A voltage-gated pore for translocation of tRNA

Mitochondrion-to-nucleus communication mediated by RNA export: a survey of potential mechanisms and players across eukaryotes

The nucleus interacts with the other organelles to perform essential functions of the eukaryotic cell. Mitochondria have their own genome and communicate back to the nucleus in what is known as mitochondrial retrograde response. Information is transferred to the nucleus in many ways, leading to wide-ranging changes in nuclear gene expression and culminating with changes in metabolic, regulatory or stress-related pathways. RNAs are emerging molecules involved in this signalling. RNAs encode precise information and are involved in highly target-specific signalling, through a wide range of processes known as RNA interference. RNA-mediated mitochondrial retrograde response requires these molecules to exit the mitochondrion, a process that is still mostly unknown. We suggest that the proteins/complexes translocases of the inner membrane, polynucleotide phosphorylase, mitochondrial permeability transition pore, and the subunits of oxidative phosphorylation complexes may be responsible for RNA export.

Chimeric mitochondrial peptides from contiguous regular and swinger RNA

Previous mass spectrometry analyses described human mitochondrial peptides entirely translated from swinger RNAs, RNAs where polymerization systematically exchanged nucleotides. Exchanges follow one among 23 bijective transformation rules, nine symmetric exchanges (X ↔ Y, e.g. A ↔ C) and fourteen asymmetric exchanges (X → Y → Z → X, e.g. A → C → G → A), multiplying by 24 DNA's protein coding potential. Abrupt switches from regular to swinger polymerization produce chimeric RNAs. Here, human mitochondrial proteomic analyses assuming abrupt switches between regular and swinger transcriptions, detect chimeric peptides, encoded by part regular, part swinger RNA. Contiguous regular- and swinger-encoded residues within single peptides are stronger evidence for translation of swinger RNA than previously detected, entirely swinger-encoded peptides: regular parts are positive controls matched with contiguous swinger parts, increasing confidence in results. Chimeric peptides are 200 × rarer than swinger peptides (3/100,000 versus 6/1000). Among 186 peptides with > 8 residues for each regular and swinger parts, regular parts of eleven chimeric peptides correspond to six among the thirteen recognized, mitochondrial protein-coding genes. Chimeric peptides matching partly regular proteins are rarer and less expressed than chimeric peptides matching non-coding sequences, suggesting targeted degradation of misfolded proteins. Present results strengthen hypotheses that the short mitogenome encodes far more proteins than hitherto assumed. Entirely swinger-encoded proteins could exist.

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Chimeric peptides are translated from contiguous regular and swinger RNA

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They are 200x rarer than mitochondrial swinger peptides

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Chimeric peptides integrated in regular mitochondrial proteins are downregulated

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Contiguous regular parts are matched positive controls for swinger parts

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The last point validates results beyond other statistical tests for robustness