1
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Zhu B, Zhang C, Wang J, Jia C, Lu T, Dai L, Chen T. Scaling Laws for Protein Folding under Confinement. J Phys Chem Lett 2024; 15:10138-10145. [PMID: 39340464 DOI: 10.1021/acs.jpclett.4c02098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2024]
Abstract
Spatial confinement significantly affects protein folding. Without the confinement provided by chaperones, many proteins cannot fold correctly. However, the quantitative effect of confinement on protein folding remains elusive. In this study, we observed scaling laws between the variation in folding transition temperature and the size of confinement, (Tf - Tfbulk)/Tfbulk ∼ L-ν. The scaling exponent v is significantly influenced by both the protein's topology and folding cooperativity. Specifically, for a given protein, v can decrease as the folding cooperativity of the model increases, primarily due to the heightened sensitivity of the unfolded state energy to changes in cage size. For proteins with diverse topologies, variations in topological complexity influence scaling exponents in multiple ways. Notably, v exhibits a clear positive correlation with contact order and the proportion of nonlocal contacts, as this complexity significantly enhances the sensitivity of entropy loss in the unfolded state. Furthermore, we developed a novel scaling argument yielding 5/3 ≤ ν ≤ 10/3, consistent with the simulation results.
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Affiliation(s)
- Bin Zhu
- College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, China
| | - Chenxi Zhang
- College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, China
| | - Jiwei Wang
- College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, China
| | - Chuandong Jia
- College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, China
| | - Teng Lu
- Computer Network Information Center, Chinese Academy of Sciences, Beijing 100083, China
| | - Liang Dai
- Department of Physics, City University of Hong Kong, Hong Kong 999077, China
- Shenzhen Research Institute, City University of Hong Kong, Shenzhen 518057, P. R. China
| | - Tao Chen
- College of Chemistry and Materials Science, Northwest University, Xi'an, 710127, China
- Key Laboratory of Polymer Processing Engineering (South China University of Technology), Ministry of Education, Guangzhou 510641, China
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2
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Liu Z. Accelerating Kinetics with Time-Reversal Path Sampling. Molecules 2023; 28:8147. [PMID: 38138635 PMCID: PMC10745403 DOI: 10.3390/molecules28248147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 12/07/2023] [Accepted: 12/13/2023] [Indexed: 12/24/2023] Open
Abstract
In comparison to numerous enhanced sampling methods for equilibrium thermodynamics, accelerating simulations for kinetics and nonequilibrium statistics are relatively rare and less effective. Here, we derive a time-reversal path sampling (tRPS) method based on time reversibility to accelerate simulations for determining the transition rates between free-energy basins. It converts the difficult uphill path sampling into an easy downhill problem. This method is easy to implement, i.e., forward and backward shooting simulations with opposite initial velocities are conducted from random initial conformations within a transition-state region until they reach the basin minima, which are then assembled to give the distribution of transition paths efficiently. The effects of tRPS are demonstrated using a comparison with direct simulations of protein folding and unfolding, where tRPS is shown to give results consistent with direct simulations and increase the efficiency by up to five orders of magnitude. This approach is generally applicable to stochastic processes with microscopic reversibility, regardless of whether the variables are continuous or discrete.
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Affiliation(s)
- Zhirong Liu
- Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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3
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Du J, Yin H, Lu Y, Lu T, Chen T. Effects of Surface Tethering on the Thermodynamics and Kinetics of Frustrated Protein Folding. J Phys Chem B 2022; 126:4776-4786. [PMID: 35731862 DOI: 10.1021/acs.jpcb.2c01982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The interaction between the protein and surface plays an important role in biology and biotechnology. To understand how surface tethering influences the folding behavior of frustrated proteins, in this work, we systematically study the thermodynamics and folding kinetics of the bacterial immunity protein Im7 and Fyn SH3 domain tethered to a surface using Langevin dynamics simulations. Upon surface tethering, the stabilization often results from the entropic effect, whereas the destabilization is usually caused by either an energetic or entropic effect. For the Fyn SH3 domain with a two-state folding manner, the influence of nonnative interactions on thermodynamic stability is not significant, while nonnative interactions can weaken the effect of surface tethering on the change in the folding rate. By contrast, for the frustrated protein Im7, depending on where the protein is tethered, the surface tethering can promote or suppress misfolding by modulating specific nonnative contacts, thereby altering the folding rate and folding mechanism. Because surface tethering can change the intrachain diffusivity of unfolding, the kinetic stability cannot be well captured by the thermodynamic stability at some tether points. This study should be helpful in general to understand how surface tethering affects the folding energy landscape of frustrated proteins.
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Affiliation(s)
- Jiang Du
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China
| | - Hongmei Yin
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China
| | - Yanfang Lu
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China
| | - Teng Lu
- Computer Network Information Center of the Chinese Academy of Sciences, Beijing 100083, P. R. China
| | - Tao Chen
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an 710127, P. R. China.,Key Laboratory of Polymer Processing Engineering (South China University of Technology), Ministry of Education, Guangzhou 510641, P. R. China
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4
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Neelamraju S, Wales DJ, Gosavi S. Protein energy landscape exploration with structure-based models. Curr Opin Struct Biol 2020; 64:145-151. [DOI: 10.1016/j.sbi.2020.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 06/30/2020] [Accepted: 07/15/2020] [Indexed: 12/11/2022]
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5
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Neelamraju S, Wales DJ, Gosavi S. Go-Kit: A Tool To Enable Energy Landscape Exploration of Proteins. J Chem Inf Model 2019; 59:1703-1708. [PMID: 30977648 DOI: 10.1021/acs.jcim.9b00007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Coarse-grained Go̅-like models, based on the principle of minimal frustration, provide valuable insight into fundamental questions in the field of protein folding and dynamics. In conjunction with commonly used molecular dynamics (MD) simulations, energy landscape exploration methods like discrete path sampling (DPS) with Go̅-like models can provide quantitative details of the thermodynamics and kinetics of proteins. Here we present Go-kit, a software that facilitates the setup of MD and DPS simulations of several flavors of Go̅-like models. Go-kit is designed for use with MD (GROMACS) and DPS (PATHSAMPLE) simulation engines that are open source. The Go-kit code is written in python2.7 and is also open source. A case study for the ribosomal protein S6 is discussed to illustrate the utility of the software, which is available at https://github.com/gokit1/gokit .
