Publication Details

Su, X. Cheng., Jergic, S., Keniry, M., Dixon, N. E. & Otting, G. (2007). Solution structure of Domains IVa and V of the tau subunit of Escherichia coli DNA polymerase III and interaction with the alpha subunit. Nucleic Acids Research, 35 (9), 2825-2832.


The solution structure of the C-terminal Domain V of the τ subunit of E. coli DNA polymerase III was determined by nuclear magnetic resonance (NMR) spectroscopy. The fold is unique to τ subunits. Amino acid sequence conservation is pronounced for hydrophobic residues that form the structural core of the protein, indicating that the fold is representative for τ subunits from a wide range of different bacteria. The interaction between the polymerase subunits τ and α was studied by NMR experiments where α was incubated with full-length C-terminal domain (τC16), and domains shortened at the C-terminus by 11 and 18 residues, respectively. The only interacting residues were found in the C-terminal 30-residue segment of τ, most of which is structurally disordered in free τC16. Since the N- and C-termini of the structured core of τC16 are located close to each other, this limits the possible distance between α and the pentameric δτ2γδ′ clamp–loader complex and, hence, between the two α subunits involved in leading- and lagging-strand DNA synthesis. Analysis of an N-terminally extended construct (τC22) showed that τC14 presents the only part of Domains IVa and V of τ which comprises a globular fold in the absence of other interaction partners.



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