Download MendeleyEnzymatic capture of an extrahelical thymine in the search for uracil in DNA.
Parker, J.B., Bianchet, M.A., Krosky, D.J., Friedman, J.I., Amzel, L.M., Stivers, J.T.(2007) Nature 449: 433-437
- PubMed: 17704764
- DOI: https://doi.org/10.1038/nature06131
- Primary Citation of Related Structures:
2OXM, 2OYT - PubMed Abstract:
The enzyme uracil DNA glycosylase (UNG) excises unwanted uracil bases in the genome using an extrahelical base recognition mechanism. Efficient removal of uracil is essential for prevention of C-to-T transition mutations arising from cytosine deamination, cytotoxic U*A pairs arising from incorporation of dUTP in DNA, and for increasing immunoglobulin gene diversity during the acquired immune response. A central event in all of these UNG-mediated processes is the singling out of rare U*A or U*G base pairs in a background of approximately 10(9) T*A or C*G base pairs in the human genome. Here we establish for the human and Escherichia coli enzymes that discrimination of thymine and uracil is initiated by thermally induced opening of T*A and U*A base pairs and not by active participation of the enzyme. Thus, base-pair dynamics has a critical role in the genome-wide search for uracil, and may be involved in initial damage recognition by other DNA repair glycosylases.
Organizational Affiliation:
Department of Pharmacology and Molecular Sciences, Johns Hopkins Medical School, 725 North Wolfe Street, Baltimore, Maryland 21205, USA.
