OpenScientist hypothesis report: conservation of the mitochondrial tRNA-processing role of S. pombe Rrg8
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The mitochondrial tRNA-processing assignment is partially supported as a manual orthology transfer, but remains unverified in S. pombe; approximately 23% pairwise identity, absence of the donor's Pfam match on O14106, and a low-confidence O14106 AlphaFold model make direct experimental confirmation especially important.
"**Verdict: Partially supported (orthology-based; unverified in *S. pombe*).**"
Use of the ND evidence code for Gene Ontology (GO) terms
Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
UniProt entry O14106 for S. pombe rrg8
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UniProt records protein-specific cytoplasm and nucleus localization assertions for O14106, both attributed to the Matsuyama ORFeome screen.
"SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:16823372}. Nucleus {ECO:0000269|PubMed:16823372}."
5' processing of Saccharomyces cerevisiae mitochondrial tRNAs requires expression of multiple genes.
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The budding-yeast ortholog RRG8/MTA1 is one of four genes (MTA1, MTA2, GEP5, PET130) required for efficient 5' processing of mitochondrial tRNAs; the proteins associate with the mitochondrial inner membrane, form high-molecular-weight complexes, and Mta1p co-immunopurifies with the RNase P protein subunit Rpm2p.
"Here, we identify four novel genes MTA1, MTA2, GEP5 and PET130 of the Saccharomycetaceae family that are necessary for an efficient processing of mitochondrial tRNAs."
Genome-wide deletion mutant analysis reveals genes required for respiratory growth, mitochondrial genome maintenance and mitochondrial protein synthesis in Saccharomyces cerevisiae.
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Rrg8 is among the previously uncharacterized RRG proteins localized to mitochondria; the rrg8 deletion is a class-I respiratory-deficient mutant that loses functional mitochondrial DNA.
"Proteins Rrg1, Rrg2, and Rrg5 through Rrg10 have been localized to mitochondria"
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Deletion of budding-yeast RRG8 causes a class-I respiratory-deficient phenotype with loss of a functional mitochondrial genome.
"Δrrg1, Δrrg2, Δrrg4, Δrrg5, Δrrg6, Δrrg8, and Δrrg9 are class I pet mutants lacking a functional mitochondrial genome."
Analysis of a genome-wide set of gene deletions in the fission yeast Schizosaccharomyces pombe.
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Genome-wide fission-yeast deletion analysis; provides the essentiality classification underlying the inviable phenotype of rrg8 deletion and notes that loss of mtDNA is lethal in fission yeast (unlike budding yeast petites), explaining why a mitochondrial gene-expression factor is essential in S. pombe.
"Loss of mtDNA is lethal in fission yeast but not in budding yeast"
A genome-wide resource of cell cycle and cell shape genes of fission yeast.
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Microscopy-based screen providing the evidence for the inviable, tapered-cell deletion phenotype of rrg8 recorded in PomBase.
"A genome-wide resource of cell cycle and cell shape genes of fission yeast"
ORFeome cloning and global analysis of protein localization in the fission yeast Schizosaccharomyces pombe.
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High-throughput C-terminal YFP-tagging localization screen; the source (via UniProt Subcellular Location) of the electronic cytoplasm and nucleus annotations for rrg8. The protein-specific image/data are not present in the abstract-only cache, so the reported localization cannot be adjudicated against the orthology-based mitochondrial assignment here.
"Next, we determined the localization of 4,431 proteins, corresponding to approximately 90% of the fission yeast proteome, by tagging each ORF with the yellow fluorescent protein."
Quantitative proteomics and phosphoproteomics profiling of meiotic divisions in the fission yeast Schizosaccharomyces pombe.
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Meiotic proteomics detecting rrg8 at the protein level, with increased abundance during meiotic division; establishes that the gene is expressed as a protein.
"Quantitative proteomics and phosphoproteomics profiling of meiotic divisions"