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Research

How PathFold learns folding dynamics

PathFold combines the representational power of large protein language models with constraints from energy-landscape theory to act as a scalable surrogate for molecular dynamics, enabling kinetic inference and misfolding divergence detection across large and diverse protein families.

Training signal

A tiered supervision signal

Direct folding trajectories exist only for a handful of small proteins. PathFold therefore integrates three complementary data tiers, which also makes the central data-availability problem of trajectory-based modelling explicit and tractable.

Tier 1

Direct MD trajectories

Long all-atom MD simulations of ~12 fast-folding proteins under 80 residues and Folding@home subsets, discretised with Markov state models into backbone dihedral distributions, contact probability maps and secondary-structure assignments.

Tier 2

Indirect kinetic observables

For larger proteins without complete trajectories: NMR conformational ensembles, HDX-MS protection factors and Φ-value data serve as partial ordering constraints.

Tier 3

Physics-informed surrogates

Gō-type energy functions, contact-order folding-rate estimates and statistical contact potentials enforce thermodynamic plausibility across the whole dataset, even without direct experimental supervision.

Each trajectory step is represented as a triple of dihedral-angle distribution, contact probability map and secondary-structure vector. For proteins under 100 residues, typically 10 to 30 discrete states capture the main events of structure formation. The modelling target is a coarse-grained, kinetically ordered trajectory, explicitly not atomistic MD resolution.

Foundation

Energy-based latent representation learning

Pre-trained protein language models such as ESM-2 and ProtT5-XL capture rich co-evolutionary dependencies, but their latent spaces are not organised by free energy and do not encode the directed, downhill nature of folding trajectories.

PathFold adapts these embeddings with an energy-informed contrastive learning scheme grounded in energy-landscape theory. Every conformation is described by residue-resolved geometric descriptors (contact maps, torsion angles, solvent exposure, secondary-structure states). A free-energy surrogate, the fraction of native contacts Q combined with a statistical contact potential, assigns a scalar energy to each conformation. Conformations with similar Q form positive pairs, distant ones negative pairs, and an InfoNCE loss in the residue-resolved embedding space pulls energetically adjacent conformations together.

The result is a thermodynamically ordered latent manifold in which neighbouring points represent plausible sequential steps along a folding pathway, the geometric foundation for PathFold-P. A lightweight two-layer MLP projects PLM embeddings (ESM-2 650M: 1280 dims; ProtT5-XL: 1024 dims) into this energy-aligned space.

UnfoldedShared intermediateNative basinKinetic trapEnergy-aligned latent space (schematic) · solid: productive folding · dashed: off-pathway divergence

Trajectory generation model

PathFold-P

A transformer-based generative model that predicts coarse-grained folding trajectories from amino acid sequences while preserving kinetic order, intermediate-state plausibility and thermodynamic consistency along the whole pathway.

  • Encoder–decoder transformer over protein language model embeddings (ESM-2, ProtT5-XL) with geometric inputs: contact maps, dihedral angles, secondary structure.
  • Temporal attention with causal masking introduces directed kinetic order; a score-based diffusion component in the latent space models stochastic relaxation on rugged energy landscapes.
  • Energy-informed training: next-step reconstruction, a free-energy-consistent loss enforcing monotonic descent, and a temporal smoothness constraint.
  • Curriculum learning from peptides under 100 residues (Chignolin, Trp-cage, WW domain) towards full-length proteins.

Misfolding & aggregation model

PathFold-M

A probabilistic model that treats misfolding as a divergence from normal folding trajectories and predicts residue-resolved misfolding and aggregation risk with calibrated uncertainty.

  • Multi-head cross-attention fuses four input streams: PLM sequence embeddings, intermediate trajectory embeddings from PathFold-P, physicochemical residue features and latent energy gradients.
  • Contrastive divergence learning separates stable folding trajectories from experimentally annotated misfolded or aggregation-prone sequences (DisProt, AmyLoad, AmyPro, ClinVar).
  • Diffusion-based augmentation generates synthetic misfolded trajectory segments for families with sparse annotations.
  • A Bayesian variational layer (Monte-Carlo dropout) yields calibrated probabilities; attention attribution localises sequence hotspots and mutation sites driving instability.

Open platform & benchmark

PathFold-Toolbox & DynBench

A modular open-source software suite that integrates both models, plus DynBench, the first standardised benchmarking framework with a public leaderboard for sequence-to-trajectory models.

  • Python SDK with a unified API for trajectory prediction and misfolding risk assessment.
  • Command-line tool for HPC batch inference across protein families and a RESTful API for pipeline integration.
  • Interactive visualisation component for trajectory display and residue-resolved misfolding risk mapping.
  • DynBench metrics: RMSD continuity, energy-descent verification, agreement with NMR / HDX-MS intermediates, residue-resolved precision–recall on disorder and aggregation annotations.

FAIR datasets

P-Track and M-Track

A curated, FAIR-compliant sequence–trajectory dataset that harmonises nine open molecular resources into a single versioned, metadata-rich release, a scientific contribution in its own right.

P-Track

Sequence–trajectory pairs

Folded and structurally well-characterised proteins, built from PDB ensembles, NMR conformers and Folding@home trajectory subsets, providing the folding supervision signal.

M-Track

Sequence–annotation pairs

Intrinsically disordered and amyloidogenic proteins with residue-resolved misfolding and aggregation labels from DisProt, AmyLoad, AmyPro and ClinVar.

Open data sources

Translational relevance

Application to neurodegenerative diseases

As a concrete health-relevance deliverable, PathFold produces variant-resolved dynamic misfolding maps for amyloid-β (Aβ40, Aβ42), tau and α-synuclein in collaboration with DZNE, the three clinically most important proteinopathies.

Neurodegenerative diseases

Variant-resolved dynamic misfolding maps for amyloid-β (Aβ40/Aβ42), tau and α-synuclein, developed together with DZNE as a proof of concept for dynamic biomarker discovery and variant prioritisation.

Protein aggregation diseases

Residue-level misfolding and aggregation risk scores for disease-associated variants and post-translational modifications, as molecular descriptors for early diagnosis and risk stratification.

Membrane protein stability & protein engineering

Trajectory-level stability indicators to support variant interpretation, stability services and precision-medicine oriented protein design.

Outputs

Open artefacts

Everything PathFold produces is released under open licenses.

All resources