Ralstonia solanacearum is a Gram-negative β-protobacterium, inhabiting water and soil and causing lethal wilt in more than 200 plants worldwide. From the soil, it can enter plant roots via wounds or secondary roots, invade the xylem vessels, and spread in the plant. This bacterium causes major agronomic and economic losses in tropical climates and threatens potatoes in temperate climates, especially with the recent extension of strains adapted to cooler environmental conditions in Europe and North America. The expression of genes encoding the machinery for adhesion to plant cells (hrp) is enhanced by plant cell wall fragments. Since host carbohydrates have been known for many years to constitute specific attachment sites for pathogen protein receptors,there is great interest in structure-function studies of bacterial proteins enabling the pathogen attachment to host glycans. However, only a limited number of their complexes with receptors have been characterized by crystallography. Most of the structural studies dealt with toxins that bind specifically to intestine or to neural glycans. Recently, adhesins located on the tip of pili from uropathogenic or enterotoxigenic Escherichia coli strains were structurally characterized. Studies of lectins involved in interactions of phytopathogens with plant glycans are in their very early stage. The search for a fucose-binding lectin in R. solanacearum led to the characterization of two soluble lectins. The first, RS-IIL, binds to fucose but has a strong preference for mannose despite its strong sequence and structural similarity to PA-IIL. The second lectin, RSL, is slightly smaller than PA-IIL (90 amino acids) and has strong affinity for fucose and fucose-containing oligosaccharides such as human ABO blood group determinants. Here you can see a crystal structure of the Ralstonia solanacearum MK-RSL lectin in complex with a sulfonato-calix[8]arene (PDB code: 8C9Y)

#molecularart ... #immolecular ... #lectin .. #complex ... #sugar .. #ralstonia ... #xray

Structure rendered with @proteinimaging and depicted with @corelphotopaint