University of Virginia Health System

Our research is focused on the structure and function of macromolecular assemblies, using the techniques of electron microscopy and computed image reconstruction. We have been working in two different areas: protein-DNA complexes active in homologous recombination and replication, and F-actin. The E. coli RecA filament has been the most intensively studied enzyme in homologous recombination, and we have been studying the helical filament that the RecA filament forms on DNA which is the scaffold within which homologous recombination is initiated (Egelman, 1993). The RecA protein induces a highly unusual structure on the DNA within this filament, and this appears to be an important aspect of RecA's enzymatic role. We have shown that the eukaryotic homolog of RecA, the Rad51 protein, forms a nearly identical structure (Ogawa et al., 1993). We have been looking at other protein-DNA complexes that act subsequent to RecA in catalyzing branch migration. This includes the RuvB protein (Yu et al., 1997), which is a member of a large superfamily of helicases. We are currently looking at other helicases, including E. coli DnaB, the bacteriophage T7 gp4, and the papilloma virus E1 proteins, which act in DNA replication. Actin is the most ubiquitous and conserved eukaryotic protein. While it was first identified in muscle, as being the main component of the thin filaments, it is equally abundant in most non-muscle cells, where it plays a key role in the control of cell form and motility. We have found that the F-actin filament can exist in a number of different structural states (Belmont et al., 1999), which provides insight into many phenomena, including the ability of the cell to control how actin specifically binds more than 40 other proteins.

Other Websites for this mentor:
http://www.people.virginia.edu/~ehe2n