1
|
Das N, Khan T, Halder B, Ghosh S, Sen P. Macromolecular crowding effects on protein dynamics. Int J Biol Macromol 2024; 281:136248. [PMID: 39374718 DOI: 10.1016/j.ijbiomac.2024.136248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2024] [Revised: 09/30/2024] [Accepted: 09/30/2024] [Indexed: 10/09/2024]
Abstract
Macromolecular crowding experiments bridge the gap between in-vivo and in-vitro studies by mimicking some of the cellular complexities like high viscosity and limited space, while still manageable for experiments and analysis. Macromolecular crowding impacts all biological processes and is a focus of contemporary research. Recent reviews have highlighted the effect of crowding on various protein properties. One of the essential characteristics of protein is its dynamic nature; however, how protein dynamics get modulated in the crowded milieu has been largely ignored. This article discusses how protein translational, rotational, conformational, and solvation dynamics change under crowded conditions, summarizing key observations in the literature. We emphasize our research on microsecond conformational and water dynamics in crowded milieus and their impact on enzymatic activity and stability. Lastly, we provided our outlook on how this field might move forward in the future.
Collapse
Affiliation(s)
- Nilimesh Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP, India
| | - Tanmoy Khan
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP, India
| | - Bisal Halder
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP, India
| | - Shreya Ghosh
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP, India
| | - Pratik Sen
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP, India.
| |
Collapse
|
2
|
Khan T, Halder B, Das N, Sen P. Role of Associated Water Dynamics on Protein Stability and Activity in Crowded Milieu. J Phys Chem B 2024; 128:8672-8686. [PMID: 39224956 DOI: 10.1021/acs.jpcb.4c04337] [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: 09/04/2024]
Abstract
Macromolecular crowding bridges in vivo and in vitro studies by simulating cellular complexities such as high viscosity and limited space while maintaining the experimental feasibility. Over the last two decades, the impact of macromolecular crowding on protein stability and activity has been a significant topic of study and discussion, though still lacking a thorough mechanistic understanding. This article investigates the role of associated water dynamics on protein stability and activity within crowded environments, using bromelain and Ficoll-70 as the model systems. Traditional crowding theory primarily attributes protein stability to entropic effects (excluded volume) and enthalpic interactions. However, our recent findings suggest that water structure modulation plays a crucial role in a crowded environment. In this report, we strengthen the conclusion of our previous study, i.e., rigid-associated water stabilizes proteins via entropy and destabilizes them via enthalpy, while flexible water has the opposite effect. In the process, we addressed previous shortcomings with a systematic concentration-dependent study using a single-domain protein and component analysis of solvation dynamics. More importantly, we analyze bromelain's hydrolytic activity using the Michaelis-Menten model to understand kinetic parameters like maximum velocity (Vmax) achieved by the system and the Michaelis-Menten coefficient (KM). Results indicate that microviscosity (not the bulk viscosity) controls the enzyme-substrate (ES) complex formation, where an increase in the microviscosity makes the ES complex formation less favorable. On the other hand, flexible associated water dynamics were found to favor the rate of product formation significantly from the ES complex, while rigid associated water hinders it. This study improves our understanding of protein stability and activity in crowded environments, highlighting the critical role of associated water dynamics.
Collapse
Affiliation(s)
- Tanmoy Khan
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, UP 208 016, India
| | - Bisal Halder
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, UP 208 016, India
| | - Nilimesh Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, UP 208 016, India
| | - Pratik Sen
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, UP 208 016, India
| |
Collapse
|
3
|
Xu S, Wang J, Dong J. Nonspecific interaction and overlap concentration influence macromolecular crowding effect on glucose oxidase activity. Int J Biol Macromol 2023; 241:124525. [PMID: 37086776 DOI: 10.1016/j.ijbiomac.2023.124525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Revised: 04/14/2023] [Accepted: 04/15/2023] [Indexed: 04/24/2023]
Abstract
Macromolecular crowding can change kinetics of enzyme catalysis. How interaction between enzymes and neighboring macromolecules contributes to the crowding effect on enzyme catalysis has not been quantitatively revealed. In this study, crowding effects of dextran and poly(ethylene glycol) (PEG) on glucose oxidase (GOx) are studied. Fluorescence resonance energy transfer experiments show the high transfer efficiency and stable interaction between the dextran and GOx. Further fluorescence quenching analysis also proves that the association of the dextran-GOx pair can become stronger than that of the PEG-GOx pair. Dextrans with concentrations above or below their chain overlap concentrations (c*) reduce Michaelis constants (Km) of GOx catalysis by 90 % or 45 %, respectively, through volume exclusion mechanism, and in the meantime elevate the enzymatic efficiency (kcat/Km) by 8-fold or by 3-fold, respectively, which is more dramatic than that found in other enzymes before. Strong association between the enzyme and the dextran results in slow turnover rates (kcat). Intermediate crowding with weak to moderate affinity to the enzyme below the c* can tune the kcat higher than in the free state. Catalysis under crowded conditions is a joint effect of the enzyme-crowder nonspecific interaction, volume exclusion and overlap condition of the crowders.
