Identification of a domain critical for Staphylococcus aureus LukED receptor targeting and lysis of erythrocytes

Marilyn T Vasquez,Ashira Lubkin,Tamara Reyes-Robles,Christopher J Day,Keenan A Lacey,Michael P Jennings,Victor J Torres

doi:10.1074/jbc.ra120.015757

Marilyn T Vasquez, Ashira Lubkin + Show 5 more

Open Access

https://doi.org/10.1074/jbc.ra120.015757

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Abstract

Leukocidin ED (LukED) is a pore-forming toxin produced by Staphylococcus aureus, which lyses host cells and promotes virulence of the bacteria. LukED enables S. aureus to acquire iron by lysing erythrocytes, which depends on targeting the host receptor Duffy antigen receptor for chemokines (DARC). The toxin also targets DARC on the endothelium, contributing to the lethality observed during bloodstream infection in mice. LukED is comprised of two monomers: LukE and LukD. LukE binds to DARC and facilitates hemolysis, but the closely related Panton-Valentine leukocidin S (LukS-PV) does not bind to DARC and is not hemolytic. The interaction of LukE with DARC and the role this plays in hemolysis are incompletely characterized. To determine the domain(s) of LukE that are critical for DARC binding, we studied the hemolytic function of LukE-LukS-PV chimeras, in which areas of sequence divergence (divergence regions, or DRs) were swapped between the toxins. We found that two regions of LukE's rim domain contribute to hemolysis, namely residues 57-75 (DR1) and residues 182-196 (DR4). Interestingly, LukE DR1 is sufficient to render LukS-PV capable of DARC binding and hemolysis. Further, LukE, by binding DARC through DR1, promotes the recruitment of LukD to erythrocytes, likely by facilitating LukED oligomer formation. Finally, we show that LukE targets murine Darc through DR1 in vivo to cause host lethality. These findings expand our biochemical understanding of the LukE-DARC interaction and the role that this toxin-receptor pair plays in S. aureus pathophysiology.

Highlights

Staphylococcus aureus is a Gram-positive pathobiont responsible for significant human disease [1]
We found that LukSE-DR1 exhibited partial hemolytic activity, whereas the other chimeras had none (Fig. 1E)
We previously found that the loss-of-function chimeras studied here are all cytotoxic to human polymorphonuclear leukocytes except for LukES-DR4 but that this chimera is still cytotoxic to CCR51 cells [8]

Summary

Introduction

Staphylococcus aureus is a Gram-positive pathobiont responsible for significant human disease [1]. D–G, hemolysis of primary human erythrocytes treated with LukE and LukS DR chimeras and indicated F subunits (n = 5– 17 donors). We tested the gain-of-function chimeras on hPMNs. We found that LukSE-DR1, LukSE-DR3, and LukSE-DR4 were all cytotoxic to hPMNs when combined with LukF-PV, at levels similar to WT LukED and LukSF-PV and noncanonical toxin pairs (Fig. 2, A and B).

Results

Conclusion