STRUCTURAL STUDIES OF NUCLEOTIDE EXCISION REPAIR ENZYMES

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Damage to DNA by endogenous and exogenous agents are the major cause of genetic mutations that give rise to different forms of cancer if the damage remains uncorrected. Nucleotide Excision Repair (NER) is one of the major DNA repair pathways functioning in both eukaryotes and prokaryotes. The NER system recognizes and repairs a broad spectrum of DNA lesions, such as cis-syn thymine dimers caused by UV light, bulky benzo[a]pyrene diol epoxide(BPDE) guanine adducts, and cis-Pt adducts. The NER system in bacteria consists of three major proteins, UvrA, UvrB, and UvrC, all of which are essential for successful damage correction. UvrA, which has strong affinity to damaged sites in DNA, has a key role in the recognition process. It also has a domain that interacts with UvrB. UvrA recognizes the site of damage, facilitates the interaction between UvrB and DNA, and then leaves the damaged site. UvrB forms a stable complex with DNA, followed by the recruitment of catalytic UvrC, which cleaves the 4th phosphodiester bond at 3' end of the lesion, and then the 8th phosphodiester bond at 5' end of the lesion. Interestingly, without UvrA, UvrB or UvrC do not have any affinity to damaged DNA. Although this repair pathway has been known for decades, only UvrB and domain structures of UvrC are available to date. In this project, our goal is to obtain crystal structures of nucleotide excision repair enzymes.