Biology subjects

Li, J.

Publications and source records attributed to Li, J..

At least 325 records · Page 18Linked to original sources

bioRxiv2026

Proteomic composition and mutual assembly of the C2a projection in vertebrate motile cilia

The central apparatus of motile cilia, consisting of central microtubules and various protein projections, is essential for dictating the ciliary movement. Although three proteins (FAP65, FAP147, and FAP70) have been localized to the C2a projection in Chlamydomonas reinhardtii, the full protein composition and functional roles of the vertebrate C2a remain inadequately defined. Here, we use three knockout mouse models corresponding to their respective homologs (Ccdc108, Mycbpap, and Cfap70) to systematically investigate their functions in vertebrates. Notably, all three knockout strains exhibit distinct phenotypes related to primary ciliary dyskinesia (PCD), including hydrocephalus and sinusitis. The ciliary incorporation of CCDC108, MYCBPAP, and CFAP70 is essential for one anothers stability, with the loss of any single component triggering C2a collapse, which destabilizes the central pair microtubules and ultimately alters the ciliary movement pattern. Furthermore, we significantly expand the vertebrate C2a proteome by identifying ARMC3 and MYCBP as additional C2a components. Collectively, our findings illuminate the proteomic composition and strict physiological requirements of the vertebrate C2a projection, providing new insights into the molecular pathogenesis of PCD. Impact StatementDeficiency in any of the interdependent C2a proteins (CCDC108, MYCBPAP, and CFAP70) collapses this central pair microtubule-associated projection, disrupting vertebrate ciliary movement and causing primary ciliary dyskinesia phenotypes in mice.

cell biology↗

bioRxiv2026

Metastatic dissemination of breast cancer stem cells requires MenaINV for lung extravasation but not survival

Cancer stemness is a pivotal driver of tumor initiation, treatment resistance, and tumor cell survival. Cancer stem cells (CSCs), though constituting only a small fraction of primary tumor cells, are progressively enriched during metastatic progression: from circulating tumor cells traveling in the bloodstream, to disseminated tumor cells lodged in the lung vasculature, to extravasated tumor cells that have entered tissue parenchyma. However, whether CSCs have an intrinsic advantage for extravasation over cancer non-stem cells (CnSCs), or simply their increased representation in circulation renders them more likely to extravasate, remains unresolved. MenaINV, an invasive isoform of the actin regulatory protein Mena, promotes tumor cell transendothelial migration in primary and secondary sites, yet the direct mechanistic link between stemness and MenaINV in lung metastasis remains unresolved. Here, using a validated fluorescent stemness reporter (SORE6) to identify CSCs, we found that CSCs display elevated MenaINV expression relative to CnSCs. High-resolution intravital imaging showed that CSCs extravasate efficiently into lung parenchyma and survive at higher levels, robustly forming metastatic lesions, while CnSCs show limited extravasation, low survival, and poor colonization. Mechanistically, MenaINV disruption in CSCs specifically impaired extravasation without affecting survival, demonstrating that MenaINV is the key extravasation effector downstream of stemness, whereas stemness-associated factors independently confer survival advantages. Moreover, reintroduction of MenaINV in CnSCs restores their extravasation ability upon which extravasated CnSCs reactivate stem program and form metastases. Overall, we discovered a hierarchical framework where stemness regulates both survival and extravasation capacity, with MenaINV as the key CSC extravasation effector. Significance: This study reveals how breast cancer stem cells achieve metastatic dominance through separable pathways: MenaINV-dependent extravasation and MenaINV-independent survival, providing rationale for targeting stem program to improve patient outcome.

cancer biology↗

bioRxiv2026

Telomere-to-telomere gap-free and phased genome assembly reveals post-allopolyploidization subgenomic diversification of tobacco centromeres

Common tobacco (Nicotiana tabacum) is an economically important crop worldwide whose allotetraploid genome sequence remains incompletely assembled. We report a 4.2Gb telomere-to-telomere gap-free N. tabacum reference genome phased into two subgenomes (subS/subT) , revealing differential evolutionary trajectories between two subgenomes marked by a rapid divergence in paternal T-genome, especially for heterochromatic centromeric regions. To understand the evolutionary dynamics of tobacco centromeres following polyploidization, we characterize the centromere architecture in tetraploid N. tabacum and its diploid progenitors, demonstrating clear subgenomic diversification and repositioning of centromeres during speciation and allopolyploidization. These findings enrich our knowledge on centromere paradox in polyploid genomes.

