Team:Hong Kong UCCKE/Description
Where did our idea come from?
1% of the World’s population suffer from gout,and it's becoming more and more prevalent. In the U.S, it affects 8.3 million of Americans. Our team’s PI’s family have been suffering from the disease for generations. As his students, and an iGEM team, we are inspired to find new detection methods and even cure for gout.
What is Gout?
Gout is a form of arthritis due to elevated levels of uric acid in the blood. At high levels, uric acid crystallizes and is accumulated at synovial fluid. This causes massive pain, and a red, tender, hot, swollen joint. The food we intake everyday contains purine, such as steak, organ meats and seafood.. . And these purines will be catalyzed by several enzymes into uric acid (as the pathway below). However, homo sapiens lacks uricase, as known as urate oxidase, which catalyzes uric acid into allantoin. Normally, uric acid dissolves in your blood and passes through your kidneys into your urine. But sometimes your body either produces too much uric acid or your kidneys excrete too little uric acid. Since uric acid has a low solubility (0.6mg/100ml) thus it crystallizes and deposits in a joint.
What is our plan?
There are three main sub-projects. We wish to detect patients’ gout symptoms, and to cure it by preventing excess uric acid from accumulating in the body. Several parts have been designed to achieve the above goals.
1.Blood uric acid level detector
Firstly, we hope to make a uric acid detector, which is Part BBa_K2197300. It encodes HucR, a repressor, and a GFP gene. Working with KRAB, a repressor enhancer, and hucO, an operative site for the above repressor, the first session of our part acts as a uric acid concentration sensitive promoter. The promoter control the expression of GFP. Engineered e.coli encodes part BBa_K2197300. By adding blood samples to culture medium which engineered e.coli is cultured, e.coli expresses different level of GFP. By measuring the GFP level with plate reader, the uric acid concentration of the sample can be estimated. This part ensures a rapid detection of uric acid concentration.
2.Uric acid decomposition
We hope to make an uric acid decomposer, Part BBa_K2197400. Having the same promoter, this cell produces urate oxidase, an enzyme catalyze the oxidation of uric acid to 5-hydroxyisourate then to allantoin (Uric acid + O2 + H2O → 5-hydroxyisourate + H2O2 5-hydroxyisourate + H2O → allantoin + CO2) . But the human gene for urate oxidase is nonfunctional. In the future, we hope to make a capsule enclosing this engineered cell so that it can taken in by patients and produces urate oxidase when it sense uric acid.
3. Uric acid transporter
We make a uric acid transporter,YgfU, which is an imitation of Glut9. Glut9, as known as olute-carrier 2A9, plays a major role in urate homeostasis by its dual role in urate handling in the kidney and uptake in the liver. For YgfU, it is an E.coli-originated uric acid transporter. Having the same promoter as the two projects above, in the presence of uric acid, YgfU is expressed, thus, the cell can absorb uric acid.
