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Project Description

A Biosensor Memory Module: Cre Sensor

Photostimulation is one of the most important non-invasive analysis methods allowing researchers to examine the relationship between metabolic processes, e.g. through activating a molecule via light treatment. We want to create a module which makes it possible to take a snapshot of the activity of a sensor at any time. Our designed system should be capable of capturing such a ‘snapshot’ of the activity of a sensor. Therefore our aim is to create a Cre recombinase whose activity can be reversibly controlled by light. By activating this construct only for a short period of time, we can use a Cre to switch on expression of Luciferase in only a limited amount of the sensor cells. Through coupling the Cre expression to the sensor we can thereby permanently write the sensor state of a given time point into the DNA of a system.

To achieve the construction of a reversibly activatable Cre recombinase we want to apply the caging mechanism described by Zhou et al [Zhou 2012]. This caging is performed by fusing a copy of a variant of the fluorescent protein Dronpa to both the C- and N-terminus of the Cre recombinase. Since this Dronpa variant is able to form monomers or dimers depending on illumination with light of different wavelengths, we hope that the dimerized form inhibits the activity of the Cre recombinase.

Because our system only needs the expression of the caged Cre construct to be dependent on a sensor, it can be combined with almost all Biosensors that include a means of transcriptional control. This gives the system a wide variety of possible applications, especially in the context of the work of other iGEM teams.