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Figure 2.
Figure 2: Comparison between hPol iota- and
Dpo4. a, Close-up views of the active sites of hPol  and
Dpo4. The fingers and palm domains and the PAD are shown in
yellow, blue and green, respectively. The DNA is shown in grey,
and the templating nucleotide and the incoming nucleotide (dTTP
in hPol and
ddADP in Dpo4) in red. The metal ion is dark blue. Highlighted
and labelled are the catalytic residues (Asp 34, Asp 126 and Glu
127 in hPol and
Asp 7, Asp 105 and Glu 106 in Dpo4), the dNTP-bonding residues
(Tyr 39, Tyr 68, Arg 71 and Lys 214 in hPol and
Tyr 12, Tyr 48, Arg 51 and Lys 159 in Dpo4), and the residues
close to the templating base (Gln 59, Lys 60, Leu 62 and Val 64
in hPol and
Val 32, Ala 42 and Ala 44 in Dpo4). Note that the templating
base is in syn conformation in the hPol active
site and in trans conformation in the Dpo4 active site. b,
Close-up views of Hoogsteen base-pairing (dA  dTTP)
in the active site of hPol and
Watson -Crick base-pairing (dT ddADP)
in the active site of Dpo4. c, Close-up views of the nascent
base pair fitting against the hPol and
Dpo4 molecular surfaces. The residues apposed to the templating
base are shown in grey and labelled on the molecular surface.
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