The following project descriptions are of systems that we will attempt to construct this summer. Additional project ideas may be added in the near future.
This project is an extension of work that was done at Biosource Genetics Corporation in 1990. What we would like to do is program bacteria to produce melanin in response to a red light stimulus. This inducible melanin production has various applications including making melanin for monitoring cellular processes. In this way, melanin would serve as a biomarker or indicator similar to the GFP but would be easily visible to the naked eye.
- Melanin production in Escherichia coli from a cloned tyrosinase gene by Della-Cioppa G, Garger SJ, Sverlow GG, Turpen TH, Grill LK.
- Synthetic biology: engineering Escherichia coli to see light by Levskaya A, Chevalier AA, Tabor JJ, Simpson ZB, Lavery LA, Levy M, Davidson EA, Scouras A, Ellington AD, Marcotte EM, Voigt CA.
During one of our brainstorming sessions we were discussing possible biosensors and came up with a fairly practical project idea: an ethylene biosensor. Why sense ethylene? Mature fruit produce and release ethylene as they ripen. Measuring the concentration of gaseous ethylene on or near the surface of the ripening fruit would allow for the indirect measurement of its degree of ripeness.
- The ethylene gas signal transduction pathway: a molecular perspective by Johnson PR, Ecker JR.
- Molecular biology of fruit maturation and ripening by Giovannoni J.
- Association of the Arabidopsis CTR1 Raf-like kinase with the ETR1 and ERS ethylene receptors by Karen L. Clark
- The ethylene-receptor family from Arabidopsis structure and function by Anthony B. Bleecker
- A strong constitutive ethylene-response phenotype conferred on Arabidopsis plants containing null mutations in the ethylene receptors ETR1 and ERS1 by Xiang Qu
- The Arabidopsis Book by G. Eric Schaller
Synthetic Biological Clock
The synthetic biological clock was one of our earliest project ideas and involves the coupling of Elowitz and Leibler's repressilator system to some actuator such as fluorescence or aroma generation. We would like to link MIT's 2006 iGEM project to the repressilator and create an aroma therapy clock in addition to linking green, yellow and red fluorescent proteins to the repressilator to make a molecular traffic light. Future applications of controlled synthetic oscillatory systems include internal, autonomous drug delivery technology.
- A synthetic oscillatory network of transcriptional regulators by Elowitz MB, Leibler S.
- MIT's 2006 iGEM Project
This system incorporates the idea of the repressilator on a larger scale, using three distinct cell types that are chemically isolated from each other (i.e., not sharing medium) and are each equipped with genes that enable bioluminescence and photosensing. Cell type 1 is bioluminescent at a particular wavelength (e.g., blue). Cell type 2 produces yellow bioluminescence unless it perceives blue light. Cell type 3 produces bioluminescence at yet another wavelength (e.g., green) unless it senses yellow light. Green light represses cell type 1 blue bioluminescence. Thus, engineered cell-cell communication with light is possible, creating a "wireless" repressilator system.
Natural phototaxis systems can be exploited to direct engineered bacteria to target areas within the body. These living machines are programmed so that once they have arrived, they produce and secrete their payload (e.g., VEGF).
Coming up with alternative fuels is a real-world problem. We're interested in using cheap, renewable feedstock to power efficient biofuel production. More to come!