scholarly journals Intricacies and surprises of nuclear–mitochondrial co-evolution

2006 ◽  
Vol 399 (2) ◽  
Author(s):  
Dagmar K. Willkomm ◽  
Roland K. Hartmann
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Rna World ◽  
Mitochondrial Protein ◽  
Mitochondrial Protein Synthesis ◽  
Trna Structure ◽  
Protein Synthesis Machinery ◽  
Biochemical Journal ◽  
Protein World ◽  
Mitochondrial Elongation

In this issue of the Biochemical Journal, Watanabe and colleagues disclose another fascinating facet of the mitochondrial protein synthesis machinery: one of the two nematode mitochondrial elongation factors Tu, EF-Tu1, specifically recognizes the D-arm of T-armless tRNAs via a 57-amino-acid C-terminal extension that compensates for the reduction in tRNA structure. This principle provides a paradigm for the evolutionary events thought to have ignited the transition from an ancient ‘RNA world’ to the ‘protein world’ of today.

The effect of chloramphenicol, ethidium bromide and cycloheximide on mortality and mitochondrial protein synthesis of adult blowflies

1980 ◽  
Vol 41 (1) ◽  
pp. 273-289
Author(s):  
B. Ashour ◽  
M. Tribe ◽  
P. Whittaker
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Drug Treatment ◽  
Ethidium Bromide ◽  
Flight Muscle ◽  
Mitochondrial Protein ◽  
Age Groups ◽  
Age Group ◽  
Mitochondrial Protein Synthesis ◽  
Inhibition Of Protein Synthesis

The effects of cycloheximide, chloramphenicol and ethidium bromide on the blowfly Calliphora erythrocephala were studied. In the first set of experiments, toxic levels were determined by examining activity and mortality of flies after injection of various doses of each drug. In the second set of experiments, the effect of drug treatment on flight muscle mitochondrial protein synthesis was determined in relation to age by following the incorporation of radioactively labelled amino acid, [3H]leucine, into mitochondrial protein in vivo. To confirm the developmental changes in flight muscle mitochondria, mitochondrial protein content per fly was estimated from emergence to 30 days of age; the highest protein level was recorded between 6 and 10 days of age. Maximum incorporation of labelled amino acid was found in newly emerged flies, and this age group was also the most sensitive to drug treatment. By the time flies had reached 6–10 days of age, amino acid incorporation had declined to about two-thirds of the rate obtained with newly emerged flies. With 6–10-day old flies, however, the highest value for flight muscle mitochondrial protein per fly was recorded, and these flies also displayed the greatest resistance to drug treatment of any age group investigated. For example, inhibition of protein synthesis following injection of 300 micrograms/fly of chloramphenicol was only about 15% below the untreated control in 6–10-day-old flies, whereas in all other age groups investigated, inhibition ranged between 30 and 50% of the controls. At 15–20 days of age, protein synthesis decreased to a third of the newly emerged flies' rate and continued to decrease further in the 30–35-day-old group, where it was less than one sixth of the youngest age group. The effect of drug treatment on these older flies was also less than that observed with newly emerged flies, especially after chloramphenicol and ethidium bromide injections. The effect of cycloheximide however, was much the same in all age groups, with inhibition of protein synthesis being 80–90% of controls. Surprisingly, cycloheximide (1–10 micrograms/fly) had little initial effect on mortality of young flies, despite almost complete blockage in the synthesis of mitochondrial proteins at these concentrations. 95% mortality occurred only when doses of 20 micrograms/fly were given. In contrast, high doses of chloramphenicol (400 micrograms/fly) and ethidium bromide (15 micrograms/fly) caused almost total mortality a few hours after injection, although such doses never induced more than about 50% inhibition of mitochondrial protein synthesis. Each drug therefore has a different site of inhibition and induces different mortality effects. Possible explanations for these differences in mortality are discussed.

scholarly journals Transmembrane BAX Inhibitor-1 Motif Containing Protein 5 (TMBIM5) Sustains Mitochondrial Structure, Shape, and Function by Impacting the Mitochondrial Protein Synthesis Machinery

Cells ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 2147
Author(s):  
Bruno Seitaj ◽  
Felicia Maull ◽  
Li Zhang ◽  
Verena Wüllner ◽  
Christina Wolf ◽  
...  
Keyword(s):  
Cell Death ◽  
Protein Synthesis ◽  
Mitochondrial Membrane ◽  
Mitochondrial Protein ◽  
Mitochondrial Protein Synthesis ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Structure ◽  
Protein Synthesis Machinery ◽  
Atp Generation ◽  
And Function

