During its infectious cycle, the influenza virus replicates its segmented viral genome into numerous copies within the nucleus of the infected cell, and exports it to the cytoplasm and toward the cell membrane. The viral protein NEP (Nuclear Export Protein) is a key component in the controlled process of viral genomic RNA segments nuclear export. NEP interacts with both viral proteins bound to the newly synthesized RNA segments and hijacks cellular factors involved in the nuclear export of regular cellular proteins.
Our goal is to elucidate this mechanism, which is poorly understood, at the molecular level, by using biochemical techniques (production and purification of recombinant proteins from bacteria or insect cells), and biophysical techniques (SEC-MALS, fluorescence anisotropy, BLI, etc.) and structural biology (cryo-electron microscopy, crystallography, SAXS).
Possible models of NEP interaction with the ribonucleoprotein (RNP, consisting of a segment of viral RNA covered with multiple copies of the nucleoprotein NP and the heterotrimeric polymerase PA-PB1-PB2 attached to the 3’ and 5’ ends of the viral RNA), the viral matrix protein M1, and the cellular factor CRM1-RanGTP responsible for nuclear export. T. Crépin
We are also investigating interactions with various cellular partners that the RNA segments encapsidated by the nucleoprotein (RiboNucleoProtein complex, RNP) may encounter, such as proteins involved in the nuclear import or the immune system.