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Figure 3.
Figure 3. Mechanism of 6-4 Photodimer Recognition
(A)
Close-up of the DDB2 hairpin insertion (green) at the lesion
with the damaged and undamaged strands depicted in yellow and
brown, respectively.
(B) Interaction of DDB2 with the
DNA^6-4PP backbone. The backbone of both strands is contacted by
an array of positively charged residues crucial for the
stabilization of the phosphate backbone compression at the
damaged site (D[+1], D[+2]). Parts of the DNA are omitted for
clarity.
(C) Close-up of the photodimer binding pocket
stabilizing the flipped-out dinucleotide. Contacting residues
are shown as stick models in yellow. The pyrimidine ring D[+1]
and the pyrimidone ring D[+2] are shown in black and gray,
respectively. Parts of the DNA have been omitted for clarity.
(D) Chemical structure of the 6-4 pyrimidine-pyrimidone
dimer.
(E) Schematic representation of interactions between
DDB2 and DNA^6-4PP (with colors as in A and B).
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