Mycolactone activation of Wiskott-Aldrich syndrome proteins underpins Buruli ulcer formation
Laure Guenin-Macé, … , Marie-France Carlier, Caroline Demangel
Laure Guenin-Macé, … , Marie-France Carlier, Caroline Demangel
Published March 15, 2013
Citation Information: J Clin Invest. 2013;123(4):1501-1512. https://doi.org/10.1172/JCI66576.
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Research Article Infectious disease

Mycolactone activation of Wiskott-Aldrich syndrome proteins underpins Buruli ulcer formation

Abstract

Mycolactone is a diffusible lipid secreted by the human pathogen Mycobacterium ulcerans, which induces the formation of open skin lesions referred to as Buruli ulcers. Here, we show that mycolactone operates by hijacking the Wiskott-Aldrich syndrome protein (WASP) family of actin-nucleating factors. By disrupting WASP autoinhibition, mycolactone leads to uncontrolled activation of ARP2/3-mediated assembly of actin in the cytoplasm. In epithelial cells, mycolactone-induced stimulation of ARP2/3 concentrated in the perinuclear region, resulting in defective cell adhesion and directional migration. In vivo injection of mycolactone into mouse ears consistently altered the junctional organization and stratification of keratinocytes, leading to epidermal thinning, followed by rupture. This degradation process was efficiently suppressed by coadministration of the N-WASP inhibitor wiskostatin. These results elucidate the molecular basis of mycolactone activity and provide a mechanism for Buruli ulcer pathogenesis. Our findings should allow for the rationale design of competitive inhibitors of mycolactone binding to N-WASP, with anti–Buruli ulcer therapeutic potential.

Authors

Laure Guenin-Macé, Romain Veyron-Churlet, Maria-Isabel Thoulouze, Guillaume Romet-Lemonne, Hui Hong, Peter F. Leadlay, Anne Danckaert, Marie-Thérèse Ruf, Serge Mostowy, Chiara Zurzolo, Philippe Bousso, Fabrice Chrétien, Marie-France Carlier, Caroline Demangel

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Figure 2

Mycolactone binding to N-WASP potentiates its actin polymerization activity.

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Mycolactone binding to N-WASP potentiates its actin polymerization activ...
(A) Effect of increasing concentrations of mycolactone on N-WASP–dependent polymerization of pyrenyl actin. Equivalent volumes of solvent were used as control. (B) CR7 dose-dependently inhibited mycolactone-induced N-WASP activation. (C) Effect of CR2, CR3, and CR7 on mycolactone-induced N-WASP activation. (D) Mycolactone dose-dependently displaced CR1-bound VCA. Silver staining of WASP CR1 and VCA, after incubation of GST-fused CR1 (immobilized on glutathione-sepharose beads) with VCA in the presence of increasing amounts of mycolactone, and analysis of bead-bound products by gel electrophoresis. No VCA served as control. Lanes were run on the same gel but were noncontiguous (black line). (E) Differential activity of mycolactone and CDC42-GTP (CDC42) on N-WASP–dependent actin polymerization.