Cited by 461Protein Structure and DynamicsEnzyme Structure and FunctionReceptor Mechanisms and Signaling

Protein Ensembles: How Does Nature Harness Thermodynamic Fluctuations for Life? The Diverse Functional Roles of Conformational Ensembles in the Cell

Open access
Wei, Guanghong, Xi, Wenhui, Nussinov, Ruth, Ma, Buyong·2016·Chemical Reviews

Abstract

All soluble proteins populate conformational ensembles that together constitute the native state. Their fluctuations in water are intrinsic thermodynamic phenomena, and the distributions of the states on the energy landscape are determined by statistical thermodynamics; however, they are optimized to perform their biological functions. In this review we briefly describe advances in free energy landscape studies of protein conformational ensembles. Experimental (nuclear magnetic resonance, small-angle X-ray scattering, single-molecule spectroscopy, and cryo-electron microscopy) and computational (replica-exchange molecular dynamics, metadynamics, and Markov state models) approaches have made great progress in recent years. These address the challenging characterization of the highly flexible and heterogeneous protein ensembles. We focus on structural aspects of protein conformational distributions, from collective motions of single- and multi-domain proteins, intrinsically disordered proteins, to multiprotein complexes. Importantly, we highlight recent studies that illustrate functional adjustment of protein conformational ensembles in the crowded cellular environment. We center on the role of the ensemble in recognition of small- and macro-molecules (protein and RNA/DNA) and emphasize emerging concepts of protein dynamics in enzyme catalysis. Overall, protein ensembles link fundamental physicochemical principles and protein behavior and the cellular network and its regulation.

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Crossref · 10.1021/acs.chemrev.5b00562

Cites

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Claims the paper makes

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  • Findingnone given

    Cys322 is located in a well-formed helix critical for catalysis.

    “Cys322 is located in a well-formed helix, which is critical for catalysis.”
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  • Findingown data

    REMD-predicted and experimentally measured Cα SCSs for K18 have a Pearson correlation coefficient of 0.614.

    “The REMD-predicted and experimentally measured Cα SCSs show a Pearson correlation coefficient of 0.614 (Fig. 6 C), consistent with previous NMR data.371”
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  • Findingown data

    K18 monomer has both ordered and disordered nature, as revealed by representative conformations of top eight most-populated RMSD-based clusters.

    “Representative conformations of the top eight most-populated RMSD-based clusters (Fig. 6 A, B) reveal the both ordered and disordered nature of the K18 monomer.”
    Quote in the paperNot a substantial claim
  • Findingown data

    In K18 monomer, cysteine-containing sequences 283DLSNVQSKCGS293 in R2 and 314DLSKVTSKCGS324 in R3 transiently sample α-helical structure.

    “Our REMD-generated data of K18 monomer show that cysteine-containing sequences 283DLSNVQSKCGS293 in R2 and 314DLSKVTSKCGS324 in R3 transiently sample α-helical structure (Fig. 7 A).”
    Quote in the paperSubstantial claim
  • Premisecitation

    In solution, protein conformational fluctuations cause even stable proteins to form ensembles of highly populated substates with thermodynamic population distributions.

    “Conformational fluctuations of proteins in solution,11 as revealed mostly by nuclear magnetic resonance (NMR) experiments and computations, make even stable proteins exist as conformational ensembles with highly populated substates whose populations follow thermodynamic distributions.12–16”
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    Findingreasoning

    A volume change of −20 to −100 mL/mol translates to a free energy change of −0.5 to −2 kcal/mol per kbar, enough to alter which conformational state dominates at high pressure.

    “In a typical case, the partial molar volume change is about −20 to −100 mL/mol, which means the free energy change is on the order of −0.5 to −2 kcal/mol per 1 kbar which may be sufficient to shift state B as the dominant species under elevated pressure in place of state A.”
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    Findingreasoning

    For a typical 25 kDa protein, the root mean square fluctuations of energy and volume are approximately 38 kcal/mol and 80 Å3, respectively.

    “One could estimate that the root mean square fluctuations of E and V are respectively:16 〈ΔE2〉≈38kcalmol−1, 〈ΔV2〉≈80Å3.”
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    Findingown data

    The lysine-cysteine distance distribution in K18 shows peaks between 5 and 10 Å, indicating the two residues are close enough as in acetyltransferase (Cα−Cα distance 8.4 Å between Lys262 and Cys304).

