scholarly journals A complex of Cox4 and mitochondrial Hsp70 plays an important role in the assembly of the cytochrome c oxidase

2013 ◽  
Vol 24 (17) ◽  
pp. 2609-2619 ◽  
Author(s):  
Lena Böttinger ◽  
Bernard Guiard ◽  
Silke Oeljeklaus ◽  
Bogusz Kulawiak ◽  
Nicole Zufall ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Affinity Purification ◽  
Nucleotide Exchange ◽  
Complex Iv ◽  
Nucleotide Exchange Factor ◽  
Key Factor ◽  
Mitochondrial Hsp70 ◽  
The Stability ◽  
Chaperone Complex

The formation of the mature cytochrome c oxidase (complex IV) involves the association of nuclear- and mitochondria-encoded subunits. The assembly of nuclear-encoded subunits like cytochrome c oxidase subunit 4 (Cox4) into the mature complex is poorly understood. Cox4 is crucial for the stability of complex IV. To find specific biogenesis factors, we analyze interaction partners of Cox4 by affinity purification and mass spectroscopy. Surprisingly, we identify a complex of Cox4, the mitochondrial Hsp70 (mtHsp70), and its nucleotide-exchange factor mitochondrial GrpE (Mge1). We generate a yeast mutant of mtHsp70 specifically impaired in the formation of this novel mtHsp70-Mge1-Cox4 complex. Strikingly, the assembly of Cox4 is strongly decreased in these mutant mitochondria. Because Cox4 is a key factor for the biogenesis of complex IV, we conclude that the mtHsp70-Mge1-Cox4 complex plays an important role in the formation of cytochrome c oxidase. Cox4 arrests at this chaperone complex in the absence of mature complex IV. Thus the mtHsp70-Cox4 complex likely serves as a novel delivery system to channel Cox4 into the assembly line when needed.

scholarly journals Hsp110 is required for spindle length control

2012 ◽  
Vol 198 (4) ◽  
pp. 623-636 ◽  
Author(s):  
Taras Makhnevych ◽  
Philip Wong ◽  
Oxana Pogoutse ◽  
Franco J. Vizeacoumar ◽  
Jack F. Greenblatt ◽  
...  
Keyword(s):  
Affinity Purification ◽  
Spindle Assembly ◽  
S Phase ◽  
Mass Spectrometry Analysis ◽  
Nucleotide Exchange ◽  
Spectrometry Analysis ◽  
Nucleotide Exchange Factor ◽  
Spindle Elongation ◽  
Chaperone Complex

Systematic affinity purification combined with mass spectrometry analysis of N- and C-tagged cytoplasmic Hsp70/Hsp110 chaperones was used to identify new roles of Hsp70/Hsp110 in the cell. This allowed the mapping of a chaperone–protein network consisting of 1,227 unique interactions between the 9 chaperones and 473 proteins and highlighted roles for Hsp70/Hsp110 in 14 broad biological processes. Using this information, we uncovered an essential role for Hsp110 in spindle assembly and, more specifically, in modulating the activity of the widely conserved kinesin-5 motor Cin8. The role of Hsp110 Sse1 as a nucleotide exchange factor for the Hsp70 chaperones Ssa1/Ssa2 was found to be required for maintaining the proper distribution of kinesin-5 motors within the spindle, which was subsequently required for bipolar spindle assembly in S phase. These data suggest a model whereby the Hsp70–Hsp110 chaperone complex antagonizes Cin8 plus-end motility and prevents premature spindle elongation in S phase.

scholarly journals Loss of the smallest subunit of cytochrome c oxidase, COX8A, causes Leigh-like syndrome and epilepsy

Brain ◽  
2015 ◽  
Vol 139 (2) ◽  
pp. 338-345 ◽  
Author(s):  
Kerstin Hallmann ◽  
Alexei P. Kudin ◽  
Gábor Zsurka ◽  
Cornelia Kornblum ◽  
Jens Reimann ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Splice Site Mutation ◽  
Wild Type ◽  
Site Mutation ◽  
Complex Iv ◽  
Exon 2 ◽  
Assembly Factor ◽  
Chain Defects ◽  
The Stability

