Molecular recognition forces between immunoglobulin G and a surface protein adhesin on living Staphylococcus aureus.
We report AFM measurements of binding events between immunoglobulin G (IgG) and protein A (PA) on the surface of live Staphylococcus aureus bacteria. The experiments were carried out with IgG molecules tethered via CM-amylose linkers to thiol SAMs on gold-coated AFM tips. For comparison, a model system consisting of protein A molecules tethered to thiol SAMs on gold-coated silicon substrates was also investigated. Histograms of binding forces for the PA-IgG bond showed comparable rupture forces of 59 and 64 pN for the model system and live bacteria, respectively. We suggest that linker molecules with a length comparable to the AFM tip radius should make it possible to detect specific binding events on the surface of live bacteria with a lateral resolution of a few tens of nanometers. Furthermore, because S. aureus is an important human pathogen, especially methicillin-resistant strains (MRSA), it is possible that additional virulence factors beyond PA can be probed using this technique.
Touhami
Ahmed
A
Department of Physics and Atmospheric Science, Dalhousie University, Halifax Nova Scotia, Canada B3H 3J5.
Jericho
Manfred H
MH
Beveridge
Terry J
TJ
D018829:Adhesins, Bacterial / Q000737:chemistry*; D000818:Animals; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000737:chemistry; D055592:Biophysical Phenomena; D001703:Biophysics; D002627:Chemistry, Physical / Q000379:methods; D007074:Immunoglobulin G / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry; D018625:Microscopy, Atomic Force / Q000379:methods; D011312:Pressure; D011485:Protein Binding; D011817:Rabbits; D013211:Staphylococcus aureus / Q000378:metabolism*; D013499:Surface Properties
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D007074:Immunoglobulin G; D008565:Membrane Proteins