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From 2011.igem.org

From the idea to a crude plan

After finding all members for our team in January 2011 we began thinking about an idea for an iGEM project. We had many different ideas, from carbondioxide eating E. coli to a biosensor for dioxines. But in the beginning of February we noticed an [http://www.spiegel.de/wissenschaft/mensch/0,1518,745019,00.html online article] about the ban of the endocrine disruptor bisphenol A in the European Union for the production of baby bottles. We thought: if it was possible to detect BPA at home using a test that everybody could use, all parents on this world would have one concern less. So we decided to build a BPA biosensor. To ensure an everyday applicability this biosensor should be cell-free, nontoxic and easy to use.

Concretizing the plans of our device

Talking about an approach for this cell-free biosensor, one of our team members said that it would be great to have a surface which could be functionalized, just like the team from Slovenia did 2010 with DNA - only in 2-D not 1-D. We wanted to go further in this direction and did literature research. This led us to a species of proteins that form periodic two-dimensional structures just on their own in a so called self-assembly - the crystalline bacterial surface layers, short: S-layers. These proteins became our system of choice: usable as a nanobiotechnological scaffold for a lot of different cell-free applications, providing S-layer BioBricks in an assembly standard for fusion proteins will allow future iGEM teams and synthetic biologists an easy arrangement of their nanobiotechnological systems of choice. Our idea of do it yourself nanobiotechnology was born.

Development of different subprojects

Our knowledge of the state of the art of S-layer applications grew. Now we needed a possibility to functionalize an S-layer surface in a way to use it as a BPA biosensor. When searching the partsregistry we found BioBricks for BPA degradation in Freiburg assembly standard. These BioBricks became the starting point of a BPA detecting enzymatic reaction. In this BPA degradation reaction NADH is converted into NAD⁺. By a sensitive and specific detection of NAD⁺, an indirect anaysis of BPA is possible. So we divided our project in three subprojects:

1. Isolating S-layer genes from different organisms and establish methods for producing purifying and immobilizing the geneproducts.
2. Enable E. coli to degrade BPA and establish an enzymatic cell-free BPA degradation.
3. Find a way to detect NAD⁺ with a high sensitivity and specificity.