Revision as of 19:32, 26 September 2012 by MarkWeijers (Talk | contribs)



Do you smell bananas?

Yeast, we choose you!

The TU Delft iGEM team is working on yeast, a simple eukaryote. One of our goals is to enable this organism to detect, or smell, the scent associated with tuberculosis or bananas. For this project, we will use the mating pathway of S. cerevisiae and change it a little in order to let it have 'smell-like' behaviour.

Sex response of S. cerevisiae

Yeast genders are called 'a' and 'α', and both genders extract pheromones called 'a'- and 'α'-pheromones. The 'a'-Yeasts are able to detect the 'α'-pheromones, and so the other way around. Upon detection, the yeast cells will show a mating response, called a shmoo.

The image below links to the page explaining more about yeast and why we decided to use it!

I'd appreciate your input!

Once the pheromone-receptors detects pheromones of another gender, the G-alpha subunit comes to action, dissociating from the GPCR complex. This protein starts a signal leading to growth arrest and to a mating response, of which the morphology is called a shmoo. To make the smelling device to detect tuberculosis, our yeast cells need a Methyl nicotinate- (the scent associated with tuberculosis) receptor. Unfortunately a methyl nicotinate receptor isn't characterized as such yet and we chose a very related ligand receptor: niacin. This receptor, due to it's chimeric properties is transported to the same place as the pheromone receptor and will use the same pathway. In the end our goal is to see whether we can change this receptor through directed mutagenesis to let it smell methyl nicotinate.

To view the plasmids we have made and the accompanying experiments you can click the image below.

At least it puts out

When the cell detects a smell, niacin in this case, we do not want the cell growth to stop, so we deleted the far1-gene, which causes growth arrest. Upon detecting this niacin molecule, we would like to see more than a mating response, the shmoo. For this reason, we added a GFP-output which is promoted by the mating response, the FUS1.

Click the image to learn more about our GFP-output!

Our product is a yeast cell which can detect methyl nicotinate, associated with tuberculosis, and shows a GFP-output upon this detection. We have also experimented with the banana smell methyl nicotinate and a couple of other smells with which the Hong Kong team has experimented before us.