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Affiliation(s)
- Sridhar Neelamraju
- Simons Centre for the Study of Living Machines , National Centre for Biological Sciences, Tata Institute of Fundamental Research , Bellary Road , Bangalore 560065 , India.,University Chemical Laboratories , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , U.K
| | - David J Wales
- University Chemical Laboratories , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , U.K
| | - Shachi Gosavi
- Simons Centre for the Study of Living Machines , National Centre for Biological Sciences, Tata Institute of Fundamental Research , Bellary Road , Bangalore 560065 , India
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6
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Neelamraju S, Gosavi S, Wales DJ. Energy Landscape of the Designed Protein Top7. J Phys Chem B 2018; 122:12282-12291. [DOI: 10.1021/acs.jpcb.8b08499] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Sridhar Neelamraju
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka 560065, India
- University Chemical Laboratories, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Shachi Gosavi
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka 560065, India
| | - David J. Wales
- University Chemical Laboratories, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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7
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Quezada AG, Cabrera N, Piñeiro Á, Díaz-Salazar AJ, Díaz-Mazariegos S, Romero-Romero S, Pérez-Montfort R, Costas M. A strategy based on thermal flexibility to design triosephosphate isomerase proteins with increased or decreased kinetic stability. Biochem Biophys Res Commun 2018; 503:3017-3022. [PMID: 30143261 DOI: 10.1016/j.bbrc.2018.08.087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 08/11/2018] [Indexed: 11/19/2022]
Abstract
Kinetic stability of proteins determines their susceptibility to irreversibly unfold in a time-dependent process, and therefore its half-life. A residue displacement analysis of temperature-induced unfolding molecular dynamics simulations was recently employed to define the thermal flexibility of proteins. This property was found to be correlated with the activation energy barrier (Eact) separating the native from the transition state in the denaturation process. The Eact was determined from the application of a two-state irreversible model to temperature unfolding experiments using differential scanning calorimetry (DSC). The contribution of each residue to the thermal flexibility of proteins is used here to propose multiple mutations in triosephosphate isomerase (TIM) from Trypanosoma brucei (TbTIM) and Trypanosoma cruzi (TcTIM), two parasites closely related by evolution. These two enzymes, taken as model systems, have practically identical structure but large differences in their kinetic stability. We constructed two functional TIM variants with more than twice and less than half the activation energy of their respective wild-type reference structures. The results show that the proposed strategy is able to identify the crucial residues for the kinetic stability in these enzymes. As it occurs with other protein properties reflecting their complex behavior, kinetic stability appears to be the consequence of an extensive network of inter-residue interactions, acting in a concerted manner. The proposed strategy to design variants can be used with other proteins, to increase or decrease their functional half-life.
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Affiliation(s)
- Andrea G Quezada
- Laboratorio de Biofisicoquímica, Departamento de Fisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México, México City 04510, Mexico.
| | - Nallely Cabrera
- Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México City, 04510, Mexico
| | - Ángel Piñeiro
- Soft Matter and Molecular Biophysics Group, Departamento de Física Aplicada, Facultad de Física, Universidad de Santiago de Compostela, Campus Vida s/n, E-15782, Santiago de Compostela, Spain
| | - A Jessica Díaz-Salazar
- Laboratorio de Biofisicoquímica, Departamento de Fisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México, México City 04510, Mexico
| | - Selma Díaz-Mazariegos
- Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México City, 04510, Mexico
| | - Sergio Romero-Romero
- Laboratorio de Fisicoquímica e Ingeniería de Proteínas, Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, 04510, Mexico
| | - Ruy Pérez-Montfort
- Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México City, 04510, Mexico
| | - Miguel Costas
- Laboratorio de Biofisicoquímica, Departamento de Fisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México, México City 04510, Mexico.
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8
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Cheng C, Wu J, Liu G, Shi S, Chen T. Effects of Non-native Interactions on Frustrated Proteins Folding under Confinement. J Phys Chem B 2018; 122:7654-7667. [DOI: 10.1021/acs.jpcb.8b04147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Chenqian Cheng
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
| | - Jing Wu
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
| | - Gaoyuan Liu
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
| | - Suqing Shi
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
| | - Tao Chen
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an 710127, P. R. China
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9
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Hu J, Chen T, Wang M, Chan HS, Zhang Z. A critical comparison of coarse-grained structure-based approaches and atomic models of protein folding. Phys Chem Chem Phys 2018; 19:13629-13639. [PMID: 28530269 DOI: 10.1039/c7cp01532a] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Structure-based coarse-grained Gō-like models have been used extensively in deciphering protein folding mechanisms because of their simplicity and tractability. Meanwhile, explicit-solvent molecular dynamics (MD) simulations with physics-based all-atom force fields have been applied successfully to simulate folding/unfolding transitions for several small, fast-folding proteins. To explore the degree to which coarse-grained Gō-like models and their extensions to incorporate nonnative interactions are capable of producing folding processes similar to those in all-atom MD simulations, here we systematically compare the computed unfolded states, transition states, and transition paths obtained using coarse-grained models and all-atom explicit-solvent MD simulations. The conformations in the unfolded state in common Gō models are more extended, and are thus more in line with experiment, than those from all-atom MD simulations. Nevertheless, the structural features of transition states obtained by the two types of models are largely similar. In contrast, the folding transition paths are significantly more sensitive to modeling details. In particular, when common Gō-like models are augmented with nonnative interactions, the predicted dimensions of the unfolded conformations become similar to those computed using all-atom MD. With this connection, the large deviations of all-atom MD from simple diffusion theory are likely caused in part by the presence of significant nonnative effects in folding processes modelled by current atomic force fields. The ramifications of our findings to the application of coarse-grained modeling to more complex biomolecular systems are discussed.
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Affiliation(s)
- Jie Hu
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
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10
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Chu X, Muñoz V. Roles of conformational disorder and downhill folding in modulating protein-DNA recognition. Phys Chem Chem Phys 2018; 19:28527-28539. [PMID: 29044255 DOI: 10.1039/c7cp04380e] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Transcription factors are thought to efficiently search for their target DNA site via a combination of conventional 3D diffusion and 1D diffusion along the DNA molecule mediated by non-specific electrostatic interactions. This process requires the DNA-binding protein to quickly exchange between a search competent and a target recognition mode, but little is known as to how these two binding modes are encoded in the conformational properties of the protein. Here, we investigate this issue on the engrailed homeodomain (EngHD), a DNA-binding domain that folds ultrafast and exhibits a complex conformational behavior consistent with the downhill folding scenario. We explore the interplay between folding and DNA recognition using a coarse-grained computational model that allows us to manipulate the folding properties of the protein and monitor its non-specific and specific binding to DNA. We find that conformational disorder increases the search efficiency of EngHD by promoting a fast gliding search mode in addition to sliding. When gliding, EngHD remains loosely bound to DNA moving linearly along its length. A partially disordered EngHD also binds more dynamically to the target site, reducing the half-life of the specific complex via a spring-loaded mechanism. These findings apply to all conditions leading to partial disorder. However, we also find that at physiologically relevant temperatures EngHD is well folded and can only obtain the conformational flexibility required to accelerate 1D diffusion when it folds/unfolds within the downhill scenario (crossing a marginal free energy barrier). In addition, the conformational flexibility of native downhill EngHD enables its fast reconfiguration to lock into the specific binding site upon arrival, thereby affording finer control of the on- and off-rates of the specific complex. Our results provide key mechanistic insights into how DNA-binding domains optimize specific DNA recognition through the control of their conformational dynamics and folding mechanism.