Collapse
Affiliation(s)
- Siyuan Xu
- College of Chemistry and Chemical Engineering, Shaoxing University, Shaoxing, Zhejiang Province 312000, China
| | - Jie Wang
- College of Chemistry and Chemical Engineering, Shaoxing University, Shaoxing, Zhejiang Province 312000, China
| | - Jian Dong
- College of Chemistry and Chemical Engineering, Shaoxing University, Shaoxing, Zhejiang Province 312000, China.
| |
Collapse
|
4
|
Ghosh S, Saurabh A, Prabhu NP. Spectroscopic studies on the stability and nucleation-independent fibrillation of partially-unfolded proteins in crowded environment. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 264:120307. [PMID: 34461523 DOI: 10.1016/j.saa.2021.120307] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 07/30/2021] [Accepted: 08/17/2021] [Indexed: 06/13/2023]
Abstract
Fibril formation of globular proteins is driven by attaining an appropriate partially-unfolded conformation. Excluded volume effect exerted by the presence of other macromolecules in the solution, as found in the cellular interior, might affect the conformational state of proteins and alter their fibril formation process. The change in structure, stability and rate of fibril formation of aggregation-prone partially-unfolded states of lysozyme (Lyz) and α-lactalbumin (ALA) in the presence of different sizes of polyethylene glycol (PEG) is examined using spectroscopic methods. Thermal denaturation and far-UV CD studies suggest that Lyz is stabilized by PEGs and the stability increases with increasing concentration of PEGs. However, the stability of ALA depends on the size and concentration of PEG. The change in enthalpy of unfolding indicates the existence of soft-interactions between the proteins and PEG along with excluded volume effect. Fibrillation rate of Lyz is not significantly altered in the presence of lower concentrations of PEGs suggesting that the crowding effect dominates the viscosity-induced retardation of protein association whereas at higher concentrations the rates are reduced. In case of ALA, the rate of fibrillation is drastically reduced; however, there is a marginal increase with the increasing concentration of PEG. The results suggest that the fibril formation is influenced by change in initial conformation of the partially-unfolded states of the proteins and their stability in the presence of the crowding agent. Further, the size and concentration of the crowding agent, and the soft-interaction between the proteins and PEG also affects the fibrillation.
Collapse
Affiliation(s)
- Subhasree Ghosh
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India
| | - Archi Saurabh
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India
| | - N Prakash Prabhu
- Department of Biotechnology & Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India.
| |
Collapse
|
5
|
Das N, Sen P. Macromolecular Crowding Effect on the Structure, Function, Conformational Dynamics and Relative Domain Movement of a Multi-Domain Protein as a function of Crowder Shape and Interaction. Phys Chem Chem Phys 2022; 24:14242-14256. [DOI: 10.1039/d1cp04842b] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The cellular environment is crowded by macromolecules of various sizes, shapes, and charges, which modulate protein structure, function and dynamics. Herein, we contemplated the effect of three different macromolecular crowders:...
Collapse
|
6
|
Siddiqui GA, Naeem A. Refolding of Hemoglobin Under Macromolecular Confinement: Impersonating In Vivo Volume Exclusion. J Fluoresc 2021; 31:1371-1377. [PMID: 34156613 DOI: 10.1007/s10895-021-02751-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 05/20/2021] [Indexed: 11/27/2022]
Abstract
Biomacromolecules evolve and function inside the cell under crowded conditions. The effect of macromolecular crowding and confinement on nature and interactions of biomacromolecules cannot be ruled out. This study demonstrates the effect of volume exclusion due to macromolecular crowding on refolding rate of Gn-HCl induced unfolded hemoglobin. The in vivo like crowding milieu was created using dextran 70. Unfolding of Hb was followed by the absorbance at 280 nm and intrinsic fluorescence intensity along with a bathochromic shift that shows the destabilization of Hb in the presence of the denaturing agent. This was supported by a decrease in soret absorbance, increased hydrodynamic radii and loss in secondary structure, evidenced from dynamic light scattering and circular dichroism experiments respectively. Refolding process of Hb was followed by an increase in soret absorbance, decrease in intrinsic fluorescence intensity with a hypsochromic shift, decreased hydrodynamic radii and gain in secondary structural content. The results revealed that the effect of confinement and volume exclusion is insignificant on the process of Hb refolding.
Collapse
Affiliation(s)
- Gufran Ahmed Siddiqui
- Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, 202002, UP, India
| | - Aabgeena Naeem
- Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, 202002, UP, India.
| |
Collapse
|
7
|
Response to crowded conditions reveals compact nucleus for amyloid formation of folded protein. QRB DISCOVERY 2021. [PMID: 37529678 PMCID: PMC10392690 DOI: 10.1017/qrd.2020.17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Abstract
Although the consequences of the crowded cell environments may affect protein folding, function and misfolding reactions, these processes are often studied in dilute solutions in vitro. We here used biophysical experiments to investigate the amyloid fibril formation process of the fish protein apo-β-parvalbumin in solvent conditions that mimic steric and solvation aspects of the in vivo milieu. Apo-β-parvalbumin is a folded protein that readily adopts an amyloid state via a nucleation–elongation mechanism. Aggregation experiments in the presence of macromolecular crowding agents (probing excluded volume, entropic effects) as well as small molecule osmolytes (probing solvation, enthalpic effects) revealed that both types of agents accelerate overall amyloid formation, but the elongation step was faster with macromolecular crowding agents but slower in the presence of osmolytes. The observations can be explained by the steric effects of excluded volume favoring assembled states and that amyloid nucleation does not involve monomer unfolding. In contrast, the solvation effects due to osmolyte presence promote nucleation but not elongation. Therefore, the amyloid-competent nuclei must be compact with less osmolytes excluded from the surface than either the folded monomers or amyloid fibers. We conclude that, in contrast to other amyloidogenic folded proteins, amyloid formation of apo-β-parvalbumin is accelerated by crowded cell-like conditions due to a nucleation process that does not involve large-scale protein unfolding.
