Ubiquinone Oxidoreductase (ubiquinone + oxidoreductase)

Distribution by Scientific Domains

Selected Abstracts

The Design and Synthesis of Novel Inhibitors of NADH:Ubiquinone Oxidoreductase.

CHEMINFORM, Issue 17 2004
Stephen D. Lindell
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Isolation and structural characterization of the Ndh complex from mesophyll and bundle sheath chloroplasts of Zea mays

FEBS JOURNAL, Issue 11 2005
Costel C. Darie
Complex I (NADH: ubiquinone oxidoreductase) is the first complex in the respiratory electron transport chain. Homologs of this complex exist in bacteria, mitochondria and chloroplasts. The minimal complex I from mitochondria and bacteria contains 14 different subunits grouped into three modules: membrane, connecting, and soluble subcomplexes. The complex I homolog (NADH dehydrogenase or Ndh complex) from chloroplasts from higher plants contains genes for two out of three modules: the membrane and connecting subcomplexes. However, there is not much information about the existence of the soluble subcomplex (which is the electron input device in bacterial complex I) in the composition of the Ndh complex. Furthermore, there are contrasting reports regarding the subunit composition of the Ndh complex and its molecular mass. By using blue native (BN)/PAGE and Tricine/PAGE or colorless-native (CN)/PAGE, BN/PAGE and Tricine/PAGE, combined with mass spectrometry, we attempted to obtain more information about the plastidal Ndh complex from maize (Zea mays). Using antibodies, we detected the expression of a new ndh gene (ndhE) in mesophyll (MS) and bundle sheath (BS) chloroplasts and in ethioplasts (ET). We determined the molecular mass of the Ndh complex (550 kDa) and observed that it splits into a 300 kDa membrane subcomplex (containing NdhE) and a 250 kDa subcomplex (containing NdhH, -J and -K). The Ndh complex forms dimers at 1000,1100 kDa in both MS and BS chloroplasts. Native/PAGE of the MS and BS chloroplasts allowed us to determine that the Ndh complex contains at least 14 different subunits. The native gel electrophoresis, western blotting and mass spectrometry allowed us to identify five of the Ndh subunits. We also provide a method that allows the purification of large amounts of Ndh complex for further structural, as well as functional studies. [source]

Neuronal expression of a single-subunit yeast NADH,ubiquinone oxidoreductase (Ndi1) extends Drosophila lifespan

AGING CELL, Issue 2 2010
Sepehr Bahadorani
Summary The ,rate of living' theory predicts that longevity should be inversely correlated with the rate of mitochondrial respiration. However, recent studies in a number of model organisms, including mice, have reported that interventions that retard the aging process are, in fact, associated with an increase in mitochondrial activity. To better understand the relationship between energy metabolism and longevity, we supplemented the endogenous respiratory chain machinery of the fruit fly Drosophila melanogaster with the alternative single-subunit NADH,ubiquinone oxidoreductase (Ndi1) of the baker's yeast Saccharomyces cerevisiae. Here, we report that expression of Ndi1 in fly mitochondria leads to an increase in NADH,ubiquinone oxidoreductase activity, oxygen consumption, and ATP levels. In addition, exogenous Ndi1 expression results in increased CO2 production in living flies. Using an inducible gene-expression system, we expressed Ndi1 in different cells and tissues and examined the impact on longevity. In doing so, we discovered that targeted expression of Ndi1 in fly neurons significantly increases lifespan without compromising fertility or physical activity. These findings are consistent with the idea that enhanced respiratory chain activity in neuronal tissue can prolong fly lifespan. [source]

In Vivo Labeling of Mitochondrial Complex I (NADH:UbiquinoneOxidoreductase) in Rat Brain Using [3H]Dihydrorotenone

Deepa J. Talpade
Abstract: Defects in mitochondrial energy metabolism have beenimplicated in several neurodegenerative disorders. Defective complex I(NADH:ubiquinone oxidoreductase) activity plays a key role in Leber'shereditary optic neuropathy and, possibly, Parkinson's disease, but there isno way to assess this enzyme in the living brain. We previously described anin vitro quantitative autoradiographic assay using[3H]dihydrorotenone ([3H]DHR) binding to complex I. Wehave now developed an in vivo autoradiographic assay for complex I using[3H]DHR binding after intravenous administration. In vivo[3H]DHR binding was regionally heterogeneous, and brain uptake wasrapid. Binding was enriched in neurons compared with glia, and white matterhad the lowest levels of binding. In vivo [3H]DHR binding wasmarkedly reduced by local and systemic infusion of rotenone and was enhancedby local NADH administration. There was an excellent correlation betweenregional levels of in vivo [3H]DHR binding and the in vitroactivities of complex II (succinate dehydrogenase) and complex IV (cytochromeoxidase), suggesting that the stoichiometry of these components of theelectron transport chain is relatively constant across brain regions. Theability to assay complex I in vivo should provide a valuable tool toinvestigate the status of this mitochondrial enzyme in the living brain andsuggests potential imaging techniques for complex I in humans. [source]

The RprY response regulator of Porphyromonas gingivalis

Ana E. Duran-Pinedo
Summary Porphyromonas gingivalis is a Gram-negative oral anaerobe associated with chronic adult periodontitis. Its ecological niche is the gingival crevice, where the organism adapts to the challenges of the infectious process such as host defence and bacterial products. Bacterial responses to environmental changes are partly regulated by two-component signal transduction systems. Several intact systems were annotated in the genome of P. gingivalis, as well as an orphan regulator encoding a homologue of RprY, a response regulator from Bacteroides fragilis. With the goal of defining the environmental cues that activate RprY in P. gingivalis, we used several strategies to identify its regulon. Results from gene expression and DNA,protein binding assays identified target genes that were either involved in transport functions or associated with oxidative stress, and indicated that RprY can act as an activator and a repressor. RprY positively activated the primary sodium pump, NADH : ubiquinone oxidoreductase (NQR), and RprY protein also interacted with the promoter regions of nqrA genes from B. fragilis and Vibrio cholerae. Given that gingival bleeding and infiltration of host defence cells are symptoms of periodontal infection, iron products released from blood and reactive oxygen species from polymorphonuclear leucocytes may be potential inducers of the RprY regulon. [source]