8IMI

A1-A2, A3-A4, B'1-B'2, C'1-C'2 cylinder in cyanobacterial phycobilisome from Anthocerotibacter panamensis (Cluster A)

Summary for 8IMI

• Entry DOI: 10.2210/pdb8imi/pdb
• EMDB information: 35530 35531 35534 35537 35541 35565
• Descriptor: ApcE, ApcA2, ApcB3, ... (6 entities in total)
• Functional Keywords: complex, photosynthesis
• Biological source: Anthocerotibacter panamensis; More
• Total number of polymer chains: 52
• Total formula weight: 1009985.79

Authors

Wang, C.H.,Yang, C.H.,Wu, H.Y.,Jiang, H.W.,Ho, M.C.,Ho, M.Y. (deposition date: 2023-03-07, release date: 2023-10-25, Last modification date: 2024-05-08)

Primary citation

Jiang, H.W.,Wu, H.Y.,Wang, C.H.,Yang, C.H.,Ko, J.T.,Ho, H.C.,Tsai, M.D.,Bryant, D.A.,Li, F.W.,Ho, M.C.,Ho, M.Y.
A structure of the relict phycobilisome from a thylakoid-free cyanobacterium.
Nat Commun, 14:8009-8009, 2023

PubMed Abstract: Phycobilisomes (PBS) are antenna megacomplexes that transfer energy to photosystems II and I in thylakoids. PBS likely evolved from a basic, inefficient form into the predominant hemidiscoidal shape with radiating peripheral rods. However, it has been challenging to test this hypothesis because ancestral species are generally inaccessible. Here we use spectroscopy and cryo-electron microscopy to reveal a structure of a "paddle-shaped" PBS from a thylakoid-free cyanobacterium that likely retains ancestral traits. This PBS lacks rods and specialized ApcD and ApcF subunits, indicating relict characteristics. Other features include linkers connecting two chains of five phycocyanin hexamers (CpcN) and two core subdomains (ApcH), resulting in a paddle-shaped configuration. Energy transfer calculations demonstrate that chains are less efficient than rods. These features may nevertheless have increased light absorption by elongating PBS before multilayered thylakoids with hemidiscoidal PBS evolved. Our results provide insights into the evolution and diversification of light-harvesting strategies before the origin of thylakoids.

PubMed: 38049400
DOI: 10.1038/s41467-023-43646-9

Experimental method

ELECTRON MICROSCOPY (2.59 Å)