Team:Johns Hopkins

Genetically engineered Saccharomyces cerevisiae that is responsive to voltage signals at a transcriptional level.

We have hijacked the calcium shock, calcineurin-CRZ1, pathway in yeast and encoded a reporter. In doing so we have characterized the voltage dependency of the CRZ1 binding site (CDRE) and so taken the first step in creating a interface between cellular systems and computers by allowing cells to respond to the language of computers, voltage signals.

Possible applications:

• We see large scale applications in synthetic biology, for the integration of computer controlled voltage signals into gene expression control. We want to create a system where genes can be turned on and off with voltage signals that be delivered at precise intervals by computers, without having to deal with a hundred different potentially costly chemical reagents. In effect making biology more engineerable.
• We are looking into creating a URA3 gene (required for uracil synthesis) downstream of our CDRE equipped promoter region, to create yeast cells whose growth is dependent on this gene being transcribed. Thus we plan to have a system where you could text a computer which was hooked up to your eletro stimulation device and you could take cells in and out of the growth cycle, just by simple preprogrammed voltage signals put out by the computer.

• We envisage a voltage activated transcriptional response to be very usefull in cardiovascular and neuronal research, by it is possible to weed out cells that display only specific action potentials. We hypothesize this could be done by causing a selectable transcriptional response to the calcium influx of the action potential.

Team: We are a team of 9 undergraduate students deeply interested in synthetic biology. We hail from a variety of disciplines including, chemistry, biology and engineering. We’re a fresh new team with varying levels of experience united by our passion for science.

Our Accomplishments

• We have extended previous work on voltage sensitivity (Valencia 2009) in S. cerevisiae, bringing the response from the biochemical domain into the transcriptional.
• We constructed a library of 7 voltage-activated yeast upstream activation sequences with varying sensitivity.
• We have characterized two full voltage-activated promoters for yeast.
• We have developed a model to describe the transcriptional response to voltage of our system.
• We have successfully leveraged post-translational modification machinery, namely phosphorylation of Crz1 by calcineurin, to initiate a transcriptional response.
• We fabricated a highly accurate microfluidic electro-stimulation setup using gold electrodes on a silicone wafer and are currently in the process of refining the fabrication technique.