“Lectins are ubiquitous proteins that can reversibly and specifically bind to carbohydrates. Carbohydrate-mediated recognition and adhesion are key events in the early steps of interaction of pathogenic or symbiotic bacteria with a host. For example, Pseudomonas aeruginosa is an opportunistic bacterium that causes lethal lung infection in cystic fibrosis patients. Photorhabdus luminescens lives in a symbiotic relationship with nematodes and is involved in insecticidal activities of these worms. Both bacteria produce several lectins, i.e. glycan receptors, which are specific for the host glycoconjugates.
The aim of this PhD thesis was to use neutron protein crystallography to provide insights into lectin-carbohydrate interactions involved in bacterial infection. Fucose-specific lectins, PLL from Photorhabdus luminescens and LecB from Pseudomonas aeruginosa, were produced in perdeuterated forms and crystallized with a ligand. A unique part of the thesis was the in vivo production of a perdeuterated monosaccharide, L-fucose, using genetically modified strains of E. coli bacteria designed by Dr. Eric Samain at CERMAV institute in Grenoble. Perdeuterated fucose has been successfully produced, purified and biophysically characterized. It was used as a ligand for crystallization trials of both PLL and LecB lectins.
Using neutron protein crystallography, we have unraveled the details of protein-carbohydrate interactions in these two fucose-specific lectins.
Gajdos, L., Forsyth, V.T., Blakeley, M.P., Haertlein, M., Imberty, A., Samain, E., Devos, J.M. (2021). Production of perdeuterated fucose from glyco-engineered bacteria. Glycobiology 31, 151–158.
Gajdos L., Blakeley M.P., Kumar A., Wimmerová M., Haertlein M., Forsyth V.T., Imberty A., Devos J.M. (2021). Visualization of hydrogen atoms in a perdeuterated lectin-fucose complex reveals key details of protein-carbohydrate interactions. Structure. doi: 10.1016/j.str.2021.03.003. Epub ahead of print. “