From 2008.igem.org


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  • The voltage output part of our project aims to mimic the signal transduction that occurs at a neural synapse.
  • We are engineering E.coli to create a voltage output on detection of glutamate. This imitates the creation of a postsynaptic potential in a dendrite when a neurotransmitter (such as glutamate) is present at the synapse.
  • The mechanism we have designed is similar to that used in the brain – relying on ion movement across the membrane, and gated ion channels.
  • To simplify the concept, we are only regulating and measuring the flux of potassium (K+) ions, and we are using a directly glutamate-gated K+ ion channel.
  • This means that on the binding of glutamate, the channels will open, allowing a K+ flux, which will change the voltage of the medium enough to be detected with a very sensitive electrode.
  • In order to set up a large enough K+ concentration gradient across the membrane for ions to flow down when the channels open, cells are grown in high K+ medium (100mM) and resuspended in low K+ medium.
  • However, E.coli also has a number of osmoregulatory systems which use relative K+ ion concentrations to control turgor. There are K+ leak channels (Kch and Kef) in the membrane, so we have chosen E.coli strains with mutations in these genes as our chassis.

Experiment Summaries

Electrical Output

Mutant Growth Rates

Cytoplasmic K+ Concentrations

Parts Construction:



Technical Information

Gene Design

Flame Photometer Calibration

OD600 (Cell Density) Calibration

Mutant Strains Information

Useful Links

Protein prediction tools

Uniprot database



Kdp operon diagram


The Kdp-ATPase system and its regulation

Potential Chassis: |Strain JW1242-1 Strain JW0710-1

Kdp mutant - paper from 1971

Worldwide E.coli Databases

Characterisation of kdpD - 2005

Investigations on Kdp Operon exp. & flux

Very interesting 2001 paper concerning Glutamate Channels

1999 paper on functional characterization of prokaryote Glu Channels

Sequenced Synechocystis PCC 6803 genome

Glutamate-gated K+ channel GluR0

Link to E.coli statistics page (CCDB Database)