Nanoscale probing of the mycobacterial cell wall

Verbelen, Claire
(2009)

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Authors
  • Verbelen, ClaireUCLouvain
    author
Supervisors
Dufrene, Yves
Abstract
(en) Studying the structure and functions of microbial cell walls is essential given the important role they play in various cellular processes and diseases, as well as their potential as drug targets. In this context, the objective of this thesis is to gain detailed molecular insight into the nanoscale properties of the medically-important organism Mycobacterium bovis BCG. To reach this goal, we developed advanced nanoscale and single-molecule atomic force microscopy (AFM) methods for analyzing microbial surfaces in physiological conditions (cell immobilization, tip functionalization, single-molecule detection and localization). Using AFM techniques, we: (i) probed the surface structure of mycobacteria before and after treatment with the antibiotic ethambutol, revealing that the drug causes major alterations of the cell wall, (ii) mapped the localization of single lipoarabinomannan molecules, demonstrating that these are not exposed on native mycobacteria, but hidden by an outermost layer of mycolic acids, (iii) measured the specific binding forces of the mycobacterial heparin binding adhesin (HBHA), that mediate homophilic HBHA-HBHA interactions, HBHA-actin interactions, and HBHA-receptor interactions, and (iv) analyzed the surface distribution and binding strength of mycobacterial fibronectin attachment proteins (FAPs), showing that these adhesins are widely exposed on the mycobacterial surface. Collectively, our data provide novel insight into the structure-function relationships of the mycobacterial cell wall. The nanoscale and single-molecule methods developed here complement traditional proteomic and molecular biological approaches for the functional analysis of surface-associated proteins, and may help in the search for novel anti-microbial drugs.
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Verbelen, C. (2009). Nanoscale probing of the mycobacterial cell wall. https://hdl.handle.net/2078.5/132578