    “The lysine−cysteine distance distribution curve in Fig. 7 (B) displays peaks between 5 and 10 Å, indicating that the two residues are close enough as in acetyltransferase with a Cα−Cα distance of 8.4 Å between Lys262 and Cys304.380”
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    Premisecitation

    When projected onto a coordinate like the fraction of native contacts, the folding landscape appears as a funnel, which resolves Levinthal's paradox.

    “Mapping the folding landscape to a single coordinate, such as the fraction of native contacts, the energy landscape can be visualized as a funnel,132 elegantly resolving Levinthal’s paradox.11”
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    Premisecitation

    Greater protein flexibility correlates with more populated states, and disordered states lie at the extreme of this range.

    “The more flexible are the proteins the larger the number of their populated states, with the disordered state being at the end of this spectrum.17”
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    Premisecitation

    Statistical energy landscape theory originated as a framework for studying protein folding.

    “The statistical energy landscape theory was developed to study protein folding.1,128–131”
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    Premisecitation

    Within one unit cell, crystal proteins may adopt different conformations, and the crystal state does not capture multiple populated substates.

    “It is now generally accepted that crystal proteins may still have different conformations in a single unit cell,9 and there are multiple, populated substates that are not captured in the crystal state.10”
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    Premisereasoning

    Under pressure, a protein can reduce its volume either by elastic compression within a sub-ensemble or by shifting its conformational equilibrium toward low-volume conformers.

    “There are two mechanisms for a protein in solution to attain a lower volume in response to pressure: ‘elastic response’ by general compression within the sub-ensemble of the conformers and a shift of the conformational equilibrium from a high-volume to a low-volume ensemble.”
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    Premisecitation

    Protein structures have intrinsic thermodynamic fluctuations, as do water molecules.

    “Protein structures must be considered as dynamic objects at the molecular level due to their intrinsic thermodynamic fluctuations16,92 as well as those of water.93–94”
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    Interpretationnone given

    Statistical thermodynamics determines the distribution of states on the energy landscape, but function, optimized by evolution, also modulates these distributions.

    “Here our thesis is that the distributions of the states on the energy landscape are determined by statistical thermodynamics; however, they are also modulated by function which is optimized by evolution.”
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    • The authors state this as an assumption: Protein function has been optimized by evolution.
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    Premisecitation

    Thermodynamic fluctuations sample pre-existing conformations; function arises from changing their relative populations, not from creating new conformations.

    “The pivotal concept that all conformations pre-exist and are sampled by thermodynamic fluctuations – with function involving not new conformations but a shift in their relative concentration – underlies current approaches and interpretations.”
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    Interpretationcitation

    According to the minimum frustration principle, evolution has optimized folding, and mutations perturb the landscape much like temperature changes.

    “The minimum frustration principle implies that nature has optimized protein folding,129,174 thus the effect of point mutations on the energy landscape is analogous to thermal perturbations.175”
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    Premisecitation

    Rough energy landscapes slow dissociation and may strengthen the dynamic interaction between streptavidin and biotin.

    “For example, the energy landscape roughness slows down dissociation kinetics and can contribute to streptavidin-biotin interaction dynamic strength.176”
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    Premisecitation

    The energy landscape framework now covers protein-ligand binding and function, with statistical methods modeling the binding landscape.

    “The energy landscape concept was extended to protein-ligand binding and function87–89,134–141 and statistical approaches were developed to describe the protein binding energy landscape.142–158”
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    Premisecitation

    Protein motions fall into slower α and faster βh fluctuations; solvent viscosity governs α motions, while the hydration shell largely drives βh fluctuations.

    “Exploiting the concept of glasses and supercooled liquids,166 protein motions could be classified by the α fluctuation (primary) and βh fluctuation (secondary).167–168 The slower α relaxation motions are inversely controlled by the solvent viscosity169–170 and the faster βh fluctuations are largely due to the hydration shell of the proteins.171”
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    Premisecitation

    Long-range contacts in the p53 linker region were required to reproduce the experimental SAXS profile, indicating allosteric communication.

    “However, long-range contacts in the p53 linker region were required to reproduce the experimental SAXS profile, indicating allosteric communication.227”
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    Premisecitation

    Mutations at hinge regions can allosterically change binding-site dynamics or create alternative binding modes by altering the set of accessible conformations.

