51
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Konnova TA, Singer CM, Nesmelova IV. NMR solution structure of the RED subdomain of the Sleeping Beauty transposase. Protein Sci 2017; 26:1171-1181. [PMID: 28345263 DOI: 10.1002/pro.3167] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 03/22/2017] [Indexed: 12/22/2022]
Abstract
DNA transposons can be employed for stable gene transfer in vertebrates. The Sleeping Beauty (SB) DNA transposon has been recently adapted for human application and is being evaluated in clinical trials, however its molecular mechanism is not clear. SB transposition is catalyzed by the transposase enzyme, which is a multi-domain protein containing the catalytic and the DNA-binding domains. The DNA-binding domain of the SB transposase contains two structurally independent subdomains, PAI and RED. Recently, the structures of the catalytic domain and the PAI subdomain have been determined, however no structural information on the RED subdomain and its interactions with DNA has been available. Here, we used NMR spectroscopy to determine the solution structure of the RED subdomain and characterize its interactions with the transposon DNA.
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Affiliation(s)
- Tatiana A Konnova
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina, 28223
| | - Christopher M Singer
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina, 28223
| | - Irina V Nesmelova
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina, 28223.,Center for Biomedical Engineering and Science, University of North Carolina, Charlotte, North Carolina, 28223
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52
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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.
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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
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53
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González-Pérez PP, Orta DJ, Peña I, Flores EC, Ramírez JU, Beltrán HI, Alas SJ. A Computational Approach to Studying Protein Folding Problems Considering the Crucial Role of the Intracellular Environment. J Comput Biol 2017; 24:995-1013. [PMID: 28177752 DOI: 10.1089/cmb.2016.0115] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Intracellular protein folding (PF) is performed in a highly inhomogeneous, crowded, and correlated environment. Due to this inherent complexity, the study and understanding of PF phenomena is a fundamental issue in the field of computational systems biology. In particular, it is important to use a modeled medium that accurately reflects PF in natural systems. In the current study, we present a simulation wherein PF is carried out within an inhomogeneous modeled medium. Simulation resources included a two-dimensional hydrophobic-polar (HP) model, evolutionary algorithms, and the dual site-bond model. The dual site-bond model was used to develop an environment where HP beads could be folded. Our modeled medium included correlation lengths and fractal-like behavior, which were selected according to HP sequence lengths to induce folding in a crowded environment. Analysis of three benchmark HP sequences showed that the modeled inhomogeneous space played an important role in deeper energy folding and obtained better performance and convergence compared with homogeneous environments. Our computational approach also demonstrated that our correlated network provided a better space for PF. Thus, our approach represents a major advancement in PF simulations, not only for folding but also for understanding functional chemical structure and physicochemical properties of proteins in crowded molecular systems, which normally occur in nature.
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Affiliation(s)
- Pedro P González-Pérez
- 1 Departamento de Matemáticas Aplicadas y Sistemas, Universidad Autónoma Metropolitana Unidad Cuajimalpa , Ciudad de México, México
| | - Daniel J Orta
- 1 Departamento de Matemáticas Aplicadas y Sistemas, Universidad Autónoma Metropolitana Unidad Cuajimalpa , Ciudad de México, México
| | - Irving Peña
- 1 Departamento de Matemáticas Aplicadas y Sistemas, Universidad Autónoma Metropolitana Unidad Cuajimalpa , Ciudad de México, México
| | - Eduardo C Flores
- 1 Departamento de Matemáticas Aplicadas y Sistemas, Universidad Autónoma Metropolitana Unidad Cuajimalpa , Ciudad de México, México
| | - José U Ramírez
- 1 Departamento de Matemáticas Aplicadas y Sistemas, Universidad Autónoma Metropolitana Unidad Cuajimalpa , Ciudad de México, México
| | - Hiram I Beltrán
- 2 Departamento de Ciencias Naturales, Universidad Autónoma Metropolitana Unidad Cuajimalpa , Ciudad de México, México
| | - Salomón J Alas
- 2 Departamento de Ciencias Naturales, Universidad Autónoma Metropolitana Unidad Cuajimalpa , Ciudad de México, México
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54
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Fonin AV, Silonov SA, Sitdikova AK, Kuznetsova IM, Uversky VN, Turoverov KK. Structure and Conformational Properties of d-Glucose/d-Galactose-Binding Protein in Crowded Milieu. Molecules 2017; 22:molecules22020244. [PMID: 28178192 PMCID: PMC6155729 DOI: 10.3390/molecules22020244] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 01/26/2017] [Accepted: 01/29/2017] [Indexed: 11/18/2022] Open
Abstract
Conformational changes of d-glucose/d-galactose-binding protein (GGBP) were studied under molecular crowding conditions modeled by concentrated solutions of polyethylene glycols (PEG-12000, PEG-4000, and PEG-600), Ficoll-70, and Dextran-70, addition of which induced noticeable structural changes in the GGBP molecule. All PEGs promoted compaction of GGBP and lead to the increase in ordering of its structure. Concentrated solutions of PEG-12000 and PEG-4000 caused GGBP aggregation. Although Ficoll-70 and Dextran-70 also promoted increase in the GGBP ordering, the structural outputs were different for different crowders. For example, in comparison with the GGBP in buffer, the intrinsic fluorescence spectrum of this protein was shifted to short-wave region in the presence of PEGs but was red-shifted in the presence of Ficoll-70 and Dextran-70. It was hypothesized that this difference could be due to the specific interaction of GGBP with the sugar-based polymers (Ficoll-70 and Dextran-70), indicating that protein can adopt different conformations in solutions containing molecular crowders of different chemical nature. It was also shown that all tested crowding agents were able to stabilize GGBP structure shifting the GGBP guanidine hydrochloride (GdnHCl)-induced unfolding curves to higher denaturant concentrations, but their stabilization capabilities did not depend on the hydrodynamic dimensions of the polymers molecules. Refolding of GGBP was complicated by protein aggregation in all tested solutions of crowding agents. The lowest yield of refolded protein was achieved in the highly concentrated solutions of PEG-12000. These data support the previous notion that the influence of macromolecular crowders on proteins is rather complex phenomenon that extends beyond the excluded volume effects.
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Affiliation(s)
- Alexander V Fonin
- Institute of Cytology of the Russian Academy of Sciences, Laboratory of Structural Dynamics, Stability and Folding of Proteins, Tikhoretsky av. 4, St. Petersburg 197046, Russia.
| | - Sergey A Silonov
- Institute of Cytology of the Russian Academy of Sciences, Laboratory of Structural Dynamics, Stability and Folding of Proteins, Tikhoretsky av. 4, St. Petersburg 197046, Russia.
