Structure of the complex I-like molecule NDH of oxygenic photosynthesis
| Autor: | Thomas G. Laughlin, David F. Savage, Andrew N. Bayne, Jean-François Trempe, Karen M. Davies |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
0106 biological sciences
0301 basic medicine Models Molecular Plastoquinone Coenzymes Photosystem I Photosynthesis Cyanobacteria 01 natural sciences Models Biological Electron Transport 03 medical and health sciences chemistry.chemical_compound Electron transfer Adenosine Triphosphate Oxidoreductase Amino Acid Sequence NADH dehydrogenase complex chemistry.chemical_classification Multidisciplinary Binding Sites Electron Transport Complex I Photosystem I Protein Complex Cryoelectron Microscopy NADPH Dehydrogenase Electron transport chain Oxygen Protein Subunits 030104 developmental biology chemistry Thylakoid Biophysics Ferredoxins Oxidation-Reduction 010606 plant biology & botany |
| Zdroj: | Nature. 566(7744) |
| ISSN: | 1476-4687 |
| Popis: | Cyclic electron flow around photosystem I (PSI) is a mechanism by which photosynthetic organisms balance the levels of ATP and NADPH necessary for efficient photosynthesis1,2. NAD(P)H dehydrogenase-like complex (NDH) is a key component of this pathway in most oxygenic photosynthetic organisms3,4 and is the last large photosynthetic membrane-protein complex for which the structure remains unknown. Related to the respiratory NADH dehydrogenase complex (complex I), NDH transfers electrons originating from PSI to the plastoquinone pool while pumping protons across the thylakoid membrane, thereby increasing the amount of ATP produced per NADP+ molecule reduced4,5. NDH possesses 11 of the 14 core complex I subunits, as well as several oxygenic-photosynthesis-specific (OPS) subunits that are conserved from cyanobacteria to plants3,6. However, the three core complex I subunits that are involved in accepting electrons from NAD(P)H are notably absent in NDH3,5,6, and it is therefore not clear how NDH acquires and transfers electrons to plastoquinone. It is proposed that the OPS subunits—specifically NdhS—enable NDH to accept electrons from its electron donor, ferredoxin3–5,7. Here we report a 3.1 A structure of the 0.42-MDa NDH complex from the thermophilic cyanobacterium Thermosynechococcus elongatus BP-1, obtained by single-particle cryo-electron microscopy. Our maps reveal the structure and arrangement of the principal OPS subunits in the NDH complex, as well as an unexpected cofactor close to the plastoquinone-binding site in the peripheral arm. The location of the OPS subunits supports a role in electron transfer and defines two potential ferredoxin-binding sites at the apex of the peripheral arm. These results suggest that NDH could possess several electron transfer routes, which would serve to maximize plastoquinone reduction and avoid deleterious off-target chemistry of the semi-plastoquinone radical. The structure of NDH, a photosynthetic membrane-protein complex that is related to respiratory complex I, is obtained by single-particle cryo-electron microscopy. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full text from SpringerLink