genomics↗

bioRxiv2026

Macrophage immunosenescence prolongs intraocular inflammation in aged mice via impaired induction of regulatory T cells

Immune-mediated intraocular inflammation, called uveitis, is a leading cause of global blindness, with the highest burden of visual impairment falling on older individuals. Immunosenescence, the functional changes in immune cells with aging, impacts the age-associated immune response, but how immunosenescence and the molecular regulators of the age-associated immune response affect the clinical course of uveitis remains unclear. In the murine model of experimental autoimmune uveitis (EAU), aged mice demonstrated a delayed onset and peak of intraocular inflammation compared to young mice. In contrast to the canonical monophasic inflammation that rapidly resolves in young mice, aged mice developed persistent, chronic inflammation. Transcriptomic and flow-cytometric analyses of immune cells and the receptor-ligand interactome revealed a dominant macrophage-CD4+ T cell signature. This signaling pathway was functionally altered on both ends: macrophages from aged mice had an impaired capacity to generate peripherally induced regulatory T cells (pTreg) through an IL-6 regulated pathway, while CD4+ T cells co-cultured with aged macrophages demonstrated increased proliferation. Our study establishes aging as a key regulator of the effector immune response in uveitis. Regulatory T cells, specifically pTreg, are essential for resolving inflammation in uveitis and an impaired ability to induce pTreg led to a sustained, chronic inflammatory uveitis phenotype in old mice, thereby linking immunosenescence to persistent neuroinflammation. These findings highlight potential therapeutic avenues for vision-threatening uveitis, especially in older patients.

immunology↗

bioRxiv2026

Systematic fusion transcript discovery in mantle cell lymphoma using long-read sequencing

Fusion transcripts are composed of hybrid RNA consisting of transcripts from two distinct genes and can arise from physical linking of genes at the DNA level, splicing or read-through transcription. In addition, there are also fusion transcripts that can occur between a protein coding gene and long non-coding RNAs. Systemic detection of all fusion transcripts at the RNA-level is important in the identification of potential therapeutic drug targets as well as biomarkers for detection, classification, and subtyping of cancer. We used long-read third-generation sequencing of RNA, Iso Sequencing to identify fusion transcripts in Mantle Cell Lymphoma (MCL) cell lines. Our results revealed widespread transcript diversity in MCL. The majority of the long-read transcripts were novel. Some of the thousands of novel transcripts we identified were fusion transcripts. These fusion transcripts had some of the longest transcripts in the MCL transcriptome. We identified the fusion junction of several select fusion transcripts involving protein coding genes including the well-known and widely expressed CTBS::GNG5 and validated their presence using other techniques. Furthermore, we also identified and validated a novel fusion transcript between the multifunctional, m6A methylation writer, RBM15, and LAMTOR5:AS, a long noncoding RNA. Use of the chemical compound, JT-607, an inhibitor of CPSF73/CPSF3 which affects both alternative polyadenylation and read-through transcription resulted in increased expression of the RBM15::LAMTOR5:AS fusion transcript. Our analysis suggests that RBM15::LAMTOR5:AS and many fusion transcripts we identified are intrachromosomal. Since the origin, significance and impact of many fusion transcripts remain unknown, our results support using an unbiased approach to identify fusion transcripts. This will help us to fully comprehend the complexity of the human transcriptome in normal biology and in disease.

