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Title | Cryo-EM captures the coordination of asymmetric electron transfer through a di-copper site in DPOR. |
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Journal, issue, pages | Nat Commun, Vol. 16, Issue 1, Page 3866, Year 2025 |
Publish date | Apr 24, 2025 |
![]() | Rajnandani Kashyap / Natalie Walsh / Jaigeeth Deveryshetty / Monika Tokmina-Lukaszewska / Kewei Zhao / Yunqiao J Gan / Brian M Hoffman / Ritimukta Sarangi / Brian Bothner / Brian Bennett / Edwin Antony / ![]() |
PubMed Abstract | Enzymes that catalyze long-range electron transfer (ET) reactions often function as higher order complexes that possess two structurally symmetrical halves. The functional advantages for such an ...Enzymes that catalyze long-range electron transfer (ET) reactions often function as higher order complexes that possess two structurally symmetrical halves. The functional advantages for such an architecture remain a mystery. Using cryoelectron microscopy we capture snapshots of the nitrogenase-like dark-operative protochlorophyllide oxidoreductase (DPOR) during substrate binding and turnover. DPOR catalyzes reduction of the C17 = C18 double bond in protochlorophyllide during the dark chlorophyll biosynthetic pathway. DPOR is composed of electron donor (L-protein) and acceptor (NB-protein) component proteins that transiently form a complex in the presence of ATP to facilitate ET. NB-protein is an αβ heterotetramer with two structurally identical halves. However, our structures reveal that NB-protein becomes functionally asymmetric upon substrate binding. Asymmetry results in allosteric inhibition of L-protein engagement and ET in one half. Residues that form a conduit for ET are aligned in one half while misaligned in the other. An ATP hydrolysis-coupled conformational switch is triggered once ET is accomplished in one half. These structural changes are then relayed to the other half through a di-nuclear copper center at the tetrameric interface of the NB-protein and leads to activation of ET and substrate reduction. These findings provide a mechanistic blueprint for regulation of long-range electron transfer reactions. |
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Methods | EM (single particle) |
Resolution | 2.7 - 3.82 Å |
Structure data | EMDB-43443, PDB-8vqh: EMDB-43444, PDB-8vqi: EMDB-43446, PDB-8vqj: EMDB-44913, PDB-9buo: EMDB-47669, PDB-9e7h: EMDB-47980, PDB-9efu: |
Chemicals | ![]() ChemComp-SF4: ![]() ChemComp-CU: ![]() ChemComp-HOH: ![]() ChemComp-PMR: ![]() ChemComp-MG: |
Source |
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![]() | OXIDOREDUCTASE / Plant Protein / Electron Transfer Enzymes / Photosynthesis |