The Transmembrane Bax Inhibitor-1 motif (TMBIM)-containing protein family is evolutionarily conserved and has been implicated in cell death susceptibility. The only member with a mitochondrial localization is TMBIM5 (also known as GHITM or MICS1), which affects cristae organization and associates with the Parkinson’s disease-associated protein CHCHD2 in the inner mitochondrial membrane. We here used CRISPR-Cas9-mediated knockout HAP1 cells to shed further light on the function of TMBIM5 in physiology and cell death susceptibility. We found that compared to wild type, TMBIM5-knockout cells were smaller and had a slower proliferation rate. In these cells, mitochondria were more fragmented with a vacuolar cristae structure. In addition, the mitochondrial membrane potential was reduced and respiration was attenuated, leading to a reduced mitochondrial ATP generation. TMBIM5 did not associate with Mic10 and Mic60, which are proteins of the mitochondrial contact site and cristae organizing system (MICOS), nor did TMBIM5 knockout affect their expression levels. TMBIM5-knockout cells were more sensitive to apoptosis elicited by staurosporine and BH3 mimetic inhibitors of Bcl-2 and Bcl-XL. An unbiased proteomic comparison identified a dramatic downregulation of proteins involved in the mitochondrial protein synthesis machinery in TMBIM5-knockout cells. We conclude that TMBIM5 is important to maintain the mitochondrial structure and function possibly through the control of mitochondrial biogenesis.

THYROXINE STIMULATION OF AMINO ACID INCORPORATION INTO MITOCHONDRIAL PROTEIN: DIFFERENCES BETWEEN IN VIVO AND IN VITRO EFFECTS

1973 ◽  
Vol 72 (4) ◽  
pp. 684-696 ◽  
Author(s):  
Amirav Gordon ◽  
Martin I. Surks ◽  
Jack H. Oppenheimer
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Mitochondrial Protein ◽  
Leucine Incorporation ◽  
Mitochondrial Protein Synthesis ◽  
Amino Acid Incorporation ◽  
Acid Incorporation ◽  
Stimulation Of

ABSTRACT The in vivo and in vitro stimulation of rat hepatic mitochondrial protein synthesis by thyroxine (T4) was compared. In confirmation of Buchanan & Tapley (1966). T4 added to isolated mitochondria rapidly stimulated [14C] leucine incorporation into mitochondrial protein. The in vitro stimulation was reversed after T4 was removed by incubating the mitochondria with bovine serum albumin (BSA). The decrease in T4 stimulation of protein synthesis appeared proportional to the T4 removed by BSA. Thus, it appears probable that exchangeable T4 controls the in vitro system. In contrast, the increase in mitochondrial protein synthesis which was observed 3 to 4 days after pretreatment of hypothyroid rats with labelled and non-radioactive T4 was not reversed by BSA treatment. Moreover, mitochondrial radioactivity could not be extracted with albumin. The in vivo phenomenon does not, therefore, appear to be related to exchangeable hormone in the mitochondria. Furthermore, the estimated quantity of T4 associated with mitochondria after in vivo stimulation was at least two orders of magnitude less than that required to produce comparable stimulation of mitochondrial protein synthesis in vitro. These findings strongly suggest that in vitro and in vivo stimulation of amino acid incorporation by T4 may be mediated by different biochemical mechanisms.

Collection of Mitochondrial tRNA Sequences and Anticodon Identification for Acheta domesticus

2019 ◽  
Vol 967 ◽  
pp. 65-70
Author(s):  
Yash Munnalal Gupta ◽  
Kittisak Buddhachat ◽  
Surin Peyachoknagul ◽  
Somjit Homchan
Keyword(s):  
Protein Synthesis ◽  
Related Species ◽  
Mitochondrial Protein ◽  
Acheta Domesticus ◽  
Synthesis Process ◽  
Trna Genes ◽  
Mitochondrial Protein Synthesis ◽  
Mitochondrial Trna ◽  
Protein Synthesis Machinery ◽  
Codon Use

