Dissertations, Theses, and Capstone Projects
Date of Degree
6-2026
Document Type
Doctoral Dissertation
Degree Name
Doctor of Philosophy
Program
Biochemistry
Advisor
Zimei Bu
Committee Members
Ruth Stark
Xiaolin Cheng
Daniel Keedy
Tai De Li
Subject Categories
Structural Biology
Keywords
Cell-cell adhesion, cell-matrix adhesion, Vinculin, Talin, conformational dynamics, mechanotransduction
Abstract
Cell–cell adhesions (adherens junctions) and cell–extracellular matrix adhesions (focal adhesions) are organized by large, multidomain scaffold proteins whose regulated conformational states govern adhesion assembly, stability, and remodeling. At both adherens junctions and focal adhesions, these complexes rely on autoinhibited adaptor proteins—including α-catenin and talin—that undergo controlled structural rearrangements to recruit binding partners and link adhesion receptors to the actin cytoskeleton. Vinculin is essential to modulate the assembly and function of adherens junction and focal adhesions, functioning as a shared actin-binding scaffold that is activated through regulated exposure of cryptic interaction interfaces. Although high-resolution structures have resolved the autoinhibited states of talin and vinculin, how their intrinsic solution-state conformational dynamics regulate activation, partner selection, and functional engagement within native adhesion assemblies remains poorly understood.
In my thesis work, I employed an integrated structural and biophysical approach to define the dynamic regulation of vinculin and talin beyond static structural snapshots. For vinculin, we identified a specific ionic network responsible for stabilizing its head-to-tail autoinhibited conformation, and reconstituted the full vinculin with the core adherens junction complex, the α-catenin•β-catenin•E-cadherin (cadherin-catenin) complex. Disruption of this “salt bridge lock” enabled vinculin opening and its effective incorporation into the cadherin-catenin complex to form a stable vinculin•α-catenin•β-catenin•E-cadherin (VABE) assembly. Using solution small-angle X-ray and neutron scattering (SAXS/SANS) combined with Monte Carlo simulation modeling, we resolved the atomistic structure of the VABE complex and revealed that the activated vinculin adopts an extended conformation within the VABE assembly, where it serves as the primary F-actin binding and F-actin bundling module. This work reveals a functional handover from the weak actin binding of α-catenin to a robust vinculin-mediated linkage, providing a structural mechanism for adhesion reinforcement through scaffold reorganization at adherens junctions.
In parallel, we determined the solution-state conformational ensemble of full-length talin in solution. Size-Exclusion Chromatography coupled with Multi-Angle Light Scattering (SEC–MALS) and Small-Angle X-ray Scattering (SEC–SAXS) measurements, together with Monte Carlo ensemble modeling constrained by experimental SAXS data, demonstrate that talin is not locked in a single compact autoinhibited state under physiological ionic conditions. Instead, talin intrinsically samples a continuum of partially extended conformations, characterized by mobility in the head FERM domain, the R3 domain, and the C-terminal tail. This intrinsic flexibility weakens key autoinhibitory interfaces, suggesting that talin is pre-configured in solution to lower the energetic barrier for integrin engagement and binding partner recruitment even in the absence of mechanical force.
Collectively, these studies establish a unified biophysical principle for mechanotransduction at cell adhesions: vinculin and talin function as dynamic conformational ensembles whose activation involves a shift in equilibrium from autoinhibited toward extended, functionally active states. This shift can be driven by specific biochemical cues or stabilized by mechanical force, enabling adhesion complexes to sense, integrate, and respond to mechanical cues. By defining the solution-state dynamics underlying vinculin and talin activation, this work advances a general framework for understanding how conformational plasticity underlies the assembly, regulation, and adaptive robustness of cell adhesion complexes.
Recommended Citation
Shi, Bright Chen Hao, "Dynamic Structure of Vinculin and Talin in Cell-Cell Adhesion and Cell-Matrix Adhesion" (2026). CUNY Academic Works.
https://academicworks.cuny.edu/gc_etds/6718
