6KGX

Structure of the phycobilisome from the red alga Porphyridium purpureum

This is a non-PDB format compatible entry.

Summary for 6KGX

• Entry DOI: 10.2210/pdb6kgx/pdb
• EMDB information: 9976
• Descriptor: Phycoerythrin alpha subunit, C-phycocyanin beta subunit, LR2, ... (28 entities in total)
• Functional Keywords: phycobilisome, complex, photosynthesis
• Biological source: Porphyridium purpureum (Red alga); More
• Total number of polymer chains: 706
• Total formula weight: 14789615.74

Authors

Sui, S.F.,Ma, J.F.,You, X.,Sun, S. (deposition date: 2019-07-12, release date: 2019-12-11, Last modification date: 2020-03-18)

Primary citation

Ma, J.F.,You, X.,Sun, S.,Wang, X.X.,Qin, S.,Sui, S.F.
Structural basis of energy transfer in Porphyridium purpureum phycobilisome.
Nature, 579:146-151, 2020

PubMed Abstract: Photosynthetic organisms have developed various light-harvesting systems to adapt to their environments. Phycobilisomes are large light-harvesting protein complexes found in cyanobacteria and red algae, although how the energies of the chromophores within these complexes are modulated by their environment is unclear. Here we report the cryo-electron microscopy structure of a 14.7-megadalton phycobilisome with a hemiellipsoidal shape from the red alga Porphyridium purpureum. Within this complex we determine the structures of 706 protein subunits, including 528 phycoerythrin, 72 phycocyanin, 46 allophycocyanin and 60 linker proteins. In addition, 1,598 chromophores are resolved comprising 1,430 phycoerythrobilin, 48 phycourobilin and 120 phycocyanobilin molecules. The markedly improved resolution of our structure compared with that of the phycobilisome of Griffithsia pacifica enabled us to build an accurate atomic model of the P. purpureum phycobilisome system. The model reveals how the linker proteins affect the microenvironment of the chromophores, and suggests that interactions of the aromatic amino acids of the linker proteins with the chromophores may be a key factor in fine-tuning the energy states of the chromophores to ensure the efficient unidirectional transfer of energy.

PubMed: 32076272
DOI: 10.1038/s41586-020-2020-7

Experimental method

ELECTRON MICROSCOPY (2.8 Å)