The relationship of cardiolipin biosynthesis to mitochondrial protein synthesis in Tetrahymena pyriformis

1983 ◽  
Vol 61 (4) ◽  
pp. 223-228 ◽  
Author(s):  
Sean M. Hemmingsen ◽  
Laura Querengesser ◽  
Paul G. Young
Keyword(s):  
Protein Synthesis ◽  
Stationary Phase ◽  
Mitochondrial Protein ◽  
Tetrahymena Pyriformis ◽  
Pulse Labelling ◽  
Mitochondrial Protein Synthesis ◽  
Mole Percent ◽  
Quantitative Measurements ◽  
Relationship Of ◽  
The Relationship

The synthesis of cardiolipin has been investigated following the inhibition of mitochondrial protein synthesis with chloramphenicol. Quantitative measurements of the amount of cardiolipin in the cell during treatment with chloramphenicol as well as pulse-labelling studies using labelled acetate were carried out. The results show that while whole cell phospholipid biosynthesis is depressed by the treatment (probably a reflection of a general cessation of growth), there is no sign of any preferential effect on cardiolipin synthesis. The data also show that as cells are reduced in size as they approach stationary phase there is a six- to seven-fold loss of total cellular phospholipids; however, the amount of cardiolipin is only reduced by four- to five-fold. There is a preferential conservation of cardiolipin as stationary phase is approached with the mole percent cardiolipin phosphorus in the cell rising from 5–7% to 10–12%.

scholarly journals Dependence of nucleus-directed rRNA synthesis upon mitochondrial protein synthesis in Tetrahymena.

1982 ◽  
Vol 2 (5) ◽  
pp. 508-516 ◽  
Author(s):  
L Ruben ◽  
A B Hooper
Keyword(s):  
Protein Synthesis ◽  
Rna Synthesis ◽  
Mitochondrial Protein ◽  
Tetrahymena Pyriformis ◽  
Cellular Protein ◽  
Rrna Synthesis ◽  
Mitochondrial Protein Synthesis ◽  
Mitochondrial Rrna ◽  
Polyadenylated Rna ◽  
Nuclear Rna

The antibiotic chloramphenicol selectively inhibited mitochondrial protein synthesis in the ciliate protozoan Tetrahymena pyriformis GL. Secondary to the inhibition of mitochondrial protein synthesis was an inhibition of nuclear RNA synthesis at a time before inhibition of cellular protein and DNA synthesis. Of the stable non-polyadenylated RNA species in Tetrahymena, the addition of chloramphenicol resulted specifically in the inhibition of synthesis of 28S + 17S and 5S rRNA transcripts. By contrast, syntheses of 4S tRNA and 21S mitochondrial rRNA were not as extensively inhibited. The addition of 60 microM hemin before the addition of chloramphenicol partially protected against the inhibition of RNA synthesis. These data indicate that continued synthesis of nucleus-directed rRNA is linked to the synthesis of mitochondrial proteins in Tetrahymena.

Dependence of nucleus-directed rRNA synthesis upon mitochondrial protein synthesis in Tetrahymena

1982 ◽  
Vol 2 (5) ◽  
pp. 508-516
Author(s):  
L Ruben ◽  
A B Hooper
Keyword(s):  
Protein Synthesis ◽  
Rna Synthesis ◽  
Mitochondrial Protein ◽  
Tetrahymena Pyriformis ◽  
Cellular Protein ◽  
Rrna Synthesis ◽  
Mitochondrial Protein Synthesis ◽  
Mitochondrial Rrna ◽  
Polyadenylated Rna ◽  
Nuclear Rna

The antibiotic chloramphenicol selectively inhibited mitochondrial protein synthesis in the ciliate protozoan Tetrahymena pyriformis GL. Secondary to the inhibition of mitochondrial protein synthesis was an inhibition of nuclear RNA synthesis at a time before inhibition of cellular protein and DNA synthesis. Of the stable non-polyadenylated RNA species in Tetrahymena, the addition of chloramphenicol resulted specifically in the inhibition of synthesis of 28S + 17S and 5S rRNA transcripts. By contrast, syntheses of 4S tRNA and 21S mitochondrial rRNA were not as extensively inhibited. The addition of 60 microM hemin before the addition of chloramphenicol partially protected against the inhibition of RNA synthesis. These data indicate that continued synthesis of nucleus-directed rRNA is linked to the synthesis of mitochondrial proteins in Tetrahymena.

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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