PMID: 23478062
Liu B, Lin J, Steitz TA
Structure of the PolIIIalpha-tauc-DNA complex suggests an atomic model of the replisome.
Structure. 2013 Apr 2;21(4):658-64. doi: 10.1016/j.str.2013.02.002. Epub 2013 Mar, 7.
The C-terminal domain (CTD) of the tau subunit of the clamp loader (tauc) binds to both the DnaB helicase and the DNA polymerase III alpha subunit (PolIIIalpha), and determines their relative positions and orientations on the leading and lagging strands. Here, we present a 3.2 A resolution structure of Thermus aquaticus PolIIIalpha in complex with tauc and a DNA substrate. The structure reveals that the CTD of tauc interacts with the CTD of PolIIIalpha through its C-terminal helix and the adjacent loop. Additionally, in this complex PolIIIalpha 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 tauc. Nevertheless, the position of the tauc on PolIIIalpha allows us to suggest an approximate model for how the PolIIIalpha is oriented and positioned on the DnaB helicase.