- Saint-Petersburg Technological Institute (Technical University), Moskovsky av. 26, Saint-Petersburg 190013, Russia.
| | - Asiya K Sitdikova
- Institute of Cytology of the Russian Academy of Sciences, Laboratory of Structural Dynamics, Stability and Folding of Proteins, Tikhoretsky av. 4, St. Petersburg 197046, Russia.
- Department of Biophysics, St. Petersburg State Polytechnical University, Polytechnicheskaya av. 29, St. Petersburg 195251, Russia.
| | - Irina M Kuznetsova
- Institute of Cytology of the Russian Academy of Sciences, Laboratory of Structural Dynamics, Stability and Folding of Proteins, Tikhoretsky av. 4, St. Petersburg 197046, Russia.
| | - Vladimir N Uversky
- Institute of Cytology of the Russian Academy of Sciences, Laboratory of Structural Dynamics, Stability and Folding of Proteins, Tikhoretsky av. 4, St. Petersburg 197046, Russia.
- Department of Molecular Medicine and Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA.
| | - Konstantin K Turoverov
- Institute of Cytology of the Russian Academy of Sciences, Laboratory of Structural Dynamics, Stability and Folding of Proteins, Tikhoretsky av. 4, St. Petersburg 197046, Russia.
- Department of Biophysics, St. Petersburg State Polytechnical University, Polytechnicheskaya av. 29, St. Petersburg 195251, Russia.
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55
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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]
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56
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Yang C, Kim SO, Kim Y, Yun SR, Choi J, Ihee H. Photocycle of Photoactive Yellow Protein in Cell-Mimetic Environments: Molecular Volume Changes and Kinetics. J Phys Chem B 2017; 121:769-779. [PMID: 28058827 DOI: 10.1021/acs.jpcb.6b13076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using various spectroscopic techniques such as UV-visible spectroscopy, circular dichroism spectroscopy, NMR spectroscopy, small-angle X-ray scattering, transient grating, and transient absorption techniques, we investigated how cell-mimetic environments made by crowding influence the photocycle of photoactive yellow protein (PYP) in terms of the molecular volume change and kinetics. Upon addition of molecular crowding agents, the ratio of the diffusion coefficient of the blue-shifted intermediate (pB) to that of the ground species (pG) significantly changes from 0.92 and approaches 1.0. This result indicates that the molecular volume change accompanied by the photocycle of PYP in molecularly crowded environments is much smaller than that which occurs in vitro and that the pB intermediate under crowded environments favors a compact conformation due to the excluded volume effect. The kinetics of the photocycle of PYP in cell-mimetic environments is greatly decelerated by the dehydration, owing to the interaction between the protein and small crowding agents, but is barely affected by the excluded volume effect. The results lead to the inference that the signaling transducer of PYP may not necessarily utilize the conformational change of PYP to sense the signaling state.
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Affiliation(s)
- Cheolhee Yang
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science , Daejeon 305-701, Republic of Korea.,Department of Chemistry, KAIST , Daejeon 305-701, Republic of Korea
| | - Seong Ok Kim
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science , Daejeon 305-701, Republic of Korea.,Department of Chemistry, KAIST , Daejeon 305-701, Republic of Korea
| | - Yonggwan Kim
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science , Daejeon 305-701, Republic of Korea.,Department of Chemistry, KAIST , Daejeon 305-701, Republic of Korea
| | - So Ri Yun
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science , Daejeon 305-701, Republic of Korea.,Department of Chemistry, KAIST , Daejeon 305-701, Republic of Korea
| | - Jungkweon Choi
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science , Daejeon 305-701, Republic of Korea.,Department of Chemistry, KAIST , Daejeon 305-701, Republic of Korea
| | - Hyotcherl Ihee
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science , Daejeon 305-701, Republic of Korea.,Department of Chemistry, KAIST , Daejeon 305-701, Republic of Korea
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57
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Hoppe T, Minton AP. Incorporation of Hard and Soft Protein-Protein Interactions into Models for Crowding Effects in Binary and Ternary Protein Mixtures. Comparison of Approximate Analytical Solutions with Numerical Simulation. J Phys Chem B 2016; 120:11866-11872. [PMID: 27779417 DOI: 10.1021/acs.jpcb.6b07736] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In order to better understand how nonspecific interactions between solutes can modulate specific biochemical reactions taking place in complex media, we introduce a simplified model aimed at elucidating general principles. In this model, solutions containing two or three species of interacting globular proteins are modeled as a fluid of spherical particles interacting through square well potentials that qualitatively capture both steric hard core repulsion and longer-ranged attraction or repulsion. The excess chemical potential, or free energy of solvation, of each particle species is calculated as a function of species concentrations, particle radii, and square well interaction range and depth. The results of analytical models incorporating two-body and three-body interactions are compared with the estimates of free energy obtained via Widom insertion into simulated equilibrium square-well fluids. The analytical models agree well with results of numeric simulations carried out for a variety of model parameters and fluid compositions up to a total particle volume fraction of ca. 0.2.
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Affiliation(s)
- Travis Hoppe
- Laboratory of Chemical Physics and ‡Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, United States Public Health Service , Bethesda, Maryland 20892, United States
| | - Allen P Minton
- Laboratory of Chemical Physics and ‡Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, United States Public Health Service , Bethesda, Maryland 20892, United States
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58
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Schwarz B, Uchida M, Douglas T. Biomedical and Catalytic Opportunities of Virus-Like Particles in Nanotechnology. Adv Virus Res 2016; 97:1-60. [PMID: 28057256 DOI: 10.1016/bs.aivir.2016.09.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Within biology, molecules are arranged in hierarchical structures that coordinate and control the many processes that allow for complex organisms to exist. Proteins and other functional macromolecules are often studied outside their natural nanostructural context because it remains difficult to create controlled arrangements of proteins at this size scale. Viruses are elegantly simple nanosystems that exist at the interface of living organisms and nonliving biological machines. Studied and viewed primarily as pathogens to be combatted, viruses have emerged as models of structural efficiency at the nanoscale and have spurred the development of biomimetic nanoparticle systems. Virus-like particles (VLPs) are noninfectious protein cages derived from viruses or other cage-forming systems. VLPs provide incredibly regular scaffolds for building at the nanoscale. Composed of self-assembling protein subunits, VLPs provide both a model for studying materials' assembly at the nanoscale and useful building blocks for materials design. The robustness and degree of understanding of many VLP structures allow for the ready use of these systems as versatile nanoparticle platforms for the conjugation of active molecules or as scaffolds for the structural organization of chemical processes. Lastly the prevalence of viruses in all domains of life has led to unique activities of VLPs in biological systems most notably the immune system. Here we discuss recent efforts to apply VLPs in a wide variety of applications with the aim of highlighting how the common structural elements of VLPs have led to their emergence as paradigms for the understanding and design of biological nanomaterials.
