Biology subjects

Dunn, A. R.

Publications and source records attributed to Dunn, A. R..

At least 19 recordsLinked to original sources

bioRxiv2026

Clustering of the Adhesion-GPCR Latrophilin-3 Drives Excitatory Synapse Assembly

Precise control of synapse formation is essential for brain function. Adhesion-GPCRs combine adhesion, signaling, and scaffold recruitment to regulate synapse formation, yet their mechanisms of action remain unclear. Here, we identify nanoscale clustering of the adhesion-GPCR Latrophilin-3 as a key mechanism regulating excitatory synapse assembly. We find that endogenous Latrophilin-3 forms densely packed nanoclusters, with larger nanoclusters enriched at excitatory synapses. To probe the functional significance of Latrophilin-3 clustering, we engineered an optogenetically controlled Latrophilin-3. Light-induced Latrophilin-3 clustering triggered robust excitatory synapse formation, which required both Latrophilin-3-mediated G-protein signaling and postsynaptic scaffold recruitment. Strikingly, clustering of a mutant Latrophilin-3 lacking known ligand-binding domains still promoted synapse formation, indicating that Latrophilin-3 ligands induce synapse assembly primarily by clustering Latrophilin-3. Our findings suggest a general paradigm by which extracellular ligand-induced clustering activates adhesion-GPCRs by generating compartmentalized signaling, which in the case of Latrophilin-3, cooperates with postsynaptic scaffold recruitment to drive synapse assembly.

neuroscience↗

bioRxiv2026

Engineering the mechanosensitivity of single DNA molecules via high-throughput microfluidic force spectroscopy

Single-molecule force spectroscopy (SMFS) is a powerful tool to measure how biomolecules respond to mechanical force, but limited sequence throughput constrains its potential. Here, we present a single-molecule, multiplexed, microfluidic force spectroscopy (SM3FS) assay that uses parallelized microfluidics to measure up to 80 sequence variants per experiment. Using SM3FS, we stretched, overstretched, or unzipped 241 different DNA structures and generated 131,847 single-molecule traces from a quarter-million observations. High sequence throughput allowed us to identify DNA structures that are kinetically stable yet mechanically fragile (Frupture < 3 pN at 0.5 pN s-1), revealing how mechanosensitivity can arise as an intrinsic property of multivalent systems. By enabling systematic sequence-function mapping under force, SM3FS opens a path to high-throughput nonequilibrium studies of biomolecules.

biophysics↗

bioRxiv2026

Cryo-ET reveals nanoscale thick filamentdisorganization in MYH7 P710R hypertrophiccardiomyopathy cardiomyocytes

Hypertrophic cardiomyopathy (HCM) is the most common monogenic inherited heart disease and is a major cause of sudden death in individuals under 35 years of age. HCM is associated with progressive tissue-level disarray and subcellular disorganization in individual cardiomyocytes. Mutations in {beta}-cardiac myosin (MYH7), the second most common genetic cause of HCM, commonly result in changes in sarcomeric force production, but how this leads to altered cell- and tissue-level organization is unclear. Here, we use cryo-electron tomography (cryo-ET) to bridge the molecular and cellular scales by visualizing the nanoscale organization of individual myosin-containing thick filaments within sarcomeres of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Compared to isogenic wild-type controls, hiPSC-CMs expressing P710R MYH7 exhibit pronounced disruption of the hexagonal packing of thick filaments within individual sarcomeres, which would be difficult to visualize using conventional light microscopy or even room-temperature electron microscopy. We also observe ribosome infiltration into areas of sarcomeric disorder for both wild-type and P710R MYH7 hiPSC-CMs, suggesting that disordered regions may be sites of local proteostasis or remodeling. Together, these data illuminate how altered myosin activity can propagate to yield dramatic changes in sarcomeric organization in HCM.

cell biology↗

bioRxiv2025

A genetically-diverse mouse model reveals a complex gene-environment regulation of cognitive resilience and susceptibility to Alzheimer disease

Alzheimers disease (AD) has a complex etiology arising from largely unknown interactions between genetic and environmental (GxE) factors. Even in populations with causal familial Alzheimers disease mutations, there is variation in disease onset and progression, suggesting that clinical symptoms are modified by genetics and environment. Identification of such modifiers is critical, as mechanisms that promote resilience to high-risk AD mutations, unhealthy diet, or aging represent promising therapeutic targets for AD; global resilience factors that protect against multiple "hits" are among the highest priority for discovery. Both genetic and environmental protective factors in AD have been identified; however, GxE factors are incredibly difficult to study in human populations given complex genomes, poor self-reporting, limited data from underrepresented groups, and incompletely documented exposomes. Here, we (1) validate novel GxE tools using population of mouse strains that model the polygenic nature of human AD, (2) characterize individuals with cognitive resilience to high-risk genetic and dietary perturbations, (3) define and quantitate roles for genetics, sex, age, and diet, and (4) present data for the discovery of complex interactions that are nearly impossible to elucidate from humans or inbred mice. We found that a high-fat high-sugar (HFHS) diet is not universally damaging, as some strains showed an improved AD-related cognitive outcome when fed a HFHS diet, suggesting the need for personalized recommendations for dietary interventions in AD. Cognitive resilience to AD is polygenic; however, we found a locus on Chr 10 that was modestly associated with cognitive resilience to AD in females, and this association was strengthened by HFHS diet, pointing to an unexpected interaction between specific genetic loci and unhealthy diet in AD risk and resilience. This study is the first of its kind to explore characteristics of AD resilience and GxE interactions in a genetically diverse mouse model. We present a subset of strains that exemplify global cognitive resilience to be leveraged for deep mechanistic studies aimed toward development of resilience-based, personalized therapeutic interventions. HighlightsO_LIAD-BXD mouse models and data repository provide unprecedented tools for understanding individual differences arising from Gene x Environment factors in aging and AD. C_LIO_LIEvidence of global cognitive resilience to AD-relevant outcomes that is partially mediated by a resilience to aging and dietary risk factors. C_LIO_LICognitive resilience in AD-BXDs its polygenic nature, with a modest locus on Chr 10 whose association with resilience was amplified by a high-fat/high-sugar diet. C_LIO_LIThe genetic factors mediating resilience to AD in humans also predict cognitive resilience in AD-BXDs, suggesting robust, translatable global resilience factors. C_LI

neuroscience↗

bioRxiv2024

Cluster Assembly Dynamics Drive Fidelity of Planar Cell Polarity Polarization

In planar cell polarity (PCP) signaling, distinct molecular subcomplexes segregate to opposite sides of each cell, where they interact across intercellular junctions to form asymmetric clusters. Although proximal-distal asymmetry within PCP clusters is the defining feature of PCP signaling, the mechanism by which this asymmetry develops remains unclear. Here, we developed a method to count the number of monomers of core PCP proteins within individual clusters in live animals and used it to infer the underlying molecular dynamics of cluster assembly and polarization. Measurements over time and space in wild type and in strategically chosen mutants demonstrate that cluster assembly is required for polarization, and together with mathematical modeling provide evidence that clusters become increasingly asymmetric and correctly oriented as they increase in size. We propose that cluster assembly dynamics amplify weak and noisy inputs into a robust cellular output, in this case cell and tissue-level polarization.

cell biology↗

bioRxiv2024

Hippocampus Glutathione S Reductase Potentially Confers Genetic Resilience to Cognitive Decline in the of AD-BXD Mouse Population

Alzheimers disease (AD) is a prevalent and costly age-related dementia. Heritable factors account for 58-79% of variation in late-onset AD, but substantial variation remains in age-of- onset, disease severity, and whether those with high-risk genotypes acquire AD. To emulate the diversity of human populations, we utilized the AD-BXD mouse panel. This genetically diverse resource combines AD genotypes with multiple BXD strains to discover new genetic drivers of AD resilience. Comparing AD-BXD carriers to noncarrier littermates, we computed a novel quantitative metric for resilience to cognitive decline in the AD-BXDs. Our quantitative AD resilience trait was heritable and genetic mapping identified a locus on chr8 associated with resilience to AD mutations that resulted in amyloid brain pathology. Using a hippocampus proteomics dataset, we nominated the mitochondrial glutathione S reductase protein (GR or GSHR) as a resilience factor, finding that the DBA/2J genotype was associated with substantially higher GR abundance. By mapping protein QTLs (pQTLs), we identified synaptic organization and mitochondrial proteins coregulated in trans with a cis-pQTL for GR. We found four coexpression modules correlated with the quantitative resilience score in aged 5XFAD mice using paracliques, which were related to cell structure, protein folding, and postsynaptic densities. Finally, we found significant positive associations between human GSR transcript abundance in the brain and better outcomes on AD-related cognitive and pathology traits in the Religious Orders Study/Memory and Aging project (ROSMAP). Taken together, these data support a framework for resilience in which neuronal antioxidant pathway activity provides for stability of synapses within the hippocampus.

