RS20L LECTIN FROM Ralstonia solanacearum
Ondřej Šulák1, Nikola Kostlánová1, Jan Adam1, Edward Mitchell2, Anne Imberty3 and Michaela Wimmerová1,4
1National Centre for Biomolecular Research & 4Department of Biochemistry, Masaryk University, Kotlarska 2, Brno, Czech Republic
2E.S.R.F Experiment Division, BP220, F-38043 Grenoble cedex, France
3CERMAV-CNRS, BP 53, F-38041 Grenoble cedex 09, France
Lectins are sugar-binding proteins of non-immune nature that play a role in cell agglutination or glycoconjugates precipitation. These lectins bind to sugar moieties in cell walls or membranes and thereby change the physiology of the membrane, thus cause agglutination, mitosis, or other biochemical changes in the cell.
Ralstonia solanacearum is a plant bacterial pathogen, which causes a wilt disease in several economically important agricultural crops, such as potatoes, tomatoes, peppers, eggplant, and banana.
Plant and animal pathogens use protein-carbohydrate interactions in their strategy for host recognition and invasion.
Until our knowledge now, the R. solanacearum bacterium has been producing three soluble lectins. RSL (MW 9900), which exhibits sugar specifity to L-fucose  and partial sequence homology to mushroom Aleuria aurantia lectin AAL , RS-IIL (MW 11601) lectin  resembles PA-IIL from human pathogen Pseudomonas aeruginosa in structure and properties but differs in sugar specifity . The last one is RS20L (MW 19903), which displays L-fucose and D-mannose and D-xylose binding ability.
This presentation describes, structurally and functionally, the RS20L, a 20 kDa lectin, which has no sequence similarity to any known lectin amino acid sequence, but the solution of crystal structure showed high structural similarity to animal galectins. However it doesn’t display any sugar specificity to D-galactose.
Further functional studies using surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC) allowed to define binding properties (afinity, kinetics) and thermodynamic parameters.
This work has been supported by Ministry of Education (MSM0021622413) and Grant Agency of Czech Republic (204/03/H016).