scholarly journals Ischemia-reperfusion induces inhibition of mitochondrial protein synthesis and cytochrome c oxidase activity in rat hippocampus

2009 ◽  
pp. 127-138
Author(s):  
P Racay ◽  
Z Tatarková ◽  
A Drgová ◽  
P Kaplan ◽  
D Dobrota
Keyword(s):  
Protein Synthesis ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Brain Ischemia ◽  
Ischemia Reperfusion ◽  
Mitochondrial Protein ◽  
Neuronal Cell ◽  
Northern Hybridization ◽  
Mitochondrial Protein Synthesis ◽  
Mitochondrial Translation

Dysfunction of mitochondria induced by ischemia is considered to be a key event triggering neuronal cell death after brain ischemia. Here we report the effect of ischemia-reperfusion on mitochondrial protein synthesis and activity of cytochrome c oxidase (EC 1.9.3.1, COX). By performing 4-vessel occlusion model of global brain ischemia, we have observed that 15 min of global ischemia led to the inhibition of COX subunit I (COXI) synthesis to 56 % of control. After 1, 3 and 24 h of reperfusion, COXI synthesis was inhibited to 46, 50 and 72 % of control, respectively. Depressed synthesis of COXI was not a result of either diminished transcription of COXI gene or increased proteolytic degradation of COXI, since both Northern hybridization and Western blotting did not show significant changes in COXI mRNA and protein level. Thus, ischemiareperfusion affects directly mitochondrial translation machinery. In addition, ischemia in duration of 15 min and consequent 1, 3 and 24 h of reperfusion led to the inhibition of COX activity to 90.3, 80.3, 81.9 and 83.5 % of control, respectively. Based on our data, we suggest that inhibition of COX activity is rather caused by ischemia-induced modification of COX polypeptides than by inhibition of mitochondrial translation.

Oxytetracycline inhibition of mitochondrial protein synthesis in bovine lymphocytes infected withTheileria parvaor stimulated by mitogen

Parasitology ◽  
1990 ◽  
Vol 101 (3) ◽  
pp. 387-393 ◽  
Author(s):  
P. R. Spooner
Keyword(s):  
Protein Synthesis ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Oxidase Activity ◽  
Mitochondrial Protein ◽  
Inhibitory Effect ◽  
Mitochondrial Protein Synthesis ◽  
Drug Concentrations ◽  
Bovine Lymphocytes

SUMMARYOxytetracycline (OTC) significantly inhibited cytochrome c oxidase activity in bovine lymphocytes infected withTheileria parvaand in uninfected mitogen-stimulated lymphocytes. The inhibitory effect was detectedin vitrowithin 24 h of treatment with drug concentrations as low as 1 µg/ml. Following mitogen stimulation of lymphocytes, concentrations of 3 and 10 µg/ml OTC completely inhibited an increase in cytochrome c oxidase activity for 48–72 h. This inhibitory activity was considered to be due to a direct effect on lymphoblast mitochondrial protein synthesis. As a consequence, adenosine triphosphate activity was significantly reduced in lymphocytes stimulated either by infection withT. parvasporozoites or by mitogen and then treated with OTC. The results also indicated that parasite mitochondrial protein synthesis was inhibited by OTC. The activity of OTC reported in this study could explain the suppression of disease following ‘infection and treatment’ immunization against East Coast fever and thein vitrodrug-inhibition of schizont development.

scholarly journals MrpL35, a mitospecific component of mitoribosomes, plays a key role in cytochrome c oxidase assembly

2017 ◽  
Vol 28 (24) ◽  
pp. 3489-3499 ◽  
Author(s):  
Jodie M. Box ◽  
Jasvinder Kaur ◽  
Rosemary A. Stuart
Keyword(s):  
Protein Synthesis ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Mitochondrial Protein ◽  
Mitochondrial Protein Synthesis ◽  
Regulatory Subunits ◽  
The Core ◽  
Yeast Strains ◽  
Oxphos System ◽  
Core Components

Mitoribosomes perform the synthesis of the core components of the oxidative phosphorylation (OXPHOS) system encoded by the mitochondrial genome. We provide evidence that MrpL35 (mL38), a mitospecific component of the yeast mitoribosomal central protuberance, assembles into a subcomplex with MrpL7 (uL5), Mrp7 (bL27), and MrpL36 (bL31) and mitospecific proteins MrpL17 (mL46) and MrpL28 (mL40). We isolated respiratory defective mrpL35 mutant yeast strains, which do not display an overall inhibition in mitochondrial protein synthesis but rather have a problem in cytochrome c oxidase complex (COX) assembly. Our findings indicate that MrpL35, with its partner Mrp7, play a key role in coordinating the synthesis of the Cox1 subunit with its assembly into the COX enzyme and in a manner that involves the Cox14 and Coa3 proteins. We propose that MrpL35 and Mrp7 are regulatory subunits of the mitoribosome acting to coordinate protein synthesis and OXPHOS assembly events and thus the bioenergetic capacity of the mitochondria.

scholarly journals Exploring the Ability of LARS2 Carboxy-Terminal Domain in Rescuing the MELAS Phenotype

Life ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 674
Author(s):  
Francesco Capriglia ◽  
Francesca Rizzo ◽  
Giuseppe Petrosillo ◽  
Veronica Morea ◽  
Giulia d’Amati ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Molecular Mechanisms ◽  
Mitochondrial Protein ◽  
Trna Synthetase ◽  
Mitochondrial Protein Synthesis ◽  
Mitochondrial Translation ◽  
Terminal Domain ◽  
Carboxy Terminal Domain ◽  
Mitochondrial Functions ◽  
Carboxy Terminal

The m.3243A>G mutation within the mitochondrial mt-tRNALeu(UUR) gene is the most prevalent variant linked to mitochondrial encephalopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome. This pathogenic mutation causes severe impairment of mitochondrial protein synthesis due to alterations of the mutated tRNA, such as reduced aminoacylation and a lack of post-transcriptional modification. In transmitochondrial cybrids, overexpression of human mitochondrial leucyl-tRNA synthetase (LARS2) has proven effective in rescuing the phenotype associated with m.3243A>G substitution. The rescuing activity resides in the carboxy-terminal domain (Cterm) of the enzyme; however, the precise molecular mechanisms underlying this process have not been fully elucidated. To deepen our knowledge on the rescuing mechanisms, we demonstrated the interactions of the Cterm with mutated mt-tRNALeu(UUR) and its precursor in MELAS cybrids. Further, the effect of Cterm expression on mitochondrial functions was evaluated. We found that Cterm ameliorates de novo mitochondrial protein synthesis, whilst it has no effect on mt-tRNALeu(UUR) steady-state levels and aminoacylation. Despite the complete recovery of cell viability and the increase in mitochondrial translation, Cterm-overexpressing cybrids were not able to recover bioenergetic competence. These data suggest that, in our MELAS cell model, the beneficial effect of Cterm may be mediated by factors that are independent of the mitochondrial bioenergetics.

scholarly journals Using mitoribosomal profiling to investigate human mitochondrial translation

2018 ◽  
Vol 2 ◽  
pp. 116
Author(s):  
Fei Gao ◽  
Maria Wesolowska ◽  
Reuven Agami ◽  
Koos Rooijers ◽  
Fabricio Loayza-Puch ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Codon Position ◽  
Mitochondrial Protein ◽  
Mitochondrial Protein Synthesis ◽  
Mitochondrial Translation ◽  
Base Pairs ◽  
Suboptimal Structure ◽  
Human Counterpart ◽  
Steady State Levels

