In optogenetics, as in nature, sensory photoreceptors serve to control cellular processes by light. Bacteriophytochrome (BphP) photoreceptors sense red and far-red light via a biliverdin chromophore and, in response, cycle between the spectroscopically, structurally, and functionally distinct Pr and Pfr states. BphPs commonly belong to two-component systems that control the phosphorylation of cognate response regulators and downstream gene expression through histidine kinase modules. We recently demonstrated that the paradigm BphP from Deinococcus radiodurans exclusively acts as a phosphatase but that its photosensory module can control the histidine kinase activity of homologous receptors. Here, we apply this insight to reprogram two widely used setups for bacterial gene expression from blue-light to red-light control. The resultant pREDusk and pREDawn systems allow gene expression to be regulated down and up, respectively, uniformly under red light by 100-fold or more. Both setups are realized as portable, single plasmids that encode all necessary components including the biliverdin-producing machinery. The triggering by red light affords high spatial resolution down to the single-cell level. As pREDusk and pREDawn respond sensitively to red light, they support multiplexing with optogenetic systems sensitive to other light colors. Owing to the superior tissue penetration of red light, the pREDawn system can be triggered at therapeutically safe light intensities through material layers, replicating the optical properties of the skin and skull. Given these advantages, pREDusk and pREDawn enable red-light-regulated expression for diverse use cases in bacteria.
|Journal||ACS Synthetic Biology|
|Early online date||23 Aug 2022|
|Publication status||Published - 21 Oct 2022|
Bibliographical note© 2022, The Authors. Published by American Chemical Society with a Creative Commons Attribution (CC-BY) License [https://creativecommons.org/licenses/by/4.0/].
This work was supported by the Academy of Finland grant 330678 (H.T.), Three-year grant 2018–2020 from the University of Helsinki (E.M and H.T.), and Bayreuth Humboldt Centre Senior Fellowship 2020 (E. M., A.M., and H.T.). A.M. acknowledges support by the Deutsche Forschungsgemeinschaft (MO2192/6–2) and the European Commission (FET Open NEUROPA, grant agreement 863214). Biomedicum Imaging Unit (BIU) core facility, University of Helsinki is acknowledged for their microscopy services. HiLife Flow Cytometry Unit, University of Helsinki is acknowledged for their flow cytometry services.
- gene expression
- sensory photoreceptor
- signal transduction
- two-component system