The Physics department colloquia are usually on Friday afternoons at 3:30 pm in Lapham Hall Room 160. Coffee and cookies are served at 3:15 pm in the same room. Anyone is welcome.

Structural Mechanisms of DNA Replication Restart
Dr. James L. Keck, Dept. of Biomolecular Chemistry, UW-Madison

Frequent collisions between cellular DNA replication complexes (replisomes) and obstacles such as damaged DNA or frozen protein complexes make DNA replication fork progression surprising sporadic. These collisions can lead to the ejection of replisomes prior to the completion of replications, which, if left unrepaired, results in cell death. As such, cells have evolved “DNA replication restart” mechanisms that reload replisomes onto abandoned DNA replication forks. In the first step in this process in bacteria, either of two “first-responder” proteins recognizes and remodels abandoned DNA replication forks and then orchestrates replisome reloading.

We have recently determined the high-resolution structures of both of these proteins (PriA DNA helicase and PriC), revealing two different molecular structures that appear to be “poised” for specific binding to replication forks. Mechanistic insights from these structures will be highlighted.