Background: Gene expression in human mitochondria has various idiosyncratic features. One of these was recently revealed as the unprecedented recruitment of a mitochondrially-encoded tRNA as a structural component of the large mitoribosomal subunit. In porcine particles this is mt-tRNAPhe whilst in humans it is mt-tRNAVal. We have previously shown that when a mutation in mt-tRNAVal causes very low steady state levels, there is preferential recruitment of mt-tRNAPhe. We have investigated whether this altered mitoribosome affects intra-organellar protein synthesis. Methods: By using mitoribosomal profiling we have revealed aspects of mitoribosome behaviour with its template mt-mRNA under both normal conditions as well as those where the mitoribosome has incorporated mt-tRNAPhe. Results: Analysis of the mitoribosome residency on transcripts under control conditions reveals that although mitochondria employ only 22 mt-tRNAs for protein synthesis, the use of non-canonical wobble base pairs at codon position 3 does not cause any measurable difference in mitoribosome occupancy irrespective of the codon. Comparison of the profile of aberrant mt-tRNAPhe containing mitoribosomes with those of controls that integrate mt-tRNAVal revealed that the impaired translation seen in the latter was not due to stalling on triplets encoding either of these amino acids. The alterations in mitoribosome interactions with start codons was not directly attributable to the either the use of non-cognate initiation codons or the presence or absence of 5’ leader sequences, except in the two bicistronic RNA units, RNA7 and RNA14 where the initiation sites are internal. Conclusions: These data report the power of mitoribosomal profiling in helping to understand the subtleties of mammalian mitochondrial protein synthesis. Analysis of profiles from the mutant mt-tRNAVal cell line suggest that despite mt-tRNAPhe being preferred in the porcine mitoribosome, its integration into the human counterpart results in a suboptimal structure that modifies its interaction with mt-mRNAs.

Rpm2, the Protein Subunit of Mitochondrial RNase P in Saccharomyces cerevisiae, Also Has a Role in the Translation of Mitochondrially Encoded Subunits of Cytochrome c Oxidase

Genetics ◽  
2001 ◽  
Vol 158 (2) ◽  
pp. 573-585
Author(s):  
Vilius Stribinskis ◽  
Guo-Jian Gao ◽  
Steven R Ellis ◽  
Nancy C Martin
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Mitochondrial Biogenesis ◽  
Mitochondrial Protein ◽  
Nuclear Gene ◽  
Rnase P ◽  
Wild Type ◽  
Protein Subunit ◽  
Mitochondrial Translation

Abstract RPM2 is a Saccharomyces cerevisiae nuclear gene that encodes the protein subunit of mitochondrial RNase P and has an unknown function essential for fermentative growth. Cells lacking mitochondrial RNase P cannot respire and accumulate lesions in their mitochondrial DNA. The effects of a new RPM2 allele, rpm2-100, reveal a novel function of RPM2 in mitochondrial biogenesis. Cells with rpm2-100 as their only source of Rpm2p have correctly processed mitochondrial tRNAs but are still respiratory deficient. Mitochondrial mRNA and rRNA levels are reduced in rpm2-100 cells compared to wild type. The general reduction in mRNA is not reflected in a similar reduction in mitochondrial protein synthesis. Incorporation of labeled precursors into mitochondrially encoded Atp6, Atp8, Atp9, and Cytb protein was enhanced in the mutant relative to wild type, while incorporation into Cox1p, Cox2p, Cox3p, and Var1p was reduced. Pulse-chase analysis of mitochondrial translation revealed decreased rates of translation of COX1, COX2, and COX3 mRNAs. This decrease leads to low steady-state levels of Cox1p, Cox2p, and Cox3p, loss of visible spectra of aa3 cytochromes, and low cytochrome c oxidase activity in mutant mitochondria. Thus, RPM2 has a previously unrecognized role in mitochondrial biogenesis, in addition to its role as a subunit of mitochondrial RNase P. Moreover, there is a synthetic lethal interaction between the disruption of this novel respiratory function and the loss of wild-type mtDNA. This synthetic interaction explains why a complete deletion of RPM2 is lethal.

Insulin stimulates mitochondrial protein synthesis and respiration in isolated perfused rat heart.

