References of "Degand, Hervé"
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See detailAtypical composition and structure of the mitochondrial dimeric ATP synthase from Euglena gracilis
Miranda Astudillo, Héctor Vicente ULiege; Yadav, Sathish; Colina-Tenorio, Lilia et al

Poster (2017, September 21)

Mitochondrial respiratory-chain complexes fromEuglenozoa comprise classical subunits described in other eukaryotes (i.e. mammals and fungi) and subunits that are restricted to Euglenozoa (e.g. Euglena ... [more ▼]

Mitochondrial respiratory-chain complexes fromEuglenozoa comprise classical subunits described in other eukaryotes (i.e. mammals and fungi) and subunits that are restricted to Euglenozoa (e.g. Euglena gracilis and Trypanosoma brucei). Herewe studied the mitochondrial F1FO-ATP synthase (or Complex V) fromthe photosynthetic eukaryote E. gracilis in detail. The enzymewas purified by a two-step chromatographic procedure and its subunit compositionwas resolved by a three-dimensional gel electrophoresis (BN/SDS/SDS).Twenty-two different subunits were identified by mass-spectrometry analyses amongwhich the canonical α, β, γ, δ, ε, and OSCP subunits, and at least seven subunits previously found in Trypanosoma. The ADP/ATP carrierwas also associated to the ATP synthase into a dimericATP synthasome. Single-particle analysis by transmission electron microscopy of the dimeric ATP synthase indicated that the structures of both the catalytic and central rotor parts are conserved while other structural features are original. These new features include a large membrane-spanning re- gion joining the monomers, an external peripheral stalk and a structure that goes through the membrane and reaches the inter membrane space below the c-ring, the latter having not been reported for any mitochondrial F-ATPase. [less ▲]

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See detailNon-classical structures and association of the OXPHOS complexes in Euglena gracilis and Polytomella sp.
Miranda Astudillo, Héctor Vicente ULiege; Yadav, Sathish; Colina-Tenorio, Lilia et al

Poster (2017, September 21)

To date, the idea that the OXPHOS complexes can associate with each other in larger structures named supercomplexes [1] is generally accepted. This association can allow a more efficient transport of ... [more ▼]

To date, the idea that the OXPHOS complexes can associate with each other in larger structures named supercomplexes [1] is generally accepted. This association can allow a more efficient transport of electrons to minimize the generation of reactive oxygen species during electron transfer reactions and can also be involved in the regulation of the mitochondrial metabolism in response to different stimuli, carbon sources or stress conditions. Recently, the arising studies outside the classical models yeast and bovine mitochondria brought to light many unusual characteristics in the ATP synthase from a wide variety of organisms. Due to this, the dimer nature of the mitochondrial ATP synthase is no longer a matter of debate. Given the large structural differences among the peripheral stator and dimerization modules of mitochondrial ATP synthases described so far, it is of relevance to study a wider number of species to gain insight into the structural diversity of their OXPHOS complexes. Recently, our group showed that at least 41 of the non-canonical subunits reported in trypanosomes are also present in Euglena complexes along with 48 classical subunits described in other eukaryotes including green plants [2]. Further purification of the complexes I, III, IV and V by liquid chromatography after solubilization with n-β-dodecyl-maltoside and the subsequent analysis by single-particle analysis from transmission electron microscopy revealed some unusual features in Euglena respiratory complexes. In the case of complex V the structures of both the catalytic and central rotor parts are conserved while other structural features are original, including a large membrane-spanning region joining the monomers, an external peripheral stalk and a structure that goes through the membrane and reaches the inter membrane space below the c-ring [3]. Complex I also shows an unusually long matricial arm. Complex IV shows an atypical shape compared to that of the bovine one. An unusual association between complexes I and V can be observed when the membranes are extracted with the mild detergent digitonin. Other case of atypical subunit composition is the complex V of chlorophycean algae. Each monomer of the enzyme has 17 polypeptides, eight of which are the conserved, main functional components, and nine polypeptides (Asa1 to Asa9) unique to this lineage that form the robust peripheral stalk in this complex [4]. This complex presents highly stable dimeric and tetrameric structures, and the respiratory complexes have an unusual capacity to reassociate in vitro and restore the functional respirasome. [less ▲]

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See detailAtypical composition and structure of the mitochondrial dimeric ATP synthase from Euglena gracilis
Yadav, K.N. Sathish; Miranda Astudillo, Héctor Vicente ULiege; Colina-Tenorio, Lili et al

in Biochimica et Biophysica Acta-Bioenergetics (2017), 1858(4), 267-275

Mitochondrial respiratory-chain complexes from Euglenozoa comprise classical subunits described in other eukaryotes (i.e. mammals and fungi) and subunits that are restricted to Euglenozoa (e.g. Euglena ... [more ▼]

