The Effect of Reactive Oxygen Species (ROS) on H-DNA-Induced Mutation Frequencies in Yeast

The integrity of DNA is threatened by stressors that can damage DNA, resulting in DNA mutations which can lead to genetic instability and diseases such as cancers. H-DNA, a three-stranded DNA structure that deviates from the standard two-stranded B-DNA helix, is mutagenic in human cells and contributes to genetic instability. H-DNA forms in certain DNA sequences with mirror symmetry and leads to mutations through double-strand breaks and translocations. In addition, reactive oxygen species (ROS) can also damage DNA leading to mutations and contributing to genetic instability. The structure of H-DNA may be more susceptible to ROS-induced damage because the single-stranded DNA structure is unprotected and exposed to solution. The purpose of this study is to determine the mutation frequencies of B-DNA and H-DNA in the presence and absence of ROS. Since H-DNA may serve as a hotspot for DNA damage, it is hypothesized that H-DNA will have a greater mutation frequency compared to the control B-DNA. An oxidative mutagenesis assay was implemented in order to mimic oxidative damage caused by ROS. Yeast Artificial Chromosome (YAC) strains that were B-DNA-forming and H-DNA-forming were used to compare mutation frequencies. Under standard conditions, H-DNA was about 13 times more mutagenic than B-DNA, which is consistent with previous literature. We are currently working on replicating our data in order to get statistically significant results in relation to the mutation frequencies under oxidative conditions.