    “mutations at the hinge regions could allosterically affect the binding-site dynamics or induce alternative binding modes by modifying the ensemble of accessible conformations220.”
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    Premisereasoning

    Fluctuation energy scales with the local glass transition temperature, while the folding frustration ratio TF/TG scales inversely with it.

    “The local glass transition temperature TG is proportional to the fluctuation energy, and therefore the protein folding frustration TF/TG is inversely proportional to the fluctuation energy.”
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    Premisecitation

    The linker sequence is not randomly distributed, and the resulting calmodulin linker conformational ensemble must be optimized for calmodulin binding.

    “The results indicated that the linker sequence is not randomly distributed; the resulting conformational ensemble of the linker must be optimized for calmodulin binding.234”
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    Premisecitation

    In p53, phosphorylation at Ser20 turns off p53-MDM2 binding and increases p53 concentration, while phosphorylation at Thr155 targets p53 for ubiquitin-mediated degradation.

    “In the case of p53, phosphorylation at Ser20 turns off p53-MDM2 binding, with a consequent increase in p53 concentration; while phosphorylation at Thr155 targets p53 to degradation by the ubiquitin system (reviewed in256).”
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    Premisecitation

    Disordered proteins lack a stable, well-defined structure under physiological conditions and exist in a continuum from less to more structured states.

    “‘Disordered’ or ‘intrinsically unstructured’ proteins lack a stable, well-defined structure under physiological conditions, existing in a continuum of conformations from the less to the more structured states.240–243”
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    Premisecitation

    Many proteins either contain at least one intrinsically disordered region or are completely disordered.

    “Many proteins either contain at least one intrinsically disordered region (IDR) (such as intrinsically disordered domains and linkers in multidomain proteins)234,237 or are completely disordered (such as IDPs which are highly flexible and dynamic).238–239”
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  • May combine two claims.

    Interpretationnone given

    The active state for a specific function is unique, unlike inactive states, and its stability or population can increase through an ensemble shift, such as by binding.

    “The active state of a specific function is a unique state, which is not the case for the inactive states; its stability (population) may increase through a shift of the ensemble, e.g. via binding.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: For a given protein function, the active state is unique while inactive states are not unique.
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    Premisecitation

    The PaaA2 antitoxin is highly compact in solution and exists as two preformed helices connected by a flexible linker, where the helices may act as molecular recognition elements for toxin inhibition.

    “The conformational ensemble of PaaA2 is highly compact and in solution the protein exists as two preformed helices, connected by a flexible linker where the helices may act as molecular recognition elements for toxin inhibition.259”
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    Premisecitation

    Kukic et al. identified 10 residues in the calmodulin interdomain linker that change conformation upon substrate binding, including five flexible and five rigid residues.

    “They identified 10 residues in the interdomain linker region that change their conformations upon substrate binding, including five flexible residues (Met76, Lys77, Thr79, Asp80 and Ser81) and five rigid residues (Arg74, Lys75, Asp78, Glu82 and Glu83).”
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    Premisecitation

    p53 has more than a dozen phosphorylation and acetylation sites with different biological signals.

    “One such example is the p53 protein, which has more than a dozen phosphorylation and acetylation sites with different biological signals.256”
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    Premisecitation

    The structures of disordered proteins are not random; the disordered state has significant metastable structures.

    “The structures of disordered proteins are not ‘random’. Rather, the disordered state has significant metastable structures.240–243,257”
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  • May combine two claims.

    Interpretationreasoning

    The apparent challenge to the paradigm that function requires distinct 3D structure is not real, because function involves a specific selected state that may have marginal stability and low barriers, giving short residence times that can evade detection.

    “Even though they appear to challenge the paradigm of structural biology, that function requires distinct 3D structure, this is not the case, since function involves a specific selected state, which may have marginal stability and low barriers, thus short residence time which may evade detection.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: For a given protein function, the active state is unique while inactive states are not unique.
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    Premisecitation

    Regulation of unstructured proteins in cells can occur at multiple levels of mRNA transcription and degradation, protein translation and degradation, and fidelity control including post-translational modifications.

    “The regulation of unstructured proteins in the cell can occur at multiple levels of mRNA transcription and degradation; protein translation and degradation; and fidelity control of transcription and translation, including post-translational modifications in functional/degradation control.254”
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    Premisecitation

    Optimal linker length, intersubunit linker flexibility, and specific contacts between the linker and interface are needed to stabilize the active procaspase 3 state.

