Difference between revisions of "Part:BBa K568001"

Revision as of 18:56, 21 September 2011

Optogenetical AND-Gate red/blue light

This logical gate is based on amber stop-codon suppression via the non-canonical tRNA supD (BBa_K228001). The blue light sensor (BBa_K238013) induces the expression of a mRNA coding for a T7-polymerase with an amber mutation (BBa_K228000), that can only be translated by ribosomes if the correct supD tRNA is present. The supD tRNA is expressed when the red light sensor (BBa_K568000) is induced. Thus, only cells which receive both signals produce the desired substances.

Usage and Biology

If the part is hit by both far red light (705 nm) and blue light (465 nm) beams, the AND-Gate is turned on. Red light induces the autophosphorylation at the cytosolic site of cph8. This leads to phosphorylation of OmpR which subsequently binds to OmpC promotor and enables transcription of the supD t-RNA. Blue light leads to dimerisation of YcgF and binding of the repressor YcgE. The formation of the YcgE-YcgF complex leads to the unbinding of YcgE from the YcgZ promoter which activates the transcription of T7ptag (T7 polymerase with the amber stop codon mutation) if enough supD tRNA is available.

This AND-gate should ensure that expression of T7ptag is only induced when both wavelengths hit bacteria with the part.

Sequence and Features

Functional Parameters

Induction with red light at 705 nm

Induction with blue light at 465 nm

Shut down of constant red light signalling with 650 nm