Experimental validation of determinants of UV sensitivity using synthetic DNA

Abstract

Treatment with ultraviolet (UV) light has been shown to be effective for disinfection of pathogens. For pathogenic risk management, it would be effective to estimate the UV sensitivity of unknown pathogenic microorganisms from their nucleotide sequences. In this study, we designed and used synthetic DNA molecules, 100–150 bases in length, to investigate not only the DNA sequences but also the secondary structures of the DNA as determinants of UV sensitivity of microorganisms. We showed that dimer-forming DNA by UV irradiation was undetectable by quantitative polymerase chain reaction (qPCR) when performed on all DNA bases. The undetectability ratio of PCR after UV irradiation indicated that UV reactivity tends to increase with the number of consecutive thymine pairs within DNA. In addition, UV reactivity was not influenced by increasing the number of complementary bonds in the DNA and the estimated free energy, indicating that complementary bonds in the DNA have no influence on the UV reactivity. The results of this study provide important information about the necessary factors determining UV sensitivity of microorganisms such as the number of consecutive thymine pairs within the DNA, which was the main driver regardless of the presence of secondary structures.