    “The combination of optimal length, IL flexibility, and specific contacts between the IL and interface are needed to stabilize the active state.”
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    Premisecitation

    Anti-correlation of distances between each L12 C-terminal domain and the anchor promotes L12's function in recruiting translation factors and controlling their ribosomal activity.

    “It was suggested that anti-correlation of the distances between each C-terminal domain and the anchor promotes the function of L12 to recruit translation factors and control their activity on the ribosome.235”
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    Premisecitation

    Intrinsically disordered linkers connecting folded domains and intrinsically disordered domains usually encode conformational flexibility essential for protein function, including regulation of transcription and translation, cellular signaling, phosphorylation, regulation of large self-assemblies, and small molecule storage.

    “Intrinsically disordered linkers connecting folded domains and intrinsically disordered domains usually encode the degrees of conformational flexibility essential for protein function,17,29,244–250,239,247,249–253 including regulation of transcription and translation, cellular signaling, phosphorylation, regulation of large multi-molecular self-assemblies and small molecule storage.249”
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    Premisecitation

    Induced fit hypothesis suggests bound conformation can be induced by binding partner when complex conformation differs from unbound.

    “The ‘induced fit’ hypothesis412 suggests that the bound conformation can be ‘induced’ by the binding partner when the conformation in the complexes differs from that in the unbound form.”
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    Premisecitation

    Histone tail conformational ensembles consist of states with varying residual order; most tails are not fully disordered and exhibit distinct organization including α-helical elements and β-hairpins.

    “demonstrated that the conformational ensembles of histone tails are composed of states with various degrees of residual order and most tails are not fully disordered, but show distinct conformational organization, containing α-helical elements and β-hairpins.368”
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    Interpretationreasoning

    MSMs have potential to identify putative allosteric binding sites or differentiate agonists/antagonists using conformational information along functional pathways.

    “Overall, these studies revealed the potential of MSMs to identify putative allosteric binding sites or to differentiate between agonists and antagonists using conformational information along putative functional pathways.”
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    Premisecitation

    Oligomeric proteins with two or more subunits make up about one third of cellular proteins, and most are symmetrical.

    “Oligomeric proteins with two or more subunits comprise about one third of the cellular proteins,266–267 most of them symmetrical.266”
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    Premisecitation

    IDPs adopt multiple conformations for function; multiple conformational ensembles collectively determine functions.

    “IDPs adopt multiple conformations for function;377–378 that is, the multiple conformational ensembles collectively determine functions.”
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    Premisecitation

    MSMs have been applied to protein folding, ligand binding, conformational change, IDP dynamics/kinetics, and ATP permeation.

    “Markov state models have been applied to a wide variety of problems, spanning protein folding,402 protein-ligand binding process,403 protein conformational change,404–405 the dynamics and kinetics of IDPs,369,406–407 and ATP permeation through membrane protein channels.408”
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    Premisecitation

    Proteins and their binding partners are flexible and exist in ensembles with certain conformational distributions.

    “Proteins and their binding partners are flexible and exist in ensembles with certain conformational distributions.”
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    Premisecitation

    Metadynamics is an enhanced sampling method widely used to explore conformational space of biomolecules.

    “Similar to the REMD method, metadynamics is also an enhanced sampling method which is widely used to explore the conformational space of biomolecules.314,381”
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    Premisenone given

    REMD and metadynamics can provide structural and thermodynamic properties of proteins but do not reproduce kinetic rates and conformational dynamics.

    “Enhanced sampling methods such as REMD and metadynamics can provide the structural and thermodynamic properties of proteins. However, they do not reproduce kinetic rates and conformational dynamics.”
    Quote in the paperSubstantial claim
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    Premisecitation

    Acetylation of tau inhibits its function and promotes pathological aggregation.

    “Acetylation of tau inhibits its function and promotes pathological aggregation.373–375”
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    Premisecitation

    MD simulations of CypA show enzyme conformational ensembles recognize diverse inhibitors and bind different configurations of peptide substrate.

    “Molecular dynamics simulations of CypA show that the ensembles of enzyme conformations recognize diverse inhibitors and bind different configurations of the peptide substrate.3”
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    Premisecitation

    GPCRs exhibit multiple inactive and active conformations, and ligand binding alters the population balance between them.

    “GPCRs exhibit multiple inactive and active conformations, and the population balance between these conformations is altered upon binding of ligands.415”
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    Interpretationcitation

    Protein conformational ensemble allows enzymes to catalyze multiple chemical steps and accommodates conformational reorganization required to stabilize transition states.

