Characterization of novel lectin PLL3 from Photorhabdus laumondii with a seven bladed beta propeller monomeric structure
|Fakulta / Pracoviště MU
|Photorhabdus is the genus of Gram-negative bioluminescent bacteria living in the mutualistic relationship with Heterorhabditis nematodes. Photorhabdus and Heterorhabditis form a complex that is highly pathogenic for insects. Focus of research was characterization of recombinant form of lectin PLL3 from P. laumondii subsp. laumondii. PLL3 was discovered to be a novel member of the structural PLL lectin family with seven-bladed beta-propeller fold. Its binding properties were investigated using hemagglutination assay and biophysical methods such as isothermal titration calorimetry and surface plasmon resonance. The structure of PLL3 was solved by X-ray crystallography. Obtained data showed that PLL3 exhibits similar binding properties as the other members of its structural family. PLL3 interacted with L-fucose and its derivatives but was also able to recognize other carbohydrates including O-methylated glycans. O-methylation is unusual glycan modification present in some species of bacteria, fungi, plants and nematodes, but not in insects or mammals. In contrast to previously described PLL family lectins, PLL3 exists as monomer in the solution as well as in the crystal structure. The monomeric state of PLL3 might be responsible for the presence of a weaker avidity effect compared to related lectins. Based on the similarity to the other lectins from PLL family and the fact that these lectins interfere with the host innate immune system, we can assume PLL3 might play a role in the interaction of P. laumondii with both nematodes and insects.