Mitochondrial respiratory-chain complexes from Euglenozoa comprise classical subunits described in other eukaryotes (i.e. mammals and fungi) and subunits that are restricted to Euglenozoa (e.g. Euglena gracilis and Trypanosoma brucei). Here we studied the mitochondrial F1FO-ATP synthase (or Complex V) from the photosynthetic eukaryote E. gracilis in detail. The enzyme was purified by a two-step chromatographic procedure and its subunit composition was resolved by a three-dimensional gel electrophoresis (BN/SDS/SDS). Twenty-two different subunits were identified by mass-spectrometry analyses among which the canonical alpha, beta, gamma, delta, epsilon and OSCP subunits, and at least seven subunits previously found in Trypanosoma. The ADP/ATP carrier was also associated to the ATP synthase into a dimeric ATP synthasome. Single-particle analysis by transmission electron microscopy of the dimeric ATP synthase indicated that the structures of both the catalytic and central rotor parts are conserved while other structural features are original. These new features include a large membrane-spanning region joining the monomers, an external peripheral stalk and a structure that goes through the membrane and reaches the inter membrane space below the c-ring, the latter having not been reported for any mitochondrial F-ATPase. [less ▲]

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See detailThe mitochondrial respiratory chain of the secondary green alga Euglena gracilis shares many additional subunits with parasitic Trypanosomatidae.
Perez, Emilie ULiege; Lapaille, Marie; Degand, Herve et al

in Mitochondrion (2014), 19 Pt B

The mitochondrion is an essential organelle for the production of cellular ATP in most eukaryotic cells. It is extensively studied, including in parasitic organisms such as trypanosomes, as a potential ... [more ▼]

The mitochondrion is an essential organelle for the production of cellular ATP in most eukaryotic cells. It is extensively studied, including in parasitic organisms such as trypanosomes, as a potential therapeutic target. Recently, numerous additional subunits of the respiratory-chain complexes have been described in Trypanosoma brucei and Trypanosoma cruzi. Since these subunits had apparently no counterparts in other organisms, they were interpreted as potentially associated with the parasitic trypanosome lifestyle. Here we used two complementary approaches to characterise the subunit composition of respiratory complexes in Euglena gracilis, a non-parasitic secondary green alga related to trypanosomes. First, we developed a phylogenetic pipeline aimed at mining sequence databases for identifying homologs to known respiratory-complex subunits with high confidence. Second, we used MS/MS proteomics after two-dimensional separation of the respiratory complexes by Blue Native- and SDS-PAGE to both confirm in silico predictions and to identify further additional subunits. Altogether, we identified 41 subunits that are restricted to E. gracilis, T. brucei and T. cruzi, along with 48 classical subunits described in other eukaryotes (i.e. plants, mammals and fungi). This moreover demonstrates that at least half of the subunits recently reported in T. brucei and T. cruzi are actually not specific to Trypanosomatidae, but extend at least to other Euglenozoa, and that their origin and function are thus not specifically associated with the parasitic lifestyle. Furthermore, preliminary biochemical analyses suggest that some of these additional subunits underlie the peculiarities of the respiratory chain observed in Euglenozoa. [less ▲]

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See detailTranscriptomics and Proteomics of a Secondary Green Alga.
Perez, Emilie ULiege; Lapaille, Marie; Degand, Hervé et al

Poster (2014, August)

Euglena gracilis is a secondary green alga related to trypanosomes that derives from a secondary endosymbiosis between a phagotrophic ancestor and a prasinophycean green alga. Our general objective is to ... [more ▼]

Euglena gracilis is a secondary green alga related to trypanosomes that derives from a secondary endosymbiosis between a phagotrophic ancestor and a prasinophycean green alga. Our general objective is to study the metabolic interactions established between the secondary plastid and the mitochondrion after the endosymbiotic event and to determine the phylogenetic origin of the genes encoding the proteins involved in the energetic pathways. As a first step, we analysed the subunit composition of the mitochondrial respiratory chain, both in silico and by targeted proteomics, to assess the extent of its similitude with the respiratory chain of Trypanosomatidae. We have shown that Euglena shares many additional subunits with trypanosomes, which suggests that these subunits are not especially associated to a parasitic lifestyle. As a second step, we sequenced the total transcriptome of Euglena and determined the phylogenetic origin of each predicted transcript using a database of about 1000 complete proteomes representing the diversity of life. These analyses confirmed that Euglena recruited its genes from a very diverse set of sources. As a third step, we performed a high-throughput analysis of the mitochondrial proteome of Euglena. Our MS/MS experiments, taking advantage of the availability of our transcriptome, mostly recovered mitochondrial proteins, which indicates that our mitochondrial extracts were quite pure. The identified proteins encompassed about 15 different mitochondrial pathways. We are now in the process of comparing the expression levels of both the transcripts and the corresponding proteins across a range of culture conditions selected to differently stimulate the mitochondrion and the plastid. [less ▲]

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See detailMitochondrial Proteomics of a Secondary Green Alga.
Perez, Emilie ULiege; Degand, Hervé; Morsomme, Pierre et al

Poster (2014, May 06)

Euglena gracilis is an alga that derives from a secondary endosymbiosis with a green alga. Our general objective is to study the interactions established between the chloroplast and the mitochondrion ... [more ▼]

