Addition of lysophospholipids with large head groups to cells inhibits Shiga toxin binding.

Ieva Ailte,Anne-Grethe Myrann,Tore Skotland,Anne Berit Dyve Lingelem,Kirsten Sandvig,Simona Kavaliauskiene,Audun Sverre Kvalvaag,Jonas Bergan

doi:10.1038/srep30336

Ieva Ailte, Anne-Grethe Myrann + Show 6 more

Open Access

https://doi.org/10.1038/srep30336

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Abstract

Shiga toxin (Stx), an AB5 toxin, binds specifically to the neutral glycosphingolipid Gb3 at the cell surface before being transported into cells. We here demonstrate that addition of conical lysophospholipids (LPLs) with large head groups inhibit Stx binding to cells whereas LPLs with small head groups do not. Lysophosphatidylinositol (LPI 18:0), the most efficient LPL with the largest head group, was selected for in-depth investigations to study how the binding of Stx is regulated. We show that the inhibition of Stx binding by LPI is reversible and possibly regulated by cholesterol since addition of methyl-β-cyclodextrin (mβCD) reversed the ability of LPI to inhibit binding. LPI-induced inhibition of Stx binding is independent of signalling and membrane turnover as it occurs in fixed cells as well as after depletion of cellular ATP. Furthermore, data obtained with fluorescent membrane dyes suggest that LPI treatment has a direct effect on plasma membrane lipid packing with shift towards a liquid disordered phase in the outer leaflet, while lysophosphoethanolamine (LPE), which has a small head group, does not. In conclusion, our data show that cellular treatment with conical LPLs with large head groups changes intrinsic properties of the plasma membrane and modulates Stx binding to Gb3.

Highlights

Membrane lipids are important regulators of basic cellular processes such as ligand binding, endocytosis and intracellular transport[1]
We here report that insertion of conical LPLs with large head groups inhibits binding of Shiga toxin (Stx) and Stx[2] to cells and that LPI even can induce dissociation of cell-bound Stx
Physical properties of the plasma membrane are regulated by the lipid composition and temperature, and in this study we have investigated effects of adding LPLs with different head groups and fatty acyl chains

Summary

Introduction

Membrane lipids are important regulators of basic cellular processes such as ligand binding, endocytosis and intracellular transport[1]. The conicity of different LPLs is strongly dependent on the size of the head group (Fig. 2) and, the saturation degree of the fatty acyl chain. Despite their low abundancy, LPLs have several roles. We published that exogenous addition of the conical lysophosphatidylinositol (LPI), but not phosphatidylinositol, protects cells against Shiga toxin (Stx) by inhibiting the binding of the toxin[26] Whether this was due to a specific effect of LPI or if a similar effect could be obtained with other LPLs, was not tested at that time. In this study we have investigated whether various LPLs affect binding of protein toxins and explored the mechanistic details of how LPI affects Stx binding

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