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Title: Insights into the Replisome from the Structure of a Ternary Complex of the DNA Polymerase III [alpha]-Subunit

The crystal structure of the catalytic {alpha}-subunit of the DNA polymerase III (PolIII{alpha}) holoenzyme bound to primer-template DNA and an incoming deoxy-nucleoside 5{prime}-triphosphate has been determined at 4.6-{angstrom} resolution. The polymerase interacts with the sugar-phosphate backbone of the DNA across its minor groove, which is made possible by significant movements of the thumb, finger, and {beta}-binding domains relative to their orientations in the unliganded polymerase structure. Additionally, the DNA and incoming nucleotide are bound to the active site of PolIII{alpha} nearly identically as they are in their complex with DNA polymerase {beta}, thereby proving that the eubacterial replicating polymerase, but not the eukaryotic replicating polymerase, is homologous to DNA polymerase {beta}. Finally, superimposing a recent structure of the clamp bound to DNA on this PolIII{alpha} complex with DNA places a loop of the {beta}-binding domain into the appropriate clamp cleft and supports a mechanism of polymerase switching.
Authors:
; ;  [1] ;  [2]
  1. (Yale)
  2. (
Publication Date:
OSTI Identifier:
1007074
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Mol. Biol.; Journal Volume: 382; Journal Issue: (4) ; 10, 2008
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; CRYSTAL STRUCTURE; DNA; DNA POLYMERASES; NUCLEOTIDES; POLYMERASES; RESOLUTION