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Affiliation(s)
- Xiakun Chu
- IMDEA Nanosciences, Faraday 9, Campus de Cantoblanco, Madrid, 28049, Spain
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11
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Huynh L, Neale C, Pomès R, Chan HS. Molecular recognition and packing frustration in a helical protein. PLoS Comput Biol 2017; 13:e1005909. [PMID: 29261665 PMCID: PMC5757960 DOI: 10.1371/journal.pcbi.1005909] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 01/08/2018] [Accepted: 11/28/2017] [Indexed: 01/25/2023] Open
Abstract
Biomolecular recognition entails attractive forces for the functional native states and discrimination against potential nonnative interactions that favor alternate stable configurations. The challenge posed by the competition of nonnative stabilization against native-centric forces is conceptualized as frustration. Experiment indicates that frustration is often minimal in evolved biological systems although nonnative possibilities are intuitively abundant. Much of the physical basis of minimal frustration in protein folding thus remains to be elucidated. Here we make progress by studying the colicin immunity protein Im9. To assess the energetic favorability of nonnative versus native interactions, we compute free energies of association of various combinations of the four helices in Im9 (referred to as H1, H2, H3, and H4) by extensive explicit-water molecular dynamics simulations (total simulated time > 300 μs), focusing primarily on the pairs with the largest native contact surfaces, H1-H2 and H1-H4. Frustration is detected in H1-H2 packing in that a nonnative packing orientation is significantly stabilized relative to native, whereas such a prominent nonnative effect is not observed for H1-H4 packing. However, in contrast to the favored nonnative H1-H2 packing in isolation, the native H1-H2 packing orientation is stabilized by H3 and loop residues surrounding H4. Taken together, these results showcase the contextual nature of molecular recognition, and suggest further that nonnative effects in H1-H2 packing may be largely avoided by the experimentally inferred Im9 folding transition state with native packing most developed at the H1-H4 rather than the H1-H2 interface. Biomolecules need to recognize one another with high specificity: promoting “native” functional intermolecular binding events while avoiding detrimental “nonnative” bound configurations; i.e., “frustration”—the tendency for nonnative interactions—has to be minimized. Folding of globular proteins entails a similar discrimination. To gain physical insight, we computed the binding affinities of helical structures of the protein Im9 in various native or nonnative configurations by atomic simulations, discovering that partial packing of the Im9 core is frustrated. This frustration is overcome when the entire core of the protein is assembled, consistent with experiment indicating no significant kinetic trapping in Im9 folding. Our systematic analysis thus reveals a subtle, contextual aspect of biomolecular recognition and provides a general approach to characterize folding frustration.
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Affiliation(s)
- Loan Huynh
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Chris Neale
- Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York, United States of America
| | - Régis Pomès
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- * E-mail: (HSC); (RP)
| | - Hue Sun Chan
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (HSC); (RP)
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12
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Quezada AG, Díaz-Salazar AJ, Cabrera N, Pérez-Montfort R, Piñeiro Á, Costas M. Interplay between Protein Thermal Flexibility and Kinetic Stability. Structure 2017; 25:167-179. [PMID: 28052236 DOI: 10.1016/j.str.2016.11.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 10/18/2016] [Accepted: 11/22/2016] [Indexed: 02/07/2023]
Abstract
Kinetic stability is a key parameter to comprehend protein behavior and it plays a central role to understand how evolution has reached the balance between function and stability in cell-relevant timescales. Using an approach that includes simulations, protein engineering, and calorimetry, we show that there is a clear correlation between kinetic stability determined by differential scanning calorimetry and protein thermal flexibility obtained from a novel method based on temperature-induced unfolding molecular dynamics simulations. Thermal flexibility quantitatively measures the increment of the conformational space available to the protein when energy in provided. The (β/α)8 barrel fold of two closely related by evolution triosephosphate isomerases from two trypanosomes are used as model systems. The kinetic stability-thermal flexibility correlation has predictive power for the studied proteins, suggesting that the strategy and methodology discussed here might be applied to other proteins in biotechnological developments, evolutionary studies, and the design of protein based therapeutics.
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Affiliation(s)
- Andrea G Quezada
- Laboratorio de Biofisicoquímica, Departamento de Fisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México, México City 04510, México
| | - A Jessica Díaz-Salazar
- Laboratorio de Biofisicoquímica, Departamento de Fisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México, México City 04510, México
| | - Nallely Cabrera
- Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City 04510, México
| | - Ruy Pérez-Montfort
- Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City 04510, México
| | - Ángel Piñeiro
- Soft Matter and Molecular Biophysics Group, Department of Applied Physics, University of Santiago de Compostela, Santiago de Compostela 15782, Spain.
| | - Miguel Costas
- Laboratorio de Biofisicoquímica, Departamento de Fisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México, México City 04510, México.
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13
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Gao M, Yang F, Zhang L, Su Z, Huang Y. Exploring the sequence-structure-function relationship for the intrinsically disordered βγ-crystallin Hahellin. J Biomol Struct Dyn 2017; 36:1171-1181. [PMID: 28393629 DOI: 10.1080/07391102.2017.1316519] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
βγ-Crystallins are a superfamily of proteins containing crystallin-type Greek key motifs. Some βγ-crystallin domains have been shown to bind Ca2+. Hahellin is a newly identified intrinsically disordered βγ-crystallin domain from Hahella chejuensis. It folds into a typical βγ-crystallin structure upon Ca2+ binding and acts as a Ca2+-regulated conformational switch. Besides Hahellin, another two putative βγ-crystallins from Caulobacter crescentus and Yersinia pestis are shown to be partially disordered in their apo-form and undergo large conformational changes upon Ca2+ binding, although whether they acquire a βγ-crystallin fold is not known. The extent of conformational disorder/order of a protein is determined by its amino acid sequence. To date how this sequence-structure relationship is reflected in the βγ-crystallin superfamily has not been investigated. In this work, we comparatively studied the sequence and structure of Hahellin with those of Protein S, an ordered βγ-crystallin, via various computational biophysical techniques. We found that several factors, including presence of a C-terminal disorder prone region, high content of energetic frustrations, and low contact density, may promote the formation of the disordered state of apo-Hahellin. We also analyzed the disorder propensities for other putative disordered βγ-crystallin domains. This study provides new clues for further understanding the sequence-structure-function relationship of βγ-crystallins.
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Affiliation(s)
- Meng Gao
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
| | - Fei Yang
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
| | - Lei Zhang
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
| | - Zhengding Su
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
| | - Yongqi Huang
- a Department of Biological Engineering and Institute of Biomedical and Pharmaceutical Sciences , Hubei University of Technology , Wuhan , Hubei 430068 , China
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14
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Song B, Charest N, Alexander Morriss-Andrews H, Molinero V, Shea JE. Systematic derivation of implicit solvent models for the study of polymer collapse. J Comput Chem 2017; 38:1353-1361. [DOI: 10.1002/jcc.24754] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 01/08/2017] [Accepted: 01/10/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Bin Song
- Department of Chemistry; The University of Utah; Salt Lake City Utah 84112-0850
| | - Nathaniel Charest
- Department of Chemistry and Biochemistry; University of California; Santa Barbara California 93106
| | - Herbert Alexander Morriss-Andrews
- Department of Chemistry and Biochemistry; University of California; Santa Barbara California 93106
- Department of Physics; University of California; Santa Barbara California 93106
| | - Valeria Molinero
- Department of Chemistry; The University of Utah; Salt Lake City Utah 84112-0850
| | - Joan-Emma Shea
- Department of Chemistry and Biochemistry; University of California; Santa Barbara California 93106
- Department of Physics; University of California; Santa Barbara California 93106
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15
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Wu J, Chen G, Zhang Z, Zhang P, Chen T. The low populated folding intermediate of a mutant of the Fyn SH3 domain identified by a simple model. Phys Chem Chem Phys 2017; 19:22321-22328. [DOI: 10.1039/c7cp04139j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The low populated on-pathway folding intermediate of the A39V/N53P/V55L Fyn SH3 domain is captured by a native-centric model augmented by sequence-dependent nonnative hydrophobic interactions.