neuroscience↗

bioRxiv2023

Cryo-electron tomography reveals the structural diversity of cardiac proteins in their cellular context

Cardiovascular diseases are a leading cause of death worldwide, but our understanding of the underlying mechanisms is limited, in part because of the complexity of the cellular machinery that controls the heart muscle contraction cycle. Cryogenic electron tomography (cryo-ET) provides a way to visualize diverse cellular machinery while preserving contextual information like subcellular localization and transient complex formation, but this approach has not been widely applied to the study of heart muscle cells (cardiomyocytes). Here, we deploy an optimized cryo-ET platform that enables cellular-structural biology in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Using this platform, we reconstructed sub-nanometer resolution structures of the human cardiac muscle thin filament, a central component of the contractile machinery. Reconstructing the troponin complex, a regulatory component of the thin filament, from within cells, we identified previously unobserved conformations that highlight the structural flexibility of this regulatory complex. We next measured the impact of chemical and genetic perturbations associated with cardiovascular disease on the structure of troponin. In both cases, we found changes in troponin structure that are consistent with known disease phenotypes--highlighting the value of our approach for dissecting complex disease mechanisms in the cellular context.

biophysics↗

bioRxiv2023

PDZ Domains from the Junctional Proteins Afadin and ZO-1 Act as Mechanosensors

Intercellular adhesion complexes must withstand mechanical forces to maintain tissue cohesion while also retaining the capacity for dynamic remodeling during tissue morphogenesis and repair. Many cell-cell adhesion complexes contain at least one PSD95/Dlg/ZO-1 (PDZ) domain situated between the adhesion molecule and the actin cytoskeleton. However, PDZ-mediated interactions are characteristically nonspecific, weak, and transient, with multiple binding partners per PDZ domain, micromolar dissociation constants, and bond lifetimes of seconds or less. Here, we demonstrate that the bonds between the PDZ domain of the cytoskeletal adaptor protein afadin and the intracellular domains of the adhesion molecules nectin-1 and JAM-A form molecular catch bonds that reinforce in response to mechanical load. In contrast, the bond between the PDZ3-SH3-GUK (PSG) domain of the cytoskeletal adaptor ZO-1 and the JAM-A intracellular domain becomes dramatically weaker in response to [~]2 pN of load, the amount generated by single molecules of the cytoskeletal motor protein myosin II. Thus, physiologically relevant forces can exert dramatic and opposite effects on the stability of two of the major linkages between cell-cell adhesion proteins and the F-actin cytoskeleton. Our data demonstrate that that PDZ domains can serve as force-responsive mechanical anchors at cell-cell adhesion complexes. More broadly, our findings suggest that mechanical force may serve as a previously unsuspected regulator of the hundreds of PDZ-ligand interactions present in animal cells.

biophysics↗

bioRxiv2023

Extracellular filaments revealed by affinity capture cryo-electron tomography of lymphocytes

Cryogenic-electron tomography (cryo-ET) has provided an unprecedented glimpse into the nanoscale architecture of cells by combining cryogenic preservation of biological structures with electron tomography. Micropatterning of extracellular matrix proteins is increasingly used as a method to prepare adherent cell types for cryo-ET as it promotes optimal positioning of cells and subcellular regions of interest for vitrification, cryo-focused ion beam (cryo-FIB) milling, and data acquisition. Here we demonstrate a micropatterning workflow for capturing minimally adherent cell types, human T-cells and Jurkat cells, for cryo-FIB and cryo-ET. Our affinity capture system facilitated the nanoscale imaging of Jurkat cells, revealing extracellular filamentous structures. It improved workflow efficiency by consistently producing grids with a sufficient number of well positioned cells for an entire cryo-FIB session. Affinity capture can be extended to facilitate high resolution imaging of other adherent and non-adherent cell types with cryo-ET.

cell biology↗

bioRxiv2023

Synaptic vesicle glycoprotein 2C enhances vesicular storage of dopamine and counters dopaminergic toxicity

Dopaminergic neurons of the substantia nigra exist in a persistent state of vulnerability resulting from high baseline oxidative stress, high energy demand, and broad unmyelinated axonal arborizations. Impairments in the storage of dopamine compound this stress due to cytosolic reactions that transform the vital neurotransmitter into an endogenous neurotoxicant, and this toxicity is thought to contribute to the dopamine neuron degeneration that occurs Parkinsons disease. We have previously identified synaptic vesicle glycoprotein 2C (SV2C) as a modifier of vesicular dopamine function, demonstrating that genetic ablation of SV2C in mice results in decreased dopamine content and evoked dopamine release in the striatum. Here, we adapted a previously published in vitro assay utilizing false fluorescent neurotransmitter 206 (FFN206) to visualize how SV2C regulates vesicular dopamine dynamics and determined that SV2C promotes the uptake and retention of FFN206 within vesicles. In addition, we present data indicating that SV2C enhances the retention of dopamine in the vesicular compartment with radiolabeled dopamine in vesicles isolated from immortalized cells and from mouse brain. Further, we demonstrate that SV2C enhances the ability of vesicles to store the neurotoxicant 1-methyl-4-phenylpyridinium (MPP+) and that genetic ablation of SV2C results in enhanced 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced vulnerability in mice. Together, these findings suggest that SV2C functions to enhance vesicular storage of dopamine and neurotoxicants, and helps maintain the integrity of dopaminergic neurons.

neuroscience↗

bioRxiv2023

Genetic background influences the 5XFAD Alzheimer's disease mouse model brain proteome

There is a pressing need to improve the translational validity of Alzheimers disease (AD) mouse models. Introducing genetic background diversity in AD mouse models has been proposed as a way to increase validity and enable discovery of previously uncharacterized genetic contributions to AD susceptibility or resilience. However, the extent to which genetic background influences the mouse brain proteome and its perturbation in AD mouse models is unknown. Here we crossed the 5XFAD AD mouse model on a C57BL/6J (B6) inbred background with the DBA/2J (D2) inbred background and analyzed the effects of genetic background variation on the brain proteome in F1 progeny. Both genetic background and 5XFAD transgene insertion strongly affected protein variance in hippocampus and cortex (n=3,368 proteins). Protein co-expression network analysis identified 16 modules of highly co-expressed proteins common across hippocampus and cortex in 5XFAD and non-transgenic mice. Among the modules strongly influenced by genetic background were those related to small molecule metabolism and ion transport. Modules strongly influenced by the 5XFAD transgene were related to lysosome/stress response and neuronal synapse/signaling. The modules with the strongest relationship to human disease--neuronal synapse/signaling and lysosome/stress response--were not significantly influenced by genetic background. However, other modules in 5XFAD that were related to human disease, such as GABA synaptic signaling and mitochondrial membrane modules, were influenced by genetic background. Most disease-related modules were more strongly correlated to AD genotype in hippocampus compared to cortex. Our findings suggest that genetic diversity introduced by crossing B6 and D2 inbred backgrounds influences proteomic changes related to disease in the 5XFAD model, and that proteomic analysis of other genetic backgrounds in transgenic and knock-in AD mouse models is warranted to capture the full range of molecular heterogeneity in genetically diverse models of AD.

neuroscience↗

bioRxiv2023

Actin polymerization drives lumen formation in a human epiblast model

Lumens or fluid-filled cavities are a ubiquitous feature of mammals and are often evolutionarily linked to the origin of body-plan complexity. Post-implantation, the pluripotent epiblast in a human embryo forms a central lumen, paving the way for gastrulation. While osmotic pressure gradients drive lumen formation in many developmental contexts, mechanisms of human epiblast lumenogenesis are unknown. Here, we study lumenogenesis in a pluripotent-stem-cell-based model of the epiblast using engineered hydrogels that model the confinement faced by the epiblast in the blastocyst. Actin polymerization into a dense mesh-like network at the apical surface generates forces to drive early lumen expansion, as leaky junctions prevent osmotic pressure gradients. Theoretical modeling reveals that apical actin polymerization into a stiff network drives lumen opening, but predicts that a switch to pressure driven lumen growth at larger lumen sizes is required to avoid buckling of the cell layer. Consistent with this prediction, once the lumen reaches a radius of around 12 m, tight junctions mature, and osmotic pressure gradients develop to drive further lumen growth. Human epiblasts show a transcriptional signature of actin polymerization during early lumenogenesis. Thus, actin polymerization drives lumen opening in the human epiblast, and may serve as a general mechanism of lumenogenesis.

