Dynamics of Proofreading by the E. coli Pol III Replicase



Publication Details

Park, J., Jergic, S., Jeon, Y., Cho, W., Lee, R., Dixon, N. E. & Lee, J. (2018). Dynamics of Proofreading by the E. coli Pol III Replicase. Cell Chemical Biology, 25 (1), 57-66.


The αεθ core of Escherichia coli DNA polymerase III (Pol III) associates with the β2 sliding clamp to processively synthesize DNA and remove misincorporated nucleotides. The α subunit is the polymerase while ε is the 3' to 5' proofreading exonuclease. In contrast to the polymerase activity of Pol III, dynamic features of proofreading are poorly understood. We used single-molecule assays to determine the excision rate and processivity of the β2 -associated Pol III core, and observed that both properties are enhanced by mutational strengthening of the interaction between ε and β2. Thus, the ε-β2 contact is maintained in both the synthesis and proofreading modes. Remarkably, single-molecule real-time fluorescence imaging revealed the dynamics of transfer of primer-template DNA between the polymerase and proofreading sites, showing that it does not involve breaking of the physical interaction between ε and β2.

Grant Number


Please refer to publisher version or contact your library.