In the field of optogenetics, light is used to precisely control cellular proteins and processes. Thus far, optogenetics has been primarily used to control events within cells. "In many cases, tools that allow precise spatiotemporal control of the properties of the extracellular environment are lacking," says Prof. Dr. Wilfried Weber, lead author of the study and member of the Speaker Team of CIBSS -- the Centre for Integrative Biological Signalling Studies. "Our ongoing research shows that optogenetics-inspired approaches hold great promise for dissecting how cells respond to dynamic changes in their environment."
The first step in creating a matrix whose stiffness can be reversibly tuned using light was to find an appropriate molecular switch. After reviewing their publicly available database of optogenetic switches, called OptoBase, the authors decided for the protein Cph1, a bacterial phytochrome which is sensitive to light: It binds to another Cph1 molecule when exposed to red light, and when exposed to far-red light the Cph1 dimers dissociate.
Authors - Version - Cph1 - Binding - Sites
The authors engineered a version of Cph1 with built-in binding sites for cells, and then used this modified photosensor to crosslink branched polyethylene glycol polymers. When the resulting hydrogel was exposed to red light, the Cph1 molecules bound one another and thereby increased the number of crosslinks and thus the stiffness of the matrix. In contrast, exposure to far-red light led...
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