Direct Detection and Visualization of UV-Induced DNA Damage

As a result of various ozone-depleting substances progressively damaging our planet’s atmosphere, UV exposure from sunlight is at an all-time high, resulting in an increased incidence of skin cancer in many populated areas. This is a pressing concern for areas with high UV exposure, including Peru, Argentina, New Zealand, and Australia with the latter two countries having the highest skin cancer rates in the world. As such, there is a dire need for an easily accessible method for civilians to determine the amount of UV exposure in their area.

Standard UV detection methods currently available such as HPLC and digital UV meters do not meet the need because they involve detection instruments that are nonportable and/or expensive, making them not only impractical for everyday use by civilians but also unavailable to those in resource-limited settings. Here, we leveraged synthetic biology tools to try and create a whole-cell biosensor that can detect UV light rapidly and at a low-cost.

To achieve this goal, we took advantage of the SOS system in E.coli competent cells. The SOS system responds to UV-induced DNA lesions by halting the cell cycle and activating the nucleotide excision repair (NER) mechanism. The NER mechanism in Escherichia coli begins with the protein UvrA, whose expression increases by 10-fold from around 25 molecules to 250 molecules upon SOS induction. We sought to measure this increase via a plasmid with GFP downstream of the UvrA promoter. This be easily visualized with a low-cost, 3D printable hand-held illuminator, similar to the ones that have been recently developed by the Lucks lab. By quantifying the level of fluorescence, we will be able to measure the UV exposure to the cell. This biological system will be integrated into a portable biosensor that can be used outside of the laboratory setting.