pH Sensors

CpxA-CpxR

CpxA-CpxR is a two-component mechanism that is activated at pH 7.4 and repressed at pH 6.0. CpxA is an intermembrane protein that autophosphorylates at a certain external pH, CpxR (a kinase) then gets phosphorylated by CpxA and acts as a transcription factor. This system originally is a transcription factor for the virF gene, but virF was replaced with a reporter. The original sequence was found in Shigella sonnei, but E. coli has a homolog of these proteins so all that is required on the construct is the appropriate prefix/suffix and CpxR binding site. The construct can be found on the iGEM registry as: K2097000, as well as on our results page here.

Composite Parts

Blue Chromoprotein

This is a composite part made up of BBa_K592009 (blue chromoprotein) and BBa_K608002 (a strong RBS and promoter). The protein exhibits a strong blue/purple color when expressed. BBa_K608002 is made up of a promoter, BBa_J23104, and an RBS, BBa_B0034. The construct can be found on the iGEM registry as: K2097001, as well as on our results page here.

Yellow-Green Chromoprotein

This is a composite part made up of BBa_K1033916 (amajLime, a yellow-green chromoprotein) and BBa_K608006 (a medium promoter and RBS). It is made up of a medium promoter, BBa_J23110, and a medium RBS, BBa_B0032. The construct can be found on the iGEM registry as: K2097002, as well as on our results page here