A direct proofreader-clamp interaction stabilizes the Pol III replicase in the polymerization mode

Slobodan Jergic, Nicholas P. Horan, Mohamed Elshenawy, Claire E. Mason, Thitima Urathamakul, Kiyoshi Ozawa, Andrew J. Robinson, Joris M H Goudsmits, Yao Wang, Xuefeng Pan, Jennifer L. Beck, Antoine M. Van Oijen, Thomas L. Huber, Samir Hamdan, Nicholas E. Dixon

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


Processive DNA synthesis by the αÉ"θ core of the Escherichia coli Pol III replicase requires it to be bound to the β 2 clamp via a site in the α polymerase subunit. How the É" proofreading exonuclease subunit influences DNA synthesis by α was not previously understood. In this work, bulk assays of DNA replication were used to uncover a non-proofreading activity of É". Combination of mutagenesis with biophysical studies and single-molecule leading-strand replication assays traced this activity to a novel β-binding site in É" that, in conjunction with the site in α, maintains a closed state of the αÉ"θ-β 2 replicase in the polymerization mode of DNA synthesis. The É"-β interaction, selected during evolution to be weak and thus suited for transient disruption to enable access of alternate polymerases and other clamp binding proteins, therefore makes an important contribution to the network of protein-protein interactions that finely tune stability of the replicase on the DNA template in its various conformational states. © 2013 European Molecular Biology Organization.
Original languageEnglish (US)
Pages (from-to)1322-1333
Number of pages12
JournalEMBO Journal
Issue number9
StatePublished - Feb 22 2013

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We thank Michelle Blayney and Linda Jessop for preliminary ESI-MS data. This work was supported by grants from the Australian Research Council, including Fellowships to KO, TH, and NED, and by a KAUST Faculty Initiated Collaborative grant to SMH and NED.

ASJC Scopus subject areas

  • General Neuroscience
  • General Biochemistry, Genetics and Molecular Biology
  • Molecular Biology
  • General Immunology and Microbiology


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