7EH8

Cryo-EM structure of the hexameric state of C-phycocyanin from Thermoleptolyngbya sp. O-77

Summary for 7EH8

• Entry DOI: 10.2210/pdb7eh8/pdb
• EMDB information: 31090
• Descriptor: C-phycocyanin alpha chain, C-phycocyanin beta chain, PHYCOCYANOBILIN (3 entities in total)
• Functional Keywords: homo hexamer, light-harvesting complex, photosynthesis
• Biological source: Leptolyngbya sp. O-77; More
• Total number of polymer chains: 12
• Total formula weight: 224544.47

Authors

Minato, T.,Teramoto, T.,Adachi, N.,Hung, N.K.,Yamada, K.,Kawasaki, M.,Akutsu, M.,Moriya, T.,Senda, T.,Ogo, S.,Kakuta, Y.,Yoon, K.S. (deposition date: 2021-03-28, release date: 2021-11-17)

Primary citation

Minato, T.,Teramoto, T.,Adachi, N.,Hung, N.K.,Yamada, K.,Kawasaki, M.,Akutsu, M.,Moriya, T.,Senda, T.,Ogo, S.,Kakuta, Y.,Yoon, K.S.
Non-conventional octameric structure of C-phycocyanin.
Commun Biol, 4:1238-1238, 2021

PubMed Abstract: C-phycocyanin (CPC), a blue pigment protein, is an indispensable component of giant phycobilisomes, which are light-harvesting antenna complexes in cyanobacteria that transfer energy efficiently to photosystems I and II. X-ray crystallographic and electron microscopy (EM) analyses have revealed the structure of CPC to be a closed toroidal hexamer by assembling two trimers. In this study, the structural characterization of non-conventional octameric CPC is reported for the first time. Analyses of the crystal and cryogenic EM structures of the native CPC from filamentous thermophilic cyanobacterium Thermoleptolyngbya sp. O-77 unexpectedly illustrated the coexistence of conventional hexamer and novel octamer. In addition, an unusual dimeric state, observed via analytical ultracentrifugation, was postulated to be a key intermediate structure in the assemble of the previously unobserved octamer. These observations provide new insights into the assembly processes of CPCs and the mechanism of energy transfer in the light-harvesting complexes.

PubMed: 34716405
DOI: 10.1038/s42003-021-02767-x

Experimental method

ELECTRON MICROSCOPY (3.06 Å)