Touhami Ahmed, Jericho Manfred H, Beveridge Terry J
Department of Physics and Atmospheric Science, Dalhousie University, Halifax Nova Scotia, Canada B3H 3J5.
Langmuir. 2007 Feb 27;23(5):2755-60. doi: 10.1021/la0628930. Epub 2007 Jan 24.
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.
我们报告了在活的金黄色葡萄球菌表面进行的免疫球蛋白G（IgG）与蛋白A（PA）结合事件的原子力显微镜（AFM）测量。实验中，IgG分子通过CM-直链淀粉连接体连接到涂金AFM探针上的硫醇自组装单分子层（SAMs）。作为比较，还研究了一个由连接到涂金硅基底上硫醇SAMs的蛋白A分子组成的模型系统。PA-IgG键结合力的直方图显示，模型系统和活细菌的断裂力分别为59 pN和64 pN，具有可比性。我们认为，长度与AFM探针半径相当的连接体分子应能使检测活细菌表面特定结合事件成为可能，横向分辨率可达几十纳米。此外，由于金黄色葡萄球菌是一种重要的人类病原体，尤其是耐甲氧西林菌株（MRSA），使用该技术有可能探测到除PA之外的其他毒力因子。
