An mTRAN-mRNA interaction mediates mitochondrial translation initiation in plants

Abstract

Plant mitochondria represent the largest group of respiring organelles on the planet. Plant mitochondrial messenger RNAs (mRNAs) lack Shine-Dalgarno-like ribosome-binding sites, so it is unknown how plant mitoribosomes recognize mRNA. We show that “mitochondrial translation factors” mTRAN1 and mTRAN2 are land plant–specific proteins, required for normal mitochondrial respiration chain biogenesis. Our studies suggest that mTRANs are noncanonical pentatricopeptide repeat (PPR)–like RNA binding proteins of the mitoribosomal “small” subunit. We identified conserved Adenosine (A)/Uridine (U)-rich motifs in the 5′ regions of plant mitochondrial mRNAs. mTRAN1 binds this motif, suggesting that it is a mitoribosome homing factor to identify mRNAs. We demonstrate that mTRANs are likely required for translation of all plant mitochondrial mRNAs. Plant mitochondrial translation initiation thus appears to use a protein-mRNA interaction that is divergent from bacteria or mammalian mitochondria.

DiffSegR: An RNA-Seq data driven method for differential expression analysis using changepoint detection

“…Because it is designed to compare two conditions, we believe that DiffSegR has the potential to change the way researchers approach differential expression analysis, especially considering the wealth of RNA-Seq based strategies aimed at capturing specific events (67). For example, it has already been used on RNA immunoprecipitation sequencing data to study translation initiation in plant mitochondria (68). We anticipate it could similarly be used to find newly transcribed RNAs compared to mature RNA control in nascent RNA analysis (69), to find differences in ribosome bound RNA in translatome analysis (70) or to discriminate structured (doublestranded RNA) from unstructured RNAs in structurome analysis (71).…”