| Structural highlights
9lzj is a 30 chain structure with sequence from Thermosynechococcus vestitus BP-1. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
| | Method: | Electron Microscopy, Resolution 3.4Å |
| Ligands: | , , , , , , , |
| Resources: | FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT |
Function
PSAA_THEVB PsaA and PsaB bind P700, the primary electron donor of photosystem I (PSI), as well as the electron acceptors A0, A1 and FX. PSI is a plastocyanin/cytochrome c6-ferredoxin oxidoreductase, converting photonic excitation into a charge separation, which transfers an electron from the donor P700 chlorophyll pair to the spectroscopically characterized acceptors A0, A1, FX, FA and FB in turn. Oxidized P700 is reduced on the lumenal side of the thylakoid membrane by plastocyanin or cytochrome c6.[1] [2] [3] [4]
Publication Abstract from PubMed
Iron-limitation is a common stress factor in natural environments. To survive under iron-starved conditions, cyanobacteria overexpress iron stress-induced protein A (IsiA), which is crucial for light-harvesting and photoprotection. Multiple IsiA proteins form a single- or double-layered architecture encircling the photosystem I (PSI) core, forming various PSI-IsiA supercomplexes. The assembly and energy transfer mechanisms of double-layered PSI-IsiA supercomplexes remain unelucidated. Here, we present high-resolution structures of two PSI-IsiA supercomplexes isolated from the cyanobacterium Thermosynechococcus elongatus BP-1 cultured under iron-starved conditions. The PSI(3)-IsiA(43) complex contains a trimeric PSI core surrounded by 43 IsiA subunits assembled into a closed double-ring. The PSI(1)-IsiA(13) complex contains 13 IsiA proteins arranged in a double-layered architecture attached to the monomeric PSI core. Atomic force microscopy demonstrates the presence and distribution of different PSI-IsiA complexes within native thylakoid membranes isolated from iron-starved cells. Our findings provide insights into the structural variability and adaptive mechanisms of PSI-IsiA complexes.
Structural basis for the assembly and energy transfer between the cyanobacterial PSI core and the double-layered IsiA proteins.,Si L, Zhang Y, Su X, Zhao X, An X, Liu LN, Cao P, Li M Nat Commun. 2025 Dec 20. doi: 10.1038/s41467-025-67295-2. PMID:41422266[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Klukas O, Schubert WD, Jordan P, Krauss N, Fromme P, Witt HT, Saenger W. Photosystem I, an improved model of the stromal subunits PsaC, PsaD, and PsaE. J Biol Chem. 1999 Mar 12;274(11):7351-60. PMID:10066799
- ↑ Klukas O, Schubert WD, Jordan P, Krau N, Fromme P, Witt HT, Saenger W. Localization of two phylloquinones, QK and QK', in an improved electron density map of photosystem I at 4-A resolution. J Biol Chem. 1999 Mar 12;274(11):7361-7. PMID:10066800
- ↑ Jordan P, Fromme P, Witt HT, Klukas O, Saenger W, Krauss N. Three-dimensional structure of cyanobacterial photosystem I at 2.5 A resolution. Nature. 2001 Jun 21;411(6840):909-17. PMID:11418848 doi:10.1038/35082000
- ↑ Krauss N, Schubert WD, Klukas O, Fromme P, Witt HT, Saenger W. Photosystem I at 4 A resolution represents the first structural model of a joint photosynthetic reaction centre and core antenna system. Nat Struct Biol. 1996 Nov;3(11):965-73. PMID:8901876
- ↑ Si L, Zhang Y, Su X, Zhao X, An X, Liu LN, Cao P, Li M. Structural basis for the assembly and energy transfer between the cyanobacterial PSI core and the double-layered IsiA proteins. Nat Commun. 2025 Dec 20. PMID:41422266 doi:10.1038/s41467-025-67295-2
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