About

Daniel Capelluto is a Professor of Biological Sciences at Virginia Tech, located in the Department of Biological Sciences within the College of Science. His major field of interest includes the biochemistry and structural biology of protein-protein and protein-lipid interactions. His current research focuses on protein domains engaged in Wnt signaling, domains that control blood clotting, multimodular proteins that regulate inflammation processes, and lipid-binding proteins that mediate the entry of oomycetes into plant cells. He has an extensive academic background, including a Ph.D. in Chemical Sciences from the University of Buenos Aires, Argentina, with a thesis on serine hydroxymethyltransferase in Trypanosomatids. His postdoctoral work was conducted at the University of Colorado Health Sciences Center, where he specialized in structural and cell biology. Capelluto has held various academic positions at Virginia Tech, including Assistant Professor and Research Assistant Professor, and has also worked as an instructor at the University of Colorado. His research contributions are recognized through numerous awards, including the Biophysical Society Faculty Bridging Travel Funds Award, the Mary Louise Anderson Cancer Research Award, and the College of Science Diversity Award, among others. He is actively involved in research that advances understanding of protein interactions and cellular processes relevant to health and disease.

Research topics

• Biochemistry
• Computer Science
• Biology
• Chemistry
• Philosophy
• Stereochemistry
• Cell biology

Selected publications

• A TOM1 variant impairs interaction with TOLLIP, autophagosome-lysosome fusion and regulation of innate immunity

  Disease Models & Mechanisms · 2025-09-01 · 2 citations

  articleOpen access

  A recently described G307D variant of the endosomal adaptor protein TOM1 causes severe early-onset multiorgan autoimmunity and combined immunodeficiency. By combining biophysical, biochemical and cell culture experiments, we show that the variant causes a defect in the interaction between TOM1 and TOLLIP, another adaptor protein involved in cargo trafficking and regulation of innate immunity. The G307D variant impairs the ability of TOM1 to reduce TOLLIP phosphatidylinositol 3-phosphate binding, an important regulatory mechanism for cargo trafficking commitment for both proteins. Our experiments using TOM1 G307D patient cells suggested that the variant affects autophagy, seen as an aggravated response to amino acid starvation and accumulation of autophagosomes due to autophagosome-lysosome fusion defect. In addition, inflammatory pathways showed excessive activation in TOM1 G307D patient cells. Our data suggest that the interaction between TOM1 and TOLLIP has a role in the regulation of the human immune system and highlight the importance of fundamental cellular functions, such as cargo trafficking, in controlling immune responses. Our study also provides insights into the caveats of immunomodulatory and stem cell therapies in patients with TOM1 pathogenic variants.

  PublisherOA PDFDOI

• The PER2:BRCA1:POU2F1(OCT-1) ternary complex represents a multi-component scaffold model for circadian gene regulation

