Facile detection of mechanical forces across proteins in cells with STReTCh

Abstract

Summary: Numerous proteins experience and respond to mechanical forces as an integral part of their cellular functions, but measuring these forces remains a practical challenge. Here, we present a compact, 11-kDa molecular tension sensor termed STReTCh (sensing tension by reactive tag characterization). Unlike existing genetically encoded tension sensors, STReTCh does not rely on experimentally demanding measurements based on Förster resonance energy transfer and is compatible with typical fix-and-stain protocols. Using a magnetic tweezers assay, we calibrate the STReTCh module and show that it responds to physiologically relevant, piconewton forces. As proof of concept, we use an extracellular STReTCh-based sensor to visualize cell-generated forces at integrin-based adhesion complexes. In addition, we incorporate STReTCh into vinculin, a cytoskeletal adaptor protein, and show that STReTCh reports on forces transmitted between the cytoskeleton and cellular adhesion complexes. These data illustrate the utility of STReTCh as a tool for visualizing molecular-scale forces in biological systems. Motivation: Visualizing the molecular-scale forces present in living cells can provide insights into numerous biological processes, but existing tools for force measurement can be challenging to use. To reduce barriers to measuring molecular forces in biological systems, we designed a molecular tension sensor, termed STReTCh, whose use follows common “fix-and-stain” workflows, making it broadly accessible to the cell biological community.

Keywords

• mechanobiology
• biosensor
• cytoskeleton
• cell adhesion
• mechanical force