9W4J
Cryo-EM structure of CpcL-PBS3
Summary for 9W4J
| Entry DOI | 10.2210/pdb9w4j/pdb |
| EMDB information | 65635 |
| Descriptor | Photosystem I-associated linker protein CpcL, C-phycocyanin alpha subunit, C-phycocyanin beta subunit, ... (6 entities in total) |
| Functional Keywords | phycobilisomes, photosynthesis |
| Biological source | Nostoc sp. PCC 7120 = FACHB-418 More |
| Total number of polymer chains | 40 |
| Total formula weight | 771755.84 |
| Authors | |
| Primary citation | Mao, Z.,Li, Z.,Li, X.,Shen, L.,Kuang, T.,Wang, W.,Shen, J.R.,Han, G. Structural insight of a photosystem I-CpcL-phycobilisome supercomplex from a cyanobacterium Anabaena sp. PCC 7120. Proc.Natl.Acad.Sci.USA, 123:e2530459123-e2530459123, 2026 Cited by PubMed Abstract: Phycobilisomes (PBSs) are supramolecular pigment-protein complexes composed of phycobiliproteins and linker proteins, serving as the major light-harvesting complexes that capture and transfer light energy to photosystem II (PSII) and photosystem I (PSI) in cyanobacteria and eukaryotic red algae. In cyanobacteria, a rod-type PBS that does not have a core is specifically connected to PSI by a linker protein CpcL to form a PSI-CpcL-PBS supercomplex. However, the mechanism of CpcL-PBS association to PSI remains unclear. Here, we report the cryoelectron microscopic structures of PSI-CpcL-PBS at 2.98 Å and CpcL-PBS at 2.93 Å resolution from a cyanobacterium sp. PCC 7120, respectively. CpcL-PBS is located on the stromal side of a PSI tetramer and exhibits a structure of three-layered PBS consisting of four linkers (CpcL, CpcC1, CpcC2, PecC) and 18 pairs of phycocyanin αβ monomers. The C-terminal transmembrane helix of CpcL inserts to the membrane and interacts with PsaA, PsaB, and PsaM of PSI at an interface I between two PSI monomers, enabling the formation of the PSI-CpcL-PBS supercomplex. The exact structure of protein subunits and arrangement of bilin and chlorophyll pigments are revealed, which provide a structural basis for the assembly of PSI-CpcL-PBS and possible excitation energy transfer pathways from antennas to PSI within this supercomplex, shedding light on the organization and attachment of CpcL-PBS in cyanobacterial thylakoids. PubMed: 41880560DOI: 10.1073/pnas.2530459123 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (2.93 Å) |
Structure validation
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