Oxidative stress regulates talin mechanosensing.

Abstract

Cellular mechanostransduction relies on the conversion of mechanical cues into chemical signals, which propagate from the focal adhesion hub through the cytoskeleton to ultimately reach the nucleus and switch on specific force-dependent transcriptional programmes. Whether the chemical properties of the environment -and namely oxidative stress- affect the first steps in mechanosensing remains unknown. Here we use a newly developed single molecule magnetic tweezers combined with UV-light to probe how oxidation of specific amino acids affects the mechanical folding of the R3 domain of the talin mechanosensor. Combined with mass spectrometry, we demonstrate that the successive oxidation of a previously cryptic methionine, first to sulfoxide and then to sulfone, decreases in each case talin's mechanical stability by ∼2 pN. While the first oxidation step can be reversed by methionine sulfoxide reductase (Msr) enzymes, evolution to sulfone is irreversible, leading to a mechanically labile protein form. Crucially, vinculin binding to the oxidised protein is significantly impaired, which we demonstrate both, at the single-molecule and single-cell levels. Our results showcase how cryptic oxidation on a single talin domain might lead to severe knock-on effects on the mechanosensing properties at the cellular level.