Lectins are proteins able to reversibly bind glycoconjugates with high specificity. Lectins mediate cell-cell interactions on molecular level and play an important role in various biological processes, including interactions between microorganisms and hosts [1]. Our research is focused on studying lectins from entomopathogenic bacterium Photorhabdus laumondii, which is known for complicated life-cycle, including mutualism and pathogenicity towards two different invertebrate hosts [2].
This contribution is focused on the PLL2 lectin. PLL2 is a member of structuraly related PLL lectin family with shared seven-bladed beta-propeller fold. Multiple binding sites are present within PLL2 monomer and are situated in between the blades. Based on their structural characteristics, binding sites can be divided into two groups; hydrophobic (H) and polar (P) [3]. We determined a set of X-ray structures of PLL2 in complex with various saccharide ligands. The analyses showed different ligand specificity of H and P sites. Dual specificity is not very common in lectins, and the existence of two sets of sites with different specificity within lectin monomer is rather unique and was not described outside the PLL lectin family.
This work was supported by GAČR (21-29622S). Experiments performed at Biomolecular Interactions and Crystallography Core Facility are supported by CIISB project of MEYS CR (LM2023042).
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