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Affiliation(s)
- B Schwarz
- Indiana University, Bloomington, IN, United States
| | - M Uchida
- Indiana University, Bloomington, IN, United States
| | - T Douglas
- Indiana University, Bloomington, IN, United States.
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59
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Stepanenko OV, Stepanenko OV, Kuznetsova IM, Uversky VN, Turoverov KK. Peculiarities of the Super-Folder GFP Folding in a Crowded Milieu. Int J Mol Sci 2016; 17:ijms17111805. [PMID: 27801849 PMCID: PMC5133806 DOI: 10.3390/ijms17111805] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 10/11/2016] [Accepted: 10/20/2016] [Indexed: 01/19/2023] Open
Abstract
The natural cellular milieu is crowded by large quantities of various biological macromolecules. This complex environment is characterized by a limited amount of unoccupied space, limited amounts of free water, and changed solvent properties. Obviously, such a tightly packed cellular environment is poorly mimicked by traditional physiological conditions, where low concentrations of a protein of interest are analyzed in slightly salted aqueous solutions. An alternative is given by the use of a model crowded milieu, where a protein of interest is immersed in a solution containing high concentrations of various polymers that serve as model crowding agents. An expected outcome of the presence of such macromolecular crowding agents is their ability to increase conformational stability of a globular protein due to the excluded volume effects. In line with this hypothesis, the behavior of a query protein should be affected by the hydrodynamic size and concentration of an inert crowder (i.e., an agent that does not interact with the protein), whereas the chemical nature of a macromolecular crowder should not play a role in its ability to modulate conformational properties. In this study, the effects of different crowding agents (polyethylene glycols (PEGs) of various molecular masses (PEG-600, PEG-8000, and PEG-12000), Dextran-70, and Ficoll-70) on the spectral properties and unfolding–refolding processes of the super-folder green fluorescent protein (sfGFP) were investigated. sfGFP is differently affected by different crowders, suggesting that, in addition to the expected excluded volume effects, there are some changes in the solvent properties.
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Affiliation(s)
- Olesya V Stepanenko
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., St. Petersburg 194064, Russia.
| | - Olga V Stepanenko
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., St. Petersburg 194064, Russia.
| | - Irina M Kuznetsova
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., St. Petersburg 194064, Russia.
| | - Vladimir N Uversky
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., St. Petersburg 194064, Russia.
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd. MDC07, Tampa, FL 33612, USA.
| | - Konstantin K Turoverov
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., St. Petersburg 194064, Russia.
- Institute of Physics, Nanotechnology and Telecommunications, Peter the Great St. Petersburg State Polytechnic University, 29 Polytechnicheskaya st., St. Petersburg 195251, Russia.
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60
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Peter EK, Pivkin IV, Shea JE. A canonical replica exchange molecular dynamics implementation with normal pressure in each replica. J Chem Phys 2016; 145:044903. [DOI: 10.1063/1.4958325] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Emanuel K. Peter
- Institute of Computational Science, Faculty of Informatics, University of Lugano, Switzerland
| | - Igor V. Pivkin
- Institute of Computational Science, Faculty of Informatics, University of Lugano, Switzerland
| | - Joan-Emma Shea
- Department of Chemistry and Biochemistry, Department of Physics, University of California, Santa Barbara, California 93106, USA
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61
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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.
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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
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62
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Sfera A, Cummings M, Osorio C. Dehydration and Cognition in Geriatrics: A Hydromolecular Hypothesis. Front Mol Biosci 2016; 3:18. [PMID: 27252943 PMCID: PMC4860410 DOI: 10.3389/fmolb.2016.00018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 04/25/2016] [Indexed: 12/11/2022] Open
Abstract
Dehydration is one of the ten most frequent diagnoses responsible for the hospital admission of elderly in the United States. It is associated with increased mortality, morbidity and an estimated cost of 1.14 billion per year (Xiao et al., 2004; Schlanger et al., 2010; Pretorius et al., 2013; Frangeskou et al., 2015). Older individuals are predisposed to dehydration encephalopathy as a result of decreased total body water (TBW) and diminished sensation of thirst. We hypothesize that thirst blunting in older individuals is the result of a defective microRNA-6842-3p failing to silence the expression of the vesicular GABA transporters (VGAT) and alpha 7 cholinergic nicotinic receptors in the subfornical organ (SFO) of the hypothalamus. We hypothesize further that resultant dehydration facilitates protein misfolding and aggregation, predisposing to neurocognitive disorders. We completed a search of predicted microRNA targets, utilizing the public domain tool miRDB and found that microRNA-6842-3p modulates the SLC6A1 and CHRNA7 genes both of which were previously hypothesized to inhibit the thirst sensation by their action on SFO. The primary aim of this article is to answer two questions: Can prevention and correction of dehydration in elderly lower age-related cognitive deterioration? Can exosomal miR-6842 in the peripheral blood predict dehydration encephalopathy in elderly?
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Affiliation(s)
- Adonis Sfera
- Department of Psychiatry, Loma Linda UniversityLoma Linda, USA; Patton State HospitalPatton, USA
| | | | - Carolina Osorio
- Department of Psychiatry, Loma Linda University Loma Linda, USA
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63
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Stepanenko OV, Roginskii DO, Stepanenko OV, Kuznetsova IM, Uversky VN, Turoverov KK. Structure and stability of recombinant bovine odorant-binding protein: III. Peculiarities of the wild type bOBP unfolding in crowded milieu. PeerJ 2016; 4:e1642. [PMID: 27114858 PMCID: PMC4841217 DOI: 10.7717/peerj.1642] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 01/08/2016] [Indexed: 11/23/2022] Open
Abstract
Contrary to the majority of the members of the lipocalin family, which are stable monomers with the specific OBP fold (a β-barrel consisting of a 8-stranded anti-parallel β-sheet followed by a short α-helical segment, a ninth β-strand, and a disordered C-terminal tail) and a conserved disulfide bond, bovine odorant-binding protein (bOBP) does not have such a disulfide bond and forms a domain-swapped dimer that involves crossing the α-helical region from each monomer over the β-barrel of the other monomer. Furthermore, although natural bOBP isolated from bovine tissues exists as a stable domain-swapped dimer, recombinant bOBP has decreased dimerization potential and therefore exists as a mixture of monomeric and dimeric variants. In this article, we investigated the effect model crowding agents of similar chemical nature but different molecular mass on conformational stability of the recombinant bOBP. These experiments were conducted in order to shed light on the potential influence of model crowded environment on the unfolding-refolding equilibrium. To this end, we looked at the influence of PEG-600, PEG-4000, and PEG-12000 in concentrations of 80, 150, and 300 mg/mL on the equilibrium unfolding and refolding transitions induced in the recombinant bOBP by guanidine hydrochloride. We are showing here that the effect of crowding agents on the structure and conformational stability of the recombinant bOBP depends on the size of the crowder, with the smaller crowding agents being more effective in the stabilization of the bOBP native dimeric state against the guanidine hydrochloride denaturing action. This effect of the crowding agents is concentration dependent, with the high concentrations of the agents being more effective.
