Structural characterization of the enterococcal polysaccharide antigen and analysis of its contribution to cell growth, division and antibiotic resist

The proposed project is focused on the functional analysis of a surface
rhamnopolysaccharide produced by all enterococci, required for normal cell growth,
division, resistance to antibiotics and pathogenesis. This enterococcal polysaccharide
antigen (EPA) is encoded by two gene clusters: (i) 18 genes extremely conserved (epaA-
epaR) encoding a core synthetic machinery and (ii) 10-20 genes variable from one strain to
another, responsible for the decoration of the polysaccharide backbone. We have built a
mutant with a complete deletion of the epa variable region and shown that the decoration of
EPA (but not its core structure) is essential for the biological activity of this polymer. We
propose investigate the structural properties of Epa and dissect the specific contribution of
this polymer and its decoration to bacterial physiology and antibiotic resistance.
We will take a multidisciplinary approach to explore EPA structure and to understand how
EPA controls the distribution and activity of surface proteins involved in cell wall assembly
and resistance to antibiotics. The project will involve state-of-the-art methodologies
including super-resolution microscopy (fluorescence and electron microscopy), structural
glycobiology (NMR, mass spectrometry) and conventional approaches to study bacterial
physiology and antimicrobial resistance. The candidate will work with members of the
supervisors' laboratories studying bacterial cell surface assembly and host-pathogen
interactions.