Benchmarking of Cph1 Mutants and DrBphP for Light-Responsive Phytochrome-Based Hydrogels with Reversibly Adjustable Mechanical Properties

Adv Biol (Weinh). 2022 Jul;6(7):e2000337. doi: 10.1002/adbi.202000337. Epub 2022 Apr 28.


In the rapidly expanding field of molecular optogenetics, the performance of the engineered systems relies on the switching properties of the underlying genetically encoded photoreceptors. In this study, the bacterial phytochromes Cph1 and DrBphP are engineered, recombinantly produced in Escherichia coli, and characterized regarding their switching properties in order to synthesize biohybrid hydrogels with increased light-responsive stiffness modulations. The R472A mutant of the cyanobacterial phytochrome 1 (Cph1) is identified to confer the phytochrome-based hydrogels with an increased dynamic range for the storage modulus but a different light-response for the loss modulus compared to the original Cph1-based hydrogel. Stiffness measurements of human atrial fibroblasts grown on these hydrogels suggest that differences in the loss modulus at comparable changes in the storage modulus affect cell stiffness and thus underline the importance of matrix viscoelasticity on cellular mechanotransduction. The hydrogels presented here are of interest for analyzing how mammalian cells respond to dynamic viscoelastic cues. Moreover, the Cph1-R472A mutant, as well as the benchmarking of the other phytochrome variants, are expected to foster the development and performance of future optogenetic systems.

Keywords: biomaterials; extracellular matrix; hydrogels; mechanosensing; molecular optogenetics; phytochromes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins* / chemistry
  • Bacterial Proteins* / genetics
  • Bacterial Proteins* / radiation effects
  • Benchmarking
  • Cyanobacteria / genetics
  • Escherichia coli / metabolism
  • Fibroblasts
  • Genetic Engineering
  • Humans
  • Hydrogels* / chemistry
  • Mechanotransduction, Cellular* / radiation effects
  • Optogenetics*
  • Photoreceptors, Microbial* / chemistry
  • Photoreceptors, Microbial* / genetics
  • Photoreceptors, Microbial* / radiation effects
  • Phytochrome* / chemistry
  • Phytochrome* / genetics
  • Phytochrome* / radiation effects
  • Protein Kinases* / chemistry
  • Protein Kinases* / genetics
  • Protein Kinases* / radiation effects
  • Viscosity


  • Bacterial Proteins
  • Hydrogels
  • Photoreceptors, Microbial
  • Phytochrome
  • Protein Kinases
  • Cph1 phytochrome protein, bacteria