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Affiliation(s)
- Olga V. Stepanenko
- Laboratory of structural dynamics, stability and folding of proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
| | - Denis O. Roginskii
- Laboratory of structural dynamics, stability and folding of proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
| | - Olesya V. Stepanenko
- Laboratory of structural dynamics, stability and folding of proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
| | - Irina M. Kuznetsova
- Laboratory of structural dynamics, stability and folding of proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
| | - Vladimir N. Uversky
- Laboratory of structural dynamics, stability and folding of proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
- Department of Molecular Medicine, University of South Florida, United States
| | - Konstantin K. Turoverov
- Laboratory of structural dynamics, stability and folding of proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
- Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia
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64
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Samanta N, Luong TQ, Das Mahanta D, Mitra RK, Havenith M. Effect of Short Chain Poly(ethylene glycol)s on the Hydration Structure and Dynamics around Human Serum Albumin. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:831-837. [PMID: 26720549 DOI: 10.1021/acs.langmuir.5b03884] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report the changes in the hydration dynamics around a globular protein, human serum albumin (HSA), in the presence of two short chain crowding agents, namely poly(ethylene glycol)s (PEG 200 and 400). The change in the network water structure is investigated using FTIR spectroscopy in the far-infrared (FIR) frequency range. Site specific changes are obtained by time-resolved fluorescence spectroscopic technique using the intrinsic fluorophore tryptophan (Trp214) of HSA. The collective hydration dynamics of HSA in the presence of PEG molecules are obtained using terahertz (THz) time domain spectroscopy (TTDS) and high intensity p-Ge THz measurements. Our study affirms a considerable perturbation of HSA hydration beyond a critical concentration of PEG.
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Affiliation(s)
- Nirnay Samanta
- Department of Chemical, Biological and Macromolecular Sciences, S.N. Bose National Centre for Basic Sciences , Block JD, Sector III, Salt Lake, Kolkata 700098, India
| | - Trung Quan Luong
- Department of Physical Chemistry II, Ruhr-University Bochum , 44780 Bochum, Germany
| | - Debasish Das Mahanta
- Department of Chemical, Biological and Macromolecular Sciences, S.N. Bose National Centre for Basic Sciences , Block JD, Sector III, Salt Lake, Kolkata 700098, India
| | - Rajib Kumar Mitra
- Department of Chemical, Biological and Macromolecular Sciences, S.N. Bose National Centre for Basic Sciences , Block JD, Sector III, Salt Lake, Kolkata 700098, India
| | - Martina Havenith
- Department of Physical Chemistry II, Ruhr-University Bochum , 44780 Bochum, Germany
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65
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Stepanenko OV, Povarova OI, Sulatskaya AI, Ferreira LA, Zaslavsky BY, Kuznetsova IM, Turoverov KK, Uversky VN. Protein unfolding in crowded milieu: what crowding can do to a protein undergoing unfolding? J Biomol Struct Dyn 2016; 34:2155-70. [PMID: 26474212 DOI: 10.1080/07391102.2015.1109554] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The natural environment of a protein inside a cell is characterized by the almost complete lack of unoccupied space, limited amount of free water, and the tightly packed crowd of various biological macromolecules, such as proteins, nucleic acids, polysaccharides, and complexes thereof. This extremely crowded natural milieu is poorly mimicked by slightly salted aqueous solutions containing low concentrations of a protein of interest. The accepted practice is to model crowded environments by adding high concentrations of various polymers that serve as model "crowding agents" to the solution of a protein of interest. Although studies performed under these model conditions revealed that macromolecular crowding might have noticeable influence on various aspects related to the protein structure, function, folding, conformational stability, and aggregation propensity, the complete picture describing conformational behavior of a protein under these conditions is missing as of yet. Furthermore, there is an accepted belief that the conformational stability of globular proteins increases in the presence crowding agents due to the excluded volume effects. The goal of this study was to conduct a systematic analysis of the effect of high concentrations of PEG-8000 and Dextran-70 on the unfolding behavior of eleven globular proteins belonging to different structural classes.
