Team:WashU StLouis/Description

As greenhouse gas emissions continue to deplete the ozone layer, addressing and minimizing the negative impact of UV radiation on Earth’s inhabitants is becoming increasingly important. Photosynthetic organisms already have evolved a certain tolerance to UV radiation due to the necessity of living their entire lives in the sunlight, but increasing UV radiation as a result of the degradation of the ozone layer is putting a strain on the repair mechanisms of many of these organisms. Since autotrophs form the basis for almost all food chains and produce oxygen for all other organisms on the planet, it is prudent to engineer systems that fortify existing UV repair mechanisms. Fortunately, organisms already exist that exhibit extraordinary UV tolerance; we hypothesize that these mechanisms can be transferred to photosynthetic organisms.

Our project has several components. The first of these is simply to compare the effectiveness of several genes on the level of UV radiation tolerance in E. coli. The first gene is uvsE, an endonuclease triggered by UV damage, which originates from Deinococcus radiodurans, an extremophile that is known to be one of the most radiation-resistant organisms in existence. This gene has already been characterized by another iGEM team and is easily accessible in a plasmid. Two of the genes are derived from Ramazzottius varieornatus, a species of tardigrade, which are organisms known for their extraordinary resistance to extreme conditions. One of these genes is Dsup, a DNA-binding protein which was recently discovered and has been shown to protect against ionizing radiation; however, no studies have yet been published on its effectiveness in protecting against UV radiation. The other tardigrade gene that will be tested is phrA, a photolyase. The tardigrade photolyase is a homologue of our final gene, the photolyase that exists in the cyanobacteria genus Synechococcus. In addition, we will be experimenting with a UV-induced promoter and plasmids with different copy numbers to see if these constructs are more efficient. After transforming these genes into E. coli, we will be transforming cyanobacteria with our gene constructs with the hope of seeing the intended effect in cyanobacteria. In order to test the efficacy of these genes, we will expose the transformed E. coli and cyanobacteria to UV light through a homemade UV exposure box.

Our main application for increased efficacy of UV repair mechanisms is the protection of crops. In the course of reading relevant literature, we have found a pattern of significant negative effects on several key aspects of plant growth due to the increase in UV radiation from the degradation of the ozone layer, and that this effect is present in many staple crops, such as wheat and corn. Any loss in the productivity of such important plants can have huge repercussions on the global food market, especially in less industrial countries that are faced with burgeoning overpopulation. Our genetic constructs could theoretically mitigate UV damage and create plants that are more suitable to a world with a changing climate.