All major cholesterol-dependent cytolysins use glycans as cellular receptors

Abstract

Cholesterol-dependent cytolysins (CDCs) form pores in cholesterol-rich membranes, but cholesterol alone is insufficient to explain their cell and host tropism. Here, we show that all eight major CDCs have high-affinity lectin activity that identifies glycans as candidate cellular receptors. Streptolysin O, vaginolysin, and perfringolysin O bind multiple glycans, while pneumolysin, lectinolysin, and listeriolysin O recognize a single glycan class. Addition of exogenous carbohydrate receptors for each CDC inhibits toxin activity. We present a structure for suilysin domain 4 in complex with two distinct glycan receptors, P1 antigen and αGal/Galili. We report a wide range of binding affinities for cholesterol and for the cholesterol analog pregnenolone sulfate and show that CDCs bind glycans and cholesterol independently. Intermedilysin binds to the sialyl-TF O-glycan on its erythrocyte receptor, CD59. Removing sialyl-TF from CD59 reduces intermedilysin binding. Glycan-lectin interactions underpin the cellular tropism of CDCs and provide molecular targets to block their cytotoxic activity.

Structural basis for tuning activity and membrane specificity of bacterial cytolysins

“…This interface is dominated by two CD59 residues decorated with O-linked glycans in the native protein 21 . ILY binds to an O-glycan prevalent on human CD59 22 , suggesting that sugar recognition may play a role in oligomerization and could be engineered to impact target-cell specificity.…”

Human Serum Albumin Binds Streptolysin O (SLO) Toxin Produced by Group A Streptococcus and Inhibits Its Cytotoxic and Hemolytic Effects

“…The CDCs share the undecapeptide and cholesterol binding motif, as well as the ability to form pores on host cell membranes via a cholesteroldependent mechanism (9,12). Although membrane cholesterol is required for the cytolytic mechanism of CDCs to form a complete transmembrane pore, also glycans receptors define the cellular tropism and are required for efficient deposition of PFTs, including CDCs, into cell membranes (8,(13)(14)(15)(16). Following secretion from bacteria as soluble monomers, CDCs bind to host cell membranes through the C-terminal domain 4 (D4), undergo oligomerization, and form the pre-pore complex, which then collapses into the membrane to form the b-barrel pore that permeabilizes target cells and causes lysis and death (8,(17)(18)(19)(20).…”

Inhibition of Pneumolysin Cytotoxicity by Hydrolysable Tannins

“…The Ply oligomerization assay was developed using erythrocytes as target cells. The use of erythrocytes was chosen since recent findings show that cell surface carbohydrates are also required for Ply oligomerization and pore formation [ 26 , 27 ]. The formation of a large 2500-kDa Ply complex was detected in Western blotting.…”