Abstract Isolated cytochrome c oxidase (complex IV) deficiency is one of the most frequent respiratory chain defects in humans and is usually caused by mutations in proteins required for assembly of the complex. Mutations in nuclear-encoded structural subunits are very rare. In a patient with Leigh-like syndrome presenting with leukodystrophy and severe epilepsy, we identified a homozygous splice site mutation in COX8A, which codes for the ubiquitously expressed isoform of subunit VIII, the smallest nuclear-encoded subunit of complex IV. The mutation, affecting the last nucleotide of intron 1, leads to aberrant splicing, a frame-shift in the highly conserved exon 2, and decreased amount of the COX8A transcript. The loss of the wild-type COX8A protein severely impairs the stability of the entire cytochrome c oxidase enzyme complex and manifests in isolated complex IV deficiency in skeletal muscle and fibroblasts, similar to the frequent c.845_846delCT mutation in the assembly factor SURF1 gene. Stability and activity of complex IV could be rescued in the patient’s fibroblasts by lentiviral expression of wild-type COX8A. Our findings demonstrate that COX8A is indispensable for function of human complex IV and its mutation causes human disease.

scholarly journals Pathology of Mitochondrial Encephalomyopathies

2005 ◽  
Vol 32 (2) ◽  
pp. 152-166 ◽  
Author(s):  
Harvey B. Sarnat ◽  
José Marín-García
Keyword(s):  
Cytochrome C ◽  
Succinate Dehydrogenase ◽  
Cytochrome C Oxidase ◽  
Oxidase Activity ◽  
Morphological Evidence ◽  
Regular Feature ◽  
Complex Iv ◽  
Genetic Studies ◽  
Mitochondrial Encephalomyopathies ◽  
Mitochondrial Cytopathy

ABSTRACT:Muscle biopsy provides the best tissue to confirm a mitochondrial cytopathy. Histochemical features often correlate with specific syndromes and facilitate the selection of biochemical and genetic studies. Ragged-red fibres nearly always indicate a combination defect of respiratory complexes I and IV. Increased punctate lipid within myofibers is a regular feature of Kearns-Sayre and PEO, but not of MELAS and MERRF. Total deficiency of succinate dehydrogenase indicates a severe defect in Complex II; total absence of cytochrome-c-oxidase activity in all myofibres correlates with a severe deficiency of Complex IV or of coenzyme-Q10. The selective loss of cytochrome-c-oxidase activity in scattered myofibers, particularly if accompanied by strong succinate dehydrogenase staining in these same fibres, is good evidence of mitochondrial cytopathy and often of a significant mtDNA mutation, though not specific for Complex IV disorders. Glycogen may be excessive in ragged-red zones. Ultrastructure provides morphological evidence of mitochondrial cytopathy, in axons and endothelial cells as well as myocytes. Abnormal axonal mitochondria may contribute to neurogenic atrophy of muscle, a secondary chronic feature. Quantitative determinations of respiratory chain enzyme complexes, with citrate synthase as an internal control, confirm the histochemical impressions or may be the only evidence of mitochondrial disease. Biological and technical artifacts may yield falsely low enzymatic activities. Genetic studies screen common point mutations in mtDNA. The brain exhibits characteristic histopathological alterations in mitochondrial diseases. Skin biopsy is useful for mitochondrial ultrastructure in smooth erector pili muscles and axons; skin fibroblasts may be grown in culture. Mitochondrial alterations occur in many nonmitochondrial diseases and also may be induced by drugs and toxins.

scholarly journals The Lebanese Allele in the PET100 Gene: Report on Two New Families with Cytochrome c Oxidase Deficiency

