Deamination of cytosine and 5-methylcytosine in DNA by radical mediated oxidation

Deamination of cytosine (C) and 5-methylcytosine (5mC) lead to GC to AT point mutations, which represent the major fraction of spontaneous mutations in a variety of genomes. We propose that most GC to AT mutations arise from the initial oxidation of C and 5C by reactive oxygen species followed by deamination of the intrinsic exocyclic amino group. In this project, we will examine the effect of DNA sequence on the formation and subsequent rate-dependent deamination of several C and 5mC oxidation products in synthetic oligonucleotides using a combination of isotopic labeling and ultra-performance liquid chromatography coupled to tandem mass spectrometry. In addition, the ability of base excision repair enzymes to repair C and 5mC damage before and after deamination will be assessed in vitro with purified enzymes and the above oligonucleotides. From these studies, we will be able to correlate specific damage with mutations in human disease and disorders related to aging.

Faculty Supervisor:

Richard Wagner

Student:

Partner:

CEA Grenoble

Discipline:

Life Sciences

Sector:

Pharmaceuticals; Life Sciences (not health); Health and Related Sciences & Technology

University:

Université de Sherbrooke

Program: