Dynamics of Proofreading by the E. coli Pol III Replicase

Authors

Jonghyun Park, Pohang University of Science and Technology
Slobodan Jergic, University of WollongongFollow
Yongmoon Jeon, Pohang University of Science and Technology
Won-Ki Cho, Pohang University of Science and Technology
Ryanggeun Lee, Pohang University of Science and Technology
Nicholas E. Dixon, University of WollongongFollow
Jong-Bong Lee, Pohang University of Science and TechnologyFollow

RIS ID

117737

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.

Abstract

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

ARC/DP150100956