Mechanisms of DNA damage recognition in mammalian nucleotide excision repair.

The ability of nucleotide excision repair (NER) to process multiple forms of DNA damage is highly dependent on the precision by which DNA modifications are located in the genome. Studies of mammalian NER have shown that this system eliminates a wide range of chemically and structurally distinct DNA lesions whereby some types of damage are repaired at higher rates than others. Although the biochemical basis for this broad but heterogeneous response to DNA damage is poorly understood, recent discoveries in closely related areas of DNA metabolism indicate that selectivity for specific sites is achieved through the assembly of nucleoprotein complexes, in which DNA is frequently bent and unwound. In many cases, selectivity may be further enhanced by the action of specialized DNA helicases. These principles in protein-DNA recognition suggest a hypothetical mechanism of damage recognition that accounts for the wide substrate range of mammalian NER and also accommodates its preference for specific DNA lesions.