Virginia United iGEM 2010

Quorum Sensing Amplifiers and a Co-design Approach for Information Processing

Synthetic biology endeavors to create information processing systems modeled on digital electronics. The use of quorum sensing can help transform an inherently analog molecular signal into a binary response and simultaneously allow the tuning of input response thresholds and signal amplification. This project demonstrates these capabilities through experimentation and modeling. Another candidate for reapplying an electronic engineering technique is the codesign of hardware and software to implement a function. In synthetic biology, codesign might mean implementing a design spec in different expression control regimes and comparing their relative merits. Our work examines the codesign concept by constructing an AND gate in three different design domains. We explore the application of these ideas with an environmental sensor. A unique aspect of our project is the collaborative nature involving five institutions at three locations, which fostered a codesign-like approach using two distinct assembly techniques.

Quorom Sensing

Normally, quorum sensing is a mechanism employed by cells in which signaling proteins are released and passed on to other cells in order to communicate certain information or to encourage other cells in the vicinity to act out certain functions. In our experiment, we wanted to utilize quorum sensing so that when theE. colicells sensed that there was a input in the environment, it would not only produce some type of fluorescent response, but also initiate the quorum sensing mechanism so that the signal would be amplified and passed on to other cells that would then react and fluoresce as well. In that manner, instead of receiving a gradual response to the stimuli, we would actually receive a quicker, more binary response that would be easier to detect and measure. Thus in our experiment, we wanted to employ quorum sensing as an amplification mechanism that would provide us with binary output, making the system easier to manipulate into a quantitative response system.

Co-Design

Fluorescent Complementation

Magliery et. al (2004) developed a method for detecting protein binding partners by fusing non-fluorescent fragments of GFP to the two peptides of interest. If the attached peptides sufficiently attract one another, the GFP fragments will be irreversibly reassemble to form a fluorescing GFP protein. We build on their work by demonstrating how GFP fragment reassembly ("fluorescent complementation") can be used to create AND logic.

Hybrid Promoters

The advancement of synthetic biology has opened the doors to almost limitless transcriptional control, given the particular biological species cooperates. The aim of the hybrid promoter circuit is to give one fluorescent output based on any two inputs. To do this, logic AND gates are designed using promoters and protein operator sites.

See Virginia United 2010's project wiki for more details.

Team Members

Virginia United is a regional team between Virginia Tech, University of Virginia, Virginia Commonwealth University, Bluefield State College, and Virginia State University. The team members spent their summer spread between labs at Virginia Tech, University of Virginia, and Virginia Commonwealth University working towards a common project.

Rohini Manaktala, Yong Wu, Megan Barron, Arjun Athreya, Austin Chamberlin, Sara Brickman, Adam Bower, Brett Tolliver, Daniel Chique, Dasha Nesterova, Jane Carter, Joe Edwards, Karis Childs, Priscilla Agyemang, Maria McClintock


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Banner photo courtesy of wfxue at Kent iGEM