Phosphorylation Reduces the Mechanical Stability of the α-Catenin/ β-Catenin Complex.

The α-catenin/β-catenin complex serves as a critical molecular interface involved in cadherin-catenin-based mechanosensing at the cell-cell adherence junction that plays a critical role in tissue integrity, repair, and embryonic development. This complex is subject to tensile forces due to internal actomyosin contractility and external mechanical micro-environmental perturbation. However, the mechanical stability of this complex has yet to be quantified. Here, we directly quantified the mechanical stability of the α-catenin/β-catenin complex and showed that it has enough mechanical stability to survive for tens to hundreds of seconds within physiological level of forces up to 10 pN. Phosphorylation or phosphotyrosine-mimetic mutations (Y142E or/and T120E) on β-catenin shorten the mechanical lifetime of the complex by tens of fold over the same force range. These results provide insights into the regulation of the α-catenin/β-catenin complex by phosphorylation.