Abstract 1133 "Effect of antioxidant on post-transcriptional modification of tRNA during UVA oxidation"

Ribonucleic acid (RNA) is a key component of the central dogma of life, and post-transcriptional modifications of RNA are important to the structure and function of RNAs. Recent studies have shown that Ultraviolet-A (UVA) irradiation, in the presence of a photosensitizer, are deleterious to RNA modifications. Formation of the oxidative products, 8-oxoguanosine (8-oxoG) and 5-guanidinohydantoin ribonucleoside (Gh), along with the degradation of modified RNAs were observed. A photosensitizer aggravated this effect by increasing the amount of reactive oxygen species (ROS). Antioxidants are known to scavenge ROS thus lowering the effect of RNA oxidation. We were interested to know if the presence of antioxidants during UVA exposure could prevent oxidative damage to modified RNAs. We conducted an in-vitro study with commercial Escherichia coli (E. coli) transfer RNA (tRNA) and a variety of antioxidants. For this purpose, glutathione (GSH), ascorbic acid (Asc) and the water-soluble derivative of vitamin E (Trolox) were used. Our in-vitro experiments conducted at fixed concentrations of GSH, Asc, and Trolox during UVA exposure showed that the presence of an antioxidant did not ablate the degradation of highly susceptible sulfur containing modified nucleosides of E. coli tRNA. However, antioxidants were found to lower the amount of oxidative damage to E. coli tRNA. Financial support of this work was provided by the National Institutes of Health (NIH GM058843). The presenter would like to thank to University of Cincinnati and members of Limbach lab.