Collapse
|
8
|
Köhn B, Kovermann M. All atom insights into the impact of crowded environments on protein stability by NMR spectroscopy. Nat Commun 2020; 11:5760. [PMID: 33188202 PMCID: PMC7666220 DOI: 10.1038/s41467-020-19616-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 10/23/2020] [Indexed: 01/16/2023] Open
Abstract
The high density of macromolecules affecting proteins due to volume exclusion has been discussed in theory but numerous in vivo experiments cannot be sufficiently understood taking only pure entropic stabilization into account. Here, we show that the thermodynamic stability of a beta barrel protein increases equally at all atomic levels comparing crowded environments with dilute conditions by applying multidimensional high-resolution NMR spectroscopy in a systematic manner. Different crowding agents evoke a pure stabilization cooperatively and do not disturb the surface or integrity of the protein fold. The here developed methodology provides a solid base that can be easily expanded to incorporate e.g. binding partners to recognize functional consequences of crowded conditions. Our results are relevant to research projects targeting soluble proteins in vivo as it can be anticipated that their thermodynamic stability increase comparably and has consequently to be taken into account to coherently understand intracellular processes.
Collapse
Affiliation(s)
- Birgit Köhn
- Department of Chemistry, University of Konstanz, Universitätsstrasse. 10, 78457, Konstanz, Germany
- Konstanz Research School Chemical Biology KoRS-CB, University of Konstanz, Universitätsstrasse. 10, 78457, Konstanz, Germany
| | - Michael Kovermann
- Department of Chemistry, University of Konstanz, Universitätsstrasse. 10, 78457, Konstanz, Germany.
- Konstanz Research School Chemical Biology KoRS-CB, University of Konstanz, Universitätsstrasse. 10, 78457, Konstanz, Germany.
| |
Collapse
|
9
|
Das N, Sen P. Shape-Dependent Macromolecular Crowding on the Thermodynamics and Microsecond Conformational Dynamics of Protein Unfolding Revealed at the Single-Molecule Level. J Phys Chem B 2020; 124:5858-5871. [DOI: 10.1021/acs.jpcb.0c03897] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Nilimesh Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP India
| | - Pratik Sen
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, UP India
| |
Collapse
|
10
|
Werner T, Horvath I, Wittung-Stafshede P. Crosstalk Between Alpha-Synuclein and Other Human and Non-Human Amyloidogenic Proteins: Consequences for Amyloid Formation in Parkinson's Disease. JOURNAL OF PARKINSON'S DISEASE 2020; 10:819-830. [PMID: 32538869 PMCID: PMC7458506 DOI: 10.3233/jpd-202085] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Accepted: 05/13/2020] [Indexed: 02/07/2023]
Abstract
It was recently shown (Sampson et al., Elife9, 2020) that an amyloidogenic protein, CsgA, present in E. coli biofilms in the gut can trigger Parkinson's disease in mice. This study emphasizes the possible role of the gut microbiome in modulation (and even initiation) of human neurodegenerative disorders, such as Parkinson's disease. As the CsgA protein was found to accelerate alpha-synuclein (the key amyloidogenic protein in Parkinson's disease) amyloid formation in vitro, this result suggests that also other amyloidogenic proteins from gut bacteria, and even from the diet (such as stable allergenic proteins), may be able to affect human protein conformations and thereby modulate amyloid-related diseases. In this review, we summarize what has been reported in terms of in vitro cross-reactivity studies between alpha-synuclein and other amyloidogenic human and non-human proteins. It becomes clear from the limited data that exist that there is a fine line between acceleration and inhibition, but that cross-reactivity is widespread, and it is more common for other proteins (among the studied cases) to accelerate alpha-synuclein amyloid formation than to block it. It is of high importance to expand investigations of cross-reactivity between amyloidogenic proteins to both reveal underlying mechanisms and links between human diseases, as well as to develop new treatments that may be based on an altered gut microbiome.
Collapse
Affiliation(s)
- Tony Werner
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Istvan Horvath
- Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | | |
Collapse
|
11
|
Abstract
Copper is a redox-active transition metal ion required for the function of many essential human proteins. For biosynthesis of proteins coordinating copper, the metal may bind before, during or after folding of the polypeptide. If the metal binds to unfolded or partially folded structures of the protein, such coordination may modulate the folding reaction. The molecular understanding of how copper is incorporated into proteins requires descriptions of chemical, thermodynamic, kinetic and structural parameters involved in the formation of protein-metal complexes. Because free copper ions are toxic, living systems have elaborate copper-transport systems that include particular proteins that facilitate efficient and specific delivery of copper ions to target proteins. Therefore, these pathways become an integral part of copper protein folding in vivo. This review summarizes biophysical-molecular in vitro work assessing the role of copper in folding and stability of copper-binding proteins as well as protein-protein copper exchange reactions between human copper transport proteins. We also describe some recent findings about the participation of copper ions and copper proteins in protein misfolding and aggregation reactions in vitro.
