9HYU
Cryo-EM structure of the Chromera velia PSI supercomplex at 1.84 Angstrom resolution
This is a non-PDB format compatible entry.
Summary for 9HYU
| Entry DOI | 10.2210/pdb9hyu/pdb |
| EMDB information | 52518 |
| Descriptor | Superoxide dismutase [Fe], Photosystem I protein (PsaM), Photosystem I protein (PsaR), ... (36 entities in total) |
| Functional Keywords | photosynthesis, photosystem i, psi-fcp complex, chrome velia, cryo-em. |
| Biological source | Chromera velia More |
| Total number of polymer chains | 19 |
| Total formula weight | 826448.78 |
| Authors | Yuan, X.,Qian, P.,Sobotka, R.,Naschberger, A. (deposition date: 2025-01-10, release date: 2026-01-28, Last modification date: 2026-03-18) |
| Primary citation | Yuan, X.,Lukes, M.,Qian, P.,Charras, Q.,Smrcka, T.,Man, P.,Kovarova, L.,Konik, P.,Heilmann, E.,Al-Amoudi, A.,Sobotka, R.,Naschberger, A. The cryo-EM structure of Photosystem I from Chromera velia with a bound superoxide dismutase heterodimer. Nat Commun, 17:913-913, 2025 Cited by PubMed Abstract: Photosystem I is a key component of the solar energy conversion machinery in oxygenic photosynthesis, and its core, where photochemistry occurs, is highly conserved. However, the coral-associated alga Chromera velia that is evolutionary linked to parasitic apicomplexans, exhibits Photosystem I with unusual features. These include the splitting of the central PsaA subunit and the binding of superoxide dismutases as regular subunits. The organization of such a unique Photosystem I was enigmatic. Here, we present the cryo-EM structure of Chromera velia Photosystem I at 1.84 Å resolution. Our work reveals a superoxide dismutase heterodimer bound to the stromal side of the core, stabilized by extensions of canonical subunits, a novel protein PsaV, and a reduced light-harvesting apparatus. We elucidate how the complex evolved to accommodate the superoxide dismutase, assemble the split PsaA, and integrate antenna proteins in a non-canonical orientation. Based on our data and prior physiological data, we propose that this specialized Photosystem I functions likely as an Mehler machine, redirecting electrons from Photosystem II back to water. This mechanism enables Chromera velia to manage redox imbalance and reduce photorespiration through localized oxygen consumption. PubMed: 41423677DOI: 10.1038/s41467-025-67637-0 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (1.84 Å) |
Structure validation
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