Two-domain LecB-like lectin: Unexpected binding properties
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| Year of publication | 2026 |
| Type | Appeared in Conference without Proceedings |
| MU Faculty or unit | |
| Citation | |
| Description | LecB (PA-IIL) is a well-characterized fucose-binding lectin from Pseudomonas aeruginosa that facilitates host colonization and biofilm formation, particularly in immunocompromised patients such as those with cystic fibrosis. Homologous LecB-like lectins occur in other pathogenic bacteria, including Burkholderia cenocepacia. Several LecB-like proteins contain an additional N-terminal domain of unknown function, suggesting broader functional diversity within this lectin family. This project investigates a putative two-domain LecB-like lectin from an insect pathogen to define its carbohydrate-binding properties. The protein consists of a canonical LecB-like carbohydrate-binding domain fused to an N-terminal accessory domain. The corresponding gene was identified through bioinformatic analysis, cloned, and expressed in E. coli. Full-length constructs and isolated domains were produced to enable domain-specific characterization. Purified proteins are being characterized by biophysical methods to assess oligomeric state, thermostability, and sample homogeneity. Crystallization trials were performed for the full-length protein and both individual domains. The structure of the N-terminal domain has been largely determined by molecular replacement and is currently being refined, while crystallization of the LecB-like domain is ongoing. Preliminary hemagglutination assays show that the LecB-like domain agglutinates red blood cells of all major blood groups, confirming lectin activity. Notably, this activity is not inhibited by the monosaccharides commonly recognized by LecB-family lectins, suggesting atypical carbohydrate specificity or a preference for more complex oligosaccharides. Predicted structural models reveal differences in the presumed ligand-binding pocket compared to the canonical LecB structure, which may explain the unusual inhibition profile. These results highlight unexpected diversity within the LecB lectin family and provide insight into carbohydrate-mediated adhesion mechanisms in pathogenic bacteria. |
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