Light-Dependent Cytoplasmic Recruitment Enhances the Dynamic Range of a Nuclear Import Photoswitch

Chembiochem. 2018 Jun 18;19(12):1319-1325. doi: 10.1002/cbic.201700681. Epub 2018 Apr 6.


Cellular signal transduction is often regulated at multiple steps to achieve more complex logic or precise control of a pathway. For instance, some signaling mechanisms couple allosteric activation with localization to achieve high signal to noise. Here, we create a system for light-activated nuclear import that incorporates two levels of control. It consists of a nuclear import photoswitch, light-activated nuclear shuttle (LANS), and a protein engineered to preferentially interact with LANS in the dark, Zdk2. First, Zdk2 is tethered to a location in the cytoplasm that sequesters LANS in the dark. Second, LANS incorporates a nuclear localization signal (NLS) that is sterically blocked from binding to the nuclear import machinery in the dark. If activated with light, LANS both dissociates from its tethered location and exposes its NLS, which leads to nuclear accumulation. We demonstrate that this coupled system improves the dynamic range of LANS in mammalian cells, yeast, and Caenorhabditis elegans and provides tighter control of transcription factors that have been fused to LANS.

Keywords: light-activated nuclear shuttles; optogenetics; photoswitches; protein engineering; signal transduction.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Active Transport, Cell Nucleus
  • Animals
  • Caenorhabditis elegans
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Light
  • Nuclear Localization Signals / genetics
  • Nuclear Localization Signals / metabolism
  • Optogenetics / methods*
  • Protein Engineering / methods*
  • Proteins / genetics
  • Proteins / metabolism


  • Nuclear Localization Signals
  • Proteins