Analysis of antibiotic resistance mechanisms developed by gram-negative bacteria

Our team, specialized in the structural study of membrane proteins, focuses its research on the public health problem of antibiotic resistance responsible for the dramatic increase of multi-resistant bacteria all over the word.

Among the different ways used by bacteria to resist to antibiotics, the active efflux through tripartite efflux pumps is one of the most important. Our main target is Pseudomonas aeruginosa (PA), a Gram-negative nosocomial opportunistic pathogen that contributes to the decline of respiratory function in cystic fibrosis (CF) patients. PA possesses mainly four efflux pumps proven to be involved in the efflux of antibiotics, MexAB-OpM also having a physiological role being involved in the capture of metals. These pumps present some specificities concerning the family of antibiotics taken in charge, and concerning the activation of their transcription leading to their overexpression. The different strategies to develop molecules blocking the function or the expression of these pumps are listed on the figure. We are conducting this research by complementary approaches linking structural biology (X-ray crystallography, SAXS, Cryo-EM (Glavier, Nat Comm 2020; Ma, Int J. Mol. Sci, 2021; Boyer, Antibiotics, 2022)) with in cellulo functional analysis (Juarez, AAC, 2018).

Development of biological tools and molecules targeting the VEGF signalling

The VEGF signaling pathway is involved in tumor vascularization. Using a drug-design approach coupled with Isothermal Titration Calorimetry (ITC) analyzes and chemical shift assays (Reille-Seroussi, Analytical Biochemistry 2017), we develop proteolysis-resistant peptidomimetics targeting the interaction of VEGF with its various receptors (Gaucher, Chem. Eur. J. 2022), presenting large health applications potential (Trapiella-Alfonso, Hypertension 2019).

Development of biological tools based on the DNA origami technique

We are also developing sophisticated 3D shapes based on DNA origami technique (Aissaoui, ACS Nano 2021; Mills, Nat Comm 2022). Two objects are in construction. One of them will act to construct large-scale DNA origami template as a breakthrough method to improve the quality of cryo-EM sample preparation and structural studies. The second DNA origami nanostructure is designed to act as a scaffold for the stabilization of two proteoliposomes to reconstitute the two-membranes environment of a tripartite efflux pump in a well-defined spatial configuration. The DNA origami technique offers the advantages of controlling the separation distance of the two membranes opposing to each other estimated to be ~20 nm (Reffay, Plos One 2009) and maintaining the supramolecular assembly of the tripartite pump stable.