1990 ◽  
Vol 259 (3) ◽  
pp. E413
Author(s):  
E E McKee ◽  
B L Grier
Keyword(s):  
Protein Synthesis ◽  
Mitochondrial Protein ◽  
Control Level ◽  
Respiratory Control ◽  
Mitochondrial Proteins ◽  
Mitochondrial Protein Synthesis ◽  
Mitochondrial Translation ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Perfused Hearts

The rates of synthesis of mitochondrial proteins by both the cytoplasmic and mitochondrial protein synthetic systems, as well as parameters of respiration, were measured and compared in mitochondria isolated from fresh, control perfused, and insulin-perfused rat hearts. The respiratory control ratio (RCR) in mitochondria from fresh hearts was 8.1 +/- 0.4 and decreased to 6.0 +/- 0.2 (P less than 0.001 vs. fresh) in mitochondria from control perfused hearts and to 6.7 +/- 0.2 (P less than 0.005 vs. fresh and P less than 0.02 vs. control perfused) for mitochondria from hearts perfused in the presence of insulin. A positive correlation between the RCR and the rate of mitochondrial translation was demonstrated in mitochondria from fresh hearts. In mitochondria isolated from control perfused hearts, the rate of protein synthesis decreased to 84 +/- 3% of the fresh rate after 30 min of perfusion and fell further to 64 +/- 3% after 3 h of perfusion. The inclusion of insulin in the perfusion buffer stimulated mitochondrial protein synthesis 1.2-fold by 1 h (P less than 0.005) and 1.34-fold by 3 h of perfusion (P less than 0.001). The addition of insulin to 1-h control perfused hearts shifted the rate of mitochondrial protein synthesis from the control level to the insulin-perfused level within 30 min of additional perfusion, whereas 1 h was required to shift the RCR values of these mitochondria from control levels to insulin-perfused levels. Thus, whereas RCR was a useful predictor of mitochondrial translation rates, it did not account for the effects of insulin on mitochondrial translation.(ABSTRACT TRUNCATED AT 250 WORDS)

Glutamyl-tRNAGln amidotransferase is essential for mammalian mitochondrial translation in vivo

2014 ◽  
Vol 460 (1) ◽  
pp. 91-101 ◽  
Author(s):  
Lucía Echevarría ◽  
Paula Clemente ◽  
Rosana Hernández-Sierra ◽  
María Esther Gallardo ◽  
Miguel A. Fernández-Moreno ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Mammalian Cells ◽  
Mitochondrial Protein ◽  
Mitochondrial Protein Synthesis ◽  
Indirect Pathway ◽  
Mitochondrial Translation

We have demonstrated that in mitochondria of mammalian cells the aminoacylation of tRNAGln is produced by an indirect pathway involving the enzyme glutamyl-tRNAGln amidotransferase. Misaminoacylated Glu-tRNAGln is rejected from the ribosomes maintaining the fidelity of the mitochondrial protein synthesis.

The mitospecific domain of Mrp7 (bL27) supports mitochondrial translation during fermentation and is required for effective adaptation to respiration

2021 ◽  
Author(s):  
Jessica M. Anderson ◽  
Jodie M. Box ◽  
Rosemary A. Stuart
Keyword(s):  
Protein Synthesis ◽  
Mitochondrial Protein ◽  
Growth Conditions ◽  
Mitochondrial Protein Synthesis ◽  
Mitochondrial Translation ◽  
Glucose Fermentation ◽  
Binding Partner ◽  
Oxphos Complex ◽  
Mitochondrial Signaling ◽  
Metabolic Conditions

We demonstrate here that mitoribosomal protein synthesis, responsible for the synthesis of oxidative phosphorylation (OXPHOS) subunits encoded by mitochondrial genome, occurs at high levels during glycolysis fermentation and in a manner uncoupled from OXPHOS complex assembly regulation. Furthermore, we provide evidence that the mitospecific domain of Mrp7 (bL27), a mitoribosomal component, is required to maintain mitochondrial protein synthesis during fermentation, but is not required under respiration growth conditions. Maintaining mitotranslation under high glucose fermentation conditions also involves Mam33 (p32/gC1qR homolog), a binding partner of Mrp7’s mitospecific domain, and together they confer a competitive advantage for a cell's ability to adapt to respiration-based metabolism when glucose becomes limiting. Furthermore, our findings support that the mitoribosome, and specifically the central protuberance (CP) region, may be differentially regulated and/or assembled, under the different metabolic conditions of fermentation and respiration. Based on our findings, we propose the purpose of mitotranslation is not limited to the assembly of OXPHOS complexes, but also plays a role in mitochondrial signaling critical for switching cellular metabolism from a glycolysis- to a respiratory-based state.

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