FIGURE 1.

DNA substrates. A, schematic representation of DNA substrates: ICL1, ICL2, ICL3, and ICL4 containing an interstrand cross-link and a non-damaged substrate (ND). Arrows indicate the direction of DNA synthesis. The site of the N²-N²-guanine cross-link is underlined. dd, dideoxynucleotide; gl, glycerol. B, structure of N²-N²-guanine cross-link. C, primer sequences used in the in vitro reactions. D, schematic representation of an N²-N²-guanine cross-link-containing 36-mer oligodeoxynucleotide that was used for generating the pMS2-ICL vector.