Oral Presentation International Plant Molecular Biology Conference 2024

Identification of key components of mitochondria-to-nuclear 'retrograde' signalling in plants (#418)

Huy Cuong Tran 1 , Vivian Schmitt 1 , Sbatie Lama 1 , Chuande Wang 2 , Alexandra Launay-Avon 3 , Katja Bernfur 4 , Kristin Hofmann 5 , Kasim Khan 1 , Véronique Brunaud 3 , Arnaud Liehrmann 3 , Benoit Castandet 3 , Fredrik Levander 5 , Allan G Rasmusson 1 , Hakim Mireau 2 , Etienne Delannoy 3 , Olivier Van Aken 1
  1. Lund University, Lund, BIOLOGIHUSET A, Sweden
  2. Institut Jean-Pierre Bourgin, INRAE, Versailles, France
  3. Universite Paris-Saclay, CNRS, INRAE, Paris, France
  4. Department of Chemistry, Lund University, Lund, Sweden
  5. Department of Immunotechnology, Lund University, Lund, Sweden

Plant mitochondria represent the largest group of respiring organelles on our planet. Plant mitochondrial mRNAs do not contain Shine-Dalgarno-like ribosome-binding sites, so it is unknown how plant mito-ribosomes recognize mRNA. We show that “mitochondrial translation factors” mTRAN1/mTRAN2 are land plant-specific proteins, required for normal mitochondrial respiration chain biogenesis. Our studies suggest mTRANs are non-canonical pentatricopeptide repeat (PPR)-like RNA-binding proteins of the mitoribosomal ’small’ subunit. Therefore, we searched the 5’ regions of plant mitochondrial mRNAs and identified conserved A/U-rich motifs. Furthermore, we show that mTRAN1 binds this motif, indicating it is a mito-ribosome homing factor to identify mRNAs. We demonstrate that mTRANs are likely universal translation initiation factors, required for translation of all plant mitochondrial mRNAs. Plant mitochondrial translation initiation thus appears to use protein-mRNA interaction, differently compared to in bacteria or mammalian mitochondria.