scholarly journals Structural and Functional Association of Trypanosoma brucei MIX Protein with Cytochrome c Oxidase Complex

2008 ◽  
Vol 7 (11) ◽  
pp. 1994-2003 ◽  
Author(s):  
Alena Zíková ◽  
Aswini K. Panigrahi ◽  
Alessandro D. Uboldi ◽  
Rachel A. Dalley ◽  
Emanuela Handman ◽  
...  
Keyword(s):  
Cell Division ◽  
Trypanosoma Brucei ◽  
Leishmania Major ◽  
Affinity Purification ◽  
Major Effect ◽  
Multiprotein Complex ◽  
Complex Iv ◽  
Mitochondrial Inner Membrane ◽  
Single Allele ◽  
Inner Membrane Protein

ABSTRACT A mitochondrial inner membrane protein, designated MIX, seems to be essential for cell viability. The deletion of both alleles was not possible, and the deletion of a single allele led to a loss of virulence and aberrant mitochondrial segregation and cell division in Leishmania major. However, the mechanism by which MIX exerts its effect has not been determined. We show here that MIX is also expressed in the mitochondrion of Trypanosoma brucei, and using RNA interference, we found that its loss leads to a phenotype that is similar to that described for Leishmania. The loss of MIX also had a major effect on cytochrome c oxidase activity, on the mitochondrial membrane potential, and on the production of mitochondrial ATP by oxidative phosphorylation. Using a tandem affinity purification tag, we found that MIX is associated with a multiprotein complex that contains subunits of the mitochondrial cytochrome c oxidase complex (respiratory complex IV), the composition of which was characterized in detail. The specific function of MIX is unknown, but it appears to be important for the function of complex IV and for mitochondrial segregation and cell division in T. brucei.

scholarly journals Super-resolution microscopy reveals arrangement of inner membrane protein complexes in mammalian mitochondria

2021 ◽  
Author(s):  
Catherine S. Palmer ◽  
Jieqiong Lou ◽  
Betty Kouskousis ◽  
Elvis Pandzic ◽  
Alexander J. Anderson ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Protein Complexes ◽  
Super Resolution ◽  
Bimodal Distribution ◽  
Complex Iv ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Cellular Context ◽  
Inner Membrane Protein ◽  
Super Resolution Microscopy

The mitochondrial inner membrane is a protein rich environment containing large multimeric complexes including complexes of the mitochondrial electron transport chain, mitochondrial translocases and quality control machineries. Although the inner membrane is highly proteinaceous, with 40–60% of all mitochondrial proteins localised to this compartment, little is known about the spatial distribution and organisation of complexes in this environment. We set out to survey the arrangement of inner membrane complexes using stochastic optical reconstruction microscopy (STORM). We show subunits of the TIM23 Complex, Tim23 and Tim44, and the Complex IV subunit COXIV form organised clusters and show distinct properties to the outer membrane protein Tom20. Density based cluster analysis indicated a bimodal distribution of Tim44 that is distinct from Tim23, suggesting distinct TIM23 subcomplexes. COXIV is arranged in larger clusters, that are disrupted upon disruption of Complex IV assembly. Thus, STORM super-resolution microscopy is a powerful approach to examine the nanoscale distribution of mitochondrial inner membrane complexes, providing a “visual” approach to obtaining pivotal information on how mitochondrial complexes exist in a cellular context.

scholarly journals Mutations in the Membrane Anchor of Yeast Cytochrome c1 Compensate for the Absence of Oxa1p and Generate Carbonate-Extractable Forms of Cytochrome c1

Genetics ◽  
1998 ◽  
Vol 150 (2) ◽  
pp. 601-611
Author(s):  
Patrice Hamel ◽  
Claire Lemaire ◽  
Nathalie Bonnefoy ◽  
Paule Brivet-Chevillotte ◽  
Geneviève Dujardin
Keyword(s):  
Electron Transfer ◽  
Complex Iii ◽  
Membrane Anchor ◽  
Suppressor Activity ◽  
Complex Iv ◽  
Transfer Activity ◽  
Suppressor Function ◽  
Mitochondrial Inner Membrane ◽  
Cytochrome C1 ◽  
Inner Membrane Protein

Abstract Oxa1p is a mitochondrial inner membrane protein that is mainly required for the insertion/assembly of complex IV and ATP synthase and is functionally conserved in yeasts, humans, and plants. We have isolated several independent suppressors that compensate for the absence of Oxa1p. Molecular cloning and sequencing reveal that the suppressor mutations (CYT1-1 to -6) correspond to amino acid substitutions that are all located in the membrane anchor of cytochrome c1 and decrease the hydrophobicity of this anchor. Cytochrome c1 is a catalytic subunit of complex III, but the CYT1-1 mutation does not seem to affect the electron transfer activity. The double-mutant cyt1-1,164, which has a drastically reduced electron transfer activity, still retains the suppressor activity. Altogether, these results suggest that the suppressor function of cytochrome c1 is independent of its electron transfer activity. In addition to the membranebound cytochrome c1, carbonate-extractable forms accumulate in all the suppressor strains. We propose that these carbonate-extractable forms of cytochrome c1 are responsible for the suppressor function by preventing the degradation of the respiratory complex subunits that occur in the absence of Oxa1p.