genetics↗

bioRxiv2026

Molecular Imaging of Collagen Turnover in Myocardial Infarction

Cardiac fibrosis is a key contributor to cardiomyopathy after myocardial infarction (MI). Existing imaging techniques can detect established fibrotic changes; however, they lack sensitivity for ongoing collagen turnover--a dynamic process involving the denaturation of collagen triple helix. Molecular imaging of this process could enhance risk assessment and aid in the development of anti-fibrotic treatments. This study aimed to evaluate 99mTc-(HE)-(GPO), a radiotracer designed to target denatured collagen, as a biomarker of collagen turnover after MI. Methods99mTc-(HE)-(GPO) incorporates glycine-proline-hydroxyproline (GPO) repeats and can hybridize with denatured single- or double-stranded collagen. MI was induced in mice by ligation of the left anterior descending artery; sham-operated animals served as controls. At 2 weeks post-MI, animals underwent myocardial perfusion imaging or contrast-enhanced CT to detect the infarct zone, followed by SPECT/CT imaging using 99mTc-(HE)-(GPO) or a control scrambled tracer. Tracer uptake was quantified in vivo and ex vivo with gamma counting and autoradiography. Different aspects of fibrosis were examined by tissue analysis, along with autoradiography with a matrix metalloproteinase-targeted radiotracer, 99mTc-RYM1. Tracer binding was also assessed in human cardiac tissue through ex vivo autoradiography. Results99mTc-(HE)-(GPO) SPECT/CT revealed significantly higher tracer uptake in the infarct zone of MI mice compared to the remote zone and sham controls (P < 0.0001 for both). Tracer uptake was confirmed by autoradiography, which showed a strong correlation between SPECT and autoradiography (R = 0.81, P < 0.01). The scrambled tracer exhibited minimal cardiac uptake, demonstrating the specificity of 99mTc-(HE)-(GPO) signal. Denatured collagen staining and 99mTc-RYM1 autoradiography showed similar patterns as ex vivo 99mTc-(HE)-(GPO) autoradiography, while the ratio of denatured collagen to procollagen in the infarct zone significantly increased from day 3 to 2 weeks post-MI. Finally, 99mTc-(HE)-(GPO) bound to human fibrotic (but not normal) cardiac tissue. Conclusion99mTc-(HE)-(GPO) enables non-invasive detection of denatured collagen as a marker of collagen remodeling in vivo, offering a promising tool for assessing fibrotic remodeling after MI. Collagen, procollagen, and denatured collagen, along with MMP activation, exhibit distinct patterns, and their combined imaging may provide a comprehensive molecular fingerprint of cardiac fibrosis, advancing personalized management of cardiomyopathy.

bioengineering↗

bioRxiv2026

Progranulin deficiency induces lipid droplet accumulation in microglia via a STAT3-GPAT3 axis

Heterozygous mutations in the progranulin (PGRN) encoding gene GRN cause frontotemporal dementia (FTD), whereas homozygous GRN mutations lead to neuronal ceroid lipofuscinosis (NCL). However, the mechanisms underlying neurodegeneration due to PGRN deficiency remain unclear. In the aged brains or under neurodegenerative conditions, the accumulation of lipid droplets (LDs) in microglia contributes to cellular dysfunction and pro-inflammatory responses, exacerbating neurodegenerative pathology. Here, we investigated how PGRN deficiency induces LD accumulation in microglia. We found that PGRN ablation significantly upregulated triglycerol-3-phosphate acyltransferase 3 (GPAT3), the first and rate-limiting enzyme for triacylglycerol biosynthesis, and increased LD formation in both Grn-/- BV2 microglial cells and Grn-/-mouse brains. Mechanistic study revealed that PGRN deficiency upregulates GPAT3 via stimulating signal transduction and activator of transcription factor 3 (STAT3) signaling. Silencing Gpat3, inhibiting GPAT3 activity with the small molecule inhibitor FSG67, or PGRN restoration reduced LD accumulation and rescued the cytotoxicity of Grn-/- microglia conditional medium (MCM) toward N2a cells. Notably, intraperitoneal administration of FSG67 or AAV-MG1.2-mCx3cr1-mGrn-eGFP-mediated microglia-specific gene therapy reduced microglial LDs and ameliorated behavior phenotypes in Grn-/- mice. Our study elucidates the role of PGRN loss in microglial lipid homeostasis and identifies the STAT3-GPAT3 axis as a potential therapeutic target for LD-associated neurodegenerative diseases.

neuroscience↗

bioRxiv2026

A dual-factor complex governs archaeal ribosome hibernation by sensing energy status

Efficient coupling of cellular energy status to ribosome regulation is fundamental for cellular survival. Here, we identify the Archaeal Ribosome regulatory Complex (ARC)--a previously uncharacterized dual-factor complex comprising ARC-P and ARC-A. Cryo-EM reveals that ARC anchors to the small ribosomal subunit, establishing a stringent blockade of the tRNA and mRNA paths via an electrostatic wedge mechanism. This hibernation state is modulated by energy status: the complex remains stably associated under low-energy conditions, whereas ATP binding triggers rapid mobilization. Genetic analyses demonstrate that ARC acts as a translational brake essential for preserving ribosomal structural integrity, with ARC-A serving as the primary inhibitory factor. Notably, while the loss of ARC accelerates growth, it impairs recovery in proportion to stress severity. Phylogenomic analysis identifies ARC as an evolutionarily novel and widely distributed dual-factor system, revealing a conserved regulatory strategy for metabolic-translational coupling across diverse archaea. Our findings define a fundamental strategy where modular complexes integrate metabolic sensing with mechanical sequestration to balance growth and persistence.

