Nucleotide Excision Repair

Synonyms

NER

Definition

Is a complex biochemical mechanism that recognizes alterations in the chemical structure of DNA due to base modification by physical agents (most notably ultraviolet radiation) or endogenous or exogenous chemicals. After recognition of the alteration in the structure of DNA, the damage is removed by excision of the oligonucleotide that contains the damage. The resulting gap is filled in by DNA polymerase using the complementary (undamaged) strand as template and finally ligated. The process is essentially error-free. There are at least 27 polypeptides required to complete the recognition, excision, and gap-filling phases.

Characteristics

NER was initially characterized in E. coliin the 1960s and was identified by the ability of wild-type bacteria to remove ultraviolet light (UV)-induced photoproducts from large molecular weight DNA. The kinetics of this process correlated well with the resumption of DNA replication and led to the idea that removal of such...