scholarly journals Characterization of the mitochondrial inner membrane protein translocator Tim17 from Trypanosoma brucei

2008 ◽  
Vol 159 (1) ◽  
pp. 30-43 ◽  
Author(s):  
Ujjal K. Singha ◽  
Emmanuel Peprah ◽  
Shuntae Williams ◽  
Robert Walker ◽  
Lipi Saha ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Trypanosoma Brucei ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Inner Membrane Protein

scholarly journals The Cross Talk between TbTim50 and PIP39, Two Aspartate-Based Protein Phosphatases, Maintains Cellular Homeostasis in Trypanosoma brucei

mSphere ◽  
2019 ◽  
Vol 4 (4) ◽  
Author(s):  
Anuj Tripathi ◽  
Ujjal K. Singha ◽  
Victor Paromov ◽  
Salisha Hill ◽  
Siddharth Pratap ◽  
...  
Keyword(s):  
Trypanosoma Brucei ◽  
Cross Talk ◽  
Developmental Regulation ◽  
Protein Phosphatases ◽  
Infectious Agent ◽  
Cellular Stress Response ◽  
Content Type ◽  
Mitochondrial Inner Membrane ◽  
Inner Membrane Protein ◽  
Metabolic Activities

Trypanosoma brucei, the infectious agent of African trypanosomiasis, must adapt to strikingly different host environments during its digenetic life cycle. Developmental regulation of mitochondrial activities is an essential part of these processes. We have shown previously that mitochondrial inner membrane protein translocase 50 in T. brucei (TbTim50) possesses a dually specific phosphatase activity and plays a role in the cellular stress response pathway. Using proteomics analysis, here we have elucidated a novel connection between TbTim50 and a protein phosphatase of the same family, PIP39, which is also a differentiation-related protein localized in glycosomes. We found that these two protein phosphatases cross talk via the AMPK pathway and modulate cellular metabolic activities under stress. Together, our results indicate the importance of a TbTim50 and PIP39 cascade for communication between mitochondria and other cellular parts in regulation of cell homeostasis in T. brucei.

scholarly journals Characterization and selective inhibition of myristoyl-CoA:protein N-myristoyltransferase from Trypanosoma brucei and Leishmania major

2006 ◽  
Vol 396 (2) ◽  
pp. 277-285 ◽  
Author(s):  
Chrysoula Panethymitaki ◽  
Paul W. Bowyer ◽  
Helen P. Price ◽  
Robin J. Leatherbarrow ◽  
Katherine A. Brown ◽  
...  
Keyword(s):  
Trypanosoma Brucei ◽  
Leishmania Major ◽  
Homo Sapiens ◽  
Selective Inhibition ◽  
Fungal Species ◽  
Chemotherapeutic Agents ◽  
Human Pathogens ◽  
Ic50 Values

The eukaryotic enzyme NMT (myristoyl-CoA:protein N-myristoyltransferase) has been characterized in a range of species from Saccharomyces cerevisiae to Homo sapiens. NMT is essential for viability in a number of human pathogens, including the fungi Candida albicans and Cryptococcus neoformans, and the parasitic protozoa Leishmania major and Trypanosoma brucei. We have purified the Leishmania and T. brucei NMTs as active recombinant proteins and carried out kinetic analyses with their essential fatty acid donor, myristoyl-CoA and specific peptide substrates. A number of inhibitory compounds that target NMT in fungal species have been tested against the parasite enzymes in vitro and against live parasites in vivo. Two of these compounds inhibit TbNMT with IC50 values of <1 μM and are also active against mammalian parasite stages, with ED50 (the effective dose that allows 50% cell growth) values of 16–66 μM and low toxicity to murine macrophages. These results suggest that targeting NMT could be a valid approach for the development of chemotherapeutic agents against infectious diseases including African sleeping sickness and Nagana.

The structural mechanics of cell division in Trypanosoma brucei

2008 ◽  
Vol 36 (3) ◽  
pp. 421-424 ◽  
Author(s):  
Sue Vaughan ◽  
Keith Gull
Keyword(s):  
Cell Division ◽  
Trypanosoma Brucei ◽  
Mammalian Cells ◽  
Reverse Genetics ◽  
Protozoan Parasite ◽  
Cell Types ◽  
Single Copy ◽  
Structural Mechanics ◽  
Sub Saharan Africa ◽  
Mammalian Host

Undoubtedly, there are fundamental processes driving the structural mechanics of cell division in eukaryotic organisms that have been conserved throughout evolution and are being revealed by studies on organisms such as yeast and mammalian cells. Precision of structural mechanics of cytokinesis is however probably no better illustrated than in the protozoa. A dramatic example of this is the protozoan parasite Trypanosoma brucei, a unicellular flagellated parasite that causes a devastating disease (African sleeping sickness) across Sub-Saharan Africa in both man and animals. As trypanosomes migrate between and within a mammalian host and the tsetse vector, there are periods of cell proliferation and cell differentiation involving at least five morphologically distinct cell types. Much of the existing cytoskeleton remains intact during these processes, necessitating a very precise temporal and spatial duplication and segregation of the many single-copy organelles. This structural precision is aiding progress in understanding these processes as we apply the excellent reverse genetics and post-genomic technologies available in this system. Here we outline our current understanding of some of the structural aspects of cell division in this fascinating organism.

