Abstract 2425 Large serine integrases: how do they know which way to go?

Site-specific DNA recombinases catalyze DNA insertions, inversions, and deletions in an extremely tidy fashion, leaving no broken phosphodiester bonds. However, the mechanism by which they do so leaves them with an interesting thermodynamic problem: the net number of high-energy bonds in the product is the same as that in the substrate. How do these enzymes drive their reactions to near completion? Furthermore, how do they “decide” which pairs of sites to pair as substrates and in what relative orientation? I will describe our progress on answering these questions for the serine-family group of site-specific recombinases termed the large serine integrases.