Structural and Functional Study of Biological Macromolecules
I. Molecular chaperone 70-kDa heat shock proteins
The 70-kDa heat shock proteins (Hsp70s) are a group of molecular chaperones that are highly conserved across many phyla. Hsp70s assist in several crucial cellular functions, including the correct folding of nascent or stress-denatured polypeptides, protein translocation across membranes, and assembly/disassembly of protein complexes. However, our understanding of these functions remains vague due to insufficient structural information. To unravel the mystery, we investigate the structure and function of Hsp70 chaperone family proteins.
II. Structural and Functional Study of the Outer and Inner Membrane Proteins involved in Protein Transport from Chloroplasts
Chloroplast biogenesis requires the import of hundreds of nuclear-encoded preproteins across the double membrane envelope from the cytosol. The mechanism of protein import into chloroplasts involves specific interactions between precursor proteins and the translocon complex in the outer (Toc complex) and inner (Tic complex) envelope membranes of chloroplasts. The main goal of this project is to determine the structures and functions of the outer and inner membrane proteins involved in the intracellular trafficking of newly synthesized polypeptides from chloroplasts by mean of X-ray crystallographic technique.
III. Structural and Functional Study of the Primosomal Proteins Involved in DNA Replication Restart
Complete and faithful replication of the genome requires the ability of cells to respond to DNA damage. Under normal growth conditions, replication forks formed at the bacterial origin of replication, oriC, frequently encounter sites of DNA damage that can result in their inactivation. These stalled replication forks must be efficiently repaired to allow replication of the genome to resume. Processes that reinitiate replication at repaired forks thus represent major housekeeping functions in bacteria that are essential for viability. In E. coli, a number of proteins, collectively referred to as the primosome, are responsible for reactivating repaired replication forks. There are seven proteins comprising the primosome, PriA, PriB, PriC, DnaT, DnaB, DnaC, and DnaG. In this project, we study the structure and function of these seven components of primosomal proteins.