developmental biology↗

bioRxiv2023

Piconewton forces mediate GAIN domain dissociation of the latrophilin-3 adhesion GPCR

Latrophilins are adhesion G-protein coupled receptors (aGPCRs) that control excitatory synapse formation. aGPCRs, including latrophilins, are autoproteolytically cleaved at their GPCR-Autoproteolysis Inducing (GAIN) domain, but the two resulting fragments remain associated on the cell surface. It is thought that force-mediated dissociation of the fragments exposes a peptide that activates G-protein signaling of aGPCRs, but whether GAIN domain dissociation can occur on biologically relevant timescales and at physiological forces is unknown. Here, we show using magnetic tweezers that physiological forces dramatically accelerate the dissociation of the latrophilin-3 GAIN domain. Forces in the 1-10 pN range were sufficient to dissociate the GAIN domain on a seconds-to-minutes timescale, and the GAIN domain fragments reversibly reassociated after dissociation. Thus, mechanical force may be a key driver of latrophilin signaling during synapse formation, suggesting a physiological mechanism by which aGPCRs may mediate mechanically-induced signal transduction.

biophysics↗

bioRxiv2022

Wildebeest Herds on Rolling Hills: Flocking on Arbitrary Curved Surfaces

The collective behavior of active agents, whether herds of wildebeest or microscopic actin filaments propelled by molecular motors, is an exciting frontier in biological and soft matter physics. Almost three decades ago, Toner and Tu developed a hydrodynamic theory of the collective action of flocks, or herds, that helped launch the modern field of active matter. One challenge faced when applying continuum active matter theories to living phenomena is the complex geometric structure of biological environments. Both macroscopic and microscopic herds move on asymmetric curved surfaces, like undulating grass plains or the surface layers of cells or embryos, which can render problems analytically intractable. In this work, we present a formulation of the Toner-Tu flocking theory that uses the finite element method to solve the governing equations on arbitrary curved surfaces. First, we test the developed formalism and its numerical implementation in channel flow with scattering obstacles and on cylindrical and spherical surfaces, comparing our results to analytical solutions. We then progress to surfaces with arbitrary curvature, moving beyond previously accessible problems to explore herding behavior on a variety of landscapes. Our approach allows the investigation of transients and dynamic solutions not revealed by analytic methods. It also enables versatile incorporation of new geometries and boundary conditions and efficient sweeps of parameter space. Looking forward, the work presented here lays the groundwork for a dialogue between Toner-Tu theory and data on collective motion in biologically-relevant geometries, from drone footage of migrating animal herds to movies of microscopic cytoskeletal flows within cells.

biophysics↗

bioRxiv2022

Coopting T cell proximal signaling molecules enables Boolean logic-gated CAR T cell control

Introductory paragraphWhile CAR T cells have altered the treatment landscape for B cell malignancies, the risk of on-target, off-tumor toxicity has hampered their development for solid tumors because most target antigens are shared with normal cells1,2. Researchers have attempted to apply Boolean logic gating to CAR T cells to prevent on-target, off-tumor toxicity3-7; however, a truly safe and effective logic-gated CAR has remained elusive8. Here, we describe a novel approach to CAR engineering in which we replace traditional ITAM-containing CD3{zeta} domains with intracellular proximal T cell signaling molecules. We demonstrate that certain proximal signaling CARs, such as a ZAP-70 CAR, can activate T cells and eradicate tumors in vivo while bypassing upstream signaling proteins such as CD3{zeta}. The primary role of ZAP-70 is to phosphorylate LAT and SLP-76, which form a scaffold for the propagation of T cell signaling. We leveraged the cooperative role of LAT and SLP-76 to engineer Logic-gated Intracellular NetworK (LINK) CAR, a rapid and reversible Boolean-logic AND-gated CAR T cell platform that outperforms other systems in both efficacy and the prevention of on-target, off-tumor toxicity. LINK CAR will dramatically expand the number and types of molecules that can be targeted with CAR T cells, enabling the deployment of these powerful therapeutics for solid tumors and diverse diseases such as autoimmunity9 and fibrosis10. In addition, this work demonstrates that the internal signaling machinery of cells can be repurposed into surface receptors, a finding that could have broad implications for new avenues of cellular engineering.

