Functions of PPR proteins

Group leader : Philippe GIEGE

Research area

The team research mainly focuses on pentatricopeptide repeat (PPR) proteins, a pivotal class of RNA binding proteins universally found in eukaryotes. Their function is mostly related to the biogenesis of organelles through the fulfilment of essential gene expression processes. Research on PPR proteins has extremely wide implications, going from human health to agriculture. The team contributes to the characterisation of the functional and mechanistic diversity of PPR proteins. Beyond PPR proteins, the functions of other a-solenoid forming proteins are also investigated.

With this research, the team investigates the functional diversity that these essential factors have acquired during the evolution of eukaryotes. In particular, the function of specific PPR proteins called PRORP involved in RNase P activity is explored. Their mode of action is deciphered and interaction networks are determined. Their evolutionary diversity is investigated through the functional characterisation of PRORP in representative model eukaryotes. The function of PPR proteins for plant mitochondrial translation is also investigated with a combination of biochemical and reverse genetic approaches. Altogether, this research should help revealing how PPR functions are integrated within the plant cell and how they affect plant physiology.

The team is part of the LabEx consortium MitoCross. It is also funded by an industrial SATT Conectus Alsace program and different ANR grants.

 

Projects

  • Functions and diversity of PRORP proteins
  • PRORP proteins mode of action
  • Translation apparatus in plant mitochondria
  • PPR proteins for virus resistance

Projects

Functions and diversity of PRORP proteins

The integration of PRORP functions within the overall framework of the plant cell is determined through the characterisation of PRORP interactomes with proteins and RNA. In order to understand the diversity and evolution of PRORP proteins, these enzymes are characterised in the green alga Chlamydomonas, the malaria parasite Plasmodium and the nematode Romanomermis. The detailed understanding of the diversity of PRORP proteins and comparisons with ribonucleoprotein RNase P are expected to give clues to understand the transition from the prebiotic RNA world to today’s world dominated by proteins.

PRORP proteins mode of action

Specificities of PPR proteins mode of action are exemplarily investigated for PRORP proteins. This project is based on biophysical analyses of these enzymes, in particular, through crystallographic and solution structure analyses of PRORP proteins alone and in complex with pre-tRNA substrates. The dynamics and kinetic parameters of this complex are also analysed with an array of biochemical and biophysical approaches. This analysis is performed in collaboration with C. Sauter (IBMC, Strasbourg).

Translation apparatus in plant mitochondria

Translation remains the most elusive step of gene expression in plant organelles. The specificities of the translation apparatus in plant mitochondria are investigated by a combination of biochemical and genetic approaches. Results suggest that Arabidopsis mitochondrial translation uses numerous PPR proteins, whose exact functions are investigated by reverse genetic methods.

PPR proteins for virus resistance

Many plant viruses are characterised by the occurrence of essential tRNA-like structures (TLS) at the 3’ end of their genomic RNA. Because virus replication takes place in the cytosol, the targeting signal of PRORP enzymes is manipulated to induce PRORP accumulation in the cytosol and the cleavage of viral TLS, leading to an arrest of virus replication. After encouraging results with Arabidopsis, this biotechnological application of PRORP research is evaluated with plants of economic relevance and an array of plant viruses.

Members

Selected Publications

  • BONNARD G., GOBERT A., PINKER F., ARRIVE M., SALINAS-GIEGÉ T. and GIEGÉ P.

    A single gene encodes both organelles and nuclear RNase P enzymes in Chlamydomonas reinhardtii

    Plant Journal, 87(3):270-80, 2016. | PMI27133210 :

  • LECHNER Marcus, ROSSMANITH Walter, HARTMANN Roland, THOLKEN Clemens, GUTMANN Bernard, GIEGÉ P. and GOBERT A.

    Distribution of Ribonucleoprotein and Protein-only RNase P in Eukarya.

    Molecular Biology and Evolution, :32, 3186-3193, 2015.

  • GOBERT A., PINKER F., FUCHSBAUER O., GUTMANN B., BOUTIN R., ROBLIN P., SAUTER C. and GIEGÉ P.

    Structural insights into protein-only RNase P complexed with tRNA

    Nature Communications, 4:1353, 2013. | PMI23322041 :

  • GUTMANN B., GOBERT A. and GIEGÉ P.

    PRORP proteins support RNase P activity in both organelles and the nucleus in Arabidopsis

    Genes and Development, 26(10):1022-7, 2012. | PMI22549728 :

  • GOBERT A., GUTMANN Bernard, TASCHNER Andreas, GOESSRINGER Markus, HOLZMANN Johan, HARTMANN Roland, ROSSMANITH Walter and GIEGÉ P.

    A single Arabidopsis organellar protein has RNase P activity.

    Nature Structural and Molecular Biology, :17, 740-744, 2010.

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