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Affiliation(s)
- Jing Wu
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of the Ministry of Education
- College of Chemistry and Materials Science
- Northwest University
- Xi'an
- P. R. China
| | - Guojun Chen
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of the Ministry of Education
- College of Chemistry and Materials Science
- Northwest University
- Xi'an
- P. R. China
| | - Zhuqing Zhang
- College of Life Sciences
- University of Chinese Academy of Sciences
- Beijing
- P. R. China
| | - Ping Zhang
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of the Ministry of Education
- College of Chemistry and Materials Science
- Northwest University
- Xi'an
- P. R. China
| | - Tao Chen
- Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of the Ministry of Education
- College of Chemistry and Materials Science
- Northwest University
- Xi'an
- P. R. China
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16
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Krobath H, Chen T, Chan HS. Volumetric Physics of Polypeptide Coil–Helix Transitions. Biochemistry 2016; 55:6269-6281. [DOI: 10.1021/acs.biochem.6b00802] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Heinrich Krobath
- Departments of Biochemistry
and Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Tao Chen
- Departments of Biochemistry
and Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Hue Sun Chan
- Departments of Biochemistry
and Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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17
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Cao H, Huang Y, Liu Z. Interplay between binding affinity and kinetics in protein-protein interactions. Proteins 2016; 84:920-33. [PMID: 27018856 DOI: 10.1002/prot.25041] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 01/24/2016] [Accepted: 03/17/2016] [Indexed: 12/18/2022]
Abstract
To clarify the interplay between the binding affinity and kinetics of protein-protein interactions, and the possible role of intrinsically disordered proteins in such interactions, molecular simulations were carried out on 20 protein complexes. With bias potential and reweighting techniques, the free energy profiles were obtained under physiological affinities, which showed that the bound-state valley is deep with a barrier height of 12 - 33 RT. From the dependence of the affinity on interface interactions, the entropic contribution to the binding affinity is approximated to be proportional to the interface area. The extracted dissociation rates based on the Arrhenius law correlate reasonably well with the experimental values (Pearson correlation coefficient R = 0.79). For each protein complex, a linear free energy relationship between binding affinity and the dissociation rate was confirmed, but the distribution of the slopes for intrinsically disordered proteins showed no essential difference with that observed for ordered proteins. A comparison with protein folding was also performed. Proteins 2016; 84:920-933. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Huaiqing Cao
- College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China.,Center for Quantitative Biology, and Beijing National Laboratory for Molecular Sciences (BNLMS), Peking University, Beijing, 100871, China
| | - Yongqi Huang
- Institute of Theoretical Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, China
| | - Zhirong Liu
- College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China.,Center for Quantitative Biology, and Beijing National Laboratory for Molecular Sciences (BNLMS), Peking University, Beijing, 100871, China
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18
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Chen T, Chan HS. Native contact density and nonnative hydrophobic effects in the folding of bacterial immunity proteins. PLoS Comput Biol 2015; 11:e1004260. [PMID: 26016652 PMCID: PMC4446218 DOI: 10.1371/journal.pcbi.1004260] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 03/29/2015] [Indexed: 11/18/2022] Open
Abstract
The bacterial colicin-immunity proteins Im7 and Im9 fold by different mechanisms. Experimentally, at pH 7.0 and 10°C, Im7 folds in a three-state manner via an intermediate but Im9 folding is two-state-like. Accordingly, Im7 exhibits a chevron rollover, whereas the chevron arm for Im9 folding is linear. Here we address the biophysical basis of their different behaviors by using native-centric models with and without additional transferrable, sequence-dependent energies. The Im7 chevron rollover is not captured by either a pure native-centric model or a model augmented by nonnative hydrophobic interactions with a uniform strength irrespective of residue type. By contrast, a more realistic nonnative interaction scheme that accounts for the difference in hydrophobicity among residues leads simultaneously to a chevron rollover for Im7 and an essentially linear folding chevron arm for Im9. Hydrophobic residues identified by published experiments to be involved in nonnative interactions during Im7 folding are found to participate in the strongest nonnative contacts in this model. Thus our observations support the experimental perspective that the Im7 folding intermediate is largely underpinned by nonnative interactions involving large hydrophobics. Our simulation suggests further that nonnative effects in Im7 are facilitated by a lower local native contact density relative to that of Im9. In a one-dimensional diffusion picture of Im7 folding with a coordinate- and stability-dependent diffusion coefficient, a significant chevron rollover is consistent with a diffusion coefficient that depends strongly on native stability at the conformational position of the folding intermediate. In order to fold correctly, a globular protein must avoid being trapped in wrong, i.e., nonnative conformations. Thus a biophysical account of how attractive nonnative interactions are bypassed by some amino acid sequences but not others is key to deciphering protein structure and function. We examine two closely related bacterial immunity proteins, Im7 and Im9, that are experimentally known to fold very differently: Whereas Im9 folds directly, Im7 folds through a mispacked conformational intermediate. A simple model we developed accounts for their intriguingly different folding kinetics in terms of a balance between the density of native-promoting contacts and the hydrophobicity of local amino acid sequences. This emergent principle is extensible to other biomolecular recognition processes.
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Affiliation(s)
- Tao Chen
- Departments of Biochemistry, of Molecular Genetics, and of Physics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Hue Sun Chan
- Departments of Biochemistry, of Molecular Genetics, and of Physics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
- * E-mail:
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19
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Dias CL, Chan HS. Pressure-Dependent Properties of Elementary Hydrophobic Interactions: Ramifications for Activation Properties of Protein Folding. J Phys Chem B 2014; 118:7488-7509. [DOI: 10.1021/jp501935f] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Cristiano L. Dias
- Department
of Physics, New Jersey Institute of Technology, University Heights, Tiernan Hall, Room 463, Newark, New Jersey 07102, United States
- Departments
of Biochemistry, Molecular Genetics, and Physics, University of Toronto, 1 King’s College Circle, Toronto, Ontario Canada M5S 1A8
| | - Hue Sun Chan
- Departments
of Biochemistry, Molecular Genetics, and Physics, University of Toronto, 1 King’s College Circle, Toronto, Ontario Canada M5S 1A8
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20
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Chen T, Chan HS. Effects of desolvation barriers and sidechains on local–nonlocal coupling and chevron behaviors in coarse-grained models of protein folding. Phys Chem Chem Phys 2014; 16:6460-79. [DOI: 10.1039/c3cp54866j] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Coarse-grained protein chain models with desolvation barriers or sidechains lead to stronger local–nonlocal coupling and more linear chevron plots.
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Affiliation(s)
- Tao Chen
- Departments of Biochemistry
- of Molecular Genetics
- of Physics
- University of Toronto
- Toronto, Canada
| | - Hue Sun Chan
- Departments of Biochemistry
- of Molecular Genetics
- of Physics
- University of Toronto
- Toronto, Canada
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21
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Huang Y, Liu Z. Do Intrinsically Disordered Proteins Possess High Specificity in Protein-Protein Interactions? Chemistry 2013; 19:4462-7. [DOI: 10.1002/chem.201203100] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Indexed: 01/08/2023]
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22
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Abstract
Coarse-grained models for protein folding and aggregation are used to explore large dimension scales and timescales that are inaccessible to all-atom models in explicit aqueous solution. Combined with enhanced configuration search methods, these simplified models with various levels of granularity offer the possibility to determine equilibrium structures, compare folding kinetics and thermodynamics with experiments for single proteins and understand the dynamic assembly of amyloid proteins leading to neurodegenerative diseases. I shall describe recent progress in developing such models, and discuss their potentials and limitations in probing the folding and misfolding of proteins with computer simulations.
