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Updated: Aug 3, 2026

Application of Stopped-flow Kinetics Methods to Investigate the Mechanism of Action of a DNA Repair Protein
Published on: April 1, 2010
Binding specificities of the mismatch binding protein, MutS, to oligonucleotides containing modified bases
K Negishi1, D Maehara, S Nakamura
1Gene Research Center, Okayama University.
Abstract:
We have studied the effects of DNA mismatch repair on mutagenesis induced by nucleoside analogs. Among them, the mutagenic action of 3,4-dihydro-6H,8H-pyrimido[4,5-c][1,2]oxazin-7-one 2'-deoxyriboside (dP) showed high susceptibility to the mismatch repair system, while mutagenesis by N4-aminocytidine and N4-hydroxycytidine was only weakly affected. 2-Aminopurine mutagenesis showed intermediate susceptibility. MutS protein specifically bound to an oligonucleotide duplex containing a dP-dG pair, while the dP-dA pair was bound only weakly. The binding to the dP-dG pair was as strong as binding to a dA-dC mismatch. These specific binding properties can explain the effective avoidance of dP-induced mutagenesis by the mismatch repair system. We have also studied the effects of the repair system on mutagenesis induced by methylating and ethylating agents.
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