Collapse
|
12
|
Kumar R, Sharma D, Kumar V, Kumar R. Factors defining the effects of macromolecular crowding on dynamics and thermodynamic stability of heme proteins in-vitro. Arch Biochem Biophys 2018; 654:146-162. [DOI: 10.1016/j.abb.2018.07.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 07/18/2018] [Accepted: 07/20/2018] [Indexed: 11/28/2022]
|
13
|
Houwman JA, van Mierlo CPM. Folding of proteins with a flavodoxin-like architecture. FEBS J 2017; 284:3145-3167. [PMID: 28380286 DOI: 10.1111/febs.14077] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/13/2017] [Accepted: 04/03/2017] [Indexed: 12/21/2022]
Abstract
The flavodoxin-like fold is a protein architecture that can be traced back to the universal ancestor of the three kingdoms of life. Many proteins share this α-β parallel topology and hence it is highly relevant to illuminate how they fold. Here, we review experiments and simulations concerning the folding of flavodoxins and CheY-like proteins, which share the flavodoxin-like fold. These polypeptides tend to temporarily misfold during unassisted folding to their functionally active forms. This susceptibility to frustration is caused by the more rapid formation of an α-helix compared to a β-sheet, particularly when a parallel β-sheet is involved. As a result, flavodoxin-like proteins form intermediates that are off-pathway to native protein and several of these species are molten globules (MGs). Experiments suggest that the off-pathway species are of helical nature and that flavodoxin-like proteins have a nonconserved transition state that determines the rate of productive folding. Folding of flavodoxin from Azotobacter vinelandii has been investigated extensively, enabling a schematic construction of its folding energy landscape. It is the only flavodoxin-like protein of which cotranslational folding has been probed. New insights that emphasize differences between in vivo and in vitro folding energy landscapes are emerging: the ribosome modulates MG formation in nascent apoflavodoxin and forces this polypeptide toward the native state.
Collapse
Affiliation(s)
- Joseline A Houwman
- Laboratory of Biochemistry, Wageningen University and Research, The Netherlands
| | | |
Collapse
|
14
|
Jia J, Peng X, Qi W, Su R, He Z. Effects of macromolecular crowding on alkaline phosphatase unfolding, conformation and stability. Int J Biol Macromol 2017; 101:373-382. [PMID: 28344089 DOI: 10.1016/j.ijbiomac.2017.03.113] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 02/27/2017] [Accepted: 03/21/2017] [Indexed: 10/19/2022]
Abstract
The interior of the cell is tightly packed with various biological macromolecules, which affects physiological processes, especially protein folding process. To explore how macromolecular crowding may influence protein folding process, alkaline phosphatase (ALP) was chosen as a model protein, and the unfolding process of ALP induced by GdnHCl was studied in the presence of crowding agents such as PEG 4000, Dextran 70 and Ficoll 70. The effect of macromolecular crowding on the denatured state of ALP was directly probed by measuring enzyme activities, fluorescence spectroscopy and circular dichroism. From the results of circular dichroism, GdnHCl induced a biphasic change, suggesting that a three-state unfolding mechanism was involved in the denaturation process irrespective of the absence or presence of crowding agents. It was also found that crowding agents had a little impact on the unfolding process of ALP. The results of phase diagrams also demonstrated that the unfolding process of ALP induced by GdnHCl was three-state mechanism. Moreover, the results of fluorescence spectra demonstrated that with the increase of GdnHCl concentration, the structure of protein had changed, but existence of crowding agents can make protein structure more stable. Our results can provide valuable information for understanding the protein folding in vivo.
Collapse
Affiliation(s)
- Jiajia Jia
- Chemical Engineering Research Center, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China
| | - Xin Peng
- School of Life Sciences, Tianjin University, Tianjin 300072, PR China.
| | - Wei Qi
- Chemical Engineering Research Center, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China; State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, PR China; Collaborative Innovation Center of Chemistry Science and Engineering (Tianjin), Tianjin 300072, PR China; Tianjin Key Laboratory of Membrane Science and Desalination Technology, Tianjin, 300072, PR China.
| | - Rongxin Su
- Chemical Engineering Research Center, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China; State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, PR China; Collaborative Innovation Center of Chemistry Science and Engineering (Tianjin), Tianjin 300072, PR China; Tianjin Key Laboratory of Membrane Science and Desalination Technology, Tianjin, 300072, PR China
| | - Zhimin He
- Chemical Engineering Research Center, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China; State Key Laboratory of Chemical Engineering, Tianjin University, Tianjin 300072, PR China
| |
Collapse
|
15
|
Shahid S, Hassan MI, Islam A, Ahmad F. Size-dependent studies of macromolecular crowding on the thermodynamic stability, structure and functional activity of proteins: in vitro and in silico approaches. Biochim Biophys Acta Gen Subj 2017; 1861:178-197. [DOI: 10.1016/j.bbagen.2016.11.014] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 11/09/2016] [Accepted: 11/10/2016] [Indexed: 11/27/2022]
|
16
|
Zhang N, An L, Li J, Liu Z, Yao L. Quinary Interactions Weaken the Electric Field Generated by Protein Side-Chain Charges in the Cell-like Environment. J Am Chem Soc 2017; 139:647-654. [DOI: 10.1021/jacs.6b11058] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Ning Zhang
- University of Chinese Academy of Sciences, Beijing 100049, China
| | | | - Jingwen Li
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhijun Liu
- National
Center for Protein Science Shanghai, Institute of Biochemistry and
Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201210, China
| | | |
Collapse
|
17
|
Kadumuri RV, Gullipalli J, Subramanian S, Jaipuria G, Atreya HS, Vadrevu R. Crowding interactions perturb structure and stability by destabilizing the stable core of the α-subunit of tryptophan synthase. FEBS Lett 2016; 590:2096-105. [PMID: 27311646 DOI: 10.1002/1873-3468.12259] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 06/06/2016] [Accepted: 06/13/2016] [Indexed: 11/12/2022]
Abstract
The consequences of crowding derived from relatively small and intrinsically disordered proteins are not clear yet. We report the effect of ficoll-70 on the structure and stability of native and partially folded states of the 29 kDa alpha subunit of tryptophan synthase (αTS). Overall, combining the changes in the circular dichroism and fluorescence spectra, in conjunction with the gradual loss of cooperativity under urea denaturation in the presence of increasing amounts of ficoll, it may be concluded that the crowding agent perturbs not only the native state but also the partially folded state of αTS. Importantly, NMR data indicate that ficoll interacts with the residues that constitute the stable core of the protein thus shedding light on the origin of the observed perturbation.