  Neurobiology of Sleep and Circadian Rhythms · 2025-11-30

  articleOpen access

  The circadian clock component PER2 coordinates daily oscillations in gene expression across multiple tissues, yet its role in assembling multi-protein regulatory complexes remains incompletely understood. Here, we report that PER2 nucleates a ternary complex with the tumor suppressor BRCA1 and the transcription factor POU2F1(OCT-1) to impose circadian control on target gene promoters. Using bacterial two-hybrid screening, we identified BRCA1 as a novel PER2-interacting protein. Biochemical mapping revealed that PER2 engages BRCA1 through multiple discrete binding interfaces: PER2 spanning residues 356-574 and 683-872 interact with both the N-terminal (1-400) and C-terminal BRCT(1670-1863) domains of BRCA1. Structural modeling predicted 361 residue contacts between PER2 and BRCA1, substantially more than the 74 contacts predicted for PER2:POU2F1(OCT-1), indicating differential affinities that enable ordered complex assembly. Sequential pull-down assays demonstrated that PER2, BRCA1, and POU domain form a stable ternary complex in vitro , with POU2F1(OCT-1) serving as the DNA-binding platform. Electrophoretic mobility shift assays revealed that pre-assembly of PER2 with POU domain inhibits DNA binding, while BRCA1 is essential for stabilizing PER2 recruitment to DNA-bound POU2F1(OCT-1). Using ESR1 as a functional readout, we demonstrate that this ternary complex directly regulates promoter activity. Circadian transcriptome analysis reveals that Esr1 exhibits robust clock-dependent oscillations that are abolished in Per1/2 double-knockout mice, while Pou2f1 and Brca1 maintain constitutive expression. These findings establish PER2 as a circadian scaffold that assembles multivalent protein complexes to temporally gate transcription, providing mechanistic insight into how circadian disruption can influence target gene expression. • PER2 directly interacts with BRCA1 through multiple discrete binding interfaces. • PER2, BRCA1, and POU2F1 (OCT-1) form a ternary complex that coordinately regulates ESR1 transcription. • An ordered assembly of POU2F1 (OCT-1), BRCA1, and PER2 is required at the ESR1 promoter for proper transcriptional regulation. • ESR1 expression exhibits circadian oscillations dependent on functional PER2 but not on rhythmic BRCA1 or POU2F1 expression. • Disruption of the ternary complex by BRCA1 mutations or circadian misalignment may mechanistically link cancer risk to circadian disruption.

  PublisherDOI

• Membrane Composition Modulates Vp54 Binding: A Combined Experimental and Computational Study

  Pathogens · 2025-10-03 · 1 citations

  articleOpen accessCorresponding

  The recruitment of peripheral membrane proteins is tightly regulated by membrane lipid composition and local electrostatic microenvironments. Our experimental observations revealed that Vp54, a viral matrix protein, exhibited preferential binding to lipid bilayers enriched in anionic lipids such as phosphatidylglycerol (PG) and phosphatidylserine (PS), compared to neutral phosphatidylcholine/phosphatidylethanolamine liposomes, and this occurred in a curvature-dependent manner. To elucidate the molecular basis of this selective interaction, we performed a series of computational analyses including helical wheel projection, electrostatic potential calculations, electric field lines simulations, and electrostatic force analysis. Our results showed that the membrane-proximal region of Vp54 adopted an amphipathic α-helical structure with a positively charged interface. In membranes containing PG or PS, electrostatic potentials at the interface were significantly more negative, enhancing attraction with Vp54. Field line and force analyses further confirmed that both the presence and spatial clustering of anionic lipids intensify membrane-Vp54 electrostatic interactions. These computational findings align with experimental binding data, jointly demonstrating that membrane lipid composition and organization critically modulate Vp54 recruitment. Together, our findings highlight the importance of electrostatic complementarity and membrane heterogeneity in peripheral protein targeting and provide a framework applicable to broader classes of membrane-binding proteins.

  PublisherOA PDFDOI

• Soybean Lectin Cross-Links Membranes by Binding Sulfatide in a Curvature-Dependent Manner

  Journal of Agricultural and Food Chemistry · 2025-05-24 · 1 citations

  articleOpen accessSenior authorCorresponding

  -acetyl-d-galactosamine (GalNAc), its lipid interactions remain unexplored. Using a novel purification method, we isolated lectin from soybean meals and characterized its interactions with GalNAc and the glycosphingolipid sulfatide. Isothermal titration calorimetry revealed micromolar affinity for GalNAc, whereas most GalNAc derivatives displayed weak or no binding. Lectin exhibited high-affinity binding to sulfatide in a membrane curvature-dependent manner. Binding of lectin to sulfatide promoted cross-linking of sulfatide-containing vesicles. Whereas sulfatide interaction was independent of GalNAc binding, suggesting distinct binding sites, vesicle cross-linking was inhibited by the sugar. Molecular dynamics simulations identified a consensus sulfatide-binding site in lectin. These findings highlight the dual ligand-binding properties of soybean lectin and may provide strategies to mitigate its antinutritional effects and improve soybean meal processing.

