Hose cell heparan sulfate proteoglycans mediate attachment and entry of Listeria monocytogenes, and the listerial surface protein ActA is involved in heparan sulfate receptor recognition

The mechanisms hy which the intracellular pathogen Listeria monocytogenes interacts with the host cell surface remain largely unknown. In this study, we investigated the role of hepar an sulfate proteoglycans (HSPG) in listerial infection, Pretreatment of bacteria with heparin or heparan sulfate (HS), hut not with other glycosaminoglycans, inhibited attachment and subsequent uptake by IC-21 murine macrophages and CHO epithelial-like cells, Specific removal of RS from target cells with heparinase III significantly impaired listerial adhesion and invasion. Mutant CNO cells deficient in NS synthesis hound and internalized significantly fewer bacteria than wild-type cells did. Pretreatment of target cells with the HS-binding proteins fibronectin and platelet factor 4, or with heparinase III, impaired listerial infectivity only in those cells expressing IIS. Moreover, a synthetic peptide corresponding to the HS-binding ligand in Plasmodium falciparum circumsporozoite protein (pepPf1) inhibited listerial attachment to IC-21 and CHO cells, A motif very similar to the HS-binding site of pepPf1 was found in the N-terminal region of ActA, the L, monocytogenes surface protein responsible Far actin-based bacterial motility and cell-to-cell spread, In tile same region of ActA, several clusters of positively charged amino acids which could function as HS-binding domains were identified, An ActA-deficient mutant was significantly impaired in attachment and entry due to altered HS recognition functions. This work shows that specific interaction with Rat HSPG receptor present on the surface of both professional and nonprofessional phagocytes is involved in L, monocytogenes cytoadhesion and invasion and strongly suggests that the bacterial surface protein ActA may be a ligand mediating HSPG receptor recognition.