Comparison of K- and N- Mutagenic Hot Spots for UVC Damage.

It has been well established that mutations in K- and N- proto-oncogenes can convert them into active oncogenes. Current molecular cancer research has been focused on determining the key steps by which cellular genes become oncogenes and not on the underlying and fundamental chemical damage mechanism and susceptibility to damage. In this study, we investigate the damage hot spots present in the N- and K- genes upon exposure to UVC radiation. Detection of damage is accomplished by a simple, sensitive, mix-and-read assay using an EvaGreen probe in a 96-well microtiter plate. Our results show that, although there is high degree of sequential similarities among K- and N- genes, they show different degrees of UV damage in different portions of their genomes. Our experiments demonstrate that overall, the K- genome is more prone to UVC damage than the N- genome. We observe that the extent of damage increases with increasing number of TTs in a sequence, consistent with previous results that show that thymine cyclobutyl photodimers are the primary DNA damage photoproducts upon UVC irradiation. This understanding of the effect of UVC radiation on various codons of K- and N- genes will help to increase our understanding about hot spots of DNA damage and the chemical damage mechanism.