5ar Multiscale Modeling Studies of Self-Assembly in Biological Systems

Hung D. Nguyen1, Charles L. Brooks III1, and Carol K. Hall2. (1) Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, TPC6, La Jolla, CA 92037, (2) Department of Chemical and Biomolecular Engineering, North Carolina State University, Engineering Building I, Box 7905, 911 Partners Way, Raleigh, NC 27695

The common theme of my research experiences has been developing a comprehensive understanding of the basic physical principles that underlie the formation of ordered protein structures in various biological systems using different novel computer simulation techniques.

My graduate research, which was under the guidance of Prof. Carol K. Hall at NCSU, focused on the development, refinement, and application of a protein model at intermediate resolution to examine the competition between protein folding and aggregation, especially the formation of ordered structures such as amyloid fibrils, which have been implicated in the pathology of several neurodegenerative diseases including Alzheimer's and Parkinson's. When coupled with discontinuous molecular dynamics, a fast alternative to standard molecular dynamics, our protein model, which contains enough genuine protein-like character to mimic real proteins, allowed us to simulate truly multi-peptide systems of polyalanines over relatively long time scales. To our knowledge, these were the first simulations to span the whole process of fibril formation from the random coil state to the fibril state on a large system. Therefore, we were able to examine the kinetics and thermodynamics of fibril formation in detail.

My postdoctoral research with Prof. Charles L. Brooks III at the Scripps Research Institute is aimed at developing multiscale models and simulation techniques for studying the self-assembly and maturation process of icosahedral viral capids, which are the coats that protect the viral genome in the form of DNA or RNA. Icosahedral capsids are composed of hundreds of copies of individual capsid proteins that must assemble correctly, rapidly, and reproducibly on a biological timescale in order to propagate an infection in vivo. Once assembled, capsid proteins undergo a rearrangement process in which large-scale conformational changes take place to achieve their viral functionalities. Elucidating the self-assembly and stability of viral capsids may have the potential to assist in developing novel approaches to interfere with viral infection. In addition, gaining insights into the capsid self-assembly process may also aid our exploitation of beneficial applications of viral capsids in medicine and materials science. So far we have learnt detailed kinetics and thermodynamics of the self-assembly of empty viral capsids by performing molecular dynamics and rigid-body Monte Carlo simulations on large systems containing multiple capsid subunits with our newly-developed geometric models. Also, we have conducted structural studies to investigate assembly mechanisms using our newly-developed united-atom model and explored the initial stages of viral capsid assembly by using all-atom CHARMM. Finally, we have examined physical properties such as elastic behavior, capsid expansion and buckling transition of numerous viral capsids using the Normal Mode analysis technique and CHARMM.

As a faculty member, one of my main proposed research areas involves investigation of the self-assembly of biological and biomimetic nanoscale materials that are based on not only amino acids but also nucleic acids.



Web Page: www.scripps.edu/~hdnguyen/index.html