Maria Antonietta Calvaruso

Publications (5)38.59 Total impact

• Article: Mitochondrial complex III stabilizes complex I in the absence of NDUFS4 to provide partial activity.

  Maria Antonietta Calvaruso, Peter Willems, Mariël van den Brand, Federica Valsecchi, Shane Kruse, Richard Palmiter, Jan Smeitink, Leo Nijtmans
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  ABSTRACT: Mitochondrial complex I (CI) is a multi-subunit enzyme that forms the major entry point of nicotinamide adenine dinucleotide (NADH) electrons into the respiratory chain. Mutations in the NDUFS4 gene, encoding an accessory subunit of this complex, cause a Leigh-like phenotype in humans. To study the nature and penetrance of the CI defect in different tissues, we investigated the role of NDUFS4 in mice with fatal mitochondrial encephalomyopathy, caused by a systemic inactivation of the Ndufs4 gene. We report that the absence of NDUFS4 in different mouse tissues results in decreased activity and stability of CI. This CI instability leads to an increased disconnection of electron influx of the NADH dehydrogenase module from the holo-complex. However, the formation of respiratory supercomplexes still allows formation of active CI in these Ndufs4 knock-out mice. These results reveal the importance of these supramolecular interactions not only for stabilization but also for the assembly of CI, which becomes especially relevant in pathological conditions.
  Human Molecular Genetics 09/2011; 21(1):115-20. · 7.64 Impact Factor
• Article: New mitochondrial tRNA HIS mutation in a family with lactic acidosis and stroke-like episodes (MELAS).

  Maria Antonietta Calvaruso, Michel A Willemsen, Richard J Rodenburg, Mariël van den Brand, Jan A M Smeitink, Leo Nijtmans
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  ABSTRACT: We report a new mutation in m.12146 A>G in the mt-tRNA(His) in a family with a remarkable clinical history having different degrees of lactic acidosis and stroke-like episodes. Biochemical measurements of a muscle biopsy established an isolated complex IV deficiency, while similar analysis of fibroblasts showed a combined complex I,III and IV deficiency. Transmitochondrial cybrid analysis proved that this tRNA(His) mutation causes the enzymatic deficiency. This family illustrates the complexity of the clinical, biochemical and genetic characteristics of a novel mtDNA encoded disorder, as well as the challenge to prove its pathogenicity.
  Mitochondrion 06/2011; 11(5):778-82. · 3.62 Impact Factor
• Source

  Available from: Knud H Nierhaus

  Article: NOA1 is an essential GTPase required for mitochondrial protein synthesis.

  Mateusz Kolanczyk, Markus Pech, Tomasz Zemojtel, Hiroshi Yamamoto, Ivan Mikula, Maria-Antonietta Calvaruso, Mariël van den Brand, Ricarda Richter, Bjoern Fischer, Anita Ritz, [......], Jan Smeitink, Uwe Kornak, Danny Chan, Martin Vingron, Pavel Martasek, Robert N Lightowlers, Leo Nijtmans, Markus Schuelke, Knud H Nierhaus, Stefan Mundlos
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  ABSTRACT: Nitric oxide associated-1 (NOA1) is an evolutionarily conserved guanosine triphosphate (GTP) binding protein that localizes predominantly to mitochondria in mammalian cells. On the basis of bioinformatic analysis, we predicted its possible involvement in ribosomal biogenesis, although this had not been supported by any experimental evidence. Here we determine NOA1 function through generation of knockout mice and in vitro assays. NOA1-deficient mice exhibit midgestation lethality associated with a severe developmental defect of the embryo and trophoblast. Primary embryonic fibroblasts isolated from NOA1 knockout embryos show deficient mitochondrial protein synthesis and a global defect of oxidative phosphorylation (OXPHOS). Additionally, Noa1⁻/⁻ cells are impaired in staurosporine-induced apoptosis. The analysis of mitochondrial ribosomal subunits from Noa1⁻/⁻ cells by sucrose gradient centrifugation and Western blotting showed anomalous sedimentation, consistent with a defect in mitochondrial ribosome assembly. Furthermore, in vitro experiments revealed that intrinsic NOA1 GTPase activity was stimulated by bacterial ribosomal constituents. Taken together, our data show that NOA1 is required for mitochondrial protein synthesis, likely due to its yet unidentified role in mitoribosomal biogenesis. Thus, NOA1 is required for such basal mitochondrial functions as adenosine triphosphate (ATP) synthesis and apoptosis.
  Molecular biology of the cell 01/2011; 22(1):1-11. · 5.98 Impact Factor
• Source

  Available from: Jan Nedergaard

  Article: Random point mutations with major effects on protein-coding genes are the driving force behind premature aging in mtDNA mutator mice.

  Daniel Edgar, Irina Shabalina, Yolanda Camara, Anna Wredenberg, Maria Antonietta Calvaruso, Leo Nijtmans, Jan Nedergaard, Barbara Cannon, Nils-Göran Larsson, Aleksandra Trifunovic
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  ABSTRACT: The mtDNA mutator mice have high levels of point mutations and linear deletions of mtDNA causing a progressive respiratory chain dysfunction and a premature aging phenotype. We have now performed molecular analyses to determine the mechanism whereby these mtDNA mutations impair respiratory chain function. We report that mitochondrial protein synthesis is unimpaired in mtDNA mutator mice consistent with the observed minor alterations of steady-state levels of mitochondrial transcripts. These findings refute recent claims that circular mtDNA molecules with large deletions are driving the premature aging phenotype. We further show that the stability of several respiratory chain complexes is severely impaired despite normal synthesis of the corresponding mtDNA-encoded subunits. Our findings reveal a mechanism for induction of aging phenotypes by demonstrating a causative role for amino acid substitutions in mtDNA-encoded respiratory chain subunits, which, in turn, leads to decreased stability of the respiratory chain complexes and respiratory chain deficiency.
  Cell metabolism 09/2009; 10(2):131-8. · 17.35 Impact Factor
• Article: Electrophoresis techniques to investigate defects in oxidative phosphorylation.

  Maria Antonietta Calvaruso, Jan Smeitink, Leo Nijtmans
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  ABSTRACT: Defects in mitochondrial oxidative phosphorylation (OXPHOS) are a frequent cause of severe inherited metabolic disorders and also contribute to aging. The OXPHOS system constitutes five multi-subunit complexes embedded in the mitochondrial inner membrane. Correct function of this system requires proper assembly of the approximately 80 proteins in the complexes, as well as numerous assembly factors. Blue native electrophoresis has become a crucial tool to investigate OXPHOS-related defects in mitochondrial disease patients. In addition, OXPHOS-assembly profiles can be obtained by two dimensional blue native/SDS gel electrophoresis, which provides additional information for identifying disease-causing mutations and insight in the role of specific proteins in the biogenesis of the OXPHOS system. Here we provide a practical guide on how to set-up the basic technique to study OXPHOS defects in patient-derived cells and tissues.
  Methods 11/2008; 46(4):281-7. · 4.01 Impact Factor