    “The protein conformational ensemble not only allows enzymes to catalyze multiple chemical steps, but accommodates the conformational reorganization required to stabilize the transition states.449”
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    Premisecitation

    The docking algorithm achieved 93% success on 10 protein ensembles (105 crystal structures, 87 ligands), significantly better than single rigid-receptor docking (75% average).

    “The docking algorithm was validated on 10 protein ensembles containing 105 crystal structures and 87 ligands and achieved a success rate of 93%, significantly better than single rigid-receptor docking (75% on average).425”
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    Interpretationcitation

    Receptor activation depends on both low energy states and the range of conformations sampled by the receptor.

    “Therefore, receptor activation depends on both low energy states and the range of the conformations sampled by the receptor.416”
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    Premisecitation

    R55K substitution at CypA active site significantly decreases catalysis, indicating active site stability likely plays an important role in the chemical step.

    “An earlier QM/MM study468 demonstrated that R55K substitution at the active site of CypA leads to a significant decrease in catalysis, indicating that the active site stability likely plays an important role in the chemical step of catalysis.”
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    Premisecitation

    Ligands can interact with similar targets in different conformations, and biological outcomes such as ERβ selective agonist depend on relative affinities of a ligand to ensembles of protein conformations.

    “It has been shown that ligands can interact with similar targets in different conformations, and that the biological outcomes like ERβ selective agonist depend on the relative affinities of a ligand to ensembles of protein conformations.414”
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    Premisecitation

    c-Myc binding conformations are partially formed in the apo ensemble, suggesting conformational selection.

    “Comparison of the apo and holo equilibrium ensembles reveals that c-Myc binding conformations are already partially formed in the apo ensemble, suggesting a conformational selection mechanism.432”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [432] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Protein motions necessary for catalysis may be an intrinsic property of the enzyme and might limit overall turnover rate.

    “This correlation could suggest that protein motions necessary for catalysis are an intrinsic property of the enzyme and might even limit the overall turnover rate.469”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [469] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    In AlkB, conformational ensemble and population shift allow co-substrate binding prior to substrate and limit premature substrate release.

    “The conformational ensemble and population shift allow the enzyme to bind the co-substrate prior to the substrate, and can also limit premature release of substrate.442”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [442] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The disordered state has significant metastable structure character, and functionally relevant conformations may have higher population times than other conformations.

    “The disordered state has a significant metastable structure character240–243,257 and functionally relevant conformations may have population times higher than of other conformations.240–242”
    Quote in the paperSubstantial claim0 of 5 sources checked
    • cites [240] source

      Not checked in the free run.

    • cites [241] source

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    • cites [242] source

      Not checked in the free run.

    • cites [243] source

      Not checked in the free run.

    • cites [257] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Promiscuous residues tend to be more flexible, and this flexibility permits a broader range of organizations in different conformers.

    “They found that promiscuous residues tend to be more flexible, and this additional flexibility permits a broader range of organizations which could take place in different conformers in the ensemble.523”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [523] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The most flexible proteins are disordered proteins, with some more folded than others.

    “Obviously, the most flexible proteins are the disordered proteins, with some more folded than others.525”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [525] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    This bias implies centrosomal proteins adopt an ensemble of disordered and partially helical conformations, with helical conformations stabilized upon complex formation depending on pH and concentration.

    “This bias implies that they adopt an ensemble of disordered and partially helical conformations, with the latter becoming stabilized when these proteins form complexes, depending on pH and concentration.527”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [527] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Weak complexes often have smaller, more planar interfaces with more polar residues.

    “Often, weak complexes have smaller contact area and the interfaces are more planar and with more polar residues,511”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [511] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Antibody-antigen interfaces have fewer hot spot residues, but Tyr is a preferred hot spot residue for immunoglobulins.

    “Even though antibody-antigen interfaces have fewer hot spot residues,496,518 Tyr is a preferred hot spot residue for immunoglobulins.119a”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [496] source

      Not checked in the free run.

    • cites [518] source

      Not checked in the free run.

    • cites 119a

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Eph-ephrin recognition involves stepwise conformational selection and population shift, with two dynamic salt bridges between EphB4 and Ephrin-B2 contributing to specific recognition.

