PreprintCited by 629Protein Structure and DynamicsMachine Learning in BioinformaticsComputational Drug Discovery Methods

The DOI matches its Crossref record; 68 of the 68 references it cites were found in a registry or an index; none of the 8 sources its claims cite is checked for support yet.

De novo protein design by deep network hallucination

Open access

Preprint — published as 10.1038/s41586-021-04184-w · Paper page

Abstract

There has been considerable recent progress in protein structure prediction using deep neural networks to infer distance constraints from amino acid residue co-evolution 1–3 . We investigated whether the information captured by such networks is sufficiently rich to generate new folded proteins with sequences unrelated to those of the naturally occuring proteins used in training the models. We generated random amino acid sequences, and input them into the trRosetta structure prediction network to predict starting distance maps, which as expected are quite featureless. We then carried out Monte Carlo sampling in amino acid sequence space, optimizing the contrast (KL-divergence) between the distance distributions predicted by the network and the background distribution. Optimization from different random starting points resulted in a wide range of proteins with diverse sequences and all alpha, all beta sheet, and mixed alpha-beta structures. We obtained synthetic genes encoding 129 of these network hallucinated sequences, expressed and purified the proteins in E coli, and found that 27 folded to monomeric stable structures with circular dichroism spectra consistent with the hallucinated structures. Thus deep networks trained to predict native protein structures from their sequences can be inverted to design new proteins, and such networks and methods should contribute, alongside traditional physically based models, to the de novo design of proteins with new functions.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

The authors invert the trRosetta structure-prediction network by Monte Carlo sampling in amino acid sequence space to “hallucinate” new 100-residue proteins with sequences unrelated to native proteins. Of 129 selected designs expressed in E. coli, 27 folded to monodisperse species with CD spectra matching the hallucinated structures, and three experimentally solved structures closely matched the models.

Key findings

  • Hallucinated sequences had very low similarity to native proteins, with best BLAST E-values to UniProt of ~0.1, while their predicted structures had TM-align scores of 0.6–0.9 to native PDB structures.
  • Of 129 hallucinated proteins expressed and purified from E. coli, 27 yielded SEC peaks corresponding to monomeric or small oligomeric species and CD spectra consistent with the target structures; 21 were highly thermostable with apparent melting temperatures above 70 °C, and alpha-beta designs showed no unfolding transitions up to 95 °C.
  • In orthogonal Rosetta folding simulations, 82 of 129 designs had lowest-energy structures close to the hallucinated structures with Cα-RMSDs <3.0 Å, and for all 129 the design model was lower in energy than any structure obtained from an extended chain.
  • Experimental structures matched hallucinated models: NMR structure of design 0515 had ~1.84 Å Cα RMSD to the model; X-ray structure of 0217 at 2.9 Å resolution had 2.53 Å backbone RMSD over all 100 residues; X-ray structure of 0738_mod at 2.4 Å resolution had 3.68 Å Cα RMSD over 96 residues, with N- and C-terminal halves aligning at 1.32 Å over 57 residues and 2.17 Å over 43 residues.

Methods

  • The trRosetta network predicts inter-residue distance and orientation distributions from sequence; a background network with similar architecture but no amino acid sequence identity information provided a reference distribution. The objective combined KL-divergence of trRosetta predictions from the background with negative KL-divergence of amino acid composition from PDB frequencies, optimized by simulated annealing in sequence space with 40,000 attempted moves, starting temperature 0.1 halved every 5,000 steps, cysteines excluded, and length L = 100.
  • Two thousand designs were generated, clustered by TM-score into 95 clusters at a 0.75 threshold; 129 sequences from 27 structural clusters were selected for experimental testing, expressed in E. coli BL21(DE3), purified by IMAC and size-exclusion chromatography, and characterized by circular dichroism, NMR, and X-ray crystallography.
  • Structural comparisons used TM-align, Theseus superposition, and Rosetta ab initio folding simulations; crystallographic data were processed with HKL2000/Scalepack and structures solved by molecular replacement.

Limitations

  • The paper states that many hallucinated proteins form oligomers in solution, likely because the network incorporated sequence features from native protein-protein interfaces; surface hydrophobic substitutions were needed to produce monomeric species in some cases.
  • The paper states that design 0738_mod showed multiple monomeric conformations in slow conformational exchange, and suggests that incorporating an explicit sidechain representation in the hallucination method could reduce such structural heterogeneity.
  • Evident from the text: only 27 of 129 expressed designs folded to monodisperse species, only three structures were determined experimentally, one of those required surface modification, and the study did not test designed functions.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1101/2020.07.22.211482

Cites

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Verification

Claims the paper makes

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Show all 44 claims

  • It may state two separate claims as one. 30
  • The quote only partly states this claim. 2
  • Probably not a substantial claim. 5
35 of 35
  • The paper relies on this without support.

    Random amino acid sequences have a vanishingly small probability of folding to a defined structure.

    “As expected for random sequences, which have a vanishingly small probability of folding to a defined structure”
  • The authors state this as an assumption.

    The background network's predictions can be viewed as representing a generic molten globule state.

    “this can loosely be viewed as representing a generic “molten globule” state”
2 of 2

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Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • The reported resolution for 0217 differs from its table entry

    Minor

    The text reports a 2.9 Å crystal structure for 0217, but the crystallographic table gives its data-collection resolution as 3.0 Å.

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  1. 10.1101/769919 · DOI

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Metadata

Authors
Anishchenko, I., Chidyausiku, T. M., Ovchinnikov, S., Pellock, S. J., & Baker, D.
Affiliations
  • University of Washington (US)
  • Howard Hughes Medical Institute (US)
Corresponding author
Baker, David
Venue
Nature
Publisher
openRxiv
Published
2020-07-23
Volume
600
Issue
7889
Pages
547-552
ISSN
0028-0836 (ISSN-L)
OpenAlex
W3216341763
Cited by
629
References
61
Citations by year
2026: 102 · 2025: 120 · 2024: 139 · 2023: 122 · 2022: 110 · 2021: 29 · 2020: 6
FWCI
31.36
Type
journal article
Language
en
Open access
Locations
  • Nature (publishedVersion)
  • bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
  • PubMed Central (acceptedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
Funders
  • Howard Hughes Medical Institute
  • Novo Nordisk Fonden (NNF18OC0030446)
  • National Institutes of Health (1s10od021527-01, DP5OD026389)
  • National Institute of General Medical Sciences (R01GM120574, R35GM141818, P30GM124165)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Structure and Dynamics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Machine Learning in Bioinformatics
  • Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Drug Discovery › Computational Drug Discovery Methods
Keywords
de novo protein design, deep neural network, hallucinations, protein structure prediction, Kullback-Leibler divergence, synthetic proteins, protein folding, circular dichroism, X-ray crystallography, nuclear magnetic resonance
MeSH terms
Amino Acid Sequence, Hallucinations, Humans, Protein Conformation, Proteins, Neural Networks, Computer, Crystallography, X-Ray

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