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Jean-François Laliberté

Virologie

Biologie moléculaire et cellulaire du virus de la mosaïque du navet

Research Interest

The molecular and cellular biology of Turnip mosaic virus, a positive-strand RNA virus

For many viruses whose genome is a positive strand RNA, genome replication takes place within membranous vesicles. My research team is interested in the VPg, a protein linked to the 5 'end of the RNA genome of turnip mosaic virus (TuMV). This proteins interacts with several viral and host proteins, particularly translation factors. We found that these interactions were taking place inside the replication vesicles induced by 6K-VPg-Pro, a precursor form of VPg. We now want to deepen our understanding of these vesicles that contain the viral replication complex. Specifically, we are investigating their content and the fine architecture in the cell. Our investigation uses the latest cell imaging technologies and provides a better understanding of not only plant viruses but also of all viruses in general. Students participating in this research acquire an excellent knowledge of virology and molecular cell and plant biotechnology. They also get expertise in recombinant DNA technologies in protein expression and confocal microscopy. These skills enable them to work not only in the field of plant biology but also in all spheres of life sciences.

 

Current Project

TuMV belongs to the large group of picornaviruses. The genome of TuMV RNA is approximately 10 000 nucleotides. It is linked to its 5 'end to a protein known as VPg, and encodes a polyprotein (Fig. 1). This polyprotein is processed by viral proteases to release ten proteins. During maturation, the production of precursor forms is also observed. In recent years we have focused our research on the role of VPg and its precursor forms (ie, VPg-Pro and 6K-VPg-Pro) in viral replication.

 

For example,6K-VPg-Pro induces the formation of membranous cytoplas micvesicles (red /orange in figure 2) aligned with microfilaments (in green) of the cell. These vesicles contain the viralreplication complex and several cellular translation factors. However, the exact content and architecture of  these vesicles and their biogenesis are not known. Our research objective is:
•to know the exact content of these vesicles;
•identify the components of the cytoskeleton and endomembrane system involved in their movement;
•to see how they are formed;
•and finally have an accurate idea of their fine architecture.

 

These vesicles are mobile within cells and traffic towards the plasma membrane (red in Figure 3), and more precisely to plasmodesmata, structures that connect cells to each other. With the technology of RNA interference, we are studying the role of these structures in systemic infection of TuMV

 

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Jean-François Laliberté et les virus des plantes ...