    “Dynamic conformational changes during the Eph-ephrin recognition were found to be stepwise conformational selection and population shift events, with two dynamic salt bridges between EphB4 and Ephrin-B2 contributing to specific recognition.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [514] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Some protein associations last for the functional lifetime of the protein, while others are transient and repeatedly form and dissociate.

    “Some associations are obligatory where one protein is bound to another throughout its functional lifetime, whereas others are transient, continuously forming and dissociating503–510.”
    Quote in the paperNot a substantial claim0 of 8 sources checked
    • cites [503] source

      Not checked in the free run.

    • cites [504] source

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    • cites [505] source

      Not checked in the free run.

    • cites [506] source

      Not checked in the free run.

    • cites [507] source

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    • cites [508] source

      Not checked in the free run.

    • cites [509] source

      Not checked in the free run.

    • cites [510] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Nidogen-1 interactions with laminin variants indicate conformational ensembles of both individual proteins and the complex, implying different interaction modes through distinct interfaces.

    “For example, the interactions of nidogen-1 with laminin variants indicate the existence of a conformational ensemble of both individual proteins and complex, implying different modes of interaction through distinct protein-protein interfaces.522”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [522] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Centrosomal proteins are larger than control human proteins and have predicted disordered regions covering 57% of their length versus 39% in the general human proteome.

    “Centrosomal proteins tend to be larger than a control set of human proteins, and are rich in predicted disordered regions, which cover 57% of their length, compared to 39% in the general human proteome.526”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [526] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    EphA4 binds ephrin-A1, ephrin-A2, ephrin-A4, ephrin-A5, and ephrin-B2 with affinities of 1.2 μm, 2.3 μm, 36 nm, 360 nm, and 10.8 μm, respectively, indicating varied ligand selectivity.

    “the binding affinities of EphA4 with ephrin-A1, ephrin-A2, ephrin-A4, ephrin-A5, and ephrin-B2 are 1.2 μm, 2.3 μm, 36 nm, 360 nm, and 10.8 μm, respectively,512 indicating varied selectivity towards various ligands.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [512] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    This cellular ensemble strategy facilitates variable environmental responses and gain of function in network evolution.

    “Such a cellular strategy facilitates variable response to the environment and gain of function in network evolution.535”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [535] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Protein disorder in the centrosome correlates with organism complexity in cell-type number, and disordered regions and phosphorylation contribute to mechanical properties and spatiotemporal regulation.

    “Interestingly, protein disorder in the centrosome correlates with complexity with the number of cell types, and the structural heterogeneity conferred by the disordered regions and phosphorylation playing an important role in its mechanical properties and regulation in space and time.528”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [528] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

    Interpretationreasoning

    Because RNA and DNA carry genetic information, protein-RNA/DNA interactions should ensure correct processing of genomic information.

    “Since RNA and DNA carry generic information, protein-RNA/DNA interactions should ensure correct processing of genomic information.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Protein-protein and protein-RNA/DNA interactions follow the same physico-chemical principles.
    • Rests on an assumption: RNA and DNA are dynamic molecules.
  • May combine two claims.

    Premisecitation

    Unphosphorylated and unbound KID is disordered; pKID-KIX interaction causes cooperative folding and binding, forming two α-helices kinked near the phosphorylated site.

    “When unphosphorylated and unbound, KID is disordered. Cooperative folding and binding occur upon pKID–KIX interaction, forming two α-helices kinked near the phosphorylated site.529”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [529] source

      Not checked in the free run.

67 of 67
  • The authors state this as an assumption.

    Protein function has been optimized by evolution.

    “modulated by function which is optimized by evolution”
  • The paper relies on this without support.

    For a given protein function, the active state is unique while inactive states are not unique.

    “The active state of a specific function is a unique state, which is not the case for the inactive states;”
  • The paper relies on this without support.

    Conformational states and dynamics observed in isolated, reconstituted, or computational systems correspond to functionally relevant states in the living cell.

    “In the heterogeneous cellular environment, protein conformations including those of symmetric oligomers may differ across time and space.”
  • The paper relies on this without support.

    Macromolecular crowding in cells can be represented by the experimental and simulation crowding models discussed.

    “In the cellular environment, the high concentration of macromolecules creates crowding effects.”
  • The paper relies on this without support.

    Antibody variable regions must be flexible to recognize highly diversified targets.

    “Antibody variable regions are necessarily flexible to enable recognition of tremendously diversified targets.”
  • The paper relies on this without support.

    Natively disordered proteins can form ordered complexes upon binding their partner.

