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Team 3 : Targeting and transport of macromolecules to plant mitochondria

Team leader : Laurence DROUARD


Research topics

  • tRNA import process into plant mitochondria (more)
  • mRNA trafficking at the surface of plant mitochondria (more)
  • tRNA metabolism within the plant cell (more)

Role in MitoCross

First goal

The team has recently developed a protein shuttle system to introduce any RNA into isolated mitochondria of various organisms (plant, yeast, human cells). Due to the absence of tools, mostly nothing is known on mitochondrial translation plant and human mitochondria. The possibility to address full-length mRNA into mitochondria opens the door to their potential translation and thus to the study of this important process

Second goal

As compared to mitochondrial protein import, RNA mitochondrial import is still poorly understood. For many years, our team is addressing questions on the tRNA import mechanism in plants, and we will continue to make efforts in a better understanding of several aspects (translocation, regulation) of the process.

Third goal

The vast majority of mitochondrial proteins are encode by the nuclear genome, translated on cytosolic ribosomes and directed to mitochondria. In the majority of proteins, their transfer involves a specific N-terminal extension of the protein (MTS, for Mitochondrial Targeting Sequence). Some mitochondrial imported proteins are also targeted to other cellular compartments. For example some proteins are dual targeted to mitochondria and chloroplasts, but the different targeting signals are not yet deciphered. One of these signals is the targeting of mRNA to mitochondria. Very recently, the team demonstrated that this process occurs in plants. We now want to understand th eprocess involved in mRNA sorting at the surface of mitochondria


Members

Photographies of team members : click here


Under the spotlight

Mitochondrial mRNAs in Chlamydomonas reinhardtii: C the difference!

RNA modifications play a major role in gene expression. The existence of poly (A) additions at the 3′-end of messenger RNAs is well known and, more recently, poly (U) additions have been studied in some detail. However, by studying mitochondrial gene expression in Chlamydomonas reinhardtii, the team of Laurence Drouard, in collaboration with Olivier Vallon’s team at the Institut de biologie physico-chimique“, discovered the addition of poly (C) at the end of mitochondrial messenger RNAs. This new type of post-transcriptional modification of messenger RNAs illustrates a biodiversity that is also reflected at the molecular level. This study was published on October 9, 2017, in the journal Nucleic Acids Research.

Actualités scientifiques de l’INSB

Polycytidylation of mitochondrial mRNAs in Chlamydomonas reinhardtii 
Thalia Salinas-Giegé, Marina Cavaiuolo, Valérie Cognat, Elodie Ubrig, Claire Remacle, Anne-Marie Duchêne, Olivier Vallon, Laurence Maréchal-Drouard
Nucleic Acids Research,  Nucleic Acids Res.,45:12963–12973, doi:10.1093/nar/gkx903. Abstract




IBMP website of the team

here


Useful link

The PlantRNA database compiles tRNA gene sequences retrieved from fully annotated plant nuclear, plastidial and mitochondrial genomes : click here

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