Cell-surface anchoring of Listeria adhesion protein on L. monocytogenes is fastened by internalin B for pathogenesis

Listeria adhesion protein (LAP) is a secreted acetaldehyde alcohol dehydrogenase (AdhE) that anchors to an unknown molecule on the Listeria monocytogenes (Lm) surface, which is critical for its intestinal epithelium crossing. In the present work, immunoprecipitation and mass spectrometry identify internalin B (InlB) as the primary ligand of LAP (KD -42 nM). InlB-deleted and naturally InlB-deficient Lm strains show reduced LAP-InlB interaction and LAP-mediated pathology in the murine intestine and brain invasion. InlB-overexpressing non-pathogenic Listeria innocua also displays LAP-InlB interplay. In silico predictions reveal that a pocket region in the C-terminal domain of tetrameric LAP is the binding site for InlB. LAP variants containing mutations in negatively charged (E523S, E621S) amino acids in the C terminus confirm altered binding confor-mations and weaker affinity for InlB. InlB transforms the housekeeping enzyme, AdhE (LAP), into a moonlighting pathogenic factor by fastening on the cell surface.

Automated summary

In this study, it is discovered that internalin B (InlB) is the main ligand of listeria adhesion protein (LAP) and their interaction is critical for listeria monocytogenes (Lm) to cross the intestinal epithelium. Deletion or deficiency of InlB reduces LAP-InlB interaction and LAP-mediated pathology in mice. InlB overexpression in non-pathogenic listeria innocua also leads to LAP-InlB interaction. In silico analysis reveals that a pocket region in the C-terminal domain of tetrameric LAP is the binding site for InlB. Mutations in negatively charged amino acids in the C terminus of LAP confirm altered binding conformation and weaker affinity for InlB. InlB transforms the housekeeping enzyme, AdhE (LAP), into a moonlighting pathogenic factor by binding to the cell surface.