70275, 2025

PubMed Abstract: Photosynthetic reaction center-light harvesting 1 (RC-LH1) core supercomplexes are essential for energy capture and electron transport in purple bacteria. Rhodospirillum rubrum, a model organism for bacterial photosynthesis, features an RC-LH1 architecture with a closed LH1 ring and lacks the peripheral LH2 antenna in the photosynthetic membranes. How this unique RC-LH1 supercomplex performs energy transfer and quinone transport remains unclear. Here, we characterized both the structural and functional properties of Rsp. rubrum RC-LH1 supercomplex using cryo-electron microscopy (cryo-EM), transient absorption (TA) spectroscopy, and cytochrome c oxidation assays. Cryo-EM of the RC-LH1 monomeric structure revealed a closed LH1 ring of 16 αβ-polypeptides encircling the RC, with weaker RC-LH1 interactions than other RC-LH1 structures reported. TA spectra and cytochrome c oxidation assays showed that Rsp. rubrum RC-LH1 monomer with a closed LH1 ring exhibits slower and more distributed excitation energy transfer (EET) kinetics from LH1 to RC and slower electron transport rates than Rba. sphaeroides RC-LH1 monomer with a large opening in the LH1 ring. Our findings provide insight into the unique architecture and spectroscopic properties of Rsp. rubrum RC-LH1 supercomplex. This study enhances our understanding of bacterial photosynthetic mechanisms and lays the foundation for bioengineering applications in artificial photosynthetic systems.

PubMed: 40384483
DOI: 10.1111/ppl.70275

Experimental method

ELECTRON MICROSCOPY (3.02 Å)