RT Journal Article
SR Electronic
T1 Distinct autoinhibitory mechanisms regulate vinculin binding by αT-catenin and αE-catenin
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.10.25.354415
DO 10.1101/2020.10.25.354415
A1 Jonathon A. Heier
A1 Sabine Pokutta
A1 Ian W. Dale
A1 Sun Kyung Kim
A1 Andrew P. Hinck
A1 William I. Weis
A1 Adam V. Kwiatkowski
YR 2020
UL http://biorxiv.org/content/early/2020/10/26/2020.10.25.354415.abstract
AB α-catenin binds directly to β-catenin and connects the cadherin-catenin complex to the actin cytoskeleton. Tension regulates α-catenin conformation: actomyosin-generated force stretches the middle(M)-region to relieve autoinhibition and reveal a binding site for the actin-binding protein vinculin. Here we describe the biochemical properties of αT(testes)-catenin, an α-catenin isoform critical for cardiac function, and how intramolecular interactions regulate vinculin binding autoinhibition. Isothermal titration calorimetry (ITC) showed that αT-catenin binds the β-catenin/N-cadherin complex with a similar low nanomolar affinity to that of αE-catenin. Limited proteolysis revealed that the αT-catenin M-region adopts a more open conformation than αE-catenin. The αT-catenin M-region binds the vinculin N-terminus with low nanomolar affinity, indicating that the isolated αT-catenin M-region is not autoinhibited and thereby distinct from αE-catenin. However, the αT-catenin head (N- and M-regions) binds vinculin 1000-fold more weakly (low micromolar affinity), indicating that the N-terminus regulates M-region binding to vinculin. In cells, αT-catenin recruitment of vinculin to cell-cell contacts requires the actin-binding domain and actomyosin-generated tension, indicating that force regulates vinculin binding. Together, our results indicate that the αT-catenin N-terminus is required to maintain M-region autoinhibition and modulate vinculin binding. We postulate that the unique molecular properties of αT-catenin allow it to function as a scaffold for building specific adhesion complexes.