Structural basis for DNA recognition and processing by UvrB.

DNA-damage recognition in the nucleotide excision repair (NER) cascade is a complex process, operating on a wide variety of damages. UvrB is the central component in prokaryotic NER, directly involved in DNA-damage recognition and guiding the DNA through repair synthesis. We report the first structure of a UvrB-double-stranded DNA complex, providing insights into the mechanism by which UvrB binds DNA, leading to formation of the preincision complex. One DNA strand, containing a 3' overhang, threads behind a p-hairpin motif of UvrB, indicating that this motif inserts between the strands of the double helix, thereby locking down either the damaged or undamaged strand. The nucleotide directly behind the p-hairpin is flipped out and inserted into a small, highly conserved pocket in UvrB.