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An abstract on an article concerning the determination of the topography of the nucleotide excision repair protein complexes with damaged DNA through photoaffinity is presented and mentions topics including protein binding, electrophoretic mobility shift assay, and proteins.

The genomic DNA is damaged under the influence of different environmental factors such as air pollutions, ultraviolet and ionizing radiation, and toxic substances that negatively impact on the humans. Air pollution by the products of incomplete combustion of hydrocarbon fuels and waste of various industries are main sources of polycyclic aromatic hydrocarbons. Some metabolites of these compounds can damage DNA through forming the bulky DNA adducts that potentially leads to mutagenesis and cancer. A nucleotide excision repair is the major pathway for the reparation of such DNA lesions in eukaryotic cells. The excision efficiency of bulky adducts depends on many factors including the structure of a substituent and degree of DNA double helix distortion induced by a lesion. The most danger for cell is clustered DNA lesions. To repair them the cooperation of different DNA repair systems is required in the process of damage recognition and removal. This review is focused on the features of repair mechanisms for DNA with bulky lesions appeared in the result of action of natural carcinogen benzo[a]pyrene as an example.

Nucleotide excision repair (NER) is one of the major DNA repair pathways in eukaryotic cells that counteract the formation of genetic damage. NER removes structurally diverse lesions such as pyrimidine dimers, arising upon UV irradiation, and bulky chemical adducts, arising upon exposure to carcinogens and some chemotherapeutic drugs. NER defects lead to severe diseases, including some forms of cancer. In view of the broad substrate specificity of NER, it is of interest to understand how a certain set of proteins recognizes various DNA lesions in the contest of a large excess of intact DNA. This review focuses on DNA damage recognition, the key and, as yet, most questionable step of NER. Understanding of mechanism of this step of NER may give a key contribution to study of similar processes of DNA damage recognition (base excision repair, mismatch repair) and regulation of assembly of various DNA repair machines. The major models of primary damage recognition and pre-incision complex assembly are considered. The model of a sequential loading of repair proteins on damaged DNA seems most reasonable in the light of the available data. The possible contribution of affinity labeling technique in study of this process is discussed.

Nucleotide excision repair is one of the most important pathways of DNA repair in eukaryotic cells. Defects of this system lead to serious diseases including certain kinds of cancer. Nucleotide excision repair is able to remove a wide range of the structurally diverse DNA damages such as UV induced pyrimidine dimers, bulky chemical adducts arising under the action of carcinogenic compounds or chemotherapeutical drugs on cellular DNA. A broad substrate specificity of this repair pathway is related to the main intriguing question that is the mechanism of damage recognition by the protein complex in the context of the large excess of undamaged DNA. This review is detailed on the key stage of nucleotide excision repair--the recognition of a lesion in DNA, which is still most debated. We have considered the main models of a primary damage recognition and preincision complex formation that have been suggested by the leading groups in this field. Data presented allow to suggest the model of sequential loading of the proteins of reparative complex on damage DNA as the most reasonable.