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Université de Fribourg

Non-canonical eukaryotic glutaminyl- and glutamyl-tRNA synthetases form mitochondrial aminoacyl-tRNA in Trypanosoma brucei

Rinehart, Jesse ; Horn, Elke K. ; Wei, David ; Söll, Dieter ; Schneider, André

In: Journal of Biological Chemistry, 2004, vol. 279, p. 1161-1166

Glutaminyl-tRNA synthetase is thought to be absent from organelles. Instead, Gln-tRNA is formed via the transamidation pathway, the other route to this essential compound in protein biosynthesis. However, it was previously shown that glutaminyl-tRNA synthetase activity is present in Leishmania mitochondria. This work identifies genes encoding glutaminyl- and glutamyl-tRNA synthetase in the...

Université de Fribourg

Mitochondrial tRNA import in Toxoplasma gondii

Crausaz Esseiva, Anne ; Naguleswaran, Arunasalam ; Hemphill, Andrew ; Schneider, André

In: Journal of Biological Chemistry, 2004, vol. 279, p. 42363-42368

Apicomplexan parasites have the smallest known mitochondrial genome. It consists of a repeated element of ~6–7 kb in length and encodes three mitochondrial proteins, a number of rRNA fragments, but no tRNAs. It has therefore been postulated that in apicomplexans all tRNAs required for mitochondrial translation are imported from the cytosol. To provide direct evidence for this process we have...

Université de Fribourg

Temporal dissection of Bax-induced events leading to fission of the single mitochondrion in Trypanosoma brucei

Crausaz Esseiva, Anne ; Chanez, Anne-Laure ; Bochud-Allemann, Natacha ; Martinou, Jean-Claude ; Hemphill, Andrew ; Schneider, André

In: EMBO reports, 2004, vol. 5, p. 268-273

The protozoan Trypanosoma brucei has a single mitochondrion and lacks an apoptotic machinery. Here we show that expression of the proapoptotic protein Bax in T. brucei causes the release of cytochrome c, the depolarization of the mitochondrial membrane potential and mitochondrial fission. However, in contrast to mammalian cells, the three events are temporally well separated. The release of...

Université de Fribourg

Multiple genetic pathways involving the Caenorhabditis elegans Bloom's syndrome genes him-6, rad-51, and top-3 are needed to maintain genome stability in the germ line

Wicky, Chantal ; Alpi, Arno ; Passannante, Myriam ; Rose, Ann ; Gartner, Anton ; Müller, Fritz

In: Molecular and Cellular Biology, 2004, vol. 24, p. 5016-5027

Bloom's syndrome (BS) is an autosomal-recessive human disorder caused by mutations in the BS RecQ helicase and is associated with loss of genomic integrity and an increased incidence of cancer. We analyzed the mitotic and the meiotic roles of Caenorhabditis elegans him-6, which we show to encode the ortholog of the human BS gene. Mutations in him-6 result in an enhanced irradiation sensitivity, a...

Université de Fribourg

Covariation of mitochondrial genome size with gene lengths: evidence for gene length reduction during mitochondrial evolution

Schneider, André ; Ebert, Dieter

In: Journal of Molecular Evolution, 2004, vol. 59, p. 90-96

Reduction of genome size and gene shortening have been observed in a number of parasitic and mutualistic intracellular symbionts. Reduction of coding capacity is also a unifying principle in the evolutionary history of mitochondria, but little is known about the evolution of gene length in mitochondria. The genes for cytochrome c oxidase subunits I–III, cytochrome b, and the large and small...

Université de Fribourg

The Caenorhabditis elegans ortholog of C21orf80, a potential new protein O-fucosyltransferase, is required for normal development

Menzel, Olivier ; Vellai, Tibor ; Takacs-Vellai, Krisztina ; Reymond, Alexandre ; Müller, Fritz ; Antonarakis, Stylianos E. ; Guipponi, Michel

In: Genomics, 2004, vol. 84, p. 320-330

Down syndrome (DS), as a phenotypic result of trisomy 21, is the most frequent aneuploidy at birth and the most common known genetic cause of mental retardation. DS is also characterized by other phenotypes affecting many organs, including brain, muscle, heart, limbs, gastrointestinal tract, skeleton, and blood. Any of the human chromosome 21 (Hsa21) genes may contribute to some of the DS...

Université de Fribourg

Chromatin diminution leads to rapid evolutionary changes in the organization of the germ line genomes of the parasitic nematodes A. suum and P. univalens

Bachmann-Waldmann, Christa ; Jentsch, Stephan ; Tobler, Heinz ; Müller, Fritz

In: Molecular and Biochemical Parasitology, 2004, vol. 134, p. 53-64

Chromatin diminution in the parasitic nematodes Ascaris suum and Parascaris univalens represents a rather complex molecular phenomenon that includes chromosomal breakage, DNA degradation and new telomere formation. At a given elimination site, DNA breakage and new telomere addition does not take place at a single chromosomal locus but at many different places within a several kilobase long...

Université de Fribourg

Integration of complex larval chemosensory organs into the adult nervous system of Drosophila

Gendre, Nanaë ; Lüer, Karin ; Friche, Sandrine ; Grillenzoni, Nicola ; Ramaekers, Ariane ; Technau, Gerhard M. ; Stocker, Reinhard F.

In: Development, 2004, vol. 131, p. 83-92

The sense organs of adult Drosophila, and holometabolous insects in general, derive essentially from imaginal discs and hence are adult specific. Experimental evidence presented here, however, suggests a different developmental design for the three largely gustatory sense organs located along the pharynx. In a comprehensive cellular analysis, we show that the posteriormost of the three organs...

Université de Fribourg

The T-stem determines the cytosolic or mitochondrial localization of trypanosomal tRNAsMet

Crausaz Esseiva, Anne ; Maréchal-Drouard, Laurence ; Cosset, Anne ; Schneider, André

In: Molecular Biology of the Cell, 2004, vol. 15, p. 2750-2757

The mitochondrion of Trypanosoma brucei lacks tRNA genes. Organellar translation therefore depends on import of cytosolic, nucleus-encoded tRNAs. Except for the cytosol-specific initiator tRNAMet, all trypanosomal tRNAs function in both the cytosol and the mitochondrion. The initiator tRNAMet is closely related to the imported elongator tRNAMet. Thus, the distinct localization of the two tRNAsMet...

Université de Fribourg

Expression of a major surface protein of Trypanosoma brucei insect forms is controlled by the activity of mitochondrial enzymes

Vassella, Erik ; Probst, Matthias ; Schneider, André ; Studer, Erwin ; Kunz Renggli, Christina ; Roditi, Isabel

In: Molecular Biology of the Cell, 2004, vol. 15, p. 3986-3993

In cycling between the mammalian host and the tsetse fly vector, trypanosomes undergo major changes in energy metabolism and surface coat composition. Early procyclic (insect) forms in the tsetse fly midgut are coated by glycoproteins known as EP and GPEET procyclins. EP expression continues in late procyclic forms, whereas GPEET is down-regulated. In culture, expression of GPEET is modulated by...