Skip to main content
Article
The unstructured C-terminus of the tau subunit of Escherichia coli DNA polymerase III holoenzyme is the site of interaction with the alpha subunit
Faculty of Science - Papers (Archive)
  • Slobodan Jergic, University of Wollongong
  • Kiyoshi Ozawa, University of Wollongong
  • Neal K Williams, Australian National University
  • Xun-Cheng Su, Australian National University
  • Daniel D Scott, Australian National University
  • Samir M Hamdan, Australian National University
  • Jeffrey A Crowther, Australian National University
  • Gottfried Otting, Australian National University
  • Nicholas E Dixon, University of Wollongong
RIS ID
16857
Publication Date
1-1-2007
Publication Details

Jergic, S., Ozawa, K., Williams, N. K., Su, X. Cheng., Scott, D. D., Hamdan, S. M., Crowther, J. A., Otting, G. & Dixon, N. E. (2007). The unstructured C-terminus of the tau subunit of Escherichia coli DNA polymerase III holoenzyme is the site of interaction with the alpha subunit. Nucleic Acids Research, 35 (9), 2813-2824.

Abstract

The τ subunit of Escherichia coli DNA polymerase III holoenzyme interacts with the α subunit through its C-terminal Domain V, τC16. We show that the extreme C-terminal region of τC16 constitutes the site of interaction with α. The τC16 domain, but not a derivative of it with a C-terminal deletion of seven residues (τC16Δ7), forms an isolable complex with α. Surface plasmon resonance measurements were used to determine the dissociation constant (KD) of the α−τC16 complex to be ∼260 pM. Competition with immobilized τC16 by τC16 derivatives for binding to α gave values of KD of 7 μM for the α−τC16Δ7 complex. Low-level expression of the genes encoding τC16 and τC16▵7, but not τC16Δ11, is lethal to E. coli. Suppression of this lethal phenotype enabled selection of mutations in the 3′ end of the τC16 gene, that led to defects in α binding. The data suggest that the unstructured C-terminus of τ becomes folded into a helix–loop–helix in its complex with α. An N-terminally extended construct, τC24, was found to bind DNA in a salt-sensitive manner while no binding was observed for τC16, suggesting that the processivity switch of the replisome functionally involves Domain IV of τ.

Citation Information
Slobodan Jergic, Kiyoshi Ozawa, Neal K Williams, Xun-Cheng Su, et al.. "The unstructured C-terminus of the tau subunit of Escherichia coli DNA polymerase III holoenzyme is the site of interaction with the alpha subunit" (2007) p. 2813 - 2824
Available at: http://works.bepress.com/nick_dixon/39/