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23
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Perezzan R, Rey A. Simulating protein unfolding under pressure with a coarse-grained model. J Chem Phys 2012; 137:185102. [DOI: 10.1063/1.4765057] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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24
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Beharry AA, Chen T, Al-Abdul-Wahid MS, Samanta S, Davidov K, Sadovski O, Ali AM, Chen SB, Prosser RS, Chan HS, Woolley GA. Quantitative analysis of the effects of photoswitchable distance constraints on the structure of a globular protein. Biochemistry 2012; 51:6421-31. [PMID: 22803618 DOI: 10.1021/bi300685a] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Photoswitchable distance constraints in the form of photoisomerizable chemical cross-links offer a general approach to the design of reversibly photocontrolled proteins. To apply these effectively, however, one must have guidelines for the choice of cross-linker structure and cross-linker attachment sites. Here we investigate the effects of varying cross-linker structure on the photocontrol of folding of the Fyn SH3 domain, a well-studied model protein. We develop a theoretical framework based on an explicit-chain model of protein folding, modified to include detailed model linkers, that allows prediction of the effect of a given linker on the free energy of folding of a protein. Using this framework, we were able to quantitatively explain the experimental result that a longer, but somewhat flexible, cross-linker is less destabilizing to the folded state than a shorter more rigid cross-linker. The models also suggest how misfolded states may be generated by cross-linking, providing a rationale for altered dynamics seen in nuclear magnetic resonance analyses of these proteins. The theoretical framework is readily portable to any protein of known folded state structure and thus can be used to guide the design of photoswitchable proteins generally.
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Affiliation(s)
- Andrew A Beharry
- Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada
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25
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Tripathi S, Portman JJ. Conformational flexibility and the mechanisms of allosteric transitions in topologically similar proteins. J Chem Phys 2011; 135:075104. [PMID: 21861587 DOI: 10.1063/1.3625636] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Conformational flexibility plays a central role in allosteric transition of proteins. In this paper, we extend the analysis of our previous study [S. Tripathi and J. J. Portman, Proc. Natl. Acad. Sci. U.S.A. 106, 2104 (2009)] to investigate how relatively minor structural changes of the meta-stable states can significantly influence the conformational flexibility and allosteric transition mechanism. We use the allosteric transitions of the domains of calmodulin as an example system to highlight the relationship between the transition mechanism and the inter-residue contacts present in the meta-stable states. In particular, we focus on the origin of transient local unfolding (cracking), a mechanism that can lower free energy barriers of allosteric transitions, in terms of the inter-residue contacts of the meta-stable states and the pattern of local strain that develops during the transition. We find that the magnitude of the local strain in the protein is not the sole factor determining whether a region will ultimately crack during the transition. These results emphasize that the residue interactions found exclusively in one of the two meta-stable states is the key in understanding the mechanism of allosteric conformational change.
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26
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Bhaskara RM, Srinivasan N. Stability of domain structures in multi-domain proteins. Sci Rep 2011; 1:40. [PMID: 22355559 PMCID: PMC3216527 DOI: 10.1038/srep00040] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 06/27/2011] [Indexed: 01/22/2023] Open
Abstract
Multi-domain proteins have many advantages with respect to stability and folding inside cells. Here we attempt to understand the intricate relationship between the domain-domain interactions and the stability of domains in isolation. We provide quantitative treatment and proof for prevailing intuitive ideas on the strategies employed by nature to stabilize otherwise unstable domains. We find that domains incapable of independent stability are stabilized by favourable interactions with tethered domains in the multi-domain context. Stability of such folds to exist independently is optimized by evolution. Specific residue mutations in the sites equivalent to inter-domain interface enhance the overall solvation, thereby stabilizing these domain folds independently. A few naturally occurring variants at these sites alter communication between domains and affect stability leading to disease manifestation. Our analysis provides safe guidelines for mutagenesis which have attractive applications in obtaining stable fragments and domain constructs essential for structural studies by crystallography and NMR.
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27
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Chan HS, Zhang Z, Wallin S, Liu Z. Cooperativity, local-nonlocal coupling, and nonnative interactions: principles of protein folding from coarse-grained models. Annu Rev Phys Chem 2011; 62:301-26. [PMID: 21453060 DOI: 10.1146/annurev-physchem-032210-103405] [Citation(s) in RCA: 164] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Coarse-grained, self-contained polymer models are powerful tools in the study of protein folding. They are also essential to assess predictions from less rigorous theoretical approaches that lack an explicit-chain representation. Here we review advances in coarse-grained modeling of cooperative protein folding, noting in particular that the Levinthal paradox was raised in response to the experimental discovery of two-state-like folding in the late 1960s, rather than to the problem of conformational search per se. Comparisons between theory and experiment indicate a prominent role of desolvation barriers in cooperative folding, which likely emerges generally from a coupling between local conformational preferences and nonlocal packing interactions. Many of these principles have been elucidated by native-centric models, wherein nonnative interactions may be treated perturbatively. We discuss these developments as well as recent applications of coarse-grained chain modeling to knotted proteins and to intrinsically disordered proteins.
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Affiliation(s)
- Hue Sun Chan
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
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28
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The contribution of entropy, enthalpy, and hydrophobic desolvation to cooperativity in repeat-protein folding. Structure 2011; 19:349-60. [PMID: 21397186 DOI: 10.1016/j.str.2010.12.018] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Revised: 11/23/2010] [Accepted: 12/10/2010] [Indexed: 11/22/2022]
Abstract
Cooperativity is a defining feature of protein folding, but its thermodynamic and structural origins are not completely understood. By constructing consensus ankyrin repeat protein arrays that have nearly identical sequences, we quantify cooperativity by resolving stability into intrinsic and interfacial components. Heteronuclear NMR and CD spectroscopy show that these constructs adopt ankyrin repeat structures. Applying a one-dimensional Ising model to a series of constructs chosen to maximize information content in unfolding transitions, we quantify stabilities of the terminal capping repeats, and resolve the effects of denaturant into intrinsic and interfacial components. Reversible thermal denaturation resolves interfacial and intrinsic free energies into enthalpic, entropic, and heat capacity terms. Intrinsic folding is entropically disfavored, whereas interfacial interaction is entropically favored and attends a decrease in heat capacity. These results suggest that helix formation and backbone ordering occurs upon intrinsic folding, whereas hydrophobic desolvation occurs upon interfacial interaction, contributing to cooperativity.
