The RecA protein of Escherichia coli is a central enzyme in recombination and SOS induction, both crucial DNA repair pathways. Furthermore, RecA and its homologues are found in all domains of life, from bacteria to humans. Much of the understanding of RecA activity has been based on interpretations of in vitro studies. One underlying assumption in this work is that all RecA activities will behave identically in the capacity to catalyze recombination and induce the SOS response. However, our work has shown that this assumption is not valid when applied to RecA filaments formed in vivo. RecA filaments formed during exponential (log phase) growth are less active for SOS induction than those formed after UV irradiation.

In my work, I have attempted to better characterize the factors that regulate RecA activity in E. coli under these different conditions. These factors can be either properties of RecA itself or other proteins or cellular conditions. We have found that ATPase activity and DNA binding are two key factors of RecA that control activity. Furthermore, other proteins, such as RecX, DinI and RecF and RecB further modulate the activity of RecA. This work has lead to a better understanding of pathways found throughout eubacteria. This understanding has ramifications in diverse fields, including bacterial pathogenesis and human cancer research.