University of California San Francisco 2006

From 2006.igem.org

Revision as of 21:15, 30 October 2006

Guess what I put in your LB buffer!

The University of California at San Francisco 2006 iGEM Team

The international Genetically Engineered Machine Competition is an opportunity for emerging young scientists of all disciplines to tinker with the proverbial Rube Goldberg machine of life. This is the UCSF team's third year in the program, and to celebrate our three years, we had a members-only contest to develop a team logo. More information on the logo is forthcoming.

It's this easy

Team Members

• Ala Trusina
• Patrick Visperas
• Kevin Shay
• Matt Eames

Faculty Advisors

• [http://www.voigtlab.ucsf.edu/ Chris Voigt]
• [http://kortemmelab.ucsf.edu/ Tanja Kortemme]

Aspirations, Dreams...

CheW, a most powerful protein

What if we could control chemotaxis? Could we put bacteria on plate and steer them through a maze? Would it be like operating a remote-controlled car?

These were the questions that inspired team UCSF to tinker with bacterial chemotaxis. Naturally, bacteria don't have the same electric components that your remote-controlled buggy does, but there are parts we can harness to control motility. Escherichia coli, for example, already possess five different chemoreceptors which respond to different attractants and repellants. If we were to place the bugs in between two separate chemicals, we might be able to control the direction of swimming by manipulating which receptor's signal we interpret.

The UCSF iGEM team has endeavored to control chemotaxis by selectively expressing CheW mutants which will participate in an orthogonal interaction with the methyl-accepting chemotaxis protein Tar. The project will be broken down into three major components:

• Design and construction of the orthogonal interaction: An existing orthogonal interaction, to be used as a starting point prior to computational redesign, was discovered by [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=1860813&query_hl=2&itool=pubmed_docsum Liu and Parkinson] in 1991.
• Implementation of the genetic switch: This will allow us to toggle between the selective expression of either CheW.
• Validation of chemotactic properties through specially developed assay: originally developed by the good folks at the [http://www.physics.upenn.edu/facultyinfo/goulian.html Goulian Lab] in 2006.

Receptor Specificity

Much work is available in the literature regarding the changing of chemoreceptor specificity. Some of the options include:

• Directed evolution
• Computational redesign
• Chimeric construction (perisplasmic and cytoplasmic domains of the different receptors can be swapped)

We will be using a mutant version of the E. coli Tar (asparate-sensitive) receptor that has been evolved to respond to phenylalanine, a natural chemorepellant. The responsiveness of this mutant has been characterized and was found to have comparable chemotactic capabilities to that of wild-type Tar.

Chassis

To eliminate interference from other naturally occuring receptors in E. coli, a strain with all receptors (Tar, Tsr, Tap, Trg, Aer) knocked out, provided by the Parkinson Lab, will be used in this work. The UCSF iGEM deleted CheW from this strain so that all CheW might be expression off the plasmid.

The plasmid will posses both constituitively active Tar varients, and will incorporate selective CheW control by means of a genetic switch.

Thanks

• [http://www.chemeng.uiuc.edu/Faculty/rao.html Chris Rao]
• [http://www.biology.utah.edu/faculty2.php?inum=6 Parkinson Lab]
• [http://www.physics.upenn.edu/facultyinfo/goulian.html Goulian Lab]

Links

• [http://www.ucsf.edu UCSF]