Distinct intramolecular interactions regulate autoinhibition of vinculin binding in αT-catenin and αE-catenin

Jonathon A. Heier, Sabine Pokutta, Ian W. Dale, Sun Kyung Kim, Andrew P. Hinck, William I. Weis, Adam V. Kwiatkowski

Research output: Contribution to journalArticlepeer-review

Abstract

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. It is not known whether the intramolecular interactions that regulate epithelial (αE)-catenin binding are conserved across the α- catenin family. Here, we describe the biochemical properties of testes (αT)-catenin, an α-catenin isoform critical for cardiac function and how intramolecular interactions regulate vinculin-binding autoinhibition. Isothermal titration calorimetry showed that αT-catenin binds the β-catenin-N-cadherin complex with a similar low nanomolar affinity to that of αEcatenin. Limited proteolysis revealed that the αT-catenin Mregion 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 Mregion 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 the 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 show 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.

Original languageEnglish (US)
Article numberA87
JournalJournal of Biological Chemistry
Volume296
DOIs
StatePublished - Jan 1 2021
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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