Fig. 1.

DNA substrates used in repair and DNA-binding assays. (A) Multicloning region of 2.4-kbp pIBI24. The underlined uracil-containing 20 mer was 5′ radiolabeled and used in second-strand synthesis to generate a double-strand plasmid for DNA–protein crosslinking. Relevant restriction sites are BamHI (B) and XhoI (X). (B) The central region of a damaged strand of the 140-bp duplex used for preparation of DNA–protein and –peptide crosslinks. The underlined uracil-containing 12 mer was 5′ radiolabeled. Relevant restriction sites are PvuII (P), HindIII (H), and SalI (S). (C) Central region of damaged strand of the 136-bp duplex used as a control substrate. The underlined 8 mer containing T[6-4]T photoproduct was 5′ radiolabeled. Relevant restriction sites are as in B. In B and C, numbers above 5′ and 3′ bars indicate distances to 5′ and 3′ termini, respectively. The uracil was removed by uracil DNA glycosylase to generate an AP site, indicated by an “O.”