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The protein Bax Inhibitor-1 (BI-1) has recently emerged as a negative regulator of plant programmed cell death (PCD), but how it functions at the biochemical level remains unknown. To elucidate its regulation and mode of action, we used suspension cells of Nicotiana tabacum to study the effects of cytokinins (CKs) on the expression level of NtBI-1 via western analysis. We found that the NtBI-1 protein...
The NADPH-oxidase complex of phagocytic cells plays a key role in the defense against invading pathogens, through the release of superoxide anion, precursor of other reactive oxygen species (ROS). NADPH-oxidase deficiency is called Chronic Granulomatous Disease (CGD), in which patients suffer from recurrent infections and from the formation of granulomas in various organs. Research on NADPH-oxidase...
Transport catalysis is analysed in terms of the “induced transition fit” (ITF) concept. The essentials of ITF are briefly elucidated, emphasizing the difference of substrate–protein interactions between enzymes and carriers exemplified by the paradigm ADP/ATP carrier (AAC). Two of the numerous applications of the ITF are discussed in more detail: unidirectional passive and active transport and the...
In most cancer cells, the ATP necessary for survival and proliferation is derived from glycolysis rather than from oxidative phosphorylations (OXPHOS) even when oxygen supply would be adequate to sustain them. This phenomenon, named “aerobic glycolysis” by Warburg many years ago, can now be explained by a mechanism up-regulating the expression of genes involved in glucose transport, glucose metabolism,...
NOX5 is a ROS-generating NADPH oxidase which contains an N-terminal EF-hand region and can be activated by cytosolic Ca 2+ elevations. However the C-terminal region of NOX5 also contains putative phosphorylation sites. In this study we used HEK cells stably expressing NOX5 to analyze the size and subcellular localization of the NOX5 protein, its mechanisms of activation, and the characteristics...
Leukocyte recruitment to sites of inflammation and infection is dependent on the presence of a gradient of locally produced chemotactic factors. This review is focused on current knowledge about the activation and regulation of chemoattractant receptors. Emphasis is placed on the members of the N-formyl peptide receptor family, namely FPR (N-formyl peptide receptor), FPRL1 (FPR like-1) and FPRL2 (FPR...
Proteins of the mitochondrial carrier family (MCF) mediate the transport of a large range of compounds, including metabolites and cofactors. They are localized mainly in the inner mitochondrial membrane, except for a few members found in the membranes of peroxisomes. Similarity searches among Dictyostelium discoideum protein sequences identified a total of 31 MCF members. All these are membrane proteins...
Genetic expression versus plasmidic overexpression of a functional recombinant fusion protein combining the yeast Saccharomyces cerevisiae mitochondrial ADP/ATP carrier (Anc2p) and the iso-1-cytochrome c (Cyc1p) has been investigated, with the main aim of increasing the polar surface of the carrier to improve its crystallization properties. The gene encoding the his6-tagged fusion protein was expressed...
Over the past decade, the capacity of non-phagocytic cells to produce superoxide has been largely documented. As in the case of the well-characterized phagocytic cells context, superoxide formation in non-phagocytic cells depends on the activity of membrane bound NADPH oxidase enzymes. Six mammalian homologues of the classical phagocytic Nox2 enzyme have been described to date, named Nox1, Nox3, Nox4,...
The inner mitochondrial membrane (IMM) is structured in cristae, which contributes to the best functioning of ions and adenylates exchange between the matrix and the intermembrane space. The central hypothesis of this paper is that the cristae structure favours a minimal mean free path of adenylates between translocation sites (translocase/ANT sites) and metabolic sites (ATPase sites). We propose...
Cytochrome b 558 is the catalytic core of the phagocyte NADPH oxidase that mediates the production of bactericidal reactive oxygen species. Cytochrome b 558 is formed by two subunits gp91-phox and p22-phox (1/1), non-covalently associated. Its activation depends on the interaction with cytosolic regulatory proteins (p67-phox, p47-phox, p40-phox and Rac) leading to an electron transfer...
The superoxide-producing phagocyte NADPH oxidase gp91 phox /Nox2 and the non-phagocytic oxidases Nox1 and Nox3 each form a complex in the membrane with p22 phox , which provides both stabilization and a docking site for organizer proteins. The p22 phox -complexed Nox2 and Nox1 are dormant on their own, and their activation requires soluble supportive proteins such as a Nox...
NOX family NADPH oxidases are enzymes whose biological function is electron transport and the generation of reactive oxygen species (ROS). NOX enzymes in mammalian organisms have received most attention. However, NOX enzymes are widely distributed in different kingdoms of life. While they are not found in prokaryotes and most unicellular eukaryotes, they are present in fungi, plants, and animals....
MicroRNAs are small non-coding RNAs that are now recognised as key regulators of gene expression in eukaryotes. Over the past few years, hundreds of miRNAs have been identified from various organisms including vertebrates, nematodes, insects and plants. A high level of conservation of some miRNAs from animals to plants underlines their crucial role in eukaryotes. Although biogenesis and mode of action...
Ribozymes are catalytic RNAs that possess the property of cutting an RNA target via site-specific cleavage after sequence-specific recognition. Ribozymes can moreover cleave multiple substrate molecules. An increasing number of studies show that ribozymes are particularly well adapted tools against cancer, silencing or down-regulating gene expression at the RNA level. We have constructed an adenine-dependent...
HIV-1 reverse transcriptase uses the host tRNA 3Lys as a primer for the synthesis of the minus DNA strand. The first event in viral replication is thus the annealing of tRNA to the primer binding site (PBS) in the 5′ UTR of the viral RNA. This event requires a major RNA rearrangement which is chaperoned by the viral NC protein. The binding of NC to nucleic acids is essentially non-specific,...
The universally conserved endoribonuclease P consists of one RNA subunit and, depending on its origin, a variable number of protein subunits. RNase P is involved in the processing of a large variety of substrates in the cell, the preferred substrate being tRNA precursors. Cleavage activity does not require the presence of the protein subunit(s) in vitro. This is true for both prokaryotic and eukaryotic...
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