DNA Polymerase III Structure
By itself, the polymerase catalytic subunit of the DNA polymerase III holoenzyme (Pol III HE), α, exhibits no special properties that hint of the Pol III HE’s high catalytic efficiency, accuracy, and enormous processivity. These properties are gained by association with other proteins through a series of distinct protein interaction domains. A PHP domain at the N-terminus of Pol III α binds the proofreading subunit, ε. A typical Mg++-dependent polymerase catalytic domain has a fold similar to the DNA polymerase β (Pol X family). Adjacent to the polymerase domain is the β-binding domain. Interaction of this domain with the β2 sliding clamp processivity factor, together with an ε−β2interaction, provides the primary determinants of the enzyme’s processivity. The C-terminus contains two domains, one an OB fold that may bind single-stranded DNA and a τ-binding domain that binds the τ-subunit of the DnaX complex. X-ray crystal structures of Pol III α in the apoenzyme form, bound...
KeywordsHydrolysis Catalysis Carboxyl Lysine Arginine
- Jergic S, Ozawa K, Williams NK, Su XC, Scott DD, Hamdan SM, Crowther JA, Otting G, Dixon NE (2007) The unstructured C-terminus of the τ subunit of Escherichia coli DNA polymerase III holoenzyme is the site of interaction with the α subunit. Nucleic Acids Res 35:2813–2824PubMedCentralCrossRefPubMedGoogle Scholar
- Jergic S, Horan NP, Elshenawy MM, Mason CE, Urathamakul T, Ozawa K, Robinson A, Goudsmits JM, Wang Y, Pan X, Beck JL, van Oijen AM, Huber T, Hamdan SM, Dixon NE (2013) A direct proofreader-clamp interaction stabilizes the Pol III replicase in the polymerization mode. EMBO J 32:1322–1333PubMedCentralCrossRefPubMedGoogle Scholar
- Ozawa K, Horan NP, Robinson A, Yagi H, Hill FR, Jergic S, Xu ZQ, Loscha KV, Li N, Tehei M, Oakley AJ, Otting G, Huber T, Dixon NE (2013) Proofreading exonuclease on a tether: the complex between the E. coli DNA polymerase III subunits alpha, epsilon, theta and beta reveals a highly flexible arrangement of the proofreading domain. Nucleic Acids Res 41:5354–5367PubMedCentralCrossRefPubMedGoogle Scholar
- Vandewiele D, Fernandez de Henestrosa AR, Timms AR, Bridges BA, Woodgate R (2002) Sequence analysis and phenotypes of five temperature sensitive mutator alleles of dnaE, encoding modified alpha-catalytic subunits of Escherichia coli DNA polymerase III holoenzyme. Mutat Res 499:85–95CrossRefPubMedGoogle Scholar
- Wing RA (2010) Structural studies of the prokaryotic replisome. Thesis/Dissertation, Yale University, p 170Google Scholar