Studies on the expression of NDH-H,a subunit of the NAD(P)H-plastoquinone-oxidoreductase of higher-plant chloroplasts |
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Authors: | Susanne Berger Ulrike Ellersiek Peter Westhoff Klaus Steinmüller |
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Institution: | (1) Institut für Entwicklungs- und Molekularbiologie der Pflanzen, Heinrich-Heine-Universität, Universitätsstrasse 1, 1 Düsseldorf, FRG |
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Abstract: | The plastid genomes of higher plants contain eleven reading frames (ndhA-K) that are homologous to genes encoding subunits of the mitochondrial NADH-ubiquinone-oxidoreductase (complex I). The carboxyterminal end of the NDH-H subunit from rice (Oryza sativa L.) was expressed as a fusion protein in Escherichia coli and antibodies against the fusion protein were generated in rabbits. The antibody was used to study the expression of NDH-H, and the following results were obtained: (i) NDH-H is expressed in mono- and dicotyledonous plants, (ii) NDH-H is localized on the stroma lamellae of the thylakoid membrane and (iii) NDH-H is expressed in etioplasts. Together with the finding that two other ndh genes (ndhI and ndhK) are expressed in plastids, these results point to the existence of an NAD(P)H-plastoquinone-oxidoreductase on the thylakoid membrane. The possible function of the enzyme in plastids is discussed and it is suggested that it works in balancing the ATP/ADP and the NADPH/NADP ratios during changing external (i.e. light) or internal (i.e. ATP and NADPH demands of biosynthetic pathways of the plastid) conditions.Abbreviations PVDF
polyvinylidene difluoride
- SDS
sodium dodecyl sulfate
We thank Professor M. Sugiura for the rice plastid DNA clone bank, Oliver Buchholz for Sorghum plastid membranes, Pioneer Hi-Bred Inc. for maize and Sorghum seeds and the Deutsche Forschungsgemeinschaft for financial support (SFB189). |
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Keywords: | NAD(P)H-plastoquinone-oxidoreductase ndhH gene Plastid DNA |
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