scholarly journals MITOCHONDRIAL PROTEIN SYNTHESIS IN HELA CELLS

1974 ◽  
Vol 60 (3) ◽  
pp. 755-763 ◽  
Author(s):  
Jonas B. Galper
Keyword(s):  
Protein Synthesis ◽  
Ethidium Bromide ◽  
Mitochondrial Protein ◽  
Specific Protein ◽  
Mitochondrial Proteins ◽  
Mitochondrial Protein Synthesis ◽  
Initiator Trna ◽  
Low Concentrations ◽  
Separate Protein

HeLa cell mitochondrial proteins have been shown to be the products of two separate protein-synthesizing systems; one, the general cellular mechanism, sensitive to inhibition by cycloheximide, the other, a specific mitochondrial system subject to inhibition by low concentrations of chloramphenicol (Galper, J. B., and J. E. Darnell. 1971. J. Mol. Biol 57:363). Preliminary data have suggested that a mitochondrial N-formyl-methionyl-tRNA (f-Met-tRNA) might be the initiator tRNA in the latter (Galper, J. B., and J. E. Darnell. 1969. Biochem. Biophys. Res. Commun. 34:205; 1971. J. Mol. Biol. 57:363). It is demonstrated here that the synthesis of these endogenous mitochondrial proteins is also subject to inhibition by ethidium bromide and decays with a half-life of 1½–2 h in cultures incubated with low concentrations of this dye. The role of formylated f-Met-tRNA as the initiator tRNA in the synthesis of mitochondrial proteins is supported by data from several experiments. The rates of ethidium bromide inhibition of both the charging of f-Met-tRNA and of the synthesis of mitochondrial proteins are strikingly similar. Inhibition by aminopterin of the formylation of f-Met-tRNA greatly depresses the rate of mitochondrial-specific protein synthesis. In the absence of the synthesis of these proteins, respiration, the levels of cytochromes a–a3 and b, and the number of mitochondrial cristae are decreased. The implications of these findings as they relate to mitochondrial biogenesis are discussed.

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.

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)

scholarly journals Physiological Role of the N-terminal Processed P4501A1 Targeted to Mitochondria in Erythromycin Metabolism and Reversal of Erythromycin-mediated Inhibition of Mitochondrial Protein Synthesis

1999 ◽  
Vol 274 (10) ◽  
pp. 6617-6625 ◽  
Author(s):  
Hindupur K. Anandatheerthavarada ◽  
C. Vijayasarathy ◽  
Shripad V. Bhagwat ◽  
Gopa Biswas ◽  
Jayati Mullick ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Mitochondrial Protein ◽  
Physiological Role ◽  
Mitochondrial Protein Synthesis

Mitochondrial DNA Medicine

2007 ◽  
Vol 27 (1-3) ◽  
pp. 5-9 ◽  
Author(s):  
Salvatore DiMauro
Keyword(s):  
Mitochondrial Dna ◽  
Protein Synthesis ◽  
Mitochondrial Protein ◽  
Point Mutations ◽  
Specific Protein ◽  
Mitochondrial Protein Synthesis ◽  
Mitochondrial Genetics ◽  
Protein Coding ◽  
Protein Coding Genes ◽  
Mitochondrial Medicine

The small, maternally inherited mitochondrial DNA (mtDNA) has turned out to be a hotbed of pathogenic mutations: 15 years into the era of ‘mitochondrial medicine’, over 150 pathogenic point mutations and countless rearrangements have been associated with a variety of multisystemic or tissue-specific human diseases. MtDNA-related disorders can be divided into two major groups: those due to mutations in genes affecting mitochondrial protein synthesis in toto and those due to mutations in specific protein-coding genes. Here we review the mitochondrial genetics and the clinical features of the mtDNA-related diseases.

scholarly journals The molecular chaperone Hsp78 confers compartment-specific thermotolerance to mitochondria.

1996 ◽  
Vol 134 (6) ◽  
pp. 1375-1386 ◽  
Author(s):  
M Schmitt ◽  
W Neupert ◽  
T Langer
Keyword(s):  
Protein Synthesis ◽  
Heat Shock ◽  
Temperature Stress ◽  
Mitochondrial Protein ◽  
Heat Inactivation ◽  
Mitochondrial Protein Synthesis ◽  
Extreme Stress ◽  
Mitochondrial Functions ◽  
Mitochondrial Hsp70

Hsp78, a member of the family of Clp/Hsp100 proteins, exerts chaperone functions in mitochondria of S. cerevisiae which overlap with those of mitochondrial Hsp70. In the present study, the role of Hsp78 under extreme stress was analyzed. Whereas deletion of HSP78 does not affect cell growth at temperatures up to 39 decrees C and cellular thermotolerance at 50 degrees C, Hsp78 is crucial for maintenance of respiratory competence and for mitochondrial genome integrity under severe temperature stress (mitochondrial thermotolerance). Mitochondrial protein synthesis is identified as a thermosensitive process. Reactivation of mitochondrial protein synthesis after heat stress depends on the presence of Hsp78, though Hsp78 does not confer protection against heat-inactivation to this process. Hsp78 appears to act in concert with other mitochondrial chaperone proteins since a conditioning pretreatment of the cells to induce the cellular heat shock response is required to maintain mitochondrial functions under severe temperature stress. When expressed in the cytosol, Hsp78 can substitute for the homologous heat shock protein Hsp104 in mediating cellular thermotolerance, suggesting a conserved mode of action of the two proteins. Thus, proteins of the Clp/Hsp100-family located in the cytosol and within mitochondria confer compartment-specific protection against heat damage to the cell.

Discrete electrophoretic products of mitochondrial protein synthesis in the Chinese hamster ovary cell line

1977 ◽  
Vol 55 (10) ◽  
pp. 1064-1074 ◽  
Author(s):  
R. W. Yatscoff ◽  
K. B. Freeman
Keyword(s):  
Protein Synthesis ◽  
Cell Line ◽  
Electrophoretic Mobility ◽  
Chinese Hamster Ovary ◽  
Mitochondrial Protein ◽  
Chinese Hamster ◽  
Mitochondrial Proteins ◽  
Mitochondrial Protein Synthesis ◽  
Cho Cell ◽  
Cho Cell Line

Mitochondrial proteins labelled with [35S]methionine for 1 h in whole Chinese hamster ovary (CHO) cells in the presence of cycloheximide or emetine, known inhibitors of cytosolic protein synthesis, have been enumerated and characterized by their electrophoretic mobility in sodium dodecyl sulfate slab gel electrophoresis. Ten distinct electrophoretic bands were observed. The components were relatively stable during a 2 h postlabelling period. The same 10 bands were also seen with the CHO cell line tsH1, labelled at 40 °C, a temperature at which cytosolic but not mitochondrial protein synthesis is inhibited in this cell line, and with isolated mitochondria labelled in the presence of cycloheximide. An 11th band was present when [3H]leucine but not [35S] methionine was used for labelling. The width of the major band suggested that it consists of two components making a total of at least 12 proteins synthesized in mitochondria. The molecular weights of these mitochondrial proteins ranged from 5000 to 50000 and there was a sixfold difference in the relative molar amounts synthesized in a 1-h period in the presence of [3H]leucine or [3SS] methionine.No differences in number or electrophoretic mobility of the mitochondrially synthesized proteins were found among the seven CHO cell lines examined. These results suggest the stability of the mitochondrial genome in the CHO cell line.

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