synthetic biology↗

bioRxiv2022

Emergent Actin Flows Explain Diverse Parasite Gliding Modes

During host infection, single-celled apicomplexan parasites like Plasmodium and Toxoplasma use a motility mechanism called gliding, which differs fundamentally from other known mechanisms of eukaryotic cell motility. Gliding is thought to be powered by a thin layer of flowing filamentous (F)-actin1- 3 sandwiched between the plasma membrane and a myosin-coated4,5 inner membrane complex. How this surface actin layer drives the diverse apicomplexan gliding modes observed experimentally - helical, circular, and twirling6,7, and patch8, pendulum9, or rolling2 - presents a rich biophysical puzzle. Here, we use single-molecule imaging to track individual actin filaments and myosin complexes in live Toxoplasma gondii. Based on these data, we hypothesize that F-actin flows arise by self-organization, rather than following a microtubule-based template as previously believed. We develop a continuum model of emergent F-actin flow within the unusual confines provided by parasite geometry. In the presence of F-actin turnover, our model predicts the emergence of a steady-state mode in which actin transport is largely rearward. Removing actin turnover leads to actin patches that recirculate up and down the cell, a "cyclosis" that we observe experimentally for drug-stabilized actin bundles in live parasites. These findings provide a mechanism by which actin turnover governs a transition between distinct self-organized F-actin states, whose properties can account for the diverse gliding modes known to occur. More broadly, we illustrate how different forms of gliding motility can emerge as an intrinsic consequence of the self-organizing properties of F-actin flow in a confined geometry.

biophysics↗

bioRxiv2022

Multi-level force-dependent allosteric enhancement of αE-catenin binding to F-actin by vinculin

Classical cadherins are transmembrane proteins whose extracellular domains link neighboring cells, and whose intracellular domains connect to the actin cytoskeleton via {beta}-catenin, - catenin. The cadherin-catenin complex transmits forces that drive tissue morphogenesis and wound healing. In addition, tension-dependent changes in E-catenin conformation enables it to recruit the actin-binding protein vinculin to cell-cell junctions, where it contributes to junctional strengthening. How and whether multiple cadherin-complexes cooperate to reinforce cell-cell junctions in response to load remains poorly understood. Here, we used single-molecule optical trap measurements to examine how multiple cadherin-catenin complexes interact with F-actin under load, and how this interaction is influenced by the presence of vinculin. We show that force oriented toward the (-) end of the actin filament results in mean lifetimes 3-fold longer than when force was applied towards the barbed (+) end. Further, load is distributed asymmetrically among complexes, such that only one bears the majority of applied load. We also measured force-dependent actin binding by a quaternary complex comprising the cadherin-catenin complex and the vinculin head region, which cannot itself bind actin. Binding lifetimes of this quaternary complex increased as additional complexes bound F-actin, but only when load was oriented toward the (-) end. In contrast, the cadherin-catenin complex alone did not show this form of cooperativity. These findings reveal multi-level, force-dependent regulation that enhances the strength of the association of multiple cadherin/catenin complexes with F-actin, conferring positive feedback that may strengthen the junction and polarize F-actin to facilitate the emergence of higher-order cytoskeletal organization.

biophysics↗

bioRxiv2022

Mechanism of the cadherin-catenin F-actin catch bond interaction

Mechanotransduction at cell-cell adhesions is crucial for the structural integrity, organization, and morphogenesis of epithelia. At cell-cell junctions, ternary E-cadherin/{beta}-catenin/E-catenin complexes sense and transmit mechanical load by binding to F-actin. The interaction with F-actin, described as a two-state catch bond, is weak in solution but is strengthened by applied force due to force-dependent transitions between weak and strong actin-binding states. Here, we provide direct evidence from optical trapping experiments that the catch bond property principally resides in the E-catenin actin-binding domain (ABD). Consistent with our previously proposed model, deletion of the first helix of the five-helix ABD bundle enables stable interactions with F-actin under minimal load that are well-described by a single-state slip bond, even when E-catenin is complexed with {beta}-catenin and E-cadherin. Our data argue for a conserved catch bond mechanism for adhesion proteins with structurally similar ABDs. We also demonstrate that a stably bound ABD strengthens load-dependent binding interactions between a neighboring complex and F-actin, but the presence of the other E-catenin domains weakens this effect. These results provide mechanistic insight to the cooperative binding of the cadherin-catenin complex to F-actin, which regulate dynamic cytoskeletal linkages in epithelial tissues.

biophysics↗