Synthetic Biology

iGEM is an international competition in the field of synthetic biology. Synthetic biology interlinks molecular biology with the methodology of engineering and therefore represents a big interdisciplinary field within the natural and engineering sciences. It focusses on the development of new biological, or biologically inspired systems, that don?t occur in nature. In general, these biological systems can differ in their order of magnitude as well as in their level of development. For example, a single bacterial protein can as much be a biological system of interest as a complex tissue of animal cells. [1]

Our this year's goal is the establishment of an on Escherichia coli cells based biological system for the specific synthesis of two chitosan pentamers (molecules with five subunits), that differ in their pattern of deacetylation. Chitosans are partly or completely deacetylated (loss of small chemical groups) chitin derivatives, which is a biopolymer of N-Acetylglucoseamines and the main substance in the exoskeleton of many insects. Chitosans have diverse biological properties and application opportunities, depending on the molecules? length, the deacetylation degree and the deacetylation pattern, making it interesting to think up a biological system, that makes it possible to synthesize a variety of these biomolecules in an orthogonal and specific manner. We are currently attempting to realize this idea by the introduction of two new protein classes in E. coli , that function as catalysators for biochemical reactions (enzymes). These proteins originate from other microorganisms and are synthesized in E. coli cells after bringing synthetic DNA into them, which causes the protein?s production.

A chitinase (first protein class) is building up chitin pentamers by connecting N-Acetylglucosamine molecules and chitin deacetylases (second protein class) are afterwards deacetylating the synthesized chitin molecules to chitosans. The final deacetylation pattern of the chitosan molecules is depending on the used chitin deacetylases. Different chitin deacetylases induce different deacetylation patterns. For the moment, the system we are working on in the lab consists of two different chitin deacetylases, that can be orthogonally expressed, making it possible to synthesize three different chitosan molecules by expressing the two enzymes either alone or combined.

To sum up our idea is to engineer a biological system for the specific synthesis of various chitosan molecules, that can easily be expanded by further chitin deacetylases or also chitinsynthases. inducing different deacetylation patterns and molecule length. Chitosans have very interesting biological properties such as supporting scar-free healing of wounds and antibacterial effects, that strongly depend on the chitosans? molecular characteristics. Since it is very difficult to synthesize chitosans with defined deacetylation patterns by conventional chemical synthesis we want to introduce a synthetic biological solution to this problem.

[1] Synthetic Biology Applying Engineering to Biology – Report of a NEST High-Level Expert Group (2005)