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Journal of Bacteriology, December 2008, p. 7614-7620, Vol. 190, No. 23
0021-9193/08/$08.00+0     doi:10.1128/JB.00974-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Interaction of the Mycobacterial Heparin-Binding Hemagglutinin with Actin, as Evidenced by Single-Molecule Force Spectroscopy

Unité de Chimie des Interfaces, Université Catholique de Louvain, Croix du Sud 2/18, B-1348 Louvain-la-Neuve, Belgium,¹ INSERM, U629, Mécanismes Moléculaires de la Pathogénie Microbienne, Lille, France,² Institut Pasteur de Lille, 1 rue du Professeur Calmette, F-59019 Lille Cedex, France,³ IFR 142, Molecular and Cellular Medicine, Lille, France,⁴ UMR 8161 CNRS Institut de Biologie de Lille-Laboratoire d'Approches Structurales de la Pathogénèse-Université des Sciences et Technologies de Lille 1-Université de Lille 2, Lille, France⁵

Received 15 July 2008/ Accepted 25 September 2008

Although Mycobacterium tuberculosis and related species are considered to be typical endosomal pathogens, recent studies have suggested that mycobacteria can be present in the cytoplasm of infected cells and cause cytoskeleton rearrangements, the mechanisms of which remain unknown. Here, we used single-molecule force spectroscopy to demonstrate that the heparin-binding hemagglutinin (HBHA), a surface adhesin from Mycobacterium tuberculosis displaying sequence similarities with actin-binding proteins, is able to bind to actin. Force curves recorded between actin and the coiled-coil, N-terminal domain of HBHA showed a bimodal distribution of binding forces reflecting the detection of single and double HBHA-actin interactions. Force curves obtained between actin and the lysine-rich C-terminal domain of HBHA showed a broader distribution of binding events, suggesting they originate primarily from intermolecular electrostatic bridges between cationic HBHA domains and anionic actin residues. We also explored the dynamics of the HBHA-actin interaction, showing that the binding force and binding frequency increased with the pulling speed and contact time, respectively. Taken together, our data indicate that HBHA is able to specifically bind actin, via both its N-terminal and C-terminal domains, strongly suggesting a role of the HBHA-actin interaction in the pathogenesis of mycobacterial diseases.

Published ahead of print on 3 October 2008.