Role of lysine-57 in the catalytic activities of Escherichia coli formamidopyrimidine-DNA glycosylase (Fpg protein).

摘要

The Escherichia coli Fpg protein is involved in the repair of oxidized residues. We examined, by targeted mutagenesis, the effect of the conserved lysine residue at position 57 upon the various catalytic activities of the Fpg protein. Mutant Fpg protein with Lys-57-->Gly (K57G) had dramatically reduced DNA glycosylase activity for the excision of 7,8-dihydro-8-oxo-guanine (8-oxoG). While wild type Fpg protein cleaved 8-oxoG/C DNA with a specificity constant ( k cat/ K M) of 0.11/(nM