In a context of studying biological targets for the development of molecules with antiinfectious and antitumor aims, our team is interested in the three-dimensional structure and interactions of proteins and nucleic acids of therapeutic interest by different spectroscopic and biophysical techniques: Nuclear Magnetic Resonance (NMR) and Molecular Modeling (MM), fluorescence spectroscopy, circular dichroism … Our objective is to determine the mechanisms of action of these molecules and their complexes in order to rationally design inhibitors of their activity. An important part of our activity concerns viral proteins NCp7, Vpr, Vpx, p6, Integrase and the CASP1NC junction of human immunodeficiency viruses (HIVs). We are also interested in the trans-translation mechanisms involved in the virulence of pathogenic bacteria. In collaboration with the chemists of our group, we are studying and optimizing the structure of small chemical compounds that inhibit the complex formed between the vascular endothelial growth factor (VEGF) and its receptor, in order to prevent tumor angiogenesis. We produce and purify in large quantities the isotopically labeled recombinant proteins and RNAs studied.
Team research topics :
Chaperone activity of the HIV and SIV nucleocapsid proteins
The HIV nucleocapsid proteins (NCp7) and VIS (NCp8), are small and highly basic proteins, characterized by the presence of two zinc finger domains of the CCHC type. NCps are involved in the reverse transcription of the viral genome into DNA and its integration into the genome of the host cell. They interact with dimeric viral RNA to specifically promote its packaging. Knowing the structure and mechanism of action of these proteins as well as their mode of interaction with their partners is an important issue in understanding viral infection and in the design of new therapeutic molecules.
Collaborations: Y. Mély, Faculty of Pharmacy, Louis Pasteur University, Illkirch; S. Amrane, IECB, Bordeaux; B. Heddi, LBPA, ENS Paris-Saclay.
Structural studies of the Vpr and Vpx proteins and their interactions
Vpr interacts with several proteins containing the WxxF motif. Among these, the UNG2, a cellular restriction factor that Vpr redirects to the proteasome in order to optimize viral replication. Vpr also interacts with the adenine nucleotide translocator (ANT), the central regulator of apoptosis, located in the inner membrane of the mitochondria. Vpr (HIV-1) and Vpx (HIV-2, SIV) are packaged in the virion by interaction with the protein p6, which plays an essential role in the assembly of the virion and its budding out of the cell. Recently, by a rapid throughput screening technique, small molecules, ligands with high affinity for Vpr, have been isolated. The ability of these new molecules to disrupt the interaction between Vpr / Vpx and its partners could help understand their role during viral replication.
Collaborations: F Margottin-Goguet Cochin, Paris France; I Alvez, IECB, Bordeaux; S Benichou, Institut Cochin, Paris, France; H de Rocquigny, Illkirch; N Chazal, L Briand, CPBS Montpellier, France; JF Guichou, CBS Montpellier, France; At Cimarelli, ENS Lyon, France.
Bevirimat derivatives, HIV maturation and assembly inhibitors
The polyprotein Pr55gag of HIV-1 is cleaved under the action of protease in matrix (MA), capsid (CA), nucleocapsid (NC), p6 and two spacer peptides SP1 and SP2. The CA-SP1 junction contains the last protease cleavage site. Bevirimat (BVM), the first maturation inhibitor, works by specifically blocking the cleavage site between CA and SP1. We have developed new water-soluble derivatives of BVM and demonstrated experimentally for the first time by NMR, a direct interaction between one of our molecules and the CA-SP1 junction. Even more recently, we have shown that these molecules act by stabilizing the helical structure of the SP1 domain, hindering access to the protease and thus disturbing maturation. A patent on bevirimat derivatives, inhibitors of HIV-1 assembly and maturation, has been filed with the European Patent Office and has recently been extended to the United States.
Collaborations: L Micouin, S Turcaud (UdP); S.S. Hong (University of Lyon1); N Chazal (University of Montpellier); M Reboud (UPMC) ; J. Mak (Griffith University, Australia) and D. Muriaux (University of Montpellier).
Targeting the VEGF-VEGFR protein interface
The system VEGF/VEGFR (Vascular Endothelial Growth Factor/Vascular Endothelial Growth Factor Receptor) regulates tumor angiogenesis involved in pathologies such as cancer. VEGF binds to two receptor tyrosine kinase, KDR and Flt-1, expressed at the surface of the endothelial cells, resulting in dimerization and receptor activation and thus leading to the proliferation and migration of endothelial cells forming new vessels. This system is therefore an ideal target for the development of a new anti-angiogenic.
Collaboration : I Broutin (UdP) ; M Vidal (UdP) ; N Inguimbert (Perpignan)
ARNtm et trans-traduction
Trans-translation is a mechanism common to all bacteria. Specific to bacteria, it ensures the rescue of ribosomes blocked on their messenger RNA and the quality control of the proteins synthesized. It is essential for fitness and vital for certain pathogens. It is provided by the mRNA and the partner protein SmpB which establish multiple and variable interactions with each other and with other partners including the ribosome.
Collaborations: Reynald Gillet, IGDR (University of Rennes 1)