DNA Origami Assembly for the Tar Chemoreceptor

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Introduction to Chemotaxis

Chemotaxis is the process by which bacteria sense chemicals in their environment. This is done through the use of chemoreceptors to sense a chemical gradient that they can follow towards higher concentrations of food or away from higher concentrations of poisons or other unfavorable conditions. The Tar chemoreceptor is involved with the sensing of aspartate, a common amino acid, by binding aspartate in the extracellular portion of the protein and then propagates a signal down the receptor to activate a pathway to alter movement. [Add picture of chemoreceptor here? Are there any that are open source?]

Possible Applications of Chemotaxis

Understanding how signals are propagated in chemotaxis would be incredibly helpful in the fight against antibiotic resistance. Being able to control bacterial movement could allow a treatment to be engineered to move bacteria either towards antibiotics, therefore reducing the necessary dosage, or away from food or nutrients, effectively starving the bacteria. In addition, being able to use bacteria as carriers for drugs could also be a novel drug delivery technique.

DNA Origami

This project involves using a DNA tetrahedron as a scaffold for the Tar chemoreceptor complex in vitro. In this model, receptor dimers are attached at three vertices of the DNA tetrahedron to make the native trimer of dimers structure seen in vivo. At the other end of the receptor, two proteins are shown: CheA, a kinase, shown in dark blue, and CheW, a coupling protein, shown in cyan.

Attachment to DNA

The protein receptor dimer is attached to the DNA tetrahedron using NTA-functionalized DNA. This means that the DNA has an NTA, or nitrilotriaceticacid, is able to coordinate with nickel ions, shown in green, which is also able to coordinate with histidines. The Tar chemoreceptor has six histidines added to the N-terminus of the protein in vitro, which should be able to coordinate with the nickel ion as well, creating a coordination complex.

Structural highlights

This is a sample scene created with SAT to by Group, and another to make of the protein. You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes.