February 2010:
The systems and IGEM entries chosen for further work are below:
Team: University of Groningen
Objective: Implementing Cellular Automata as a regular spatial arrangement of bacteria.
Summary: Using and modifying existing quorum sensing mechanisms and motifs in E. Coli, a synthetic system was created in which E. coli can be made to produce a fluorescent reporter in response to specified concentrations of a bio-signalling molecule homoserine lactone (HSL) in a coordinated and self regulating fashion. The number of nearby E. coli bacteria and their production of this signalling molecule can thusly be used to produced complex patterns and designs with only a single user/researcher input.
Team:ULB-Brussels
Objective: To produce a natural, biodegradable, wet-environment capable glue using a bacterial polysaccharide.
Summary: Using choice genes from the bacteria Caulobacter crescentus, the team attempted to use the chemotaxic response of E.coli to aspartate to stimulate the aggregation of bacteria at a specific repair site followed by the proliferation of bacteria at this repair site. When the size of the bacterial colony reaches a critical, defined size, corresponding to a certain level of homoserine lactone (HSL) synthesis, glue production would begin. High levels of HSL will result in a shut-down of glue production.
Team:| University of Edinburgh
Objective: Engineering bacteria to produce starch from the cellulose in waste biomass
Secondary: Engineering Escherichia coli to produce the vitamin A precursor β-carotene.
Summary: cAMP is a by-product and is indicative of low glucose levels in the cytoplasm. cAMP receptor protein (CRP) binds cytoplasmic cAMP to form a transcription factor complex. This transcription factor in turn upregulated the transcription of the following genes
1. |comK : A transcription factor involved in modulating transcription of other genes involved in this cascade.
2. |cenA : An endonuclease responsible for breaking internal bonds between glucose molecules in cellulose.
3. |Cex : An exonuclease responsible for cleaving glucose molecules on the ends of the cellulose molecule.
4. |bgIX : Cleaves the bonds between glucose molecules in |cellobiose
These proteins break the cellulose molecule into glucose. Glucose secreting mechanisms are not common in bacteria, thus a self-lysis device was engineered into this circuit. When levels of comK reach significant levels, corresponding to high glucose levels, it activates the transcription of the protein E which is under the control of [|pComK]. This protein lyses the bacteria, releasing glucose. The glucose is taken up by nearby bacteria which is then converted to starch by the action of Isoamylases 1&2 (|SU1, |ISO2) and Granule-bound starch synthase (|GBS1)
- andref1989@hotmail.com 13:30, 19 October 2010 (EDT):
