Engineering stability in the Escherichia coli β clamp

• Online Access: http://hdl.handle.net/2047/D20286914

Sliding processivity clamps are ring-shaped proteins found in all domains of life that encircle DNA and play essential roles in replication and repair. Clamps are vital to all organisms as they greatly increase the speed and processivity of replicative polymerases allowing for the accurate replication of entire genomes. Bacterial sliding clamps are attractive drug targets for combating multidrug-resistant bacteria. Clamp loaders place clamps onto DNA by first binding ATP and ATP hydrolysis results in clamp loader ejection from the clamp and DNA. Research on clamps and clamp loaders over the past 25 years has provided many mechanistic details on the loading reaction but many questions are still left unanswered. The need for active clamp opening by the clamp loader varies across species and it correlates with the stability of the ring structure in solution. The β clamp has been shown to be a closed ring in solution with a long residence time on DNA.