Structural characterization of a plant photosystem I and NAD(P)H dehydrogenase supercomplex |
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Authors: | Lukáš Nosek René Lenobel Ivo Chamrád Egbert J. Boekema Marek Šebela Petr Ilík |
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Affiliation: | 1. Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacky University, , 783 71 Olomouc, Czech Republic;2. Department of Protein Biochemistry and Proteomics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacky University, , 783 71 Olomouc, Czech Republic;3. Electron Microscopy Group, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, , 9747 AG Groningen, The Netherlands |
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Abstract: | Cyclic electron transport (CET) around photosystem I (PSI) plays an important role in balancing the ATP/NADPH ratio and the photoprotection of plants. The NAD(P)H dehydrogenase complex (NDH) has a key function in one of the CET pathways. Current knowledge indicates that, in order to fulfill its role in CET, the NDH complex needs to be associated with PSI; however, until now there has been no direct structural information about such a supercomplex. Here we present structural data obtained for a plant PSI–NDH supercomplex. Electron microscopy analysis revealed that in this supercomplex two copies of PSI are attached to one NDH complex. A constructed pseudo‐atomic model indicates asymmetric binding of two PSI complexes to NDH and suggests that the low‐abundant Lhca5 and Lhca6 subunits mediate the binding of one of the PSI complexes to NDH. On the basis of our structural data, we propose a model of electron transport in the PSI–NDH supercomplex in which the association of PSI to NDH seems to be important for efficient trapping of reduced ferredoxin by NDH. |
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Keywords: | clear native electrophoresis
Hordeum vulgare
single particle electron microscopy PSI– NDH supercomplex cyclic electron transport |
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