Team:Technion Israel/Description

S.Tar

FlashLab

Our vision:

Imagine if you could direct entire bacterial populations towards a specific location, this ability could have amazing applications such as research, bioremediation, substance detection etc.

Project S.Tar aims to give the iGEM community this ability, with the hope that future teams may utilize it and find it useful. In addition, and as an implementation of this ability, we designed FlashLab – a biological detection tool.

Chemotaxis

Chemotaxis is the movement of an organism in response to an external chemical stimulus.
This system is used by many organisms to navigate their immediate environment
The E. coli chemotaxis system is considered a model system that illustrates some of the core principles of chemotactic movement (1).
A detailed explanation on the chemotaxis system and the intercellular processes involved can be found here.

Fig. 1: Scheme of chemotaxis concept.

S.Tar – In control of chemotaxis

Project Super Tar - S.Tar in short, is designed to be a novel broadband platform for controlled chemotaxis. The base of our project is the E. coli Tar chemoreceptor or more specifically, its ligand binding domain (LBD).
We show that by mutating the native Tar LBD (2) or by interchanging it with that of other receptors (3), the E. coli chemotaxis system can be programmed to respond to completely new ligands.

Fig. 3: S.Tar project - Programming the chemoreceptors to respond to new ligands by modifying the ligand binding domain.

To demonstrate the potential of our system, we performed two experiments:
1. We replaced the Tar LBD with that of the PctA chemoreceptor and demonstrated a chemotactic response to its repellent – TCE, a substance which the native Tar cannot recognize.
2. We used computational biology to redesign the native Tar receptor to bind Histamine instead of its original ligand- Aspartate. We demonstrated a chemotactic response from the mutated receptor.

Using S.Tar, scientists will be able to control the movement of bacteria and direct them towards or away from a target material. This system can have vast applications in bioremediation and, as we show in our project, detection.

FlashLab – A S.Tar detector

As an application of our system, we designed an easy-to-use detection system, which utilizes the high sensitivity of the chemotactic response. FlashLab is a simple and cheap platform for the detection of any chemoeffector, using S.Tar bacteria.

Fig. 4: Flash Lab - our designed detection chip.

References:
1. Bi, S. and Lai, L., 2015. Bacterial chemoreceptors and chemoeffectors. Cellular and Molecular Life Sciences, 72(4), pp.691-708.

2. Moretti, R., Bender, B.J., Allison, B. and Meiler, J., 2016. Rosetta and the Design of Ligand Binding Sites. Computational Design of Ligand Binding Proteins, pp.47-62.

3. Reyes‐Darias, J.A., Yang, Y., Sourjik, V. and Krell, T., 2015. Correlation between signal input and output in PctA and PctB amino acid chemoreceptor of Pseudomonas aeruginosa. Molecular microbiology, 96(3), pp.513-525.