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|Author(s):||T. K. Hazra; T. Izumi; R Venkataraman; Y W. Kow; M. Dizdaroglu; Somenath Mitra;|
|Title:||Characterization of a Novel 8-Oxoguanine-DNA Glycosylase Activity in Escherichia Coli and Identification of the Enzyme as Endonuclease VIII|
|Published:||September 01, 2000|
|Abstract:||8-oxoguanine (G*), induced by reactive oxygen species, is mutagenic because it mispairs with A. The major G*-DNA glycosylase (OGG), namely, OGG1 in eukaryotes, or MutM in Escherichia coli, excises G* when paired in DNA with C, G and T, but not A, presumably because removal of G* from a G* A pair would be mutagenic. However, repair of G* will prevent mutation when it is incorporated in the nascent strand opposite A. This could be carried out by a second OGG, OGG2, identified in yeast and human cells. We have now characterized a new OGG activity E. coli and then identified it to be endonuclease VIII (Nei) discovered as a damaged pyrimidine-specific DNA glycosylase. Nei shares sequence homology and reaction mechanism with MutM, and is similar to human OGG2 in being able to excise G* when paired with A (or G). Kinetic analysis of wild type Nei showed that it has significant activity for excising G* relative to Dihydrouracil. The presence of OGG2 type enzyme in both E. coli and Eukaryotes, which is at least as efficient in excision G* from a G* A(or G) pair as from a G* C pair, supports the possibility of G* repair in the nascent DNA strand.|
|Citation:||Journal of Biological Chemistry|
|Pages:||pp. 27762 - 27767|
|Keywords:||DNA glycosylases,DNA repair,excision kinetics,mismatch repair,ogg2 protein,oxidative DNA damage|
|Research Areas:||DNA, Bioscience & Health, Chemistry|