Visualisation of hydrogen atoms in a perdeuterated lectin-fucose complex reveals key details of protein-carbohydrate interactions

30 March 2021
The pathogenic bacteria attach themselves to the cells which they attack thanks to the sugars present on their membrane. A crucial mechanism to study, because it would help to treat these infections without reinforcing the resistance of the bacteria. To do this, researchers from CERMAV (CNRS), the Laue-Langevin Institute (ILL) and CEITEC (Masaryk University, Czech Republic) have modified a sugar so that it responds to neutron crystallography, a technique that reveals how bacteria cling to sugars. This work, published in the journal Structure, could extend to more complex sugars to better understand different biological phenomena and propose new anti-infectious strategies. Caption: Fucose molecule in the lectin binding site. The blue grid represents the density determined by x-rays and the green grid the density determined by the neutrons around the fucose and the amino acids of the lectin. Hydrogen atoms (here isotope deuterium) are represented by yellow balls. The continuity of the green grid between the fucose and the amino acids allows a direct view of the hydrogen bonds. © L. Gajdos. / Click on the title for more information.

Abstract:

“Carbohydrate-binding proteins from pathogenic bacteria and fungi have been shown to be implicated in various pathological processes, where they interact with glycans present on the surface of the host cells. These interactions are part of the initial processes of infection of the host and are very important to study at the atomic level. Here, we report the room temperature neutron structures of PLL lectin from Photorhabdus laumondii in its apo form and in complex with deuterated L-fucose, which is, to our knowledge, the first neutron structure of a carbohydrate-binding protein in complex with a fully deuterated carbohydrate ligand. A detailed structural analysis of the lectin-carbohydrate interactions provides information on the hydrogen bond network, the role of water molecules, and the extent of the CH-π stacking interactions between fucose and the aromatic amino acids in the binding site.”

The  article is available over here.