Euglena gracilis is an alga that derives from a secondary endosymbiosis with a green alga. Our general objective is to study the interactions established between the chloroplast and the mitochondrion during the endosymbiosic event and to determine the phylogenetic origin of the genes encoding the proteins involved in these interactions. As a first step, we performed a high-throughput analysis of the mitochondrial proteome of Euglena gracilis. Our MS/MS experiments mostly recover mitochondrial proteins representing 15 mitochondrial pathways, which indicates that our mitochondrial extracts are relatively pure, but the phylogenetic origins of the corresponding genes are surprisingly diverse. [less ▲]

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See detailMitochondrial Proteomics of a Secondary Green Alga
Perez, Emilie ULiege; Degand, Hervé; Morsomme, Pierre et al

Poster (2012, June)

Euglena gracilis is an alga that derives from a secondary endosymbiosis with a green alga. Our general objective is to study the interactions established between the chloroplast and the mitochondrion ... [more ▼]

Euglena gracilis is an alga that derives from a secondary endosymbiosis with a green alga. Our general objective is to study the interactions established between the chloroplast and the mitochondrion during the endosymbiosic event and to determine the phylogenetic origin of the genes encoding the proteins involved in these interactions. As a first step, we performed a high-throughput analysis of the mitochondrial proteome of Euglena gracilis. Our MS/MS experiments mostly recover mitochondrial proteins representing 15 mitochondrial pathways, which indicates that our mitochondrial extracts are relatively pure, but the phylogenetic origins of the corresponding genes are surprisingly diverse. [less ▲]

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See detailATSPO-related protein localizes to the early secretory pathway in Arabidopsis, but is targeted to mitochondria when expressed in yeast
Vanhee, Celine; Guillon, Stéphanie; Masquelier, Danièle et al

in Journal of Experimental Botany (2011), 62(2), 497-508

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See detailAtypical subunit composition of the chlorophycean mitochondrial F1FO ATP synthase and role of Asa7 protein in stability and oligomycin resistance of the enzyme.
Lapaille, Marie; Escobar-Ramirez, Adelma; Degand, Hervé et al

in Molecular Biology and Evolution (2010), 27(7), 1630-1644

Background. In yeast, mammals, and land plants, mitochondrial F(1)F(O) ATP synthase (complex V) is a remarkable enzymatic machinery which comprises about 15 conserved subunits. Peculiar among eukaryotes ... [more ▼]

Background. In yeast, mammals, and land plants, mitochondrial F(1)F(O) ATP synthase (complex V) is a remarkable enzymatic machinery which comprises about 15 conserved subunits. Peculiar among eukaryotes, complex V from Chlamydomonadales algae (order of chlorophycean class) has an atypical subunit composition of its peripheral stator and dimerization module, with 9 subunits of unknown evolutionary origin (Asa subunits). In vitro, this enzyme exhibits an increased stability of its dimeric form, and in vivo, Chlamydomonas reinhardtii cells are insensitive to oligomycins, which are potent inhibitors of proton translocation through the F(O) moiety. Methodology/Principal Findings. In this work, we showed that the atypical features of the Chlamydomonadales complex V enzyme are shared by the other chlorophycean orders. By biochemical and in silico analyses, we detected several atypical Asa subunits in Scenedesmus obliquus (Sphaeropleales) and Chlorococcum ellipsoideum (Chlorococcales). In contrast, Complex V has a canonical subunit composition in other classes of Chlorophytes (Trebouxiophyceae, Prasinophyceae, and Ulvophyceae) as well as in Streptophytes (land plants) and in Rhodophytes (red algae). Growth, respiration and ATP levels in Chlorophyceae were also barely affected by oligomycin concentrations that affect representatives of the other classes of Chlorophytes. We finally studied the function of the Asa7 atypical subunit by using RNA interference in C. reinhardtii. Although the loss of Asa7 subunit has no impact on cell bioenergetics or mitochondrial structures, it destabilizes in vitro the enzyme dimeric form and renders growth, respiration and ATP level sensitive to oligomycins. Conclusions/Significance. Altogether, our results suggest that the loss of canonical components of the Complex V stator happened at the root of chlorophycean lineage and was accompanied by the recruitment of novel polypeptides. Such a massive modification of Complex V stator features might have conferred novel properties, including the stabilization of the enzyme dimeric form and the shielding of the proton channel. In these respects, we discuss an evolutionary scenario for F(1)F(O) ATP synthase in the whole green lineage (i.e. Chlorophyta and Streptophyta). [less ▲]

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See detailF1FO ATP synthase mutants in Chlamydomonas: Stability and oligomycin resistance mediated by atypical Asa7 protein; interaction between chloroplastic and mitochondrial bioenergetics
Lapaille, Marie ULiege; Escobar-Ramírez, Adelma; Degand, Hervé et al

in Biochimica et Biophysica Acta (BBA) - Bioenergetics (2010), 1797(Supplement 1), 29

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