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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

Conference (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
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 detailAtypical structure and subunit composition of respiratory complexes in Euglena gracilis
Miranda Astudillo, Héctor Vicente ULiege; Yadav, Sathish; Colina-Tenorio, Lilia et al

Conference (2016, August 14)

Euglena gracilis, a non-parasitic secondary green alga related to trypanosomes, has a complex mitochondrial oxidative phosphorylation system constituted by atypical respiratory enzymes (complexes I - V ... [more ▼]

Euglena gracilis, a non-parasitic secondary green alga related to trypanosomes, has a complex mitochondrial oxidative phosphorylation system constituted by atypical respiratory enzymes (complexes I - V). Recently, the analysis of the subunit composition of respiratory complexes by 2D BN/SDS PAGE has shown that at least 41 of the non-canonical subunits reported in trypanosomes are also present in this alga along with 48 classical subunits described in other eukaryotes including green plants. In the present study the complexes I, III, IV and V were further purified from isolated mitochondria using liquid chromatography after solubilization with n-dodecyl-maltoside. Using a 3D BN/SDS/SDS PAGE analysis, we resolved their subunit composition and confirmed the atypical subunit composition of Euglena respiratory complexes. The apparent molecular mass of purified complexes I and V (1.5 and 2.2MDa, respectively) is far above the classical ones. Single-particle analysis from transmission electron microscopy revealed some unusual features for complexes I, IV and V, including smaller angles between monomers and additional membrane extensions for the ATP synthase. Complex I also shows an unusual long matricial arm. Meanwhile the complex IV shows an atypical shape compared with the bovine one. [less ▲]

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See detailEstructura y composición polipeptídica atípicas de los complejos respiratorios de Euglena gracilis
Miranda Astudillo, Héctor Vicente ULiege; Yadav, Sathish; Colina-Tenorio, Lilia et al

Conference (2015, November 10)

Euglena gracilis, un alga secundaria no parásita relacionada con los tripanosomas, tiene un sistema de fosforilación oxidativa mitocondrial complejo constituido por enzimas respiratorias atípicas ... [more ▼]

Euglena gracilis, un alga secundaria no parásita relacionada con los tripanosomas, tiene un sistema de fosforilación oxidativa mitocondrial complejo constituido por enzimas respiratorias atípicas. Recientemente, el análisis bioinformático y mediante 2D BN/SDS PAGE de la composición de subunidades de estos complejos respiratorios mostró que al menos 41 de las subunidades no canónicas reportadas en tripanosomas están también presentes en esta alga, así como 48 subunidades clásicas descritas en otros eucariotes. En el presente trabajo, los complejos I, III, IV y V fueron purificados a partir de mitocondrias aisladas mediante cromatografía líquida después de ser solubilizados con n-dodecil-maltósido. Utilizando los complejos purificados se realizó un análisis 3D BN/SDS/SDS PAGE y posterior espectrometría de masas, mediante esta estrategia se resolvieron e identificaron las subunidades que los componen, lo que confirmó la composición polipeptídica atípica de los complejos respiratorios de esta alga. La masa molecular aparente de los complejos purificados I y V (1.5 y 2.2 MDa, respectivamente) se encuentra muy por encima de los complejos clásicos. Por su parte, el análisis de partícula única a partir de imágenes de microscopía electrónica de transmisión reveló algunas características estructurales inusuales en el complejo V, estas incluyen ángulos menores entre los monómeros y algunas extensiones adicionales de la región membranal, mientras que el complejo I mostró también una extensión en el brazo extramembranal. [less ▲]

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See detailInduction of the Alternative NF-{kappa}B Pathway by Lymphotoxin {alpha}{beta} (LT{alpha}{beta}) Relies on Internalization of LT{beta} Receptor
Ganeff, Corine; Remouchamps, Caroline ULiege; Boutaffala, Layla et al

in Molecular & Cellular Biology (2011), 21

Several tumor necrosis factor receptor (TNFR) family members activate both the classical and the alternative NF-κB pathways. However, how a single receptor engages these two distinct pathways is still ... [more ▼]

Several tumor necrosis factor receptor (TNFR) family members activate both the classical and the alternative NF-κB pathways. However, how a single receptor engages these two distinct pathways is still poorly understood. Using lymphotoxin β receptor (LTβR) as a prototype, we showed that activation of the alternative, but not the classical, NF-κB pathway relied on internalization of the receptor. Further molecular analyses revealed a specific cytosolic region of LTβR essential for its internalization, TRAF3 recruitment, and p100 processing. Interestingly, we found that dynamin-dependent, but clathrin-independent, internalization of LTβR appeared to be required for the activation of the alternative, but not the classical, NF-κB pathway. In vivo, ligand-induced internalization of LTβR in mesenteric lymph node stromal cells correlated with induction of alternative NF-κB target genes. Thus, our data shed light on LTβR cellular trafficking as a process required for specific biological functions of NF-κB. [less ▲]

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See detailTNFL–Induced p100 processing (TIPP) relies on the internalization of the cognate TNFR
Ganeff, Corinne; Galopin, Géraldine; Remouchamps, Caroline ULiege et al

Conference (2010, January)

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