IGEM:Brown/2007/Sensor/What to detect?

Bacterial signal transduction network in a genomic perspective

author: Michael Y. Galperin

Tables 1 and 2 show what types of signalling molecules are present in different types of prokaryotes.

It looks like S_TKc (Serine-Threonine kinase, catalytic) would work best for E. Coli because there are not many of them in E. Coli naturally. Or, we may want to use a signalling protein that doesn't exist yet in E. Coli, to prevent confusion and false signals.

Signal transduction: Hair brains in bacterial chemotaxis

authors: Jeff Stock and Mikhail Levit

In their ‘ON’ state, in the absence of attractants, several receptors bind to CheA in such a way that CheA is activated over 100-fold [24], and conversely CheA binding to the receptors appears to be required for long-range structural interactions that serve to organize the array. In the ‘OFF’ state, in the presence of attractants, it is as if the CheA dimer is torn apart by binding to the receptor network.

In E. coli, at least five different receptors — Tar, Tsr, Tap, Trg and Aer — appear to be intermingled within the same complex.

a) Tar: aspartate and maltose; cobalt and nickel

b) Tsr: serine

c) Tap: Taxis towards peptides

d) Trg: ribose and galactose

e) Aer: directs taxis towards ribose, galactose, maltose, malate, proline and alanine

a. CheA is a kinase that takes a phosphate off of ATP and attaches it to itself

b. CheW connects CheA to the chemoreceptor

Binding Proteins

author: Dr. Leonidas G. Bachas

Sensing System for Zinc Based on Zinc-Binding Protein

Zinc is an essential element in our diet. Too little zinc can cause problems, but too much zinc is also harmful. Severe soil zinc deficiency can cause complete crop failure. Certain microorganisms are known to survive in highly toxic environments contaminated with toxic species such as mercury, arsenic, cadmium, zinc, lead, copper or nickel. Resistance is associated with presence of resistance operons which are precisely regulated. Operon consists of gene for regulatory protein to which toxic metals binds and induce the expression of other genes of operon. Detoxification occurs either by pumping the toxic metals out of the cell or by expression of metallothionein, a cysteine rich protein that chelates heavy metals. We plan to take advantage of this specific binding between the regulatory protein and the toxic species in order to develop a sensing system for the target toxic analyte. In this project we have replaced the genes of the operon for zinc resistance with the genes that encode for reporter proteins to develop a biosensor for zinc.