This report presents the structural determination and epitope mapping of the conformational anti‑tau antibody DC11. The authors crystallized the antibody Fab fragment and combined biochemical and biophysical assays—ELISA, NMR, and crosslinking mass spectrometry—with computational docking of tau321–391 conformations to define the antibody–antigen interaction. The results link DC11’s conformational specificity to truncated, misfolded tau species and to an antibody‑dependent promotion of tau aggregation observed in vitro.
DC11 is a conformational antibody reported to discriminate between physiological full‑length tau proteins and misfolded, truncated tau proteins. Prior work cited by the authors indicated that DC11 can catalyze in vitro tau aggregation, suggesting it binds a tau conformation that is related to an early or pre‑aggregation state. These functional observations motivated structural and epitope mapping studies to resolve the molecular basis of DC11 specificity.
The Fab fragment of DC11 was crystallized and its structure determined. Structural coordinates are available via the public protein structure repository cited by the authors (PDB accession referenced in the source). The high‑resolution Fab structure provides the molecular scaffold — the paratope geometry and complementarity‑determining region arrangement — required for mapping how DC11 recognizes conformational epitopes on truncated tau.
Binding between DC11 and truncated tau proteins was characterized using multiple, complementary techniques.
ELISA was employed to detect and quantify DC11 reactivity with truncated tau species, confirming selective recognition of non‑native tau forms relative to full‑length tau.
Solution NMR experiments were used to probe the interaction in solution and to detect conformational changes or site‑specific perturbations upon complex formation.
Crosslinking mass spectrometry (XL‑MS) provided distance‑constrained information that supports assignment of interacting regions between DC11 and truncated tau.
Together, these orthogonal methods establish a consistent binding signature and constrain possible epitope locations on the truncated tau constructs analyzed. The source abstract does not report numeric binding affinities, the detailed NMR chemical shift perturbations, or the full list of crosslinked residue pairs; those items would be found in the full preprint and supplementary materials.
To generate a structural model of the antibody–antigen complex, the authors used conformations of a truncated tau segment (tau321–391) sampled by coarse‑grained molecular dynamics simulations. Representative tau321–391 conformations were docked into the DC11 Fab paratope to produce a putative model of the complex that is consistent with crystallographic, NMR, ELISA and XL‑MS constraints.
This integrative modeling approach leverages the resolved Fab structure and experimental interaction data to place the tau segment in a binding orientation compatible with the crosslinking restraints and NMR perturbations reported.
The combination of structural, biophysical and computational evidence supports a model in which DC11 recognizes a conformational state of truncated tau that corresponds to a pre‑aggregation or aggregation‑competent form. This recognition may underlie the previously observed DC11‑mediated catalysis of tau aggregation in vitro. By mapping the epitope and establishing a plausible binding mode, the study provides molecular context for how a conformational antibody can distinguish and potentially modulate tau species linked to pathological aggregation.
The authors cite a structure accession (PDB entry referenced in the source). The preprint lists funders including EU NextGenerationEU, the Scientific Grant Agency of the Slovak Republic and the Slovak Academy of Sciences (VEGA), and the European Union’s Horizon Europe iNEXT Discovery program. The authors declared no competing interests in the preprint.
The source abstract summarizes methods and the integrative strategy but does not include specific experimental parameters or quantitative results. Details not reported in the abstract include numeric affinity measurements, residue‑level contact maps, crystallographic resolution and refinement statistics, and full NMR or crosslinking datasets. These items would need to be consulted in the full preprint or supplementary material for complete interpretation.
The preprint citation and DOI are provided in the source. The authors also reference the public structure deposition (PDB accession noted in the preprint). For full datasets, methods, and residue‑level results, consult the complete preprint and supplementary files as indicated by the authors.