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

Abstract

The mechanisms by which the intracellular pathogen Listeria monocytogenes interacts with the host cell surface remain largely unknown. In this study, we investigated the role of heparan sulfate proteoglycans (HSPG) in listerial infection. Pretreatment of bacteria with heparin or heparan sulfate (HS), but not with other glycosaminoglycans, inhibited attachment and subsequent uptake by IC-21 murine macrophages and CHO epithelial-like cells. Specific removal of HS from target cells with heparinase III significantly impaired listerial adhesion and invasion. Mutant CHO cells deficient in HS synthesis bound 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 HS. 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 for actin-based bacterial motility and cell-to-cell spread. In the 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 an 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.

Interaction of Listeria monocytogenes with the intestinal epithelium

“…L. monocytogenes can bind extracellular matrix proteins (e.g. ¢bronectin [16], and heparan sulfate proteoglycans [17]) which is also a common trait of many other pathogens [18,19]. Therefore, this observation may explain the apparently random nature of human listeriosis in otherwise healthy individuals [14] in that all humans periodically experience slight mucosal damage which is normally quickly repaired [20], and hence a damaged individual may be at more risk of an L. monocytogenes infection.…”

Innate defenses in the liver during Listeria infection

“…Indeed, multiple molecules expressed by Listeria, i.e. internalin, ActA, and lipoteichoic acid, promote entry into cells by respective interactions with host cell surface E-cadherin, heparan sulfate proteoglycan receptors, and type I macrophage scavenger receptors (72)(73)(74)(75). It has been assumed, without clear experimental evidence, that Listeria phagocytosed by Kupffer cells escape the phagolysosomes and transmigrate intracellularly into hepatocytes.…”

The microtubule depolymerizing drugs nocodazole and colchicine inhibit the uptake of Listeria monocytogenes by P388D1 macrophages

“…The members of the internalin multigene family internalin A and B (InlA and InlB) were shown to be involved in invasion of epithelial cells and hepatocytes [2,3], but the role of InlA in endothelial cell invasion is still under debate [4,5]. The listerial surface protein ActA, originally described as required only for intracellular motility was re-cently shown to be involved in heparan-sulfate proteoglycan receptor mediated uptake of L. monocytogenes [6]. The major secreted protein of L. monocytogenes, p60, is involved in e¤cient uptake by ¢broblasts but not necessary for epithelial cell invasion [7].…”