Cited by 686Protein Structure and DynamicsEnzyme Structure and FunctionBiochemical and Structural Characterization

The DOI matches its Crossref record; 107 of the 107 references it cites were found in a registry or an index; none of the 83 sources its claims cite is checked for support yet.

3D domain swapping: As domains continue to swap

Open access
Liu, Yanshun, Eisenberg, David·2002·Protein Science

Abstract

Three‐dimensional (3D) domain swapping creates a bond between two or more protein molecules as they exchange their identical domains. Since the term '3D domain swapping' was first used to describe the dimeric structure of diphtheria toxin, the database of domain‐swapped proteins has greatly expanded. Analyses of the now about 40 structurally characterized cases of domain‐swapped proteins reveal that most swapped domains are at either the N or C terminus and that the swapped domains are diverse in their primary and secondary structures. In addition to tabulating domain‐swapped proteins, we describe in detail several examples of 3D domain swapping which show the swapping of more than one domain in a protein, the structural evidence for 3D domain swapping in amyloid proteins, and the flexibility of hinge loops. We also discuss the physiological relevance of 3D domain swapping and a possible mechanism for 3D domain swapping. The present state of knowledge leads us to suggest that 3D domain swapping can occur under appropriate conditions in any protein with an unconstrained terminus. As domains continue to swap, this review attempts not only a summary of the known domain‐swapped proteins, but also a framework for understanding future findings of 3D domain swapping.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

This review summarizes about 40 structurally characterized 3D domain-swapped proteins, emphasizing diverse swapped domains, flexible hinge loops, and examples including RNase A, T7 helicase, human prion, and cystatin C. It proposes that 3D domain swapping can occur under appropriate conditions in any protein with an unconstrained terminus and may relate to oligomerization, allostery, and amyloid formation.

Key findings

  • About 40 domain-swapped proteins have known structures; all swapped domains except one are from either the N or C terminus, and swapped domains vary widely in size, sequence, and secondary structure, with no specific sequence motif found.
  • RNase A can swap both N- and C-terminal domains: structures include the N-terminal swapped dimer (2.1 Å), C-terminal swapped dimer (1.75 Å), and cyclic C-terminal swapped trimer (2.2 Å); RNase A is the first protein found to form both linear and cyclic domain-swapped oligomers.
  • Blood coagulant factor IX/X-binding protein is the only known example of 3D domain swapping in the middle of the molecule and the only known domain-swapped heterodimer; T7 gene 4 ring helicase forms open oligomeric domain swapping along a six-fold screw axis and requires swapping for hexamerization and activity.
  • Human prion and human cystatin C form domain-swapped dimers and are amyloidogenic, suggesting domain swapping and amyloid formation may share common intermediates; physiological relevance is supported for some proteins, such as RNase A dimerization at pH 6.5 and 37°C with a dissociation constant of ∼2 mM, but considered artifact for others such as barnase at pH 4.5 and truncated TrkA Domain 5.

Methods

  • Review and structural synthesis of domain-swapped proteins, tabulating bona fide examples, quasi-domain-swapped proteins, and candidates in Tables 1–3 with PDB codes, residue counts, swapped domains, hinge loops, and functions.
  • Compares crystal and NMR structures plus biochemical data from cited studies, with detailed discussion of six examples: IX/X-binding protein, RNase A trimers, glyoxalase I, T7 helicase, human prion, and human cystatin C.
  • Main analysis is qualitative structural comparison and synthesis of a free-energy/mechanism model for 3D domain swapping.

Limitations

  • The paper states that the mechanism of 3D domain swapping remains elusive, few studies have examined it, and it is unclear whether the domain-swapped dimer is the building block for amyloid fibers.
  • The paper states that RNase A tetramer structures are unknown and models are hypothetical; glyoxalase I C-terminal domain swapping is ambiguous because there are two ways to define the monomer, and the crystal structure of the monomer is needed.
  • Evident from the text: this is a review without new experimental data, and some hinge-loop residues in candidate proteins are speculative and marked with question marks.

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

Integrity signals

Registry

Crossref · 10.1110/ps.0201402

Cites

107 of 107 references verified0 citation errors · 0 not checkable

Statistics

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Verification

Claims the paper makes

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Show all 61 claims

  • Probably not a substantial claim. 3
  • It may state two separate claims as one. 46
48 of 48
  • The paper relies on this without support.

    The set of about 40 structurally characterized domain-swapped proteins is representative of domain-swapped proteins generally.

    “Analyses of the now about 40 structurally characterized cases of domain-swapped proteins reveal that most swapped domains are at either the N or C terminus”
    “To date, about 40 domain-swapped proteins have known structures.”
  • The paper relies on this without support.

    The biochemical behavior of Pseudomonas putida Glx I (55% sequence identity to human Glx I) can be used to infer the active-site completeness and domain-swapping state of human Glx I.

    “Biochemical data show an equilibrium of monomer and dimer in Glx I from Pseudomonas putida (55% sequence identity to human Glx I), and both the monomer and the dimer are active (Saint-Jean et al. 1998).”
    “Based on these biochemical data, we regard human Glx I as a protein with two domains swapped, as proposed by Cameron et al. (1997).”
  • The paper relies on this without support.

    Thermodynamic activity exceeds concentration.

    “That is, thermodynamic activity exceeds concentration.”
  • The paper relies on this without support.

    The greater entropy of the monomer makes it more favored thermodynamically.

    “First, the greater entropy of the monomer makes it more favored thermodynamically.”
4 of 4

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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.

  • C-terminal-swapped trimer is called N-terminal-swapped

    Minor

    The sentence calls the cyclic RNase A trimer N-terminal-swapped but then says it swaps C-terminal strands. Elsewhere, the paper identifies the cyclic trimer as C-terminal-swapped.

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Metadata

Authors
Liu, Y., & Eisenberg, D.
Affiliations
Howard Hughes Medical Institute (US)
Corresponding author
Eisenberg, David
Venue
Protein Science
Publisher
Wiley
Published
2002-06
Volume
11
Issue
6
Pages
1285-1299
ISSN
  • 0961-8368 (ISSN-L)
  • 1469-896X
OpenAlex
W2160082320
Cited by
684
References
106
Citations by year
2026: 6 · 2025: 15 · 2024: 16 · 2023: 14 · 2022: 12 · 2021: 37 · 2020: 21 · 2019: 21 · 2018: 18 · 2017: 18 · 2016: 41 · 2015: 31 · 2014: 34 · 2013: 25 · 2012: 35
FWCI
3.37
Type
journal article
Language
en
Open access
Locations
  • Protein Science (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • National Science Foundation
  • National Institutes of Health
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Structure and Dynamics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Structural Biology › Enzyme Structure and Function
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Biochemical and Structural Characterization
Keywords
protein-protein interaction, diphtheria toxin, amyloid proteins, protein flexibility, protein structure
MeSH terms
Animals, Humans, Models, Molecular, Protein Binding, Proteins, Protein Structure, Tertiary, Dimerization

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