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Affiliation(s)
- Olga V Stepanenko
- a Laboratory of Structural Dynamics, Stability and Folding of Proteins , Institute of Cytology, Russian Academy of Sciences , St. Petersburg , Russia
| | - Olga I Povarova
- a Laboratory of Structural Dynamics, Stability and Folding of Proteins , Institute of Cytology, Russian Academy of Sciences , St. Petersburg , Russia
| | - Anna I Sulatskaya
- a Laboratory of Structural Dynamics, Stability and Folding of Proteins , Institute of Cytology, Russian Academy of Sciences , St. Petersburg , Russia
| | - Luisa A Ferreira
- b Cleveland Diagnostics , 3615 Superior Ave., Suite 4407B, Cleveland , OH 44114 , USA
| | - Boris Y Zaslavsky
- b Cleveland Diagnostics , 3615 Superior Ave., Suite 4407B, Cleveland , OH 44114 , USA
| | - Irina M Kuznetsova
- a Laboratory of Structural Dynamics, Stability and Folding of Proteins , Institute of Cytology, Russian Academy of Sciences , St. Petersburg , Russia
| | - Konstantin K Turoverov
- a Laboratory of Structural Dynamics, Stability and Folding of Proteins , Institute of Cytology, Russian Academy of Sciences , St. Petersburg , Russia.,c Department of Biophysics , Peter the Great St. Petersburg Polytechnic University , St. Petersburg , 195251 , Russia
| | - Vladimir N Uversky
- a Laboratory of Structural Dynamics, Stability and Folding of Proteins , Institute of Cytology, Russian Academy of Sciences , St. Petersburg , Russia.,d Department of Molecular Medicine and Byrd Alzheimer's Research Institute, Morsani College of Medicine , University of South Florida , Tampa , FL 33612 , USA
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66
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Ishrat M, Imtaiyaz Hassan M, Ahmad F, Moosavi-Movahedi AA, Islam A. Effect of dextran on the thermodynamic stability and structure of ribonuclease A. JOURNAL OF THE IRANIAN CHEMICAL SOCIETY 2015. [DOI: 10.1007/s13738-015-0726-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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67
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Sohail A, Bhat SA, Siddiqui AA, Zaman M, Khan RH, Bano B. Conformational transitions induced byin vitromacromolecular crowding lead to the amyloidogenesis of buffalo heart cystatin. J Mol Recognit 2015; 28:699-709. [DOI: 10.1002/jmr.2484] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 05/02/2015] [Accepted: 05/08/2015] [Indexed: 01/04/2023]
Affiliation(s)
- Aamir Sohail
- Department of Biochemistry, Faculty of Life Sciences; AMU; Aligarh India
| | - Sheraz A. Bhat
- Department of Biochemistry, Faculty of Life Sciences; AMU; Aligarh India
| | - Azad A. Siddiqui
- Department of Biochemistry, Faculty of Life Sciences; AMU; Aligarh India
| | - Masihuz Zaman
- Interdisciplinary Biotechnology Unit (IBU); AMU; Aligarh India
| | - Rizwan H. Khan
- Interdisciplinary Biotechnology Unit (IBU); AMU; Aligarh India
| | - Bilqees Bano
- Department of Biochemistry, Faculty of Life Sciences; AMU; Aligarh India
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68
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Kuznetsova IM, Zaslavsky BY, Breydo L, Turoverov KK, Uversky VN. Beyond the excluded volume effects: mechanistic complexity of the crowded milieu. Molecules 2015; 20:1377-409. [PMID: 25594347 PMCID: PMC6272634 DOI: 10.3390/molecules20011377] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 01/09/2015] [Indexed: 11/16/2022] Open
Abstract
Macromolecular crowding is known to affect protein folding, binding of small molecules, interaction with nucleic acids, enzymatic activity, protein-protein interactions, and protein aggregation. Although for a long time it was believed that the major mechanism of the action of crowded environments on structure, folding, thermodynamics, and function of a protein can be described in terms of the excluded volume effects, it is getting clear now that other factors originating from the presence of high concentrations of “inert” macromolecules in crowded solution should definitely be taken into account to draw a more complete picture of a protein in a crowded milieu. This review shows that in addition to the excluded volume effects important players of the crowded environments are viscosity, perturbed diffusion, direct physical interactions between the crowding agents and proteins, soft interactions, and, most importantly, the effects of crowders on solvent properties.
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Affiliation(s)
- Irina M. Kuznetsova
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., St. Petersburg 194064, Russia; E-Mails: (I.M.K.); (K.K.T.)
- St. Petersburg State Polytechnical University, 29 Polytechnicheskaya st., St. Petersburg 195251, Russia
| | - Boris Y. Zaslavsky
- Cleveland Diagnostics, 3615 Superior Ave., Suite 4407B, Cleveland, OH 44114, USA; E-Mail:
| | - Leonid Breydo
- Department of Molecular Medicine and USF Health Byrd Alzheimer’s Research Institute, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd. MDC07, Tampa, FL 33612, USA; E-Mails:
| | - Konstantin K. Turoverov
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., St. Petersburg 194064, Russia; E-Mails: (I.M.K.); (K.K.T.)
- St. Petersburg State Polytechnical University, 29 Polytechnicheskaya st., St. Petersburg 195251, Russia
| | - Vladimir N. Uversky
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Ave., St. Petersburg 194064, Russia; E-Mails: (I.M.K.); (K.K.T.)
- Department of Molecular Medicine and USF Health Byrd Alzheimer’s Research Institute, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd. MDC07, Tampa, FL 33612, USA; E-Mails:
- Biology Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-813-974-5816; Fax: +1-813-974-7357
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69
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Stadler AM, Koza MM, Fitter J. Determination of Conformational Entropy of Fully and Partially Folded Conformations of Holo- and Apomyoglobin. J Phys Chem B 2014; 119:72-82. [DOI: 10.1021/jp509732q] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Andreas M. Stadler
- Jülich
Centre for Neutron Science JCNS and Institute for Complex Systems
ICS, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | | | - Jörg Fitter
- Institute
of Complex Systems (ICS-5): Molecular Biophysics, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- I.
Physikalisches Institut (IA), AG Biophysik, RWTH Aachen, Sommerfeldstrasse
14, 52074 Aachen, Germany
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70
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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: 355] [Impact Index Per Article: 35.5] [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.
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71
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de Souza TP, Fahr A, Luisi PL, Stano P. Spontaneous Encapsulation and Concentration of Biological Macromolecules in Liposomes: An Intriguing Phenomenon and Its Relevance in Origins of Life. J Mol Evol 2014; 79:179-92. [DOI: 10.1007/s00239-014-9655-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 11/10/2014] [Indexed: 12/31/2022]
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Abstract
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All biological processes take place
in highly crowded cellular
environments. However, the effect that molecular crowding agents have
on the folding and catalytic properties of RNA molecules remains largely
unknown. Here, we have combined single-molecule fluorescence resonance
energy transfer (smFRET) and bulk cleavage assays to determine the
effect of a molecular crowding agents on the folding and catalysis
of a model RNA enzyme, the hairpin ribozyme. Our single-molecule data
reveal that PEG favors the formation of the docked (active) structure
by increasing the docking rate constant with increasing PEG concentrations.
Furthermore, Mg2+ ion-induced folding in the presence of
PEG occurs at concentrations ∼7-fold lower than in the absence
of PEG, near the physiological range (∼1 mM). Lastly, bulk
cleavage assays in the presence of the crowding agent show that the
ribozyme’s activity increases while the heterogeneity decreases.
Our data is consistent with the idea that molecular crowding plays
an important role in the stabilization of ribozyme active conformations in vivo.
