Team:ESBS-Strasbourg/proteolux/overview

• Scientific Background

Proteolux is a light-controllable specific protein degradation system. The system contains several parts: the bacterial ClpXP protease from E. Coli and the specific recognition sequence (DAS-tag) for ClpX for the degradation part as the photoreceptor protein phytochrome B (PhyB) and the phytochrome interacting factor 6(PIF6) from A. thaliana for the light-dependent part of the system.

The ClpXP proteases consist of three main parts: the ClpX unit and two units of ClpP. The ClpX forms a hexametric ring and binds to a double heptamer of ClpP. The ClpX is responsible for recognizing proteins bearing a specific degradation tag, unfolding and leading them into the catalytic core of the enzyme, where two ClpP subunits break down the peptides bonds.

PhyB is characterized by a red/far-red photochromicity. Through red-light absorption (650–670 nm) PhyB undergoes a rapid conformational change from its ground state Pr to its active state Pfr. The structural change allows the binding of different interacting factors (PIF).The process is completely reversible through absorption in the near infra-red spectrum (705-740nm). PhyB is fused to the N terminus of a trimeric form of ClpX that lacks the N-terminus in which the subunits were connected with a flexible linker to stabilize the enzyme.

Target proteins are fused to the PIF and tagged with the specific degradation sequence which, through light activation, brings the degradation sequence in proximity to ClpX and guides them to the catalytic core of the protease. Therefore a specific degradation of proteins containing the degradation sequence can be induced by a light signal.