biochemistry↗

bioRxiv2026

Isolation and Characterisation of Hair Follicle-Derived Melanocytes

Melanocytes are unique population of cells which produce melanin pigment. However, the property of melanocytes from hair follicle and epidermis, particularly, their molecular signatures remained largely unknown. In this study, we investigated the properties of epidermis and hair follicle melanocytes by biochemical and molecular biological assays. We found that epidermal melanocytes are differentiated and mature form of hair follicle melanocytes, and they are potentially related. Irradiation with NB-UVB did not induce cell death of hair follicle melanocytes as observed in epidermal melanocytes, but activate hair follicle melanocytes, promote proliferation and migration. In situ study suggested that after UVB irradiation, root sheath of hair follicles, particularly proximity of interfollicular epidermis and hair bulb become darker, suggesting migration and maturation of hair follicle melanocytes after UVB irradiation, rather than cell death. This observation provides hints and evidence to the relationship between hair follicle and epidermal melanocytes, helps to explain the contradiction of melanocytes cell death after UVB irradiation and the use of UVB in treatment of vitiligo lesion, as well as the perifollicular repigmentation phenomenon observed in vitiligo lesion after NB-UVB phototherapy.

cell biology↗

bioRxiv2026

An Asynchronous Production Line of Meiotic Prophase I in the Mouse Fetal Ovary

The initiation of meiosis in the mammalian female germline has long been described as a synchronous event, occurring within a narrow developmental window. Here, we challenge this paradigm through a systematic, quantitative analysis of meiotic entry and progression in the mouse fetal ovary. Using dynamic expression profiling of key regulators Stra8, Sycp1, and Sycp3 alongside proliferation markers, we demonstrate that germ cells enter meiosis asynchronously and continuously between embryonic days E12.5 and E16.5. During this extended period, mitotic proliferation persists, indicating that germ cells are progressively recruited into the meiotic pathway rather than halting division simultaneously. Homologous chromosome synapsis, marked by Sycp1/Sycp3 co-localization, initiates at E14.5 and is completed prenatally by E18.5. Integrating these data into a continuous-time Markov chain model, we derive a "meiotic clock" that predicts fixed temporal intervals from meiotic entry to synapsis completion ([~]72 hours) and to meiotic arrest ([~]91 hours), regardless of entry time. This model provides a predictive framework for germ cell development and establishes that female meiotic initiation is a prolonged, asynchronous production line rather than a synchronized transition, reshaping our understanding of oogenesis and its regulatory logic. TEASERThe initiation of female meiosis in mice is redefined as an asynchronous, continuous production line from E12.5 to E16.5, supported by a predictive "meiotic clock" model with fixed temporal intervals for synapsis and arrest.

developmental biology↗

bioRxiv2026

Deep learning-guided design of cell type-specific AAV promoters

Precise cell type targeting is critical for both clinical and experimental applications of adeno-associated viral (AAV) vectors, yet engineering vectors with cell type-specific activity remains a challenge. Here, we compared three strategies leveraging single-cell chromatin accessibility data to design cell type-specific AAV promoters, including a deep learning-based method to generate de novo regulatory sequences. When applied to target retinal ganglion cells or horizontal cells in mouse retina, deep learning-guided design consistently outperformed rational approaches, yielding synthetic promoters with stronger and more specific expression in vivo. Synthetic AAV promoters supported diverse transgenes, enabling the recording and ablation of targeted cells. Promoter activity was also maintained in human retinal organoids, suggesting that deep learning-designed sequences may be suitable for translation. Our findings highlight the potential of deep learning to synthesize cell type-specific AAV promoters and establish a versatile platform for cell type targeting with broad implications for gene therapy and basic research.

synthetic biology↗

bioRxiv2026

Hierarchical Encoding of Regulatory Mechanisms and Expression Syntax by a foundational genomic sequence-to-function model

