Team:RHIT/Description
Project Description
Secondary metabolites produced by microbes are often used in manufacturing processes. Due to the fact that these metabolites are produced during anaerobic respiration, being able to control, or “switch off” aerobic respiration could make industrial microbe use more efficient. S. cerevisiae, or baker’s yeast, is a common eukaryote used in manufacturing products including food and alcoholic beverages. This microbe is unique in that it can survive without its mitochondria by using anaerobic respiration. In order to “turn off” the mitochondria, mitochondrial ribosomal genes can be manipulated, causing mitochondrial ribosomal function to cease, therefore halting aerobic respiration.
We created a system that allowed for control of the mitochondrial ribosomal protein S12 (mRPS12), using a copper repressible promoter (CTR1). In high concentrations of copper ions, this gene will be repressed and aerobic respiration will be turned off. However, copper chelator bathocuproine disulfonate (BCS), which has higher affinity for copper ions, can then be added to the system, therefore derepressing the gene and turning the mitochondria back on.
This concept has many applications in industry. Yeast growth follows an S-curve, with secondary metabolite generation occurring at the end of the exponential phase into the stationary phase. By regulating aerobic respiration, these yeast can begin generating secondary metabolites sooner and therefore can produce more over their lifespan. Also, due to the fact that the mitochondria would not be functioning, it is not necessary to grow these yeast in an oxygen-free environment.
We show that using a control system can allow for a mitochondrial “switch” that can force yeast into anaerobic respiration while in the presence of oxygen.
Previous Project Improvements
We improved the documentation of the GPD promoter previously inserted into the iGEM database. This GPD promoter had a number of different sequences with no way to differentiate between them. They had been referred to in a number of projects since creation and used interchangeably, even though they were not. Our work consisted of sorting the different GPD promoters and sequences and organizing them in a more useful manner.