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.
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.
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.