ordered conformational changes in damaged dna induced by nucleotide excision repair factors in response to genotoxic attacks cells activate sophisticated dna repair pathways such as nucleotide excision repair ner which consists of damage removal via dual incision and dna resynthesis using permanganate footprinting as well as highly purified factors we show that ner is a dynamic process that takes place in a number of successive steps during which the dna is remodeled around the lesion in response to the various ner factors xpchr23b first recognizes the damaged structure and initiates the opening of the helix from position 3 to 6 tfiih is then recruited and in the presence of atp extends the opening from position 6 to 6 it also displaces xpc downstream from the lesion thereby providing the topological structure for recruiting xpa and rpa which will enlarge the opening once targeted by xpg the damaged dna is further melted from position 19 to 8 xpg and xpfercc1 endonucleases then cut the damaged dna at the limit of the opened structure that was previously labeled by the positioning of xpchr23b and tfiih