Nuclear omnipotent suppressors of premature termination codons in mitochondrial genes affect the 37S mitoribosomal subunit

Boguta, Magdalena; Mieszczak, Maria; Zagórski, Włodzimierz

doi:10.1007/bf00365647

Cited by 5 publications

(3 citation statements)

References 27 publications

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“…Thus, the number of mitochondrial ribosomal proteins given in fig. 1 reflects a minimum, and it is not surprising that the number of proteins in the 2D pattern differs from previous reports [19,20]. For the majority of mitochondrial proteins it has been shown that an amino-terminal presequence is necessary for their transport into mitochondria, and that this leader peptide is cleaved off the precursor protein during that process [21].…”

Section: Resultsmentioning

confidence: 75%

Mitochondrial ribosomes of yeast: Isolation of individual proteins and N‐terminal sequencing

Graack¹,

Grohmann²,

Choli³

1988

FEBS Letters

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Proteins of the small and large subunits of mitcchondrial ribosomes from the yeast Succharomyces cerevisiae were isolated and characterized by two-dimensional gel electrophoresis. Ribosomal proteins of the large subunit were separated by reverse-phase HPLC and up to 37 amino acid residues of the N-terminal sequences of L3, L4, L9 and L31 were determined. No significant homology to ribosomal protein sequences so far determined from other organisms was found.

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Section: Resultsmentioning

confidence: 75%

Mitochondrial ribosomes of yeast: Isolation of individual proteins and N‐terminal sequencing

Graack¹,

Grohmann²,

Choli³

1988

FEBS Letters

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“…Genetic studies indicated an allele-specific, gene non-specific omnipotent mode of suppression that could result from decreased translation fidelity of premature stop codons (Kruszewska & Slonimski, 1984b;Zagorski et al, 1987b). This hypothesis was in part verified by direct biochemical data (Boguta et al, 1988;Mieszczak & Zagorski, 1987b). Recent studies identified nam3-1 and nam3-2 as alleles of the nuclear gene MRF1 encoding the mitochondrial release factor corresponding, respectively, to mrf1-145 352 S®I and mrf1-136 216 S®Y (Towpik et al, 2004).…”

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confidence: 92%

Translational readthrough of a termination codon in the yeast mitochondrial mRNA VAR1 as a result of mutation in the release factor mRF1.

Claisse

Boguta²,

Zagórski³

2005

Acta Biochim Pol

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Yeast mitochondrial DNA codes for eight major polypeptides. Translation of he mitochondrially encoded polypeptides in strains with mutated mitochondrial release factor, mRF1, was found to result in the synthesis of a novel protein, V2. Different mrf1 alleles were associated with different efficiency of V2p synthesis. Translation of V2p was enhanced by paromomycin. Comparative analysis of peptides resulting from protease digestion indicated that V2p is a derivative of Var1p. According to our hypothesis, V2p represents a readthrough product of the natural stop codon in VAR1 mRNA.An effective way of investigating the expression of genes in mtDNA is based on studying the control exerted by the nucleus over mitochondrial functions. This is due to replication, transcription and translation apparatus in mitochondria being composed mostly of polypeptides encoded by nuclear DNA. The yeast Saccharomyces cerevisiae, being a facultative anaerobe, offers distinct advantages for mitochondrial genetic studies. Several hundred respiratory deficient point mutations or small deletions, called mit -, have been genetically mapped and assigned to genes in mtDNA. Respiration of mitstrain Vol. 52 No. 1/2005 [129][130][131][132][133][134][135][136][137] QUARTERLY .

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“…NAM], NAM2, NAM7, and NAM8 suppressors are involved in both translation and splicing (2,13,26,40). The recessive suppressor mutations nam3 and ribosome series suppressors (5,36,37,68) seem to be analogous to Escherichia coli ribosomal ram suppressors in the sense of their allelespecific, gene-nonspecific mode of action (18). Those suppressors presumably act by decreasing the fidelity of translation resulting from the changes in mitochondrial r-proteins.…”

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confidence: 99%

NAM9 Nuclear Suppressor of Mitochondrial Ochre Mutations in Saccharomyces cerevisiae Codes for a Protein Homologous to S4 Ribosomal Proteins from Chloroplasts, Bacteria, and Eucaryotes

Boguta

Dmochowska

Borsuk

et al. 1992

Molecular and Cellular Biology

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We report the genetic characterization, molecular cloning, and sequencing of a novel nuclear suppressor, the NAM9 gene from Saccharomyces cerevisiae, which acts on mutations of mitochondrial DNA. The strain NAM9-1 was isolated as a respiration-competent revertant of a mitochondrial mit mutant which carries the V25 ochre mutation in the oxi1 gene. Genetic characterization of the NAM9-1 mutation has shown that it is a nuclear dominant omnipotent suppressor alleviating several mutations in all four mitochondrial genes tested and has suggested its informational, and probably ribosomal, character. The NAM9 gene was cloned by transformation of the recipient oxi1-V25 mutant to respiration competence by using a gene bank from the NAM9-1 rho o strain. Orthogonal-field alternation gel electrophoresis analysis and genetic mapping localized the NAM9 gene on the right arm of chromosome XIV. Sequence analysis of the NAM9 gene showed that it encodes a basic protein of 485 amino acids with a presequence that could target the protein to the mitochondrial matrix. The N-terminal sequence of 200 amino acids of the deduced NAM9 product strongly resembles the S4 ribosomal proteins from chloroplasts and bacteria. Significant although less extensive similarity was found with ribosomal cytoplasmic proteins from lower eucaryotes, including S. cerevisiae. Chromosomal inactivation of the NAM9+ gene is not lethal to the cell but leads to respiration deficiency and loss of mitochondrial DNA integrity. We conclude that the NAM9 gene product is a mitochondrial ribosomal counterpart of S4 ribosomal proteins found in other systems and that the suppressor acts through decreasing the fidelity of translation.

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Nuclear omnipotent suppressors of premature termination codons in mitochondrial genes affect the 37S mitoribosomal subunit

Cited by 5 publications

References 27 publications

Mitochondrial ribosomes of yeast: Isolation of individual proteins and N‐terminal sequencing

Mitochondrial ribosomes of yeast: Isolation of individual proteins and N‐terminal sequencing

Translational readthrough of a termination codon in the yeast mitochondrial mRNA VAR1 as a result of mutation in the release factor mRF1.

NAM9 Nuclear Suppressor of Mitochondrial Ochre Mutations in Saccharomyces cerevisiae Codes for a Protein Homologous to S4 Ribosomal Proteins from Chloroplasts, Bacteria, and Eucaryotes

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