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Affiliation(s)
- Bishnu P Paudel
- Department of Medicine, Section of Virology, and Single Molecule Imaging Group, MRC-Clinical Sciences Centre, Imperial College London , Du Cane Road, London W12 0NN, U.K
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73
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Goldenberg DP, Argyle B. Minimal effects of macromolecular crowding on an intrinsically disordered protein: a small-angle neutron scattering study. Biophys J 2014; 106:905-14. [PMID: 24559993 DOI: 10.1016/j.bpj.2013.12.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 11/26/2013] [Accepted: 12/02/2013] [Indexed: 01/04/2023] Open
Abstract
Small-angle neutron scattering was used to study the effects of macromolecular crowding by two globular proteins, i.e., bovine pancreatic trypsin inhibitor and equine metmyoglobin, on the conformational ensemble of an intrinsically disordered protein, the N protein of bacteriophage λ. The λ N protein was uniformly labeled with (2)H, and the concentrations of D2O in the samples were adjusted to match the neutron scattering contrast of the unlabeled crowding proteins, thereby masking their contribution to the scattering profiles. Scattering from the deuterated λ N was recorded for samples containing up to 0.12 g/mL bovine pancreatic trypsin inhibitor or 0.2 g/mL metmyoglobin. The radius of gyration of the uncrowded protein was estimated to be 30 Å and was found to be remarkably insensitive to the presence of crowders, varying by <2 Å for the highest crowder concentrations. The scattering profiles were also used to estimate the fractal dimension of λ N, which was found to be ∼1.8 in the absence or presence of crowders, indicative of a well-solvated and expanded random coil under all of the conditions examined. These results are contrary to the predictions of theoretical treatments and previous experimental studies demonstrating compaction of unfolded proteins by crowding with polymers such as dextran and Ficoll. A computational simulation suggests that some previous treatments may have overestimated the effective volumes of disordered proteins and the variation of these volumes within an ensemble. The apparent insensitivity of λ N to crowding may also be due in part to weak attractive interactions with the crowding proteins, which may compensate for the effects of steric exclusion.
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Affiliation(s)
| | - Brian Argyle
- Department of Biology, University of Utah, Salt Lake City, Utah
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74
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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
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75
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The effects of varying poly(ethylene glycol) hydrogel crosslinking density and the crosslinking mechanism on protein accumulation in three-dimensional hydrogels. Acta Biomater 2014; 10:4167-74. [PMID: 24887284 DOI: 10.1016/j.actbio.2014.05.023] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 04/28/2014] [Accepted: 05/22/2014] [Indexed: 01/05/2023]
Abstract
Matrix stiffness has been shown to play an important role in modulating various cell fate processes such as differentiation and cell cycle. Given that the stiffness can be easily tuned by varying the crosslinking density, poly(ethylene glycol) (PEG) hydrogels have been widely used as an artificial cell niche. However, little is known about how changes in the hydrogel crosslinking density may affect the accumulation of exogenous growth factors within 3-D hydrogel scaffolds formed by different crosslinking mechanisms. To address such shortcomings, we measured protein diffusivity and accumulation within PEG hydrogels with varying PEG molecular weight, concentration and crosslinking mechanism. We found that protein accumulation increased substantially above a critical mesh size, which was distinct from the protein diffusivity trend, highlighting the importance of using protein accumulation as a parameter to better predict the cell fates in addition to protein diffusivity, a parameter commonly reported by researchers studying protein diffusion in hydrogels. Furthermore, we found that chain-growth-polymerized gels allowed more protein accumulation than step-growth-polymerized gels, which may be the result of network heterogeneity. The strategy used here can help quantify the effects of varying the hydrogel crosslinking density and crosslinking mechanism on protein diffusion in different types of hydrogel. Such tools could be broadly useful for interpreting cellular responses in hydrogels of varying stiffness for various tissue engineering applications.
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76
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Crowded milieu prevents fibrillation of hen egg white lysozyme with retention of enzymatic activity. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2014; 138:8-16. [DOI: 10.1016/j.jphotobiol.2014.04.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 04/22/2014] [Accepted: 04/24/2014] [Indexed: 11/18/2022]
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77
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Watkins HM, Simon AJ, Ricci F, Plaxco KW. Effects of crowding on the stability of a surface-tethered biopolymer: an experimental study of folding in a highly crowded regime. J Am Chem Soc 2014; 136:8923-7. [PMID: 24919057 PMCID: PMC4091282 DOI: 10.1021/ja411486g] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
![]()
The high packing densities and fixed
geometries with which biomolecules
can be attached to macroscopic surfaces suggest that crowding effects
may be particularly significant under these often densely packed conditions.
Exploring this question experimentally, we report here the effects
of crowding on the stability of a simple, surface-attached DNA stem-loop.
We find that crowding by densely packed, folded biomolecules destabilizes
our test-bed biomolecule by ∼2 kJ/mol relative to the dilute
(noninteracting) regime, an effect that presumably occurs due to steric
and electrostatic repulsion arising from compact neighbors. Crowding
by a dense brush of unfolded biomolecules, in contrast, enhances its
stability by ∼6 kJ/mol, presumably due to excluded volume and
electrostatic effects that reduce the entropy of the unfolded state.
Finally, crowding by like copies of the same biomolecule produces
a significantly broader unfolding transition, likely because, under
these circumstances, the stabilizing effects of crowding by unfolded
molecules increase (and the destabilizing effects of neighboring folded
molecules decrease) as more and more neighbors unfold. The crowding
of surface-attached biomolecules may thus be a richer, more complex
phenomenon than that seen in homogeneous solution.
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Affiliation(s)
- Herschel M Watkins
- Interdepartmental Program in Biomolecular Science and Engineering, University of California at Santa Barbara , Santa Barbara, California 93106, United States
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78
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Stabilization of Bovine Intestine Alkaline Phosphatase by Sugars. Biosci Biotechnol Biochem 2014; 76:95-100. [DOI: 10.1271/bbb.110553] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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79
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Hassan S, Schade M, Shaw CP, Lévy R, Hamm P. Response of villin headpiece-capped gold nanoparticles to ultrafast laser heating. J Phys Chem B 2014; 118:7954-62. [PMID: 24597838 DOI: 10.1021/jp500845f] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The integrity of a small model protein, the 36-residue villin headpiece HP36, attached to gold nanoparticles (AuNP) is examined, and its response to laser excitation of the AuNPs is investigated. To that end, it is first verified by stationary IR and CD spectroscopy, together with denaturation experiments, that the folded structure of the protein is fully preserved when attached to the AuNP surface. It is then shown by time-resolved IR spectroscopy that the protein does not unfold, even upon the highest pump fluences that lead to local temperature jumps on the order of 1000 K of the phonon system of the AuNPs, since that temperature jump persists for too short a time of a few nanoseconds only to be destructive. Judged from a blue shift of the amide I band, indicating destabilized or a few broken hydrogen bonds, the protein either swells, becomes more unstructured from the termini, or changes its degree of solvation. In any case, it recovers immediately after the excess energy dissipates into the bulk solvent. The process is entirely reversible for millions of laser shots without any indication of aggregation of the protein or the AuNPs and with only a minor fraction of broken protein-AuNP thiol bonds. The work provides important cornerstones in designing laser pulse parameters for maximal heating with protein-capped AuNPs without destroying the capping layer.