2019 ◽  
Vol 08 (03) ◽  
pp. 172-178 ◽  
Author(s):  
Hicham Mansour ◽  
Sandra Sabbagh ◽  
Sami Bizzari ◽  
Stephany El-Hayek ◽  
Eliane Chouery ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Lactic Acidosis ◽  
Developmental Delay ◽  
Cytochrome C Oxidase ◽  
Brain Magnetic Resonance Imaging ◽  
Global Developmental Delay ◽  
Mitochondrial Complex ◽  
Oxidase Deficiency ◽  
Complex Iv ◽  
Cytochrome C Oxidase Deficiency

AbstractCytochrome c oxidase deficiency is caused by mutations in any of at least 30 mitochondrial and nuclear genes involved in mitochondrial complex IV biogenesis and structure, including the recently identified PET100 gene. Here, we report two families, of which one is consanguineous, with two affected siblings each. In one family, the siblings presented with developmental delay, seizures, lactic acidosis, abnormal brain magnetic resonance imaging, and low muscle mitochondrial complex IV activity at 30%. In the other family, the two siblings, now deceased, had a history of global developmental delay, failure to thrive, muscular hypotonia, seizures, developmental regression, respiratory insufficiency, and lactic acidosis. By whole exome sequencing, a missense mutation in exon 1 of the PET100 gene (c.3G > C; [p.Met1?]) was identified in both families. A review of the clinical description and literature is discussed, highlighting the importance of this variant in the Lebanese population.

scholarly journals A J-protein is an essential subunit of the presequence translocase–associated protein import motor of mitochondria

2003 ◽  
Vol 163 (4) ◽  
pp. 707-713 ◽  
Author(s):  
Kaye N. Truscott ◽  
Wolfgang Voos ◽  
Ann E. Frazier ◽  
Maria Lind ◽  
Yanfeng Li ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Protein Import ◽  
Protein Translocation ◽  
Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
The Matrix ◽  
Inner Membrane Protein ◽  
Mitochondrial Hsp70 ◽  
Essential Subunit ◽  
J Protein

Transport of preproteins into the mitochondrial matrix is mediated by the presequence translocase–associated motor (PAM). Three essential subunits of the motor are known: mitochondrial Hsp70 (mtHsp70); the peripheral membrane protein Tim44; and the nucleotide exchange factor Mge1. We have identified the fourth essential subunit of the PAM, an essential inner membrane protein of 18 kD with a J-domain that stimulates the ATPase activity of mtHsp70. The novel J-protein (encoded by PAM18/YLR008c/TIM14) is required for the interaction of mtHsp70 with Tim44 and protein translocation into the matrix. We conclude that the reaction cycle of the PAM of mitochondria involves an essential J-protein.

scholarly journals COX16 promotes COX2 metallation and assembly during respiratory complex IV biogenesis

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Abhishek Aich ◽  
Cong Wang ◽  
Arpita Chowdhury ◽  
Christin Ronsör ◽  
David Pacheu-Grau ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Site Formation ◽  
Mitochondrial Oxidative Phosphorylation ◽  
Assembly Lines ◽  
Complex Iv ◽  
Oxidative Phosphorylation System ◽  
Water Formation ◽  
Copper Center ◽  
Redox Centers

Cytochrome c oxidase of the mitochondrial oxidative phosphorylation system reduces molecular oxygen with redox equivalent-derived electrons. The conserved mitochondrial-encoded COX1- and COX2-subunits are the heme- and copper-center containing core subunits that catalyze water formation. COX1 and COX2 initially follow independent biogenesis pathways creating assembly modules with subunit-specific, chaperone-like assembly factors that assist in redox centers formation. Here, we find that COX16, a protein required for cytochrome c oxidase assembly, interacts specifically with newly synthesized COX2 and its copper center-forming metallochaperones SCO1, SCO2, and COA6. The recruitment of SCO1 to the COX2-module is COX16- dependent and patient-mimicking mutations in SCO1 affect interaction with COX16. These findings implicate COX16 in CuA-site formation. Surprisingly, COX16 is also found in COX1-containing assembly intermediates and COX2 recruitment to COX1. We conclude that COX16 participates in merging the COX1 and COX2 assembly lines.

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