Cell proliferation requires timely and reliable DNA replication. Genetic and biochemical evidence reveals that the replication process is subject to a variety of conflict mechanisms, including DNA damage, concurrent DNA transcription, and DNA-bound protein complexes which can all act to stall the replication process. Without a mechanism for rapid and efficient resolution, these conflicts have the potential to cause genomic instability and even cell death. The frequency of these conflicts and their consequences to replisome structure remain unknown. We report the direct visualization of single replication conflicts with single-molecule sensitivity in two model organisms well suited for single-molecule microscopy (E. coli and Bacillus subtilis) and characterize the dynamics of these conflicts in vivo. These direct observations of the replication process reveal that conflicts are vastly more frequent than previously hypothesized and imply that the restart process in fact plays out multiple times in a typical cell cycle.
Lunch@ 11:45, Seminar 12-1:00