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29
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30
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Huang Y, Liu Z. Smoothing molecular interactions: The “kinetic buffer” effect of intrinsically disordered proteins. Proteins 2010; 78:3251-9. [DOI: 10.1002/prot.22820] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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31
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Huang Y, Liu Z. Nonnative interactions in coupled folding and binding processes of intrinsically disordered proteins. PLoS One 2010; 5:e15375. [PMID: 21079758 PMCID: PMC2973977 DOI: 10.1371/journal.pone.0015375] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 08/18/2010] [Indexed: 11/19/2022] Open
Abstract
Proteins function by interacting with other molecules, where both native and nonnative interactions play important roles. Native interactions contribute to the stability and specificity of a complex, whereas nonnative interactions mainly perturb the binding kinetics. For intrinsically disordered proteins (IDPs), which do not adopt rigid structures when being free in solution, the role of nonnative interactions may be more prominent in binding processes due to their high flexibilities. In this work, we investigated the effect of nonnative hydrophobic interactions on the coupled folding and binding processes of IDPs and its interplay with chain flexibility by conducting molecular dynamics simulations. Our results showed that the free-energy profiles became rugged, and intermediate states occurred when nonnative hydrophobic interactions were introduced. The binding rate was initially accelerated and subsequently dramatically decreased as the strength of the nonnative hydrophobic interactions increased. Both thermodynamic and kinetic analysis showed that disordered systems were more readily affected by nonnative interactions than ordered systems. Furthermore, it was demonstrated that the kinetic advantage of IDPs (“fly-casting” mechanism) was enhanced by nonnative hydrophobic interactions. The relationship between chain flexibility and protein aggregation is also discussed.
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Affiliation(s)
- Yongqi Huang
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
- Center for Theoretical Biology, Peking University, Beijing, China
- Beijing National Laboratory for Molecular Sciences, Peking University, Beijing, China
| | - Zhirong Liu
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
- Center for Theoretical Biology, Peking University, Beijing, China
- Beijing National Laboratory for Molecular Sciences, Peking University, Beijing, China
- * E-mail:
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32
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Qi Y, Huang Y, Liang H, Liu Z, Lai L. Folding simulations of a de novo designed protein with a betaalphabeta fold. Biophys J 2010; 98:321-9. [PMID: 20338854 DOI: 10.1016/j.bpj.2009.10.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2009] [Revised: 10/08/2009] [Accepted: 10/13/2009] [Indexed: 01/06/2023] Open
Abstract
betaalphabeta structural motifs are commonly used building blocks in protein structures containing parallel beta-sheets. However, to our knowledge, no stand-alone betaalphabeta structure has been observed in nature to date. Recently, for the first time that we know of, a small protein with an independent betaalphabeta structure (DS119) was successfully designed in our laboratory. To understand the folding mechanism of DS119, in the study described here, we carried out all-atom molecular dynamics and coarse-grained simulations to investigate its folding pathways and energy landscape. From all-atom simulations, we successfully observed the folding event and got a stable folded structure with a minimal root mean-square deviation of 2.6 A with respect to the NMR structure. The folding process can be described as a fast collapse phase followed by rapid formation of the central helix, and then slow formation of a parallel beta-sheet. By using a native-centric Gō-like model, the cooperativity of the system was characterized in terms of the calorimetric criterion, sigmoidal transitions, conformation distribution shifts, and free-energy profiles. DS119 was found to be an incipient downhill folder that folds more cooperatively than a downhill folder, but less cooperatively than a two-state folder. This may reflect the balance between the two structural elements of DS119: the rapidly formed alpha-helix and the slowly formed parallel beta-sheet. Folding times estimated from both the all-atom simulations and the coarse-grained model were at microsecond level, making DS119 another fast folder. Compared to fast folders reported previously, DS119 is, to the best of our knowledge, the first that exhibits a parallel beta-sheet.
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Affiliation(s)
- Yifei Qi
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, and Center for Theoretical Biology, Peking University, Beijing, China
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33
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The implications of gene heterozygosity for protein folding and protein turnover. J Theor Biol 2010; 265:554-64. [PMID: 20493885 DOI: 10.1016/j.jtbi.2010.05.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2009] [Revised: 04/11/2010] [Accepted: 05/17/2010] [Indexed: 12/14/2022]
Abstract
The offspring of closely related parents often suffer from inbreeding depression, sometimes resulting in a slower growth rate for inbred offspring relative to non-inbred offspring. Previous research has shown that some of the slower growth rate of inbred organisms can be attributed to the inbred organisms' increased levels of protein turnover. This paper attempts to show that the higher levels of protein turnover among inbred organisms can be attributed to accumulations of misfolded and aggregated proteins that require degradation by the inbred organisms' protein quality control systems. The accumulation of misfolded and aggregated proteins within inbred organisms are the result of more negative free energies of folding for proteins encoded at homozygous gene loci and higher concentrations of potentially aggregating non-native protein species within the cell. The theory presented here makes several quantitative predictions that suggest a connection between protein misfolding/aggregation and polyploidy that can be tested by future research.
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34
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35
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Competition between native topology and nonnative interactions in simple and complex folding kinetics of natural and designed proteins. Proc Natl Acad Sci U S A 2010; 107:2920-5. [PMID: 20133730 DOI: 10.1073/pnas.0911844107] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
We compared folding properties of designed protein Top7 and natural protein S6 by using coarse-grained chain models with a mainly native-centric construct that accounted also for nonnative hydrophobic interactions and desolvation barriers. Top7 and S6 have similar secondary structure elements and are approximately equal in length and hydrophobic composition. Yet their experimental folding kinetics were drastically different. Consistent with experiment, our simulated folding chevron arm for Top7 exhibited a severe rollover, whereas that for S6 was essentially linear, and Top7 model kinetic relaxation was multiphasic under strongly folding conditions. The peculiar behavior of Top7 was associated with several classes of kinetic traps in our model. Significantly, the amino acid residues participating in nonnative interactions in trapped conformations in our Top7 model overlapped with those deduced experimentally. These affirmations suggest that the simple ingredients of native topology plus sequence-dependent nonnative interactions are sufficient to account for some key features of protein folding kinetics. Notably, when nonnative interactions were absent in the model, Top7 chevron rollover was not correctly predicted. In contrast, nonnative interactions had little effect on the quasi linearity of the model folding chevron arm for S6. This intriguing distinction indicates that folding cooperativity is governed by a subtle interplay between the sequence-dependent driving forces for native topology and the locations of favorable nonnative interactions entailed by the same sequence. Constructed with a capability to mimic this interplay, our simple modeling approach should be useful in general for assessing a designed sequence's potential to fold cooperatively.
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36
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Water dynamics clue to key residues in protein folding. Biochem Biophys Res Commun 2010; 392:95-9. [DOI: 10.1016/j.bbrc.2010.01.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 01/04/2010] [Indexed: 11/23/2022]
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37
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Kinetic advantage of intrinsically disordered proteins in coupled folding-binding process: a critical assessment of the "fly-casting" mechanism. J Mol Biol 2009; 393:1143-59. [PMID: 19747922 DOI: 10.1016/j.jmb.2009.09.010] [Citation(s) in RCA: 212] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Revised: 06/29/2009] [Accepted: 09/04/2009] [Indexed: 11/20/2022]
Abstract
Intrinsically disordered proteins (IDPs) are recognized to play important roles in many biological functions such as transcription and translation regulation, cellular signal transduction, protein phosphorylation, and molecular assemblies. The coupling of folding with binding through a "fly-casting" mechanism has been proposed to account for the fast binding kinetics of IDPs. In this article, experimental data from the literature were collated to verify the kinetic advantages of IDPs, while molecular simulations were performed to clarify the origin of the kinetic advantages. The phosphorylated KID-kinase-inducible domain interacting domain (KIX) complex was used as an example in the simulations. By modifying a coarse-grained model with a native-centric Gō-like potential, we were able to continuously tune the degree of disorder of the phosphorylated KID domain and thus investigate the intrinsic role of chain flexibility in binding kinetics. The simulations show that the "fly-casting" effect is not only due to the greater capture radii of IDPs. The coupling of folding with binding of IDPs leads to a significant reduction in binding free-energy barrier. Such a reduction accelerates the binding process. Although the greater capture radius has been regarded as the main factor in promoting the binding rate of IDPs, we found that this parameter will also lead to the slower translational diffusion of IDPs when compared with ordered proteins. As a result, the capture rate of IDPs was found to be slower than that of ordered proteins. The main origin of the faster binding for IDPs are the fewer encounter times required before the formation of the final binding complex. The roles of the interchain native contacts fraction (Q(b)) and the mass-center distance (DeltaR) as reaction coordinates are also discussed.
