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