Jay H. Choi, Ph.D.

The left-handed parallel β-helix (LβH) fold has recently received attention as a possible structure for the prion protein (PrP) in its misfolded state. In light of this interest, I have developed an experimental system to examine the structural requirements of the LβH fold, using a known LβH protein, UDP-N-acetylglucosamine acyltransferase (LpxA), from E. coli. Based on the sequence analysis and structural studies of the LβH, I have constructed the recombinant PrP-LpxA and tested its functional activity in an E. coli antibiotic sensitivity assay. I am currently focusing on expression and spectroscopic chracterization of the PrP-LpxA recombinant proteins.

In recent decades, the rapid growth of the Internet has triggered an information revolution of unprecedented magnitude. However, especially in light of healthcare and medical products, the overflowing information could result in potentially harmful effects on both healthcare professionals and patients who do not use the information appropriately. The goal of this project is to provide a community and knowledge base where healthcare professionals and patients can freely exchange and share knowledge about medical treatments and products, which will in turn empower and educate the general public about their illnesses and which treatments may be most beneficial.

I developed a new efficient algorithm to identify sequence patterns in biological data based on a heuristic approach of combining the greedy and gibbs algorithm. Since the size of input sequences in biological applications is often quite large, the time complexity becomes a critical factor in the development of sequence analysis software. Therefore, I have developed an efficient heuristic algorithm to achieve a fast computing and performance compatible to greedy algorithm.

The proliferating cell nuclear antigen (PCNA) is involved in various metabolic processes including DNA replication, DNA repair and cell cycle control. I investigated how the site-directed mutations of PCNA gene affected its function in DNA replication. The mutant PCNA genes were expressed and purified from E. coli strain, and functional properties were determined by in-vitro characterization. The mutant PCNAs showed growth defects and elevated sensitivity to DNA-damaging agents, indicating that the mutations in PCNA caused the defects in DNA replication and DNA repair.