  PublisherDOI

• TOM1 G307D variant alters interaction with TOLLIP impairing autophagosome-lysosome fusion and regulation of innate immunity

  Research Square · 2024-04-05

  preprintOpen access
  PublisherOA PDFDOI

• An Internal Linker and pH Biosensing by Phosphatidylinositol 5-Phosphate Regulate the Function of the ESCRT-0 Component TOM1

  SSRN Electronic Journal · 2024-01-01

  preprintOpen accessSenior author
  PublisherDOI

• An internal linker and pH biosensing by phosphatidylinositol 5-phosphate regulate the function of the ESCRT-0 component TOM1

  Structure · 2024-08-28 · 1 citations

  articleSenior author
  PublisherDOI

• The impact of sulfatide loss on the progress of Alzheimer's disease

  Clinical and Translational Discovery · 2023-08-01 · 2 citations

  articleOpen accessSenior authorCorresponding

  Alzheimer's disease (AD) is a progressive neurogenerative disorder associated with age, marked by a gradual decline in memory, cognitive impairment, and behavioural changes. Among its key pathological traits is the presence of extracellular neuritic plaques enriched in β-amyloid coupled with a decline in neuronal synapses and an accumulation of lipid granules. Within the brain, myelinating glial cells play a crucial role in providing electrical insulation and facilitating the swift propagation of action potential along neuronal axons. Approximately 80% of myelin's dry weight is composed of lipids,1 which not only establish an optimal membrane fluidity but also provide the essential hydrophobic insulation required for effective action potential conduction. The composition of myelin lipids includes cholesterol, phospholipids, and sphingolipids. Among sphingolipids, sphingomyelin, ceramides, and sulfatide (ST) stand out as prominent enriched constituents within myelin membranes.1 ST, predominantly located at the outer leaflet of the cell membrane across all eukaryotic cells, is associated with a variety of cellular processes including platelet aggregation, cell survival, immune responses, and host–pathogen interactions.2 The enzyme cerebroside sulfotransferase, located within the Golgi apparatus, catalyses the conversion of galactocerebroside into ST, whereas the turnover of ST is mediated by the lysosomal arylsulfatase/saposin B complex.2 Lipidomic and metabolomic studies reveal disrupted lipid metabolism in early stages of individuals with AD, evidenced by reduced ST levels (e.g., the study of Hong et al.3) and by near-total depletion of the sphingolipid in the brains of deceased individuals with AD.4 Accumulating evidence underscores the role of glia-mediated inflammation as a major contributor to the progression of AD, including cognitive shortfalls.5 In mice where the enzyme cerebroside sulfotransferase is conditionally knocked out, the loss of ST in the central nervous system triggers the activation of microglia and astrocytes associated with AD, the upregulation of AD-related genes, and the modulation of the immune/microglia network, all of which promote cognitive deficits and neuroinflammation.6 Another major player that is impacted by ST deficiency is apolipoprotein E (ApoE), which participates in the transport of ST to brain cells.7 ST-loaded ApoE is recognised by members of the low-density lipoprotein receptor superfamily, leading to most ST molecules undergoing degradation within late endosomal and lysosomal compartments. The deposition of β-amyloid, resulting from the breakdown of the amyloid protein precursor, serves as a hallmark of AD. The association of ApoE to ST facilitates β-amyloid clearance via an endocytic pathway.8 Experiments carried out using a knockout mice model with deficient levels of ST have revealed that the expression of the ApoE gene is upregulated as a compensatory response to the loss of ST; however, the increased ApoE levels do not trigger the activation of astrocytes and microglia.6 The spinal cord serves as a bridge between the central nervous system and the rest of the body. Clinical dysfunction of the spinal cord has shown associations with patients affected by AD. The degeneration of the spinal cord has been proposed as an internal marker for AD-related dementia.9 Moreover, spinal cord injury has been identified as a factor that