    “Upon binding their partner, natively disordered proteins can form ordered complexes.”
  • The paper relies on this without support.

    Cell-signaling proteins have disproportionately intrinsically unstructured regions.

    “Cell-signaling proteins also have disproportionately intrinsically unstructured regions.”
  • The paper relies on this without support.

    Protein-protein and protein-RNA/DNA interactions follow the same physico-chemical principles.

    “Protein-protein and protein-RNA/DNA interactions should follow the same physico-chemical principles.”
  • The paper relies on this without support.

    RNA and DNA are dynamic molecules.

    “Both RNA and DNA are dynamic molecules.”
  • The paper relies on this without support.

    Protein conformational ensembles correlate with gene regulation.

    “Protein conformational ensembles should correlate with gene regulation.”
  • The paper relies on this without support.

    Biomacromolecules are dynamical objects that continuously interconvert between structures of varying energies.

    “Biomacromolecules are dynamical objects; they continuously interconvert between structures with varying energies.”
11 of 11

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Native protein conformations are often described as time-averaged ensembles with Boltzmann-type distributions, especially for IDPs and proteins with IDRs.

    “Native conformations of proteins are often described as time averaged ensembles of conformations with Boltzmann-type distributions, especially IDPs and proteins with IDRs100,101.”

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.

  • Temperature and volume are interchanged in the variable definitions

    Minor

    The list assigns T to volume and V to temperature, but the paper explicitly defines V as volume earlier in the same section.

1 of 1

Cites

Flagged first, then by citations

7 of the 585 references couldn’t be matched to a known paper.

Research works printed but not linked: 14

  1. 10.1063/1.455536 · DOI · Paper page
  2. Gekko K., 2015, High Pressure Bioscience, 72, 10.1007/978-94-017-9918-8_5 · DOI
  3. Dickson A., 2015, J. Comput. Chem.
  4. 10.1073/pnas.92.8.3626 · DOI · Paper page
  5. 10.1096/fj.14-257287 · DOI
  6. 10.1186/2046-1682-5-2 · DOI · Paper page
  7. 10.1021/jz501457f · DOI
  8. 10.1002/prot.1107 · DOI · Paper page
  9. 10.1111/j.1742-4658.2005.04948.x · DOI · Paper page
  10. 10.1038/nsmb.2555 · DOI · Paper page
  11. Menichetti G., 2014, Theor. Biol. Forum., 107, 77
  12. Laskowski R. A., 1996, Protein Sci., 5, 2438
  13. 10.1002/prot.1107 · DOI · Paper page
  14. 10.1016/s0968-0004(03)00003-3 · DOI

Cited by

Sorted by citations

Authors
Wei, G., Xi, W., Nussinov, R., & Ma, B.
Affiliations
  • Fudan University (CN)
  • Tel Aviv University (IL)
  • National Cancer Institute (US)
Corresponding author
  • Wei, Guanghong
  • Ma, Buyong
Venue
Chemical Reviews
Published
2016-01-25
Volume
116
Issue
11
Pages
6516-6551
ISSN
  • 0009-2665 (ISSN-L)
  • 1520-6890
OpenAlex
W2265800909
Cited by
436
References
585
Citations by year
2026: 57 · 2025: 48 · 2024: 34 · 2023: 42 · 2022: 43 · 2021: 42 · 2020: 36 · 2019: 45 · 2018: 33 · 2017: 35 · 2016: 20
FWCI
4.00
Type
journal article
Language
en
Open access
Locations
  • Chemical Reviews (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
Funders
  • National Cancer Institute (HHSN261200800001E)
  • National Natural Science Foundation of China (11274075, 91227102)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Structure and Dynamics
  • Physical Sciences › Materials Science › Materials Chemistry › Enzyme Structure and Function
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Receptor Mechanisms and Signaling
Keywords
protein conformational ensembles, free energy landscape, thermal fluctuations, protein flexibility, intrinsically disordered proteins, multidomain proteins, protein complexes, intracellular crowding, protein-ligand recognition, enzyme catalysis, protein dynamics, replica exchange molecular dynamics, metadynamics, Markov state models
MeSH terms
Humans, Markov Chains, Protein Conformation, Proteins, Thermodynamics, Nuclear Magnetic Resonance, Biomolecular, Molecular Dynamics Simulation, Protein Interaction Maps, Intrinsically Disordered Proteins

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-07.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-07.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

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