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38
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Larriva M, Prieto L, Bruscolini P, Rey A. A simple simulation model can reproduce the thermodynamic folding intermediate of apoflavodoxin. Proteins 2009; 78:73-82. [DOI: 10.1002/prot.22521] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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39
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Ferguson A, Liu Z, Chan HS. Desolvation Barrier Effects Are a Likely Contributor to the Remarkable Diversity in the Folding Rates of Small Proteins. J Mol Biol 2009; 389:619-36. [DOI: 10.1016/j.jmb.2009.04.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 04/01/2009] [Accepted: 04/06/2009] [Indexed: 11/25/2022]
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40
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Barrick D. What have we learned from the studies of two-state folders, and what are the unanswered questions about two-state protein folding? Phys Biol 2009; 6:015001. [PMID: 19208936 DOI: 10.1088/1478-3975/6/1/015001] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Small proteins with globular structures often fold by simple all-or-none mechanisms, both in an equilibrium and a kinetic sense, despite the very large number of partly folded conformations available. This type of 'two-state' folding will be discussed in terms of experimental tests, underlying molecular mechanisms, and limits to two-state behavior. Factors that appear to be important for two-state folding include topology (sequence distance of contacts in the native structure), molecular cooperativity and local energy distribution. Because their local stability distributions and cooperativities can be dissected and analyzed separately from topological features, recent studies of the folding of symmetric proteins will be discussed as a means to better understand the origins of two-state folding.
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Affiliation(s)
- Doug Barrick
- T C Department of Biophysics, The Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21218, USA.
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41
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Costas M, Rodríguez-Larrea D, De Maria L, Borchert TV, Gómez-Puyou A, Sanchez-Ruiz JM. Between-species variation in the kinetic stability of TIM proteins linked to solvation-barrier free energies. J Mol Biol 2008; 385:924-37. [PMID: 18992756 DOI: 10.1016/j.jmb.2008.10.056] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 10/16/2008] [Accepted: 10/20/2008] [Indexed: 11/17/2022]
Abstract
Theoretical, computational, and experimental studies have suggested the existence of solvation barriers in protein unfolding and denaturation processes. These barriers are related to the finite size of water molecules and can be envisioned as arising from the asynchrony between water penetration and breakup of internal interactions. Solvation barriers have been proposed to play roles in protein cooperativity and kinetic stability; therefore, they may be expected to be subject to natural selection. We study the thermal denaturation, in the presence and in the absence of chemical denaturants, of triosephosphate isomerases (TIMs) from three different species: Trypanosoma cruzi, Trypanosoma brucei, and Leishmania mexicana. In all cases, denaturation was irreversible and kinetically controlled. Surprisingly, however, we found large differences between the kinetic denaturation parameters, with T. cruzi TIM showing a much larger activation energy value (and, consequently, much lower room-temperature, extrapolated denaturation rates). This disparity cannot be accounted for by variations in the degree of exposure to solvent in transition states (as measured by kinetic urea m values) and is, therefore, to be attributed mainly to differences in solvation-barrier contributions. This was supported by structure-energetics analyses of the transition states and by application of a novel procedure to estimate from experimental data the solvation-barrier impact at the entropy and free-energy levels. These analyses were actually performed with an extended protein set (including six small proteins plus seven variants of lipase from Thermomyces lanuginosus and spanning a wide range of activation parameters), allowing us to delineate the general trends of the solvation-barrier contributions. Overall, this work supports that proteins sharing the same structure and function but belonging to different organisms may show widely different solvation barriers, possibly as a result of different levels of the selection pressure associated with cooperativity, kinetic stability, and related factors.
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Affiliation(s)
- Miguel Costas
- Laboratorio de Biofisicoquímica, Departamento de Fisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México, Cd Universitaria, México DF 04510, México.
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42
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Badasyan A, Liu Z, Chan HS. Probing possible downhill folding: native contact topology likely places a significant constraint on the folding cooperativity of proteins with approximately 40 residues. J Mol Biol 2008; 384:512-30. [PMID: 18823994 DOI: 10.1016/j.jmb.2008.09.023] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Revised: 09/06/2008] [Accepted: 09/10/2008] [Indexed: 10/21/2022]
Abstract
Experiments point to appreciable variations in folding cooperativity among natural proteins with approximately 40 residues, indicating that the behaviors of these proteins are valuable for delineating the contributing factors to cooperative folding. To explore the role of native topology in a protein's propensity to fold cooperatively and how native topology might constrain the degree of cooperativity achievable by a given set of physical interactions, we compared folding/unfolding kinetics simulated using three classes of native-centric C(alpha) chain models with different interaction schemes. The approach was applied to two homologous 45-residue fragments from the peripheral subunit-binding domain family and a 39-residue fragment of the N-terminal domain of ribosomal protein L9. Free-energy profiles as functions of native contact number were computed to assess the heights of thermodynamic barriers to folding. In addition, chevron plots of folding/unfolding rates were constructed as functions of native stability to facilitate comparison with available experimental data. Although common Gō-like models with pairwise Lennard-Jones-type interactions generally fold less cooperatively than real proteins, the rank ordering of cooperativity predicted by these models is consistent with experiment for the proteins investigated, showing increasing folding cooperativity with increasing nonlocality of a protein's native contacts. Models that account for water-expulsion (desolvation) barriers and models with many-body (nonadditive) interactions generally entail higher degrees of folding cooperativity indicated by more linear model chevron plots, but the rank ordering of cooperativity remains unchanged. A robust, experimentally valid rank ordering of model folding cooperativity independent of the multiple native-centric interaction schemes tested here argues that native topology places significant constraints on how cooperatively a protein can fold.
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Affiliation(s)
- Artem Badasyan
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada M5S 1A8
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43
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Dumon C, Varvak A, Wall MA, Flint JE, Lewis RJ, Lakey JH, Morland C, Luginbühl P, Healey S, Todaro T, DeSantis G, Sun M, Parra-Gessert L, Tan X, Weiner DP, Gilbert HJ. Engineering hyperthermostability into a GH11 xylanase is mediated by subtle changes to protein structure. J Biol Chem 2008; 283:22557-64. [PMID: 18515360 DOI: 10.1074/jbc.m800936200] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Understanding the structural basis for protein thermostability is of considerable biological and biotechnological importance as exemplified by the industrial use of xylanases at elevated temperatures in the paper pulp and animal feed sectors. Here we have used directed protein evolution to generate hyperthermostable variants of a thermophilic GH11 xylanase, EvXyn11. The Gene Site Saturation Mutagenesis (GSSM) methodology employed assesses the influence on thermostability of all possible amino acid substitutions at each position in the primary structure of the target protein. The 15 most thermostable mutants, which generally clustered in the N-terminal region of the enzyme, had melting temperatures (Tm) 1-8 degrees C higher than the parent protein. Screening of a combinatorial library of the single mutants identified a hyperthermostable variant, EvXyn11TS, containing seven mutations. EvXyn11TS had a Tm approximately 25 degrees C higher than the parent enzyme while displaying catalytic properties that were similar to EvXyn11. The crystal structures of EvXyn11 and EvXyn11TS revealed an absence of substantial changes to identifiable intramolecular interactions. The only explicable mutations are T13F, which increases hydrophobic interactions, and S9P that apparently locks the conformation of a surface loop. This report shows that the molecular basis for the increased thermostability is extraordinarily subtle and points to the requirement for new tools to interrogate protein folding at non-ambient temperatures.