increases susceptibility to the development of AD.10 In a recent publication by Xianlin Han and his team, new insights into the impact of ST loss on the progression of AD have emerged. Using shotgun lipidomics, the authors have pinpointed a decrease in the overall lipid content within the spinal cords of AD individuals when compared to the lipid composition observed in the spinal cords of those with normal cognitive function.11 The impact of these changes was more pronounced in white matter compared to grey matter. The reduction in ST levels within myelin lipids extracted from AD patients was remarkable and displayed a correlation with increased severity of tau-associated AD pathology. Alongside the total decline in lipid content, changes in the levels of specific proteins were also detected in the spinal cords of AD patients. For instance, the destabilisation of myelin sheath in AD spinal cords was reflected through a reduction in the levels of myelin-associated oligodendrocyte basic protein, whereas activation of the microglia in these samples was evident by the elevated expression of the microglial marker allograft inflammatory factor 1. Lower urinary tract dysfunction, such as urinary incontinence, tends to manifest during the middle to late stages of AD patients, yet the underlying cause remains elusive. To underpin their findings in AD spinal cords and establish a mechanistic rationale for AD-associated urinary incontinence, Han and colleagues utilised a mouse model deficient in cerebroside sulfotransferase, the enzyme responsible for ST synthesis. The reduction of the total lipid content seen in these mice concurred with the measurements observed in the spinal cords of AD patients. Likewise, changes in the levels of proteins associated with AD were apparent, mirroring the neuroinflammation patterns observed in AD individuals. In the AD micemodel, the urinary bladder was found to be enlarged and heavier in comparison to control mice. Despite having comparable water intake among all mice, those in the AD model displayed a reduced daily urine volume, suggesting a possible connection with their enlarged bladder size. The enlarged bladder was specifically correlated to the impaired function of the central nervous system, a characteristic feature of neurogenic bladder. Through transcriptome analysis of differentially expressed genes, Han and colleagues demonstrated that the loss of ST in both human AD and the mouse model spinal cords prompts enhanced inflammatory responses, accompanied with a deterioration in the function of neurons and oligodendrocytes. Furthermore, in both human AD and the mouse AD model spinal cords, the loss of ST led to the expression of the gene encoding phospholipase C γ2. This membrane-binding enzyme hydrolyses phosphatidylinositol 4,5-bisphosphate, resulting in the production of diacylglycerol and inositol 1,4,5-trisphosphate. These molecules serve as second messengers in pathways that regulate cell survival and cytokine production. Indeed, elevated levels of cytokines were observed in both human AD and mouse AD model spinal cords. Substantial evidence in the literature underscores the pivotal role of ST in maintaining proper neuronal function, and its loss is associated with the onset and progression of AD. The study conducted by Han and colleagues not only supports these notions but also provides insights into the implications of decreased ST levels in both individuals with AD and through the use of an mouse model. These deficits are concomitant with alterations in the regulation of proteins implicated in neural function and lipid metabolism, alongside the manifestation of bladder dysfunction. The novel insights gathered from these findings hold promise for shaping future therapeutic strategies aimed at ameliorating the lives of individuals suffering AD. D.G.S.C. acknowledges support from the National Institutes of General Medical Sciences (R01GM129525). The contents of this article do not represent the views of the National Institutes of Health. The authors declare no conflicts of interest.

  PublisherOA PDFDOI

• Comparative Binding Affinity Analysis of Soybean Meal Bowman-Birk and Kunitz Trypsin Inhibitors in Interactions with Animal Serine Proteases

