Team:WashU StLouis
What is Happening?
For the last century as a consequence of industrialization, greenhouse gas emissions have depleted the ozone layer, especially at the Earth's poles. One function of the ozone layer is to absorb UV radiation emitted by the sun, protecting life on Earth from its harmful effects on organisms' DNA. When exposed to UV, DNA tends to form pyrimidine dimers which interfere with DNA replication and translation and can lead to mutations and cell death. While many focus their attention on the effects of UV radiation on humans, photosynthetic organisms must also be considered because they are responsible for the world's oxygen and form the basis for nearly all food chains. Though many photosynthetic organisms already have UV repair mechanisms, it is becoming increasingly necessary to fortify and supplement these mechanisms because of the drastic increase of UV exposure within the last century.
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.
Contact us at washu.igem@gmail.com