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Affiliation(s)
- Shabir Hassan
- Department of Chemistry, University of Zurich , Zurich, Switzerland
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80
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Taraban MB, Yu L, Feng Y, Jouravleva EV, Anisimov MA, Jiang ZX, Yu YB. Conformational transition of a non-associative fluorinated amphiphile in aqueous solution. RSC Adv 2014. [DOI: 10.1039/c4ra09752a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A non-associative fluorinated amphiphile was synthesized. Instead of self-association at high concentrations, this amphiphile undergoes conformational transition in which the hydrophilic tails wrap around the fluorocarbon core to shield it from water, bearing certain similarity to protein folding in a crowded environment.
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Affiliation(s)
- Marc B. Taraban
- Department of Pharmaceutical Sciences
- University of Maryland
- Baltimore, USA
| | - Li Yu
- School of Pharmaceutical Sciences
- Wuhan University
- Wuhan, China
| | - Yue Feng
- Department of Pharmaceutical Sciences
- University of Maryland
- Baltimore, USA
| | - Elena V. Jouravleva
- Light Scattering Center
- Institute for Physical Science and Technology
- University of Maryland
- College Park
- , USA
| | - Mikhail A. Anisimov
- Light Scattering Center
- Institute for Physical Science and Technology
- University of Maryland
- College Park
- , USA
| | | | - Y. Bruce Yu
- Department of Pharmaceutical Sciences
- University of Maryland
- Baltimore, USA
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81
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Sugimoto N. Noncanonical structures and their thermodynamics of DNA and RNA under molecular crowding: beyond the Watson-Crick double helix. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 307:205-73. [PMID: 24380597 DOI: 10.1016/b978-0-12-800046-5.00008-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
How does molecular crowding affect the stability of nucleic acid structures inside cells? Water is the major solvent component in living cells, and the properties of water in the highly crowded media inside cells differ from that in buffered solution. As it is difficult to measure the thermodynamic behavior of nucleic acids in cells directly and quantitatively, we recently developed a cell-mimicking system using cosolutes as crowding reagents. The influences of molecular crowding on the structures and thermodynamics of various nucleic acid sequences have been reported. In this chapter, we discuss how the structures and thermodynamic properties of nucleic acids differ under various conditions such as highly crowded environments, compartment environments, and in the presence of ionic liquids, and the major determinants of the crowding effects on nucleic acids are discussed. The effects of molecular crowding on the activities of ribozymes and riboswitches on noncanonical structures of DNA- and RNA-like quadruplexes that play important roles in transcription and translation are also described.
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Affiliation(s)
- Naoki Sugimoto
- Frontier Institute for Biomolecular Engineering Research (FIBER) and Faculty of Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe, Japan.
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82
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Choi E, Mondal J, Yethiraj A. Coarse-grained models for aqueous polyethylene glycol solutions. J Phys Chem B 2013; 118:323-9. [PMID: 24350686 DOI: 10.1021/jp408392b] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new coarse-grained force field is developed for polyethylene glycol (PEG) in water. The force field is based on the MARTINI model but with the big multipole water (BMW) model for the solvent. The polymer force field is reparameterized using the MARTINI protocol. The new force field removes the ring-like conformations seen in simulations of short chains with the MARTINI force field; these conformations are not observed in atomistic simulations. We also investigate the effect of using parameters for the end-group that are different from those for the repeat units, with the MARTINI and BMW/MARTINI models. We find that the new BMW/MARTINI force field removes the ring-like conformations seen in the MARTINI models and has more accurate predictions for the density of neat PEG. However, solvent-separated-pairs between chain ends and slow dynamics of the PEG reflect its own artifacts. We also carry out fine-grained simulations of PEG with bundled water clusters and show that the water bundling can lead to ring-like conformations of the polymer molecules. The simulations emphasize the pitfalls of coarse-graining several molecules into one site and suggest that polymer-solvent systems might be a stringent test for coarse-grained force fields.
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Affiliation(s)
- Eunsong Choi
- Department of Physics, and ‡Department of Chemistry, University of Wisconsin , Madison, Wisconsin 53706, United States
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83
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Nakano SI, Miyoshi D, Sugimoto N. Effects of molecular crowding on the structures, interactions, and functions of nucleic acids. Chem Rev 2013; 114:2733-58. [PMID: 24364729 DOI: 10.1021/cr400113m] [Citation(s) in RCA: 367] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Shu-ichi Nakano
- Department of Nanobiochemistry, Faculty of Frontiers of Innovative Research in Science and Technology (FIRST) and Frontier Institute for Biomolecular Engineering Research (FIBER), Konan University , 7-1-20 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan
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84
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Strulson CA, Yennawar NH, Rambo RP, Bevilacqua PC. Molecular crowding favors reactivity of a human ribozyme under physiological ionic conditions. Biochemistry 2013; 52:8187-97. [PMID: 24187989 PMCID: PMC3882164 DOI: 10.1021/bi400816s] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In an effort to relate RNA folding to function under cellular-like conditions, we monitored the self-cleavage reaction of the human hepatitis delta virus-like CPEB3 ribozyme in the background of physiological ionic concentrations and various crowding and cosolute agents. We found that at physiological free Mg(2+) concentrations (∼0.1-0.5 mM), both crowders and cosolutes stimulate the rate of self-cleavage, up to ∼6-fold, but that in 10 mM Mg(2+) (conditions widely used for in vitro ribozyme studies) these same additives have virtually no effect on the self-cleavage rate. We further observe a dependence of the self-cleavage rate on crowder size, wherein the level of rate stimulation is diminished for crowders larger than the size of the unfolded RNA. Monitoring effects of crowding and cosolute agents on rates in biological amounts of urea revealed additive-promoted increases at both low and high Mg(2+) concentrations, with a maximal stimulation of more than 10-fold and a rescue of the rate to its urea-free values. Small-angle X-ray scattering experiments reveal a structural basis for this stimulation in that higher-molecular weight crowding agents favor a more compact form of the ribozyme in 0.5 mM Mg(2+) that is essentially equivalent to the form under standard ribozyme conditions of 10 mM Mg(2+) without a crowder. This finding suggests that at least a portion of the rate enhancement arises from favoring the native RNA tertiary structure. We conclude that cellular-like crowding supports ribozyme reactivity by favoring a compact form of the ribozyme, but only under physiological ionic and cosolute conditions.
