IGEM:Brown/2007/Sensor/What to detect?
From OpenWetWare
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.