Lectins play important roles in infections by pathogenic bacteria, for example, in host colonization, persistence and biofilm formation. Among Gram-negative bacteria, numerous homologs of the fuco-/mannophilic Pseudomonas aeruginosa lectin LecB have been reported. In contrast, reports on orthologs from its lectin LecA are rare despite the protein’s role in biofilm formation and virulence of the WHO priority 1 pathogen P. aeruginosa.
The entomopathogenic bacterium Photorhabdus luminescens symbiotically lives in insect-infecting Heterorhabditis nematodes and kills the insect host upon invasion by the nematode. The P. luminescens genome harbors the gene plu2096 coding for a novel lectin that we named PllA. This protein has a strict specificity of PllA for α-galactoside- terminating glycoconjugates which could be explained by its crystal structure.
Further, we report a novel ortholog of LecA from the ESKAPE pathogen Enterobacter spp.. This protein has been cloned, expressed and purified. Biochemical characterization and analysis of its glycan binding revealed an unexpected specificity for distinct human blood group antigens and, surprisingly, a lack of galactose-binding which is conserved among the previously characterized relatives LecA and PllA.
- Beshr, G.; Sikandar, A.; Jemiller, E.-M.; Klymiuk, N.; Hauck, D.; Wagner, S.; Wolf, E.; Koehnke, J.; Titz, A. Photorhabdus luminescens lectin A (PllA) - a new probe for detecting α-galactoside- terminating glycoconjugates. J. Biol. Chem. 2017, 292(48), 19935-19951.