  ACS Food Science & Technology · 2023-08-08 · 9 citations

  articleOpen accessSenior authorCorresponding

  Raw soybeans are not suitable for consumption due to their high levels of anti-nutritional factors, such as trypsin inhibitors (TIs). The two main TIs in soybean, the Kunitz trypsin inhibitor (KTI) and the Bowman-Birk trypsin inhibitor (BBTI), were isolated to evaluate the impact of meal processing on their binding affinities for animal serine proteases. BBTI showed a ∼10-fold stronger affinity for trypsin compared to KTI, whereas KTI showed a ∼40-fold stronger affinity for chymotrypsin than BBTI. No correlation was observed between the TI concentration in soybean meal and affinity for trypsin. Further analysis using mass spectrometry and protein sequence identified distinct reactive site loops for protease binding in BBTI and KTI variants, which were associated with their binding affinities for specific serine proteases. Our findings indicate that KTI and BBTI have a preference when interacting with specific animal serine proteases, suggesting that both inhibitors are equally important when considering the nutritional quality of soybean meal, regardless of their concentration.

  PublisherDOI

• <i>Xanthomonas euvesicatoria</i> effector <i>Xe</i> AvrRxo1 triggers a Rxo1-mediated defense response in <i>Nicotiana benthamiana</i> and its chaperone Xe4429 functions as an antitoxin, an expression repressor, and an enhancer of <i>Xe</i> AvrRxo1 secretion

  bioRxiv (Cold Spring Harbor Laboratory) · 2023-12-04

  preprintOpen access

  Summary Xanthomonas euvesicatoria ( X. euvesicatoria ) is the causal agent of bacterial spot disease that threatens pepper and tomato production around the globe. X. euvesicatoria gene Xe4428 encodes a type III effector (T3E) that shares 89.67% amino acid identity with Xanthomonas oryzae pv. oryzicola ( Xoc ) T3E AvrRxo1. Deletion of Xe4428 in the genome of X. euvesicatoria (strain Xcv85-10) compromised its virulence to infect pepper and Nicotiana benthamiana plants. Transient co-expression of Xe4428 and Rxo1 on pepper and N. benthamiana plant leaves results in a robust hypersensitive reaction. Thus, Xe4428, renamed as Xe AvrRxo1, is a bona fide orthologue of Xoc AvrRxo1 that possesses both virulence and avirulence functions. Expression of Xe AvrRxo1 in E. coli and X. euvesicatoria is toxic to both bacterial cells. Another X. euvesicatoria gene Xe4429 , encodes a putative chaperone of Xe AvrRxo1, which can interact with XeAvrRxo1 to suppress its toxicity in X. euvesicatoria and E. coli bacterial cells. Xe4429 also binds to the promoter region of XeavrRxo1 and represses its transcription/translation in X. euvesicatoria bacterial cells. In addition, expression of Xe4429 can enhance the secretion and translocation of Xe AvrRxo1 into plant cells. Therefore, Xe4429 functions as an antitoxin, a transcription repressor, and a type III chaperone that is capable of enhancing the secretion and translocation of Xe AvrRxo1 during pathogenesis.

  PublisherOA PDFDOI

Recent grants

• Revealing the regulatory mechanisms of endosomal cargo transporters

  NSF · $841k · 2024–2026

• Molecular mechanism of TIRAP membrane targeting

  NIH · $161k · 2014–2017

• NIH Grant R03HD065999

  NIH · $153k · 2013

Frequent coauthors

• Carla V. Finkielstein

  Biomedical Research Institute

  44 shared

• S. Y. Xiao

  20 shared

• Wen Xiong

  Hubei University of Arts and Science

  18 shared

• Tuoxian Tang

  Virginia Tech

  17 shared

• Jeffrey F. Ellena

  McCormick (United States)

  13 shared

• Xiaolin Zhao

  Northeast Normal University

  11 shared

• Geoffrey S. Armstrong

  University of Colorado Boulder

  9 shared

• Brett M. Tyler

  Oregon State University

  9 shared

Awards & honors

• Biophysical Society, Faculty Bridging Travel Funds Award (20…
• Mary Louise Anderson Cancer Research Award (2016)
• Scholar of the Week, Virginia Tech (2015)
• College of Science Diversity Award (2015)
• Favorite Faculty, Virginia Tech (2014)