Collapse
Affiliation(s)
- Rajashekar Varma Kadumuri
- Department of Biological Sciences, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad, India
| | - Jagadeesh Gullipalli
- Department of Biological Sciences, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad, India
| | - SriVidya Subramanian
- Department of Biological Sciences, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad, India
| | - Garima Jaipuria
- NMR Research Centre, Indian Institute of Science, Bangalore, India
| | | | - Ramakrishna Vadrevu
- Department of Biological Sciences, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad, India
| |
Collapse
|
18
|
Paul SS, Sil P, Chakraborty R, Haldar S, Chattopadhyay K. Molecular Crowding Affects the Conformational Fluctuations, Peroxidase Activity, and Folding Landscape of Yeast Cytochrome c. Biochemistry 2016; 55:2332-43. [DOI: 10.1021/acs.biochem.6b00053] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Simanta Sarani Paul
- Protein
Folding and Dynamics Laboratory, Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C.
Mullick Road, Kolkata 700032, India
| | - Pallabi Sil
- Protein
Folding and Dynamics Laboratory, Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C.
Mullick Road, Kolkata 700032, India
| | - Ritobrita Chakraborty
- Protein
Folding and Dynamics Laboratory, Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C.
Mullick Road, Kolkata 700032, India
| | - Shubhasis Haldar
- Department
of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz
18, 82152 Martinsried, Germany
| | - Krishnananda Chattopadhyay
- Protein
Folding and Dynamics Laboratory, Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S. C.
Mullick Road, Kolkata 700032, India
| |
Collapse
|
19
|
Kumar R, Sharma D, Jain R, Kumar S, Kumar R. Role of macromolecular crowding and salt ions on the structural-fluctuation of a highly compact configuration of carbonmonoxycytochrome c. Biophys Chem 2015; 207:61-73. [DOI: 10.1016/j.bpc.2015.09.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 09/04/2015] [Accepted: 09/06/2015] [Indexed: 11/25/2022]
|
20
|
Yu H, Rathore SS, Shen C, Liu Y, Ouyang Y, Stowell MH, Shen J. Reconstituting Intracellular Vesicle Fusion Reactions: The Essential Role of Macromolecular Crowding. J Am Chem Soc 2015; 137:12873-83. [PMID: 26431309 DOI: 10.1021/jacs.5b08306] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Intracellular vesicle fusion is mediated by SNAREs and Sec1/Munc18 (SM) proteins. Despite intensive efforts, the SNARE-SM mediated vesicle fusion reaction has not been faithfully reconstituted in biochemical assays. Here, we present an unexpected discovery that macromolecular crowding is required for reconstituting the vesicle fusion reaction in vitro. Macromolecular crowding is known to profoundly influence the kinetic and thermodynamic behaviors of macromolecules, but its role in membrane transport processes such as vesicle fusion remains unexplored. We introduced macromolecular crowding agents into reconstituted fusion reactions to mimic the crowded cellular environment. In this crowded assay, SNAREs and SM proteins acted in concert to drive efficient membrane fusion. In uncrowded assays, by contrast, SM proteins failed to associate with the SNAREs and the fusion rate decreased more than 30-fold, close to undetectable levels. The activities of SM proteins were strictly specific to their cognate SNARE isoforms and sensitive to biologically relevant mutations, further supporting that the crowded fusion assay accurately recapitulates the vesicle fusion reaction. Using this crowded fusion assay, we also showed that the SNARE-SM mediated fusion reaction can be modulated by two additional factors: NSF and α-SNAP. These findings suggest that the vesicle fusion machinery likely has been evolutionarily selected to function optimally in the crowded milieu of the cell. Accordingly, macromolecular crowding should constitute an integral element of any reconstituted fusion assay.
Collapse
Affiliation(s)
- Haijia Yu
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder , Boulder, Colorado 80309, United States
| | - Shailendra S Rathore
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder , Boulder, Colorado 80309, United States
| | - Chong Shen
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder , Boulder, Colorado 80309, United States
| | - Yinghui Liu
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder , Boulder, Colorado 80309, United States
| | - Yan Ouyang
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder , Boulder, Colorado 80309, United States
| | - Michael H Stowell
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder , Boulder, Colorado 80309, United States
| | - Jingshi Shen
- Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder , Boulder, Colorado 80309, United States
| |
Collapse
|
21
|
What macromolecular crowding can do to a protein. Int J Mol Sci 2014; 15:23090-140. [PMID: 25514413 PMCID: PMC4284756 DOI: 10.3390/ijms151223090] [Citation(s) in RCA: 374] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 12/04/2014] [Accepted: 12/05/2014] [Indexed: 01/17/2023] Open
Abstract
The intracellular environment represents an extremely crowded milieu, with a limited amount of free water and an almost complete lack of unoccupied space. Obviously, slightly salted aqueous solutions containing low concentrations of a biomolecule of interest are too simplistic to mimic the “real life” situation, where the biomolecule of interest scrambles and wades through the tightly packed crowd. In laboratory practice, such macromolecular crowding is typically mimicked by concentrated solutions of various polymers that serve as model “crowding agents”. Studies under these conditions revealed that macromolecular crowding might affect protein structure, folding, shape, conformational stability, binding of small molecules, enzymatic activity, protein-protein interactions, protein-nucleic acid interactions, and pathological aggregation. The goal of this review is to systematically analyze currently available experimental data on the variety of effects of macromolecular crowding on a protein molecule. The review covers more than 320 papers and therefore represents one of the most comprehensive compendia of the current knowledge in this exciting area.
