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Abstract

Antibiotic resistance has become a costly issue in the modern health world. To combat this, many new avenues for therapeutics have been explored. One such avenue is anti-virulence therapies that prevent infections rather than generally inhibit growth of bacteria. However, in order to accomplish this, a better understanding of how bacteria defend against the body’s defenses is needed. To find possible anti-virulence therapeutics against Escherichia coli, the nitric oxide detoxification system was studied by examining the effect that nitric oxide has on translational errors. E. coli has evolved to develop nitric oxide stress mechanisms that allow it to cope with these toxic environments. One such mechanism is the use of nitric oxide dioxygenases to convert potentially harmful nitric oxide into a safer nitrate ion. By using a dual-fluorescence error diagnosis plasmid in Δhmp E. coli, the stop codon readthrough rate was quantified and examined. This analysis revealed that the TAG readthrough rate decreased under nitric oxide stress, while the TGA readthrough rate remained largely unaffected. Furthermore, TAG had significantly more readthrough than TGA with or without nitric oxide stress. This is perhaps a surprising result as previous studies showed TGA readthrough was higher than TAG readthrough in wild type E. coli grown in Luria Bertani broth for 24 hours without nitric oxide stress. The difference in readthrough rate could be due to the growth in different media and the response to nitric oxide stress that had not been previously studied. These findings contribute to a better understanding of bacterial nitric oxide defenses and lay the foundation for future work.