Self Assembly of Biomolecules at Nano Scales-Structure and Kinetics

Weixian Shi, Bristol-Myers Squibb Company, 1 Squibb Drive, New Brunswick, NJ 08901 and Ronald G. Larson, Chemical Engineering, University of Michigan, 2300 Hayward Street, 3074 H.H. Dow, Ann Arbor, MI 48109.

The self-organization of biomolecules, like DNA and proteins, are not only biologically important but also crucial to the understanding of general polymer behaviors. One of the powerful tools to visualize self-organized structures is atomic force microscopy (AFM). In this study, the nano complex formed by RecA protein and DNA molecules were investigated using AFM. The structure of complexes formed with and without the presence of single-stranded DNA binding (SSB) protein was found to be distinct from each other. More complicated but ordered assembly was seen when SSB was added in the preparation. SSB assists the assembly process between DNA and RecA protein by removing the secondary structure on DNA molecules which prevents continuous binding of RecA. The biological function of the complex was also evaluated using gel electrophoresis. The kinetics were determined and a preliminary mechanism was identified.