Susan Egan - Associate Professor of Molecular Biosciences, KU

Many activator proteins function by directly contacting RNA polymerase (RNAP), however the exact effects of these interactions aren't well understood. The long-range goal of Susan Egan's research is to shed light on the structure of the transcription activator protein RhaR and to relate this structure to the molecular mechanisms used by RhaR to activate transcription. In the presence of L-rhamnose, a sugar, RhaR activates expression of the Escherichia coli rhaSR operon. Full activation of rhaSR expression also requires the CRP protein. The central hypothesis is that specific interactions between RhaR, CRP and RNAP are required for transcription activation. Uncovering the structure for RhaR will help Egan and her lab gain a better understanding of these interactions.

The finding that many regions of the crystal structure of a bacterial and a yeast RNAP can be virtually superimposed suggests that they may use similar mechanisms for interaction with activators. Also, RhaR is a member of the large AraC/Xy1S family of activators, many of which activate virulence factors in bacterial pathogens and so are of interest as antibacterial targets. Understanding the mechanisms used by AraC/Xy1S family members to activate transcription will be important for rational design of anti-AraC/Xy1S family agents.