Deciphering the comprehensive regulatory rules encoded in the genomic sequence remains a central challenge in functional genomics, requiring a paradigm shift from descriptive annotations to a mechanistic understanding of the entire genome. Here, we introduce HERMES (Hierarchical Encoding of Regulatory Mechanisms and Expression Syntax), a framework that progressively defines a fundamental sequence vocabulary for the complex regulatory genome and parses gene expression syntax into transparent biological insights. Specifically, we trained a foundational sequence-to-function model on a massive compendium of 137,127 functional genomics profiles spanning diverse biochemical marks and cellular conditions, including DNA methylation, transcription factor binding, polymerase binding, histone marks, chromatin accessibility and RNA expression across various tissues, cell lines and cell types. By harnessing the high-fidelity sequence representations of HERMES, we established a context-specific regulatory vocabulary comprising 40 distinct sequence classes and fine-grained subclusters spanning the entire genome. We interrogated the sequence determinants of diverse promoters and tissue-specific enhancers, and further identified a housekeeping genes-specific promoter sub-class, driven by ETS, YY1 and CCAAT motifs. To further decode transcriptional regulation, HERMES was leveraged to predict cell-type-specific gene expression and the enhancer perturbation effects. Extensive evaluations confirmed that the cis-regulatory elements and their interactions were captured to predict gene expression underlying different cellular conditions, and simultaneously revealed divergent enhancer dependencies between housekeeping genes (HKGs) and highly variable genes (HVGs). Ultimately, we distilled the complex sequence-to-function model into a biologically interpretable rulebook of Enhancer-Promoter interaction grammar. Synthesizing all the insights, we propose a unified compatibility model, where HKGs utilize a strong-promoter architecture for high-output expression, while HVGs depend on a context-dependent syntax driven by compatible promoters and enhancers. In summary, HERMES bridges the gap between predictive modeling and biological mechanism, transforming sequence representations into a comprehensive functional encyclopedia and a quantitative grammar of the complex regulatory genome.

bioinformatics↗

bioRxiv2026

Stimulated human cortical waves: spatiotemporal dynamics across development

Traveling waves of neural activity are fundamental to cortical function, yet their spatiotemporal dynamics and structural constraints remain less understood in human brain. Conventional analyses focus on network topology and spatial geometry of neural signals, with limited emphasis on wave dynamics at high spatiotemporal resolutions. Here, we applied a manifold-based optical flow algorithm to an open-access intracranial electroencephalography (iEEG) dataset from the single-pulse stimulation cortico-cortical evoked potentials (CCEPs) paradigm, enabling direct construction of high-temporal-resolution cortical neural activity velocity fields. Spatiotemporal mode decomposition revealed a hierarchical organization: large-scale plane waves (mediating global propagation) dominate, complemented by local patterns for local computation. Dominant plane wave directions correlate with underlying white matter fibre tract orientations, indicating anatomical guidance of cortical dynamics. Velocity field singularities (sources, sinks, spirals and saddles) are non-randomly distributed, associating with default mode network (DMN) hubs. We further identified a nonlinear relationship between cortical wave speed and age, with developmental phases paralleling white matter maturation and aging. Our findings link cortical wave dynamics to anatomy, functional networks, and neurodevelopment, establishing wave speed as a potential yet important biomarker for brain function and health.

neuroscience↗

bioRxiv2026

Healthcare Infrastructure Shapes Evolutionary Trade-offs and Geographic Dissemination of Multidrug-Resistant Acinetobacter baumannii

Antimicrobial-resistant pathogens pose an existential threat to modern medicine, yet the evolutionary forces driving their adaptation in healthcare systems remain largely unexplored. We revealed that hospital network architecture functions as a primary selective pressure, driving pathogen evolution through infrastructure-dependent virulence-transmission trade-offs. Phylogenomic analysis of 5,023 Acinetobacter baumannii isolates across Chinas centralized healthcare system identifies two co-existing evolutionary strategies: a virulence-optimized clade (ESL2.4) that spread slowly (20.4 km per year) in low-connectivity hospitals, and a transmission-optimized clade (ESL2.5) that disseminate rapidly (65.2 km per year) through mega-city healthcare hubs, likely attributed to its capsule conversion and increased upper respiratory colonization. Comparative analysis with European A. baumannii populations demonstrates that healthcare connectivity, not geography, governs pathogen distribution through convergent genomic adaptations. Our simulation suggests competitive asymmetries of the two clades, following the ecotype principle and enabling stable coexistence. The COVID-19 pandemic provided a natural experiment validating these mechanisms: outpatient restrictions reduced transmission-optimized lineage spread by 89%, while virulence-optimized lineage persisted through inpatient networks. These findings establish healthcare infrastructure as a critical evolutionary driver with immediate implications for predicting and controlling antimicrobial resistance emergence across diverse healthcare systems.

