Team:Toulouse/Project/Chemotaxis

Figure 1: Schema of the chemotaxis module

What is chemotaxis?

Chemotaxis is a bacterial function which induces a movement toward a gradient of concentration of a molecule of interest. With this system the bacteria are able to swim to a location containing higher concentrations of molecules such as sugar, amino acid, vitamins... Chemotactic-signal transducers respond to changes in the concentration of attractants and repellents in the environment, transduce the signal from the outside to the inside of the cell, and facilitate sensory adaptation through the variation of the level of methylation.

More information on this module

Chemotaxis is used as a way to detect and come close to the location of fungi infection. During its growth, fungi release N-acetylglucosamine (NAG), the basic unit of chitin which composed its cell wall. Thus, there should exist a gradient of the concentration of NAG around the fungi.

It is known that B. subtilis is able to detect and to swim towards glucose using the Methyl-accepting chemotaxis protein, henceforth called McpA (MCPA_BACSU).
Some bacteria are attracted by NAG, like Vibrio cholerae which has a NAG regulated methyl-accepting chemotaxis protein: VCD (VCD_000306).

Figure 2: Chimeric protein of chemotaxis

Therefore, our idea is to switch the natural glucose specificity of B. subtilis', mediated by McpA, to a NAG specificity. To achieve this, we need to change the extracellular domain of McpA, responsible for the specificity, by the extracellular domain of VCD. The whole sequence has been designed in silico and codon optimized for the transcription in B. subtilis before its synthesis.

Figure 3: Construction of the chemotaxis gene

References

• K. Meibom,L. Xibing, A. Nielsen, CY. Wu, S. Roseman, and G. Schoolnik. The Vibrio cholerae chitin utilization program . The National Academy of Sciences of the USA (2004).

• C. Kristich, and GW. Ordal. Bacillus subtilis CheD is a chemoreceptor modification enzyme required for chemotaxis. J Biol Chem. 2002 Jul 12;277(28):25356-62. Epub 2002 May 13.
  

Overview

Binding