Optogenetic Downregulation of Protein Levels with an Ultrasensitive Switch Sophia Hasenjäger Jonathan Trauth Sebastian Hepp Juri Goenrich Lars-Oliver Essen Christof Taxis 10.1021/acssynbio.8b00471.s001 https://acs.figshare.com/articles/journal_contribution/Optogenetic_Downregulation_of_Protein_Levels_with_an_Ultrasensitive_Switch/7998890 Optogenetic control of protein activity is a versatile technique to gain control over cellular processes, for example, for biomedical and biotechnological applications. Among other techniques, the regulation of protein abundance by controlling either transcription or protein stability found common use as this controls the activity of any type of target protein. Here, we report modules of an improved variant of the photosensitive degron module and a light-sensitive transcription factor, which we compared to doxycycline-dependent transcriptional control. Given their modularity the combined control of synthesis and stability of a given target protein resulted in the synergistic down regulation of its abundance by light. This combined module exhibits very high switching ratios, profound downregulation of protein abundance at low light-fluxes, and fast protein depletion kinetics. Overall, this synergistic optogenetic multistep control (SOMCo) module is easy to implement and results in a regulation of protein abundance superior to each individual component. 2019-04-08 00:00:00 module Ultrasensitive Switch Optogenetic control optogenetic multistep control light-sensitive transcription factor regulation protein depletion kinetics doxycycline-dependent transcriptional control protein abundance target protein