Viral Macromolecular Complexes

Projects

Alphavirus replication complexes

The mainstream of our research is the functional and structural characterization of the alphavirus replication complex. Alphavirus, like chikungunya virus (CHIK) or eastern equine encephalitis virus (EEEV), cause zoonotic infectious diseases with high impact in global human health. The viral genome replication and gene expression is carried out by the multifunctional viral replication complex associated to membranes.

Interestingly this complex can adopt different functions depending on its state of maturation. Our goal is to structurally and functionally characterize the different functional states of the replication complex in order to propose an integrative mechanistic model accurately describing at the molecular level the viral infection cycle and its regulation. The results will provide invaluable insights and tools for the development of new strategies for the treatment of these concerning infectious diseases.

Bunyavirus replication machinnery

The Bunyavirales is a very large and diverse order of segmented negative stranded viruses (sNSV) comprising more than 350 species classified in many families including Hantaviridae and Nairoviridae, which count with several human highly pathogenic viruses. Thus, it is necessary to (i) understand their mechanism of infection and (ii) to develop effective drugs to counteract them.

In this context, we study two critical steps of bunyavirus viral cycle: replication and transcription. These reactions are carried out by the multifunctional viral polymerase (L) which specifically interacts with the 3’ and 5’ ends of viral RNA segments. Whereas initiation of replication is performed de novo, without requiring any primer, initiation of transcription is performed by the unique ‘cap-snatching’ mechanism. The recently atomic resolution structures of Infuenza A and LACV allowed us to propose the first comprehensive structure-based model of bunyavirus replication, possibly applicable also to other NSVs but also led to new essential questions to be answered. Therefore, we aim the structural and functional characterization of Bunyavirus polymerases.  

Yeast retrotransposon integration

Retroelements replicate by reverse transcription of their RNA genome into a cDNA that is stably integrated into the host-cell genome by their own integrase (IN). Integration does not occur randomly in vivo, revealing a retroelement-specific pattern of preferred sites, which depends mostly of INs interaction with cellular factors that tether integration to specific sites. However, the mechanisms by which these factors interact with IN and contribute to the integration process are still poorly understood. Important understandings on retroviral biology have been gained by studying yeast Ty LTR retrotransposons. Ty1 targets its integration to RNA Polymerase III (Pol III)-transcribed genes, which are gene-poor regions of the yeast genome. This remarkable integration site selectivity has been well studied in vivo and in vitro. However, there is no structural information on the integration process or interaction with Pol III. In this project, we will investigate what are the mechanisms of integration and how the interactions between Ty1 IN and different components of the Pol III machinery contribute to the site selection.

HT protein production and HT techniques development (Renaud Vincentelli)

Link to the service: https://www.afmb.univ-mrs.fr/en/facility/structural-biology/high-throughput-cloning-expression-in-bacteria-purification-and-interaction-of-recombinant-proteins/

Biophysical techniques (Maria Mate)

Link to the service: https://www.afmb.univ-mrs.fr/en/facility/structural-biology/biophysical-techniques/