Collapse
|
22
|
Kim YC, Bhattacharya A, Mittal J. Macromolecular Crowding Effects on Coupled Folding and Binding. J Phys Chem B 2014; 118:12621-9. [DOI: 10.1021/jp508046y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Young C. Kim
- Center
for Computational Materials Science, Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Apratim Bhattacharya
- Department
of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Jeetain Mittal
- Department
of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| |
Collapse
|
23
|
Abstract
Here we describe biosensors that provide readouts for protein stability in the cytosolic compartment of prokaryotes. These biosensors consist of tripartite sandwich fusions that link the in vitro stability or aggregation susceptibility of guest proteins to the in vivo resistance of host cells to the antibiotics kanamycin, spectinomycin, and nourseothricin. These selectable markers confer antibiotic resistance in a wide range of hosts and are easily quantifiable. We show that mutations within guest proteins that affect their stability alter the antibiotic resistances of the cells expressing the biosensors in a manner that is related to the in vitro stabilities of the mutant guest proteins. In addition, we find that polyglutamine tracts of increasing length are associated with an increased tendency to form amyloids in vivo and, in our sandwich fusion system, with decreased resistance to aminoglycoside antibiotics. We demonstrate that our approach allows the in vivo analysis of protein stability in the cytosolic compartment without the need for prior structural and functional knowledge.
Collapse
|
24
|
Christiansen A, Wittung-Stafshede P. Quantification of excluded volume effects on the folding landscape of Pseudomonas aeruginosa apoazurin in vitro. Biophys J 2014; 105:1689-99. [PMID: 24094410 DOI: 10.1016/j.bpj.2013.08.038] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 08/09/2013] [Accepted: 08/15/2013] [Indexed: 11/15/2022] Open
Abstract
Proteins fold and function inside cells that are crowded with macromolecules. Here, we address the role of the resulting excluded volume effects by in vitro spectroscopic studies of Pseudomonas aeruginosa apoazurin stability (thermal and chemical perturbations) and folding kinetics (chemical perturbation) as a function of increasing levels of crowding agents dextran (sizes 20, 40, and 70 kDa) and Ficoll 70. We find that excluded volume theory derived by Minton quantitatively captures the experimental effects when crowding agents are modeled as arrays of rods. This finding demonstrates that synthetic crowding agents are useful for studies of excluded volume effects. Moreover, thermal and chemical perturbations result in free energy effects by the presence of crowding agents that are identical, which shows that the unfolded state is energetically the same regardless of method of unfolding. This also underscores the two-state approximation for apoazurin's unfolding reaction and suggests that thermal and chemical unfolding experiments can be used in an interchangeable way. Finally, we observe increased folding speed and invariant unfolding speed for apoazurin in the presence of macromolecular crowding agents, a result that points to unfolded-state perturbations. Although the absolute magnitude of excluded volume effects on apoazurin is only on the order of 1-3 kJ/mol, differences of this scale may be biologically significant.
Collapse
|
25
|
Ådén J, Wittung-Stafshede P. Folding of an Unfolded Protein by Macromolecular Crowding in Vitro. Biochemistry 2014; 53:2271-7. [DOI: 10.1021/bi500222g] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jörgen Ådén
- Department of Chemistry, Umeå University, 90187 Umeå, Sweden
| | | |
Collapse
|
26
|
Luby-Phelps K. The physical chemistry of cytoplasm and its influence on cell function: an update. Mol Biol Cell 2014; 24:2593-6. [PMID: 23989722 PMCID: PMC3756912 DOI: 10.1091/mbc.e12-08-0617] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
From the point of view of intermolecular interactions, the cytoplasmic space is more like a crowded party in a house full of furniture than a game of tag in an empty field. Understanding the physical chemical properties of cytoplasm is thus of key importance for understanding cellular function. This article attempts to provide an entrée into the current literature on this subject and offers some general guidelines for thinking about intracellular biochemistry.
Collapse
Affiliation(s)
- Kate Luby-Phelps
- Department of Cell Biology, UT Southwestern Medical School, Dallas, TX 75390, USA.
| |
Collapse
|
27
|
A simple quantitative model of macromolecular crowding effects on protein folding: Application to the murine prion protein(121–231). Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.04.056] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
28
|
Christiansen A, Wang Q, Cheung MS, Wittung-Stafshede P. Effects of macromolecular crowding agents on protein folding in vitro and in silico. Biophys Rev 2013; 5:137-145. [PMID: 28510156 DOI: 10.1007/s12551-013-0108-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 01/31/2013] [Indexed: 01/24/2023] Open
Abstract
Proteins fold and function inside cells which are environments very different from that of dilute buffer solutions most often used in traditional experiments. The crowded milieu results in excluded-volume effects, increased bulk viscosity and amplified chances for inter-molecular interactions. These environmental factors have not been accounted for in most mechanistic studies of protein folding executed during the last decades. The question thus arises as to how these effects-present when polypeptides normally fold in vivo-modulate protein biophysics. To address excluded volume effects, we use synthetic macromolecular crowding agents, which take up significant volume but do not interact with proteins, in combination with strategically selected proteins and a range of equilibrium and time-resolved biophysical (spectroscopic and computational) methods. In this review, we describe key observations on macromolecular crowding effects on protein stability, folding and structure drawn from combined in vitro and in silico studies. As expected based on Minton's early predictions, many proteins (apoflavodoxin, VlsE, cytochrome c, and S16) became more thermodynamically stable (magnitude depends inversely on protein stability in buffer) and, unexpectedly, for apoflavodoxin and VlsE, the folded states changed both secondary structure content and, for VlsE, overall shape in the presence of macromolecular crowding. For apoflavodoxin and cytochrome c, which have complex kinetic folding mechanisms, excluded volume effects made the folding energy landscapes smoother (i.e., less misfolding and/or kinetic heterogeneity) than in buffer.
