Characterization of monomeric lectin PLL3 from Photorhabdus laumondii
|Year of publication
|MU Faculty or unit
|Photorhabdus laumondii belongs to the genus of Gram-negative bacteria which live in the gut of Heterorhabditis nematodes. Photorhabdus and Heterorhabditis form a mutualistic complex that is highly pathogenic for a variety of insects. P. laumondii produces five structurally related lectins – proteins, that are generally involved in cell signaling and play important role in many physiological as well as pathophysiological processes. Focus of this research was functional and structural characterization of recombinant form of lectin PLL3 from P. laumondii subsp. laumondii. Its structure was solved by X-ray crystallography and it was revealed, that PLL3 is a new member of the PLL lectin family with seven-bladed ß propeller fold. In comparison to previously characterised PLL lectins, PLL3 exists as a monomer both in the crystal structure and in the solution. Its activity was evaluated by hemagglutination assay and its inhibition. Binding properties of PLL3 toward saccharide ligands were investigated by biophysical methods such as isothermal titration calorimetry and surface plasmon resonance. PLL3 exhibited affinity toward L-fucose and its derivatives but was also able to interact with O-methylated glycans. These unusually modified glycans are ordinarily present in some species of bacteria, fungi, plants and nematodes, but are missing in insects or mammals. PLL3 is similar to the other lectins from PLL family which can interfere with the host innate immune system. Therefore there is an assumption that also PLL3 might play a role in the interaction of P. laumondii with both nematodes and insects.