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Figure 2.
Fig. 2. Crystal structure of a replicating complex of T.
aquaticus PolIIIα. (a) A view of the crystal structure of the
replicating complex of T. aquaticus PolIIIα. Domains are
labeled as follows: PHP nuclease, yellow; palm, pink; thumb,
light green; index finger, light blue; middle finger, dark blue;
β-binding, orange; and CTD, red. The template and primer
strands are represented as spheres and shown in wheat and white,
respectively. The primer-terminal 3′ base is depicted with
blue spheres, and the incoming nucleotide is depicted with red
spheres. PolIIIα is depicted in a cartoon representation. The
density for the downstream DNA template strand is represented in
mesh. (b) Close-up of the active site of PolIIIα. PolIIIα is
depicted using a surface representation. The DNA substrate is
depicted as sticks and shown as in the left panel. The incoming
nucleotide and primer-terminal 3′ base are shown in red and
blue, respectively. Key active-site residues are labeled as
follows: D463, D465, and D618 are shown in red; K616 is in
yellow; S426 is in green; and R767 is in blue. The active-site
helix is shown in magenta.
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