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Affiliation(s)
- Claire Dumon
- Institute for Cell and Molecular Biosciences, Newcastle University, The Medical School, Newcastle Upon Tyne NE2 4HH, United Kingdom
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44
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Cooperative folding kinetics of BBL protein and peripheral subunit-binding domain homologues. Proc Natl Acad Sci U S A 2008; 105:2397-402. [PMID: 18272497 DOI: 10.1073/pnas.0708480105] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recent experiments claiming that Naf-BBL protein follows a global downhill folding raised an important controversy as to the folding mechanism of fast-folding proteins. Under the global downhill folding scenario, not only do proteins undergo a gradual folding, but folding events along the continuous folding pathway also could be mapped out from the equilibrium denaturation experiment. Based on the exact calculation using a free energy landscape, relaxation eigenmodes from a master equation, and Monte Carlo simulation of an extended Muñoz-Eaton model that incorporates multiscale-heterogeneous pairwise interactions between amino acids, here we show that the very nature of a two-state cooperative transition such as a bimodal distribution from an exact free energy landscape and biphasic relaxation kinetics manifest in the thermodynamics and folding-unfolding kinetics of BBL and peripheral subunit-binding domain homologues. Our results provide an unequivocal resolution to the fundamental controversy related to the global downhill folding scheme, whose applicability to other proteins should be critically reexamined.
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45
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Moghaddam MS, Chan HS. Pressure and temperature dependence of hydrophobic hydration: Volumetric, compressibility, and thermodynamic signatures. J Chem Phys 2007; 126:114507. [PMID: 17381220 DOI: 10.1063/1.2539179] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The combined effect of pressure and temperature on hydrophobic hydration of a nonpolar methanelike solute is investigated by extensive simulations in the TIP4P model of water. Using test-particle insertion techniques, free energies of hydration under a range of pressures from 1 to 3000 atm are computed at eight temperatures ranging from 278.15 to 368.15 K. Corresponding enthalpy, entropy, and heat capacity accompanying the hydration process are estimated from the temperature dependence of the free energies. Partial molar and excess volumes calculated using pressure derivatives of the simulated free energies are consistent with those determined by direct volume simulations; but direct volume determination offers more reliable estimates for compressibility. At 298.15 K, partial molar and excess isothermal compressibilities of methane are negative at 1 atm. Partial molar and excess adiabatic (isentropic) compressibilities are estimated to be also negative under the same conditions. But partial molar and excess isothermal compressibilities are positive at high pressures, with a crossover from negative to positive compressibility at approximately 100-1000 atm. This trend is consistent with experiments on aliphatic amino acids and pressure-unfolded states of proteins. For the range of pressures simulated, hydration heat capacity exhibits little pressure dependence, also in apparent agreement with experiment. When pressure is raised at constant room temperature, hydration free energy increases while its entropic component remains essentially constant. Thus, the increasing unfavorability of hydration under raised pressure is seen as largely an enthalpic effect. Ramifications of the findings of the authors for biopolymer conformational transitions are discussed.
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Affiliation(s)
- Maria Sabaye Moghaddam
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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46
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Ma BG, Guo JX, Zhang HY. Direct correlation between proteins' folding rates and their amino acid compositions: An ab initio folding rate prediction. Proteins 2006; 65:362-72. [PMID: 16937389 DOI: 10.1002/prot.21140] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Discovering the mechanism of protein folding, in molecular biology, is a great challenge. A key step to this end is to find factors that correlate with protein folding rates. Over the past few years, many empirical parameters, such as contact order, long-range order, total contact distance, secondary structure contents, have been developed to reflect the correlation between folding rates and protein tertiary or secondary structures. However, the correlation between proteins' folding rates and their amino acid compositions has not been explored. In the present work, we examined systematically the correlation between proteins' folding rates and their amino acid compositions for two-state and multistate folders and found that different amino acids contributed differently to the folding progress. The relation between the amino acids' molecular weight and degeneracy and the folding rates was examined, and the role of hydrophobicity in the protein folding process was also inspected. As a consequence, a new indicator called composition index was derived, which takes no structure factors into account and is merely determined by the amino acid composition of a protein. Such an indicator is found to be highly correlated with the protein's folding rate (r > 0.7). From the results of this work, three points of concluding remarks are evident. (1) Two-state folders and multistate folders have different rate-determining amino acids. (2) The main determining information of a protein's folding rate is largely reflected in its amino acid composition. (3) Composition index may be the best predictor for an ab initio protein folding rate prediction directly from protein sequence from the standpoint of practical application.
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Affiliation(s)
- Bin-Guang Ma
- Shandong Provincial Research Center for Bioinformatic Engineering and Technique, Center for Advanced Study, Shandong University of Technology, Zibo 255049, People's Republic of China.
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Knott M, Chan HS. Criteria for downhill protein folding: Calorimetry, chevron plot, kinetic relaxation, and single-molecule radius of gyration in chain models with subdued degrees of cooperativity. Proteins 2006; 65:373-91. [PMID: 16909416 DOI: 10.1002/prot.21066] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Recent investigations of possible downhill folding of small proteins such as BBL have focused on the thermodynamics of non-two-state, "barrierless" folding/denaturation transitions. Downhill folding is noncooperative and thermodynamically "one-state," a phenomenon underpinned by a unimodal conformational distribution over chain properties such as enthalpy, hydrophobic exposure, and conformational dimension. In contrast, corresponding distributions for cooperative two-state folding are bimodal with well-separated population peaks. Using simplified atomic modeling of a three-helix bundle-in a scheme that accounts for hydrophobic interactions and hydrogen bonding-and coarse-grained C(alpha) models of four real proteins with various degrees of cooperativity, we evaluate the effectiveness of several observables at defining the underlying distribution. Bimodal distributions generally lead to sharper transitions, with a higher heat capacity peak at the transition midpoint, compared with unimodal distributions. However, the observation of a sigmoidal transition is not a reliable criterion for two-state behavior, and the heat capacity baselines, used to determine the van't Hoff and calorimetric enthalpies of the transition, can introduce ambiguity. Interestingly we find that, if the distribution of the single-molecule radius of gyration were available, it would permit discrimination between unimodal and bimodal underlying distributions. We investigate kinetic implications of thermodynamic noncooperativity using Langevin dynamics. Despite substantial chevron rollovers, the relaxation of the models considered is essentially single-exponential over an extended range of native stabilities. Consistent with experiments, significant deviations from single-exponential behavior occur only under strongly folding conditions.
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Affiliation(s)
- Michael Knott
- Department of Biochemistry, and of Medical Genetics and Microbiology, Protein Engineering Network of Centres of Excellence, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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