From Dusk till Dawn: One-Plasmid Systems for Light-Regulated Gene Expression

Signaling photoreceptors mediate diverse organismal adaptations in response to light. As light-gated protein switches, signaling photoreceptors provide the basis for optogenetics, a term that refers to the control of organismal physiology and behavior by light. We establish as novel optogenetic tools the plasmids pDusk and pDawn, which employ blue-light photoreceptors to confer light-repressed or light-induced gene expression in Escherichia coli with up to 460-fold induction upon illumination. Key features of these systems are low background activity, high dynamic range, spatial control on the 20-μm scale, independence from exogenous factors, and ease of use. In optogenetic experiments, pDusk and pDawn can be used to specifically perturb individual nodes of signaling networks and interrogate their role. On the preparative scale, pDawn can induce by light the production of recombinant proteins and thus represents a cost-effective and readily automated alternative to conventional induction systems.

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► Photoreceptors underpin optogenetics, that is, the control of physiology and behavior by light.
► The plasmids pDusk and pDawn offer blue-light-regulated gene expression.
► Expression from pDawn is up-regulated 460-fold under blue light.
► The plasmids offer portability, high dynamic range, low background, and spatial control.
► The plasmids are suitable for optogenetics and for production of recombinant proteins.