Abstract 15552: Acute Estrogen-GPER1 Stimulation Preserves Mitochondrial Inner Membrane Protein (Mitofilin) From Degradation caused by Ischemia/Reperfusion Stress

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Tanoya L. C Harris ◽  
Bjorn Olde ◽  
Fredrik Leeb-Lundberg ◽  
Jean C. Bopassa
Keyword(s):  
Electron Microscopy ◽  
Spatial Organization ◽  
Ischemia Reperfusion ◽  
Estrogen Treatment ◽  
Mitochondrial Inner Membrane ◽  
Mitochondrial Integrity ◽  
Inner Membrane Protein ◽  
Estrogen Effect ◽  
And Function ◽  
High Resolution Microscopy

Introduction: We recently found that acute estrogen treatment delays the mitochondrial permeability transition pore opening and reduces ROS production after ischemia/reperfusion, suggesting that estrogen promotes mitochondrial integrity. As mitochondrial inner membrane protein (mitofilin) has been found to control mitochondrial cristae morphology and function, we investigated whether estrogen effect on mitochondrial integrity after ischemia/reperfusion involved regulation of mitofilin via G-Protein Coupled Estrogen Receptor1 (GPER1) activation. Methods: Isolated hearts from male WT (C57BL/6NCrL), and GPER1-/- mice were perfused using Langendorff technique, with and without estrogen (40 nM). Hearts were subjected to 20 min global ischemia followed by 10 min reperfusion. Mitochondria were isolated, and 2D-DIGE followed by mass spectrometry was performed. Mitofilin expression was confirmed by Western blot analysis in mitochondrial fractions. Mitofilin distribution in cardiomyocytes, and its spatial organization in single mitochondria were visualized using high resolution microscopy. Electron microscopy was used to observe the state of mitochondrial cristae morphology. Results: Analysis revealded 52 unique proteins of interest, in which mitofilin was identified. Immunoblot analysis confirmed an increased in mitofilin level with estrogen treatment as compared to control in WT but not in GPER1-/-. We found, as observed in non-ischemic myocytes, that mitofilin in estrogen-treated cardiomyocytes was distributed in the peri-membrane and T-tubules, while only peri-membrane mitofilin was more visible in control group. High resolution microscopy showed a better spatial organization of mitofilin in single mitochondria with estrogen treatment compared to control, in which mitofilin was almost absent. Electron microscopy revealded that mitochondrial morphology was preserved with estrogen treatment, as cristae were well organized compared to control, in which cristae were disrupted. Conclusion: These data indicate that estrogen up-regulates mitofilin expression during ischemia/reperfusion. Estrogen effect on mitofilin may contribute to improved mitochondrial integrity and function.

Leishmania type II dehydrogenase is essential for parasite viability irrespective of the presence of an active complex I

2021 ◽  
Vol 118 (42) ◽  
pp. e2103803118
Author(s):  
Margarida Duarte ◽  
Cleide Ferreira ◽  
Gurleen Kaur Khandpur ◽  
Tamara Flohr ◽  
Jannik Zimmermann ◽  
...  
Keyword(s):  
Complex I ◽  
Nadh Dehydrogenase ◽  
Leishmania Major ◽  
Proton Translocation ◽  
Protozoan Parasite ◽  
Type I ◽  
Type Ii ◽  
Active Complex ◽  
Mitochondrial Inner Membrane ◽  
Candidate Target

Type II NADH dehydrogenases (NDH2) are monotopic enzymes present in the external or internal face of the mitochondrial inner membrane that contribute to NADH/NAD+ balance by conveying electrons from NADH to ubiquinone without coupled proton translocation. Herein, we characterize the product of a gene present in all species of the human protozoan parasite Leishmania as a bona fide, matrix-oriented, type II NADH dehydrogenase. Within mitochondria, this respiratory activity concurs with that of type I NADH dehydrogenase (complex I) in some Leishmania species but not others. To query the significance of NDH2 in parasite physiology, we attempted its genetic disruption in two parasite species, exhibiting a silent (Leishmania infantum, Li) and a fully operational (Leishmania major, Lm) complex I. Strikingly, this analysis revealed that NDH2 abrogation is not tolerated by Leishmania, not even by complex I–expressing Lm species. Conversely, complex I is dispensable in both species, provided that NDH2 is sufficiently expressed. That a type II dehydrogenase is essential even in the presence of an active complex I places Leishmania NADH metabolism into an entirely unique perspective and suggests unexplored functions for NDH2 that span beyond its complex I–overlapping activities. Notably, by showing that the essential character of NDH2 extends to the disease-causing stage of Leishmania, we genetically validate NDH2—an enzyme without a counterpart in mammals—as a candidate target for leishmanicidal drugs.

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