O-methylation is an unusual sugar modification with a function that is not fully understood. Given its occurrence and recognition by lectins involved in the immune response, methylated sugars were proposed to represent a conserved pathogen-associated molecular pattern. We describe the interaction of O-methylated saccharides with two β-propeller lectins, the newly described PLL2 from the entomopathogenic bacterium Photorhabdus laumondii, and its homologue PHL from the related human pathogen Photorhabdus asymbiotica. The crystal structures of PLL2 and PHL revealed up to 10 out of 14 potential binding sites per protein subunit to be occupied with O-methylated structures. The avidity effect strengthens the interaction by 4 orders of magnitude. PLL2 and PHL also interfere with the early immune response by modulating the production of reactive oxygen species and phenoloxidase activity. Since bacteria from Photorhabdus spp. have a complex life cycle involving pathogenicity towards different hosts, the involvement of PLL2 and PHL might contribute to the pathogen overcoming insect and human immune system defences in the early stages of infection. DATABASES: Structural data are available in PDB database under the accession numbers 6RG2, 6RGG, 6RFZ, 6RG1, 6RGU, 6RGW, 6RGJ, and 6RGR.
- MeSH
- bakteriální proteiny chemie metabolismus MeSH
- cukry metabolismus MeSH
- gramnegativní bakteriální infekce imunologie metabolismus mikrobiologie MeSH
- hemocyty imunologie metabolismus MeSH
- hemolymfa imunologie metabolismus MeSH
- imunita imunologie MeSH
- imunitní systém imunologie metabolismus MeSH
- interakce hostitele a patogenu imunologie MeSH
- lektiny chemie metabolismus MeSH
- lidé MeSH
- metylace MeSH
- můry MeSH
- Photorhabdus imunologie metabolismus fyziologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The Photorhabdus species is a Gram-negative bacteria of the family Morganellaceae that is known for its mutualistic relationship with Heterorhabditis nematodes and pathogenicity toward insects. This study is focused on the characterization of the recombinant lectin PLL3 with an origin in P. laumondii subsp. laumondii. PLL3 belongs to the PLL family of lectins with a seven-bladed β-propeller fold. The binding properties of PLL3 were tested by hemagglutination assay, glycan array, isothermal titration calorimetry, and surface plasmon resonance, and its structure was determined by X-ray crystallography. Obtained data revealed that PLL3 binds similar carbohydrates to those that the other PLL family members bind, with some differences in the binding properties. PLL3 exhibited the highest affinity toward l-fucose and its derivatives but was also able to interact with O-methylated glycans and other ligands. Unlike the other members of this family, PLL3 was discovered to be a monomer, which might correspond to a weaker avidity effect compared to homologous lectins. Based on the similarity to the related lectins and their proposed biological function, PLL3 might accompany them during the interaction of P. laumondii with both the nematode partner and the insect host.
- MeSH
- bakteriální proteiny chemie genetika metabolismus MeSH
- fruktosa metabolismus MeSH
- kalorimetrie MeSH
- krystalografie rentgenová MeSH
- lektiny chemie genetika metabolismus MeSH
- Photorhabdus metabolismus MeSH
- povrchová plasmonová rezonance MeSH
- rekombinantní proteiny chemie metabolismus MeSH
- sekundární struktura proteinů MeSH
- vazebná místa MeSH
- Publikační typ
- časopisecké články MeSH
A recently described bangle lectin (PHL) from the bacterium Photorhabdus asymbiotica was identified as a mainly fucose-binding protein that could play an important role in the host-pathogen interaction and in the modulation of host immune response. Structural studies showed that PHL is a homo-dimer that contains up to seven L-fucose-specific binding sites per monomer. For these reasons, potential ligands of the PHL lectin: α-L-fucopyranosyl-containing mono-, di-, tetra-, hexa- and dodecavalent ligands were tested. Two types of polyvalent structures were investigated - calix[4]arenes and dendrimers. The shared feature of all these structures was a C-glycosidic bond instead of the more common but physiologically unstable O-glycosidic bond. The inhibition potential of the tested structures was assessed using different techniques - hemagglutination, surface plasmon resonance, isothermal titration calorimetry, and cell cross-linking. All the ligands proved to be better than free L-fucose. The most active hexavalent dendrimer exhibited affinity three orders of magnitude higher than that of standard L-fucose. To determine the binding mode of some ligands, crystal complex PHL/fucosides 2 - 4 were prepared and studied using X-ray crystallography. The electron density in complexes proved the presence of the compounds in 6 out of 7 fucose-binding sites.
- MeSH
- antibakteriální látky chemie farmakologie terapeutické užití MeSH
- bakteriální infekce farmakoterapie mikrobiologie MeSH
- bakteriální proteiny antagonisté a inhibitory chemie izolace a purifikace metabolismus MeSH
- dendrimery chemie farmakologie terapeutické užití MeSH
- erytrocyty MeSH
- fukosa analogy a deriváty farmakologie terapeutické užití MeSH
- hemaglutinace účinky léků MeSH
- interakce hostitele a patogenu účinky léků MeSH
- krystalografie rentgenová MeSH
- lektiny antagonisté a inhibitory chemie izolace a purifikace metabolismus MeSH
- lidé MeSH
- ligandy MeSH
- molekulární modely MeSH
- Photorhabdus metabolismus MeSH
- povrchová plasmonová rezonance MeSH
- rekombinantní proteiny chemie izolace a purifikace metabolismus MeSH
- vazebná místa MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
