7EXT

Cryo-EM structure of cyanobacterial phycobilisome from Synechococcus sp. PCC 7002

This is a non-PDB format compatible entry.

Summary for 7EXT

• Entry DOI: 10.2210/pdb7ext/pdb
• EMDB information: 31373
• Descriptor: Phycobilisome rod-core linker polypeptide CpcG, Allophycocyanin subunit alpha-B, PHYCOCYANOBILIN, ... (11 entities in total)
• Functional Keywords: phycobilisome, synechococcus sp. pcc 7002, cryo-em, photosynthesis
• Biological source: Synechococcus sp. PCC 7002 (Agmenellum quadruplicatum); More
• Total number of polymer chains: 240
• Total formula weight: 4778193.35

Authors

Zheng, L.,Zheng, Z.,Li, X.,Wang, G.,Zhang, K.,Wei, P.,Zhao, J.,Gao, N. (deposition date: 2021-05-28, release date: 2021-10-06, Last modification date: 2025-09-17)

Primary citation

Zheng, L.,Zheng, Z.,Li, X.,Wang, G.,Zhang, K.,Wei, P.,Zhao, J.,Gao, N.
Structural insight into the mechanism of energy transfer in cyanobacterial phycobilisomes.
Nat Commun, 12:5497-5497, 2021

PubMed Abstract: Phycobilisomes (PBS) are the major light-harvesting machineries for photosynthesis in cyanobacteria and red algae and they have a hierarchical structure of a core and peripheral rods, with both consisting of phycobiliproteins and linker proteins. Here we report the cryo-EM structures of PBS from two cyanobacterial species, Anabaena 7120 and Synechococcus 7002. Both PBS are hemidiscoidal in shape and share a common triangular core structure. While the Anabaena PBS has two additional hexamers in the core linked by the 4th linker domain of ApcE (L). The PBS structures predict that, compared with the PBS from red algae, the cyanobacterial PBS could have more direct routes for energy transfer to ApcD. Structure-based systematic mutagenesis analysis of the chromophore environment of ApcD and ApcF subunits reveals that aromatic residues are critical to excitation energy transfer (EET). The structures also suggest that the linker protein could actively participate in the process of EET in both rods and the cores. These results provide insights into the organization of chromophores and the mechanisms of EET within cyanobacterial PBS.

PubMed: 34535665
DOI: 10.1038/s41467-021-25813-y

Experimental method

ELECTRON MICROSCOPY (3.5 Å)