Difference between revisions of "Part:BBa K1073035"

Revision as of 09:13, 25 September 2013

Inducible ampR expression combined with RhlR, LasI and eforRed expression cassettes

This device is a combination of BBa_K1073028 and BBa_K1073032 and includes parts of the rhl and las quorum sensing system of Pseudomonas aeruginosa. It includes constitutive expression cassettes for RhlR, LasI and eforRed.

The expression of ampR is regulated by the promoter of the rhl system. In order to induce ampR expression the transcription regulator RhlR and the specific autoinducer molecule N-buturyl homoserine lactone have to be present. N-buturyl-HSL is synthesized by RhlI (this protein is not included in the construct). However, N-buturyl-HSL can be added to the culture broth. RhlR and N-buturyl-HSL build a complex that binds to specific sequences of the promoter region and induces expression of the downstream gene (in this case ampR).

LasI synthesizes the specific autoinducer of the las quorum sensing system N-3-oxododecanoyl homoserine lactone. The autoinducer molecules are secreted into the surrounding medium.

The expression of eforRed can be used as selection marker. EforRed exhibits a strong pink color when expressed and is visible to naked eye in less than 24 h during incubation on agar plates or in liquid culture.

Usage and Biology

This device is intended to be used in concert with BBa_K1073034. Two different strains containing BBa_K1073034 and BBa_K1073035 respectively will together synthesize all molecules required to induce the promoters of the rhl and las system and thus activating the expression of ampR. Using both BBa_K1073034 and BBa_K1073035 a synthetic consortia between two strains can be created when they are incubated in ampicillin containing medium. The two strains depend on each other and can only grow when the other is present in the culture broth.

It can also be used without BBa_K1073034 when synthetic N-buturyl-HSL is added to the culture broth.

iGEM Team Braunschweig 2013:

Left: Growth curve of E. coli Top10 containing BBa_K1073035 on the high copy plamsid pSB1C3. Comparison of growth in ampicillin containing complex medium in presence and absence of rhl autoinducer N-buturyl-HSL.

Right: Expression of chromoproteins expression cassettes amilGFP (BBa_K1073024), eforRed (BBa_K1073022) and aeBlue (BBa_K1073020). The eforRed expression cassette is included in BBa_K1073035 and cells containing this construct can be easily identified by this marker.

Sequence and Features