Figure 2.

UV-induced DNA lesion formation affected by nucleotide positioning in nucleosome. Within an individual nucleosome, due to the rotation of nucleotides within the DNA double helix, nucleotides are periodically positioned close to (‘inner’) or far from (‘outer’) the histone core every ~10 bp. Compared to the ‘outer’ positions, nucleotides at the ‘inner’ positions have constrained flexibility. Thus, UV induces dimer formation more frequently at ‘outer’ dipyrimidines where DNA bending is more flexible.