Staphylococcus aureus vWF-binding protein triggers a strong interaction between clumping factor A and host vWF

Albertus Viljoen,Marion Mathelié-Guinlet,Yves F Dufrêne,Dominique Missiakas,Giampiero Pietrocola,Pietro Speziale,Felipe Viela

doi:10.1038/s42003-021-01986-6

Abstract

The Staphylococcus aureus cell wall-anchored adhesin ClfA binds to the very large blood circulating protein, von Willebrand factor (vWF) via vWF-binding protein (vWbp), a secreted protein that does not bind the cell wall covalently. Here we perform force spectroscopy studies on living bacteria to unravel the molecular mechanism of this interaction. We discover that the presence of all three binding partners leads to very high binding forces (2000 pN), largely outperforming other known ternary complexes involving adhesins. Strikingly, our experiments indicate that a direct interaction involving features of the dock, lock and latch mechanism must occur between ClfA and vWF to sustain the extreme tensile strength of the ternary complex. Our results support a previously undescribed mechanism whereby vWbp activates a direct, ultra-strong interaction between ClfA and vWF. This intriguing interaction represents a potential target for therapeutic interventions, including synthetic peptides inhibiting the ultra-strong interactions between ClfA and its ligands.

Highlights

The Staphylococcus aureus cell wall-anchored adhesin ClfA binds to the very large blood circulating protein, von Willebrand factor via vWF-binding protein, a secreted protein that does not bind the cell wall covalently
What is the binding strength of the vWF-vWbpClfA ternary complex? Single S. aureus cells were incubated with purified vWF-binding protein (vWbp) and probed with atomic force microscopy (AFM) tips modified with vWF
To avoid Staphylococcal protein A (SpA)-dependent vWF-binding, which occurs at a frequency of ~15% when using strain S. aureus Newman[20], we used a variant of S. aureus SH1000, a laboratory strain that produces reduced amounts of SpA29, and over-produces ClfA from a multicopy plasmid[28,30]

Summary

Introduction

The Staphylococcus aureus cell wall-anchored adhesin ClfA binds to the very large blood circulating protein, von Willebrand factor (vWF) via vWF-binding protein (vWbp), a secreted protein that does not bind the cell wall covalently. Our results support a previously undescribed mechanism whereby vWbp activates a direct, ultra-strong interaction between ClfA and vWF. VWF multimerization is triggered by the sequential formation of disulfide bonds between the C-terminal CK domains of two protomers leading to tail-to-tail homodimerization followed by disulfide linkage between N-terminal D3 domains of adjacent dimers[10,11] This self-assembly process results in the formation of right-handed helical tubules that are stocked in the Weibel-Palade bodies of endothelial cells, from which they are secreted into the circulation[10,12]. In vitro as well as in vivo perfusion experiments demonstrated that vWbp/

Methods

Results

Conclusion