title: Structural characterization of a plant photosystem I and NAD(P)H dehydrogenase supercomplex.
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.
authors: Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71, Olomouc, Czech Republic.
authors: Roman
authors: R
authors: Kouřil
authors: Ondřej
authors: O
authors: Strouhal
authors: Lukáš
authors: L
authors: Nosek
authors: René
authors: R
authors: Lenobel
authors: Ivo
authors: I
authors: Chamrád
authors: Egbert J
authors: EJ
authors: Boekema
authors: Marek
authors: M
authors: Šebela
authors: Petr
authors: P
authors: Ilík
mesh_terms: D004579:Electron Transport; D005288:Ferredoxins / Q000378:metabolism; D001467:Hordeum / Q000737:chemistry / Q000201:enzymology* / Q000528:radiation effects; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D008854:Microscopy, Electron; D008958:Models, Molecular; D009243:NAD / Q000378:metabolism; D009252:NADPH Dehydrogenase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D063347:Native Polyacrylamide Gel Electrophoresis; D010084:Oxidation-Reduction; D045331:Photosystem I Protein Complex / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry / Q000201:enzymology / Q000528:radiation effects; D020524:Thylakoids / Q000378:metabolism
chemical_list: D005288:Ferredoxins; D045342:Light-Harvesting Protein Complexes; D045331:Photosystem I Protein Complex; D009243:NAD; D009252:NADPH Dehydrogenase
keywords: Hordeum vulgare; PSI-NDH supercomplex; clear native electrophoresis; cyclic electron transport; single particle electron microscopy