AVS 53rd International Symposium
    Biomaterial Interfaces Tuesday Sessions
       Session BI1-TuM

Paper BI1-TuM12
Detection and Mapping of Individual Adhesins on Living Bacteria using Atomic Force Microscopy

Tuesday, November 14, 2006, 11:40 am, Room 2001

Session: Microbe-Surface Interactions
Presenter: V. Dupres, Université Catholique de Louvain, Belgium
Authors: V. Dupres, Université Catholique de Louvain, Belgium
F.D. Menozzi, Institut Pasteur de Lille, France
Y.F. Dufrene, Université Catholique de Louvain, Belgium
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Bacterial pathogens adhere to host cells via the specific interaction between surface proteins, referred to as adhesins, and host surface receptors. Although much progress has been made in the identification and characterization of adhesins borne by pathogenic bacteria, the molecular details underlying such interactions remain largely unknown owing to the lack of appropriate probing techniques. In this work, we used atomic force microscopy (AFM) with tips bearing biologically active molecules to measure the specific binding forces of individual adhesins and to map their distribution on the surface of living bacteria.@footnote 1@ First, we determined the adhesion forces between the heparin-binding haemagglutinin adhesin (HBHA) produced by Mycobacterium tuberculosis, the etiologic agent of tuberculosis, and heparin, used as a model receptor. We obtained a bimodal distribution of the adhesion forces with average forces of 50 pN and 117 pN, which could be attributed to one and two binding events between HBHA and heparin. Both the adhesion frequency and adhesion force increased with contact time, indicating that the HBHA-heparin complex is formed via multiple intermolecular bridges. We then mapped the spatial distribution of single HBHA molecules on the surface of living mycobacteria using heparin-modified tips. Strikingly, adhesion events were observed in about half of the locations and were concentrated into nanodomains over the mycobacterial surface. @FootnoteText@ @footnote 1@ Dupres V., Menozzi F.D., Locht C., Clare B.H., Abbott N.L., Cuenot S., Bompard C., Raze D. and Dufrene Y.F., Nat. Methods, 2, 515-520 (2005).