The plastid ndh genes code for an NADH-specific dehydrogenase: Isolation of a complex I analogue from pea thylakoid membranes Journal Article

Author(s): Sazanov, Leonid A; Burrows, Paul A; Nixon, Peter J
Article Title: The plastid ndh genes code for an NADH-specific dehydrogenase: Isolation of a complex I analogue from pea thylakoid membranes
Abstract: The plastid genomes of several plants contain ndh genes-homologues of genes encoding subunits of the proton-pumping NADH:ubiquinone oxidoreductase, or complex I, involved in respiration in mitochondria and eubacteria. From sequence similarities with these genes, the ndh gene products have been suggested to form a large protein complex (Ndh complex); however, the structure and function of this complex remains to be established. Herein we report the isolation of the Ndh complex from the chloroplasts of the higher plant Pisum sativum. The purification procedure involved selective solubilization of the thylakoid membrane with dodecyl maltoside, followed by two anion-exchange chromatography steps and one size-exclusion chromatography step. The isolated Ndh complex has an apparent total molecular mass of approximately 550 kDa and according to SDS/PAGE consists of at least 16 subunits including NdhA, NdhI, NdhJ, NdhK, and NdhH, which were identified by N-terminal sequencing and immunoblotting. The Ndh complex showed an NADH- and deamino-NADH-specific dehydrogenase activity, characteristic of complex I, when either ferricyanide or the quinones menadione and duroquinone were used as electron acceptors. This study describes the isolation of the chloroplast analogue of the respiratory complex I and provides direct evidence for the function of the plastid Ndh complex as an NADH:plastoquinone oxidoreductase. Our results are compatible with a dual role for the Ndh complex in the chloro-respiratory and cyclic photophosphorylation pathways.
Keywords: priority journal; pea; Chloroplast; oxidoreductase; reduced nicotinamide adenine dinucleotide amino terminal sequence; conference paper; enzyme isolation; gene isolation; mitochondrial respiration; plastid; protein purification; proton transport; solubilization; structure activity relation; thylakoid membrane
Journal Title: PNAS
Volume: 95
Issue 3
ISSN: 1091-6490
Publisher: National Academy of Sciences  
Date Published: 1998-02-03
Start Page: 1319
End Page: 1324
Sponsor: This work was supported by grants from The Royal Society and the Biotechnology and Biological Sciences Research Council.
DOI: 10.1073/pnas.95.3.1319
Open access: no