Interaction between the protein InlB of Listeria monocytogenes and lipoteichoic acid: a novel mechanism of protein association at the surface of Gram‐positive bacteria

Abstract

SummaryInlB is a Listeria monocytogenes protein that is sufficient to promote entry in a variety of mammalian cells. The last 232-amino-acid domain (Csa) of InlB has been shown to mediate attachment on the listerial surface, although its sequence does not suggest any known mechanism of association to the bacterial surface. InlB is present both on the bacterial surface and in culture supernatants. As has been recently demonstrated, both forms of InlB, soluble and surfacebound, can trigger signalling in host cells. To elucidate the specific role of each of the two forms, it was important to understand how InlB associates with the bacterial surface. Using microscopy, we find evidence that InlB is partially buried in the cell wall layer, and using fractionation experiments we demonstrate that InlB associates with the bacterial cytoplasmic membrane. Moreover, using purified lipoteichoic acid (LTA) and the three polypeptides InlB, Csa, or InlB⌬Csa (InlB lacking the last 232 amino acids), we demonstrate that LTA is a ligand for the Csa domain of InlB. These results provide the first evidence of an interaction between lipoteichoic acids and a bacterial protein involved in adhesion and signalling, and highlight a new mechanism of protein association on the surface of Gram-positive bacteria.

The arsenal of virulence factors deployed byListeria monocytogenesto promote its cell infection cycle

“…75 The GW modules of InlB mediate the binding of this protein to the bacterial surface by non-covalent interactions with LTAs. 37 The crystal structures of the LRR and LRR/IR domains and full-length protein indicate that InlB has a highly elongated structure, suggesting an interaction with multiple cell receptors, that cooperate in bacterial uptake. [76][77][78] Indeed, various host receptors have been identified for InlB: gC1qR, c-Met and glycosaminoglycans (GAGs).…”

“…Its C-terminal cell wall-anchoring (CWA) domain contains eight glycine-tryptophan (GW) modules, through which Ami associates to the bacterial surface, putatively by interaction with lipoteichoic acids (LTAs). [35][36][37] The CWA domain of Ami has been shown to mediate bacterial adhesion to human epithelial cells. 38,39 In addition, an ami mutant is attenuated in the liver of intravenously infected mice, suggesting a role in L. monocytogenes virulence.…”

“…The C-terminal domain of InlB contains GW repeats that are involved in non-covalent cell wall interactions. 37 The LRR and IR regions of InlA were shown to be required and sufficient to promote entry of Listeria into human epithelial cells. 62 The host cell receptor for InlA is E-cadherin, 63 a transmembrane glycoprotein involved in cell-cell adhesion.…”

The complete genome sequence of the meat-borne lactic acid bacterium Lactobacillus sakei 23K

“…One set is composed of two proteins (LSA1159, LSA1165) containing an N-terminal cell-wall binding LysM domain (PF01476) and a C-terminal domain observed in autoaggregation-promoting factors of intestinal lactobacilli and enterococci 35 . The second set (LSA0194, LSA0313) are proteins containing a C-terminal cell-wall binding P60 domain (PF00877) and a N-terminal sequence of two repeated GW-like modules involved in lipoteichoic acid binding 36 . Each set is composed of one slightly acidic protein (pI 5.3-6.4; LSA0313 and LSA1159) and one highly basic protein (pI 4 8.9-8.7, LSA0194 and LSA1165) suggesting different binding properties or environment-dependent production (meat surface versus intestinal tract).…”

Hepatitis B viral infection in maintenance hemodialysis patients: A three year follow-up

“…It has been suggested that the hemodialysis procedures lower HBV DNA levels by various mechanisms: the clearance of HBV DNA by the dialysate, the entrapment of HCV DNA particles onto the membrane surface of dialyzers, and the production of cytokines and other substances during hemodialysis sessions. Rampino et al [29] have measured a prolonged and marked production of hepatocyte growth factor (HGF) during hemodialysis sessions, and have suggested a beneficial effect of HGF through hepatocyte proliferation and accelerated liver repair. Badalamenti et al [30] observed that IFN-alpha levels markedly increase after dialysis using both cellulose and synthetic membranes.…”