The mitochondria are organelles found within eukaryotic cell, possess own small circular DNA (mtDNA) apart from the most of DNA found in cell nucleus. The transcription and translation of mtDNA requires tRNA that often encoded by mtDNA itself. The mtDNA evolves faster than genomic DNA primary due to mitochondrial dysfunction and pathogenesis. The genes of mitochondria tRNA (mt tRNA) are prone to mutate that links to mitochondrial activity and protein synthesis machinery. It is important to understand the codon use by mt tRNA for Acheta domesticus to understand evolutionary relationship within closely related species and mitochondrial protein synthesis machinery. The present study uses the High throughput RNA sequencing data to identify mt tRNA genes using to examine the codon use for mitochondrial protein synthesis process. The conservative property of tRNA secondary structure assisted identified and confirmed anchored tRNA sequences with respective amino acid anticodon according to genetic code for tRNA in mtDNA. This study provides mt tRNA sequences to understand evolution of mitochondrial tRNA of Acheta domesticus with other related species to establish phylogeny. Moreover, mt tRNAs are the exons that provides partial sequences for mitochondria DNA. The novel approach for tRNA identification will guide other studies for PCR free in silico analysis.

scholarly journals Insulin fails to enhance mTOR phosphorylation, mitochondrial protein synthesis, and ATP production in human skeletal muscle without amino acid replacement

2012 ◽  
Vol 303 (9) ◽  
pp. E1117-E1125 ◽  
Author(s):  
Rocco Barazzoni ◽  
Kevin R. Short ◽  
Yan Asmann ◽  
Jill M. Coenen-Schimke ◽  
Matthew M. Robinson ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Enzyme Activities ◽  
Muscle Protein ◽  
Mitochondrial Protein ◽  
Mitochondrial Genes ◽  
Mrna Levels ◽  
Mitochondrial Enzyme ◽  
Mitochondrial Protein Synthesis ◽  
Atp Production

Systemic insulin administration causes hypoaminoacidemia by inhibiting protein degradation, which may in turn inhibit muscle protein synthesis (PS). Insulin enhances muscle mitochondrial PS and ATP production when hypoaminoacidemia is prevented by exogenous amino acid (AA) replacement. We determined whether insulin would stimulate mitochondrial PS and ATP production in the absence of AA replacement. Using l-[1,2-13C]leucine as a tracer, we measured the fractional synthetic rate of mitochondrial as well as sarcoplasmic and mixed muscle proteins in 18 participants during sustained (7-h) insulin or saline infusion ( n = 9 each). We also measured muscle ATP production, mitochondrial enzyme activities, mRNA levels of mitochondrial genes, and phosphorylation of signaling proteins regulating protein synthesis. The concentration of circulating essential AA decreased during insulin infusion. Mitochondrial, sarcoplasmic, and mixed muscle PS rates were also lower during insulin (2–7 h) than during saline infusions despite increased mRNA levels of selected mitochondrial genes. Under these conditions, insulin did not alter mitochondrial enzyme activities and ATP production. These effects were associated with enhanced phosphorylation of Akt but not of protein synthesis activators mTOR, p70S6K, and 4EBP1. In conclusion, sustained physiological hyperinsulinemia without AA replacement did not stimulate PS of mixed muscle or protein subfractions and did not alter muscle mitochondrial ATP production in healthy humans. These results support that insulin and AA act in conjunction to stimulate muscle mitochondrial function and mitochondrial protein synthesis.

scholarly journals Selective synthesis of mitochondrial proteins by Chinese hamster ovary cells severely starved for various amino acids.

1984 ◽  
Vol 98 (4) ◽  
pp. 1603-1605 ◽  
Author(s):  
J W Chamberlain ◽  
J W Pollard ◽  
C P Stanners
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Chinese Hamster Ovary ◽  
Mitochondrial Protein ◽  
Chinese Hamster ◽  
Protein Synthesis Inhibitor ◽  
Mitochondrial Protein Synthesis ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases

Chinese hamster ovary (CHO) cells were subjected to severe amino acid starvation for histidine, leucine, methionine, asparagine, tyrosine, glutamine, valine, and lysine, using amino acid analogs or mutations in specific aminoacyl-tRNA synthetases. At protein synthetic rates of less than 5%, in all cases, the newly synthesized proteins were found on two-dimensional electrophoretic gels to consist of a few intensely labeled spots, with the exception of lysine. This pattern could also be produced by strong inhibition of cytoplasmic protein synthesis with cycloheximide, and was abolished by preincubation with the mitochondrial protein synthesis inhibitor chloramphenicol. It appears therefore that the spots represent mitochondrial protein synthesis and that animal cells must have separate aminoacyl-tRNA synthetases for mitochondrial tRNAs corresponding to all these amino acids except, possibly, for lysine.

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.

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