Application and Development of Biological AFM for the Study of Bacterial Toxins.
Final Progress rept. 1 Jun 95-31 May 99
VERMONT UNIV BURLINGTON DEPT OF PHYSICS
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The support from the U.S. Army Research Office has allowed us to develop novel instrumentation and methods to use state-of-the-art atomic force microscopy in biological applications. We have developed several methods to facilitate high-resolution structural studies of supported membranes, revealing their structural and functional behaviors that have eluded being discovered with other conventional methods. These studies have also established a solid foundation for our structural elucidation of molecular level conformation of membranous bacterial toxins, such as cholera toxin and alpha-hemolysin. In collaboration with Prof. Hagan Bayley, we have shown that two mutants of alpha-hemolysin assembled into heptamer in biologically relevant conditions. The combination of molecular engineering and in situ high-resolution structural elucidation shows a great promise in future success of tackling difficult biological problems. Our progress in the study of supported membranes has allowed us to investigate the behavior of genetic materials when they interact with bilayer membranes. We have found the two-dimensional condensation of DNA on cationic lipid bilayers and a strong binding of DNA to zwitterionic lipid bilayers. These results provide structural information in our understanding of the mechanisms that govern the packing of genetic materials in cellular organisms and the process of gene delivery trials.
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