Collapse
Affiliation(s)
| | - Qian Wang
- Department of Physics, University of Houston, Houston, TX, 77204, USA
| | - Margaret S Cheung
- Department of Physics, University of Houston, Houston, TX, 77204, USA
| | | |
Collapse
|
29
|
Chen E, Christiansen A, Wang Q, Cheung MS, Kliger DS, Wittung-Stafshede P. Effects of macromolecular crowding on burst phase kinetics of cytochrome c folding. Biochemistry 2012; 51:9836-45. [PMID: 23145850 DOI: 10.1021/bi301324y] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Excluded volume and viscosity effects of crowding agents that mimic crowded conditions in vivo on "classical" burst phase folding kinetics of cytochrome c are assessed in vitro. Upon electron transfer-triggered folding of reduced cytochrome c, far-UV time-resolved circular dichroism (TRCD) is used to monitor folding under different conditions. Earlier work has shown that folding of reduced cytochrome c from the guanidinium hydrochloride-induced unfolded ensemble in dilute phosphate buffer involves kinetic partitioning: one fraction of molecules folds rapidly, on a time scale identical to that of reduction, while the remaining population folds more slowly. In the presence of 220 mg/mL dextran 70, a synthetic macromolecular crowding agent that occupies space but does not interact with proteins, the population of the fast folding step for cytochrome c is greatly reduced. Increasing the viscosity with sucrose to the same microviscosity exhibited by the dextran solution showed no significant decrease in the amplitude of the fast-folding phase of cytochrome c. Experiments show that the unfolded-state heme ligation remains bis-His in the presence of dextran 70, but coarse-grained simulations suggest that the unfolded-state ensemble becomes more compact in the presence of crowders. We conclude that excluded volume effects alter unfolded cytochrome c such that access to fast-folding conformations is reduced.
Collapse
Affiliation(s)
- Eefei Chen
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | | | | | | | | | | |
Collapse
|
30
|
Kurniawan NA, Enemark S, Rajagopalan R. Crowding Alters the Folding Kinetics of a β-Hairpin by Modulating the Stability of Intermediates. J Am Chem Soc 2012; 134:10200-8. [DOI: 10.1021/ja302943m] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Søren Enemark
- Singapore-MIT Alliance, National University of Singapore, Singapore 117576
| | - Raj Rajagopalan
- Singapore-MIT Alliance, National University of Singapore, Singapore 117576
| |
Collapse
|
31
|
Samiotakis A, Cheung MS. Folding dynamics of Trp-cage in the presence of chemical interference and macromolecular crowding. I. J Chem Phys 2012; 135:175101. [PMID: 22070323 DOI: 10.1063/1.3656691] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Proteins fold and function in the crowded environment of the cell's interior. In the recent years it has been well established that the so-called "macromolecular crowding" effect enhances the folding stability of proteins by destabilizing their unfolded states for selected proteins. On the other hand, chemical and thermal denaturation is often used in experiments as a tool to destabilize a protein by populating the unfolded states when probing its folding landscape and thermodynamic properties. However, little is known about the complicated effects of these synergistic perturbations acting on the kinetic properties of proteins, particularly when large structural fluctuations, such as protein folding, have been involved. In this study, we have first investigated the folding mechanism of Trp-cage dependent on urea concentration by coarse-grained molecular simulations where the impact of urea is implemented into an energy function of the side chain and/or backbone interactions derived from the all-atomistic molecular dynamics simulations with urea through a Boltzmann inversion method. In urea solution, the folding rates of a model miniprotein Trp-cage decrease and the folded state slightly swells due to a lack of contact formation between side chains at the terminal regions. In addition, the equilibrium m-values of Trp-cage from the computer simulations are in agreement with experimental measurements. We have further investigated the combined effects of urea denaturation and macromolecular crowding on Trp-cage's folding mechanism where crowding agents are modeled as hard-spheres. The enhancement of folding rates of Trp-cage is most pronounced by macromolecular crowding effect when the extended conformations of Trp-cast dominate at high urea concentration. Our study makes quantitatively testable predictions on protein folding dynamics in a complex environment involving both chemical denaturation and macromolecular crowding effects.
Collapse
|
32
|
Denos S, Dhar A, Gruebele M. Crowding effects on the small, fast-folding protein lambda6-85. Faraday Discuss 2012; 157:451-500. [PMID: 23230782 PMCID: PMC3834863 DOI: 10.1039/c2fd20009k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2024]
Abstract
The microsecond folder lambda6-85 is a small (9.2 kDa = 9200 amu) five helix bundle protein. We investigated the stability of lambda6-85 in two different low-fluorescence crowding matrices: the large 70 kDa carbohydrate Ficoll 70, and the small 14 kDa thermophilic protein SubL. The same thermal stability of secondary structure was measured by circular dichroism in aqueous buffer, and at a crowding fraction phi = 15 +/- 1% of Ficoll 70. Tryptophan fluorescence detection (probing a tertiary contact) yielded the same thermal stability in Ficoll, but 4 degrees C lower in aqueous buffer. Temperature-jump kinetics revealed that the relaxation rate, corrected for bulk viscosity, was very similar in Ficoll and in aqueous buffer. Thus viscosity, hydrodynamics and crowding seem to compensate one another. However, a new fast phase was observed in Ficoll, attributed to crowding-induced downhill folding. We also measured the stability of lambda6-85 in phi = 14 +/- 1% SubL, which acts as a smaller more rigid crowder. Significantly greater stabilization (7 to 13 degrees C depending on probe) was observed than in the Ficoll matrix. The results highlight the importance of crowding agent choice for studies of small, fast-folding proteins amenable to comparison with molecular dynamics simulations.
