title: Structure of the PolIIIα-τc-DNA complex suggests an atomic model of the replisome.
abstract: The C-terminal domain (CTD) of the τ subunit of the clamp loader (τc) binds to both the DnaB helicase and the DNA polymerase III α subunit (PolIIIα), and determines their relative positions and orientations on the leading and lagging strands. Here, we present a 3.2 Å resolution structure of Thermus aquaticus PolIIIα in complex with τc and a DNA substrate. The structure reveals that the CTD of τc interacts with the CTD of PolIIIα through its C-terminal helix and the adjacent loop. Additionally, in this complex PolIIIα displays an open conformation that includes the reorientations of the oligonucleotide-binding fold and the thumb domain, which may be an indirect result of crystal packing due to the presence of the τc. Nevertheless, the position of the τc on PolIIIα allows us to suggest an approximate model for how the PolIIIα is oriented and positioned on the DnaB helicase.
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Jinzhong
authors.initials: J
authors.lastname: Lin
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Steitz
mesh_terms: D003001:Cloning, Molecular; D003460:Crystallization; D004247:DNA / Q000737:chemistry*; D004258:DNA Polymerase III / Q000737:chemistry*; D004261:DNA Replication / Q000235:genetics*; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry*; D011487:Protein Conformation; D019914:Taq Polymerase / Q000737:chemistry*; D013824:Thermus / Q000201:enzymology*; D014157:Transcription Factors / Q000737:chemistry*
chemical_list: D046912:Multiprotein Complexes; D014157:Transcription Factors; D004247:DNA; D019914:Taq Polymerase; C041273:transcription factor tau; D004258:DNA Polymerase III