microbiology↗

bioRxiv2026

Isothermal Detection of Influenza D using RT-LAMP

The Orthomyxoviridae family includes influenza D virus (IDV), an emerging pathogen primarily affecting cattle and swine, with evidence of cross-species transmission and potential zoonotic risk. Although active human infections have yet to been confirmed, high seroprevalence in cattle-exposed populations highlights the need for continued surveillance. Here, a rapid, field-deployable RT-LAMP assay for IDV detection was developed and validated, with 99.2% specificity and sensitivity ranging from 95.6% (Cq < 30) to 81.8% (Cq < 40). This method offers a cost-effective, accessible alternative to RT-qPCR, enabling improved monitoring of IDV, and reinforcing preparedness for emerging influenza threats.

microbiology↗

bioRxiv2026

A mediterranean-mimicking diet harnesses gut microbiota-derived 3-IAA to rejuvenate T cell

Diet profoundly shapes the tumor microenvironment through metabolite modulation, yet the mechanisms linking diet, gut microbiota, and antitumor immunity remain unclear. Here, we demonstrate that a mediterranean-mimicking diet (MedDiet) suppresses tumor growth by orchestrating a microbiota-metabolite-immune axis. MedDiet selectively enriched Bacteroides thetaiotaomicron (B. thetaiotaomicron) in the gut, whose administration recapitulated tumor suppression. Both MedDiet and B. thetaiotaomicron elevated plasma levels of the tryptophan metabolite indole-3-acetic acid (3-IAA). Mechanistically, 3-IAA enhanced CD8+ T cell cytotoxicity and alleviated exhaustion by inhibiting the integrated stress response, sustaining antitumor immunity in vivo. Importantly, 3-IAA synergized with anti-PD-1 therapy to further restrain tumor progression. Finally, we developed a MedDiet Score to predict patient survival and response to immunotherapy. These findings reveal that dietary modulation of gut microbiota can reshape systemic metabolites to potentiate T cell-mediated antitumor responses. Our study identifies 3-IAA as a metabolite-based adjuvant for immune checkpoint therapy and highlights the translational potential of diet-driven immunomodulation in cancer treatment.

cancer biology↗

bioRxiv2026

Mena (ENAH) Promotes KRAS-Driven Tumor Growth and Metastatic Progression in Pancreatic Ductal Adenocarcinoma

Metastatic pancreatic ductal adenocarcinoma (PDAC) remains incurable and is projected to become the second leading cause of cancer-related death by 2030. Despite therapeutic advances, median survival remains under one year. Activating KRAS mutations drive the majority of PDAC and underlie their highly aggressive behavior. Although emerging KRAS inhibitors show promise, resistance limits their clinical efficacy, underscoring the need to identify additional regulators of mutant KRAS signaling. We investigated the role of the actin-regulatory protein Mena (ENAH) in KRASG12D-driven PDAC using novel in vitro and orthotopic in vivo models with Mena overexpression and knockdown. Mena overexpression markedly increased primary tumor growth and spontaneous liver metastasis, whereas Mena knockdown delayed tumor onset and reduced metastatic burden. Mechanistically, Mena depletion significantly decreased AKT and ERK activity downstream of KRAS in a SHIP2-mediated manner, indicating that Mena enhances oncogenic signaling required for PDAC progression. These findings reveal Mena as a critical modulator of KRASG12D-driven pancreatic tumor growth and metastasis. By promoting key survival and proliferation pathways, Mena contributes to the aggressive phenotype characteristic of KRAS-mutant PDAC and represents a promising therapeutic target for patients with both locoregional and metastatic disease.

cancer biology↗

bioRxiv2026

Probing the scalability of ultra stable catch bond complexes

The catch bond complex between serine-aspartate repeat protein G (SdrG) from Staphylococcus epidermidis and the beta chain of fibrinogen (Fg{beta}) exhibits two distinct rupture populations when dissociated under tensile force. Such complexes present exciting possibilities for developing dynamic biomaterials due to their unique response to shear force. However, the environmental responsiveness of this complex and its influence on adhesion behaviour in multi-valent systems remain underexplored. Using AFM-single molecule force spectroscopy (AFM-SMFS) and spinning disk adhesion (SDA) assays, we examined how protein orientation, mutations, and environment influence the stability and scaling behaviour of this catch bond system. Our findings confirmed that anchor point location (i.e., the direction from which the protein is pulled) strongly influences catch bond behaviour, while an S338H mutation in the binding domain destabilised the interaction in both single-molecule and multi-valent adhesion assays. This research examines how catch bond behaviour translates from the nanoscale to microscale using single molecule and multi-valent cell adhesion measurements and provides a toolkit for exploiting catch bonds towards macroscale material applications.

biophysics↗