Collapse
Affiliation(s)
- Sharlene Denos
- Center for Biophysics and Computational Biology, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
| | - Apratim Dhar
- Department of Chemistry, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
| | - Martin Gruebele
- Center for Biophysics and Computational Biology, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
- Department of Chemistry, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
- Department of Physics, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
| |
Collapse
|
33
|
Dhar A, Girdhar K, Singh D, Gelman H, Ebbinghaus S, Gruebele M. Protein stability and folding kinetics in the nucleus and endoplasmic reticulum of eucaryotic cells. Biophys J 2011; 101:421-30. [PMID: 21767495 DOI: 10.1016/j.bpj.2011.05.071] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 05/21/2011] [Accepted: 05/24/2011] [Indexed: 11/29/2022] Open
Abstract
We measure the stability and folding relaxation rate of phosphoglycerate kinase (PGK) Förster resonance energy transfer (FRET) constructs localized in the nucleus or in the endoplasmic reticulum (ER) of eukaryotic cells. PGK has a more compact native state in the cellular compartments than in aqueous solution. Its native FRET signature is similar to that previously observed in a carbohydrate-crowding matrix, consistent with crowding being responsible for the compact native state of PGK in the cell. PGK folds through multiple states in vitro, but its folding kinetics is more two-state-like in the ER, so the folding mechanism can be modified by intracellular compartments. The nucleus increases PGK stability and folding rate over the cytoplasm and ER, even though the density of crowders in the nucleus is no greater than in the ER or cytoplasm. Nuclear folding kinetics (and to a lesser extent, thermodynamics) vary less from cell to cell than in the cytoplasm or ER, indicating a more homogeneous crowding and chemical environment in the nucleus.
Collapse
Affiliation(s)
- A Dhar
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | | | | | | | | | | |
Collapse
|
34
|
Wittung-Stafshede P. Protein folding inside the cell. Biophys J 2011; 101:265-6. [PMID: 21767477 DOI: 10.1016/j.bpj.2011.06.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 06/03/2011] [Accepted: 06/09/2011] [Indexed: 10/18/2022] Open
|
35
|
Kang M, Roberts C, Cheng Y, Chang CEA. Gating and Intermolecular Interactions in Ligand-Protein Association: Coarse-Grained Modeling of HIV-1 Protease. J Chem Theory Comput 2011; 7:3438-46. [PMID: 26598172 DOI: 10.1021/ct2004885] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Most biological processes are initiated or mediated by the association of ligands and proteins. This work studies multistep, ligand-protein association processes by Brownian dynamics simulations with coarse-grained models for HIV-1 protease (HIVp) and its neutral ligands. We report the average association times when the ligand concentration is 100 μM. The influence of crowding on the simulated binding time was also studied. HIVp has flexible loops that serve as a gate during the ligand binding processes. It is believed that the flaps are partially closed most of the time in its free state. To accelerate our simulations, we fixed a part of the HIVp and reparameterized our coarse-grained model, using atomistic molecular dynamics simulations, to reproduce the "gating" motions of HIVp. HIVp-ligand interactions changed the gating behavior of HIVp and helped ligands diffuse on HIVp surface to accelerate binding. The structural adjustment of the ligand toward its final stable state was the limiting step in the binding processes, which is highly system dependent. The intermolecular attraction between the ligands and crowder proteins contributes the most to the crowding effects. The results highlight broader implications in recognition pathways under more complex environment that considers molecular dynamics and conformational changes. This work brings insights into ligand-protein associations and is helpful in the design of targeted ligands.
Collapse
Affiliation(s)
- Myungshim Kang
- Department of Chemistry, University of California , Riverside, California, United States
| | - Christopher Roberts
- Department of Chemistry, University of California , Riverside, California, United States
| | - Yuhui Cheng
- Pacific Northwest National Laboratory , Richland, Washington, United States
| | - Chia-En A Chang
- Department of Chemistry, University of California , Riverside, California, United States
| |
Collapse
|
36
|
Konermann L, Pan Y, Stocks BB. Protein folding mechanisms studied by pulsed oxidative labeling and mass spectrometry. Curr Opin Struct Biol 2011; 21:634-40. [PMID: 21703846 DOI: 10.1016/j.sbi.2011.05.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 05/21/2011] [Accepted: 05/26/2011] [Indexed: 12/14/2022]
Abstract
Deciphering the mechanisms of protein folding remains a considerable challenge. In this review we discuss the application of pulsed oxidative labeling for tracking protein structural changes in a time-resolved fashion. Exposure to a microsecond OH pulse at selected time points during folding induces the oxidation of solvent-accessible side chains, whereas buried residues are protected. Oxidative modifications can be detected by mass spectrometry. Folding is associated with dramatic accessibility changes, and therefore this method can provide detailed mechanistic insights. Solvent accessibility patterns are complementary to H/D exchange investigations, which report on the extent of hydrogen bonding. This review highlights the application of pulsed OH labeling to soluble proteins as well as membrane proteins.
Collapse
Affiliation(s)
- Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, ON N6A 5B7, Canada.
| | | | | |
Collapse
|