Interaction of Listeria monocytogenes autolysin amidase with glycosaminoglycans promotes listerial adhesion to mouse hepatocytes

Adherence to the cell surface is a key event during infection of pathogenic microorganisms. We have previously reported that autolysin amidase (Ami) of Listeria monocytogenes promotes an efficient listerial adherence to mouse hepatocytes and requires for listerial pathogenicity. Cell wall anchoring (CWA) domain of Ami has been shown to bind lipoteichoic acid on listerial cell wall but the binding of Ami to host cell surface molecules remains to be determined. In this study, we present evidence here that Ami promotes efficient adherence of L. monocytogenes to mouse hepatocytes mediated by glycosaminoglycans (GAGs). The adhesion of L. monocytogenes wild type but not Ami-deficient mutant to the hepatocytes was dramatically attenuated by 4-nitrophenyl-β-D-xylopyranoside, a specific inhibitor of GAG association to cell surface. Full-length and truncated Ami were used to investigate the binding of Ami to GAGs and we found that four-repeated CWA of Ami is sufficient to bind GAGs on the host cell surface. Competitive assay and surface plasmon resonance demonstrated that Ami interacts with sulfated GAGs but not non-sulfated GAGs. The results suggest that Ami acts as an adhesin of L. monocytogenes to hepatocytes by interaction via its four-repeated CWA domain and sulfated GAGs.