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Affiliation(s)
- Christopher A. Strulson
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Neela H. Yennawar
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Robert P. Rambo
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720
| | - Philip C. Bevilacqua
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
- Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
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85
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Denatured state structural property determines protein stabilization by macromolecular crowding: a thermodynamic and structural approach. PLoS One 2013; 8:e78936. [PMID: 24265729 PMCID: PMC3827121 DOI: 10.1371/journal.pone.0078936] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 09/26/2013] [Indexed: 11/19/2022] Open
Abstract
Understanding of protein structure and stability gained to date has been acquired through investigations made under dilute conditions where total macromolecular concentration never surpasses 10 g l−1. However, biological macromolecules are known to evolve and function under crowded intracellular environments that comprises of proteins, nucleic acids, ribosomes and carbohydrates etc. Crowded environment is known to result in altered biological properties including thermodynamic, structural and functional aspect of macromolecules as compared to the macromolecules present in our commonly used experimental dilute buffers (for example, Tris HCl or phosphate buffer). In this study, we have investigated the thermodynamic and structural consequences of synthetic crowding agent (Ficoll 70) on three different proteins (Ribonuclease-A, lysozyme and holo α-lactalbumin) at different pH values. We report here that the effect of crowding is protein dependent in terms of protein thermal stability and structure. We also observed that the structural characteristics of the denatured state determines if crowding will have an effect or not on the protein stability.
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86
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Cui J, Waltman P, Le VH, Lewis EA. The effect of molecular crowding on the stability of human c-MYC promoter sequence I-motif at neutral pH. Molecules 2013; 18:12751-67. [PMID: 24132198 PMCID: PMC6270392 DOI: 10.3390/molecules181012751] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 09/26/2013] [Accepted: 10/10/2013] [Indexed: 12/20/2022] Open
Abstract
We have previously shown that c-MYC promoter sequences can form stable i-motifs in acidic solution (pH 4.5-5.5). In terms of drug targeting, the question is whether c-MYC promoter sequence i-motifs will exist in the nucleus at neutral pH. In this work, we have investigated the stability of a mutant c-MYC i-motif in solutions containing a molecular crowding agent. The crowded nuclear environment was modeled by the addition of up to 40% w/w polyethylene glycols having molecular weights up to 12,000 g/mol. CD and DSC were used to establish the presence and stability of c-MYC i-motifs in buffer solutions over the pH range 4 to 7. We have shown that the c-MYC i-motif can exist as a stable structure at pH values as high as 6.7 in crowded solutions. Generic dielectric constant effects, e.g., a shift in the pKa of cytosine by more than 2 units (e.g., 4.8 to 7.0), or the formation of non-specific PEG/DNA complexes appear to contribute insignificantly to i-motif stabilization. Molecular crowding, largely an excluded volume effect of added PEG, having a molecular weight in excess of 1,000 g/mol, appears to be responsible for stabilizing the more compact i-motif over the random coil at higher pH values.
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Affiliation(s)
- Jingjing Cui
- Department of Chemistry, Mississippi State University, Mississippi State, MS 39762, USA.
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87
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Trovato F, Nifosì R, Di Fenza A, Tozzini V. A Minimalist Model of Protein Diffusion and Interactions: The Green Fluorescent Protein within the Cytoplasm. Macromolecules 2013. [DOI: 10.1021/ma401843h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Fabio Trovato
- Center
for Nanotechnology and Innovation @ NEST-Istituto Italiano di Tecnologia, 56127 Pisa, Italy
- Scuola Normale Superiore, Piazza
San Silvestro 12, 56127 Pisa, Italy
| | - Riccardo Nifosì
- NEST- Istituto Nanoscienze, CNR, 56127 Pisa, Italy
- Scuola Normale Superiore, Piazza
San Silvestro 12, 56127 Pisa, Italy
| | - Armida Di Fenza
- Scuola Normale Superiore, Piazza
San Silvestro 12, 56127 Pisa, Italy
- MGU, MRC Harwell, Harwell
Science and Innovation Campus, Oxfordshire OX11 0RD, U.K
| | - Valentina Tozzini
- NEST- Istituto Nanoscienze, CNR, 56127 Pisa, Italy
- Scuola Normale Superiore, Piazza
San Silvestro 12, 56127 Pisa, Italy
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88
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Karasawa A, Swier LJYM, Stuart MCA, Brouwers J, Helms B, Poolman B. Physicochemical factors controlling the activity and energy coupling of an ionic strength-gated ATP-binding cassette (ABC) transporter. J Biol Chem 2013; 288:29862-71. [PMID: 23979139 DOI: 10.1074/jbc.m113.499327] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cells control their volume through the accumulation of compatible solutes. The bacterial ATP-binding cassette transporter OpuA couples compatible solute uptake to ATP hydrolysis. Here, we study the gating mechanism and energy coupling of OpuA reconstituted in lipid nanodiscs. We show that anionic lipids are essential both for the gating and the energy coupling. The tight coupling between substrate binding on extracellular domains and ATP hydrolysis by cytoplasmic nucleotide-binding domains allows the study of transmembrane signaling in nanodiscs. From the tight coupling between processes at opposite sides of the membrane, we infer that the ATPase activity of OpuA in nanodiscs reflects solute translocation. Intriguingly, the substrate-dependent, ionic strength-gated ATPase activity of OpuA in nanodiscs is at least an order of magnitude higher than in lipid vesicles (i.e. with identical membrane lipid composition, ionic strength, and nucleotide and substrate concentrations). Even with the chemical components the same, the lateral pressure (profile) of the nanodiscs will differ from that of the vesicles. We thus propose that membrane tension limits translocation in vesicular systems. Increased macromolecular crowding does not activate OpuA but acts synergistically with ionic strength, presumably by favoring gating interactions of like-charged surfaces via excluded volume effects.
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Affiliation(s)
- Akira Karasawa
- From the Departments of Biochemistry and Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, Netherlands Proteomics Centre
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89
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Direct observation of protein unfolded state compaction in the presence of macromolecular crowding. Biophys J 2013; 104:694-704. [PMID: 23442920 DOI: 10.1016/j.bpj.2012.12.020] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 11/20/2012] [Accepted: 12/06/2012] [Indexed: 11/22/2022] Open
Abstract
Proteins fold and function in cellular environments that are crowded with other macromolecules. As a consequence of excluded volume effects, compact folded states of proteins should be indirectly stabilized due to destabilization of extended unfolded conformations. Here, we assess the role of excluded volume in terms of protein stability, structural dimensions and folding dynamics using a sugar-based crowding agent, dextran 20, and the small ribosomal protein S16 as a model system. To specifically address dimensions, we labeled the protein with BODIPY at two positions and measured Trp-BODIPY distances under different conditions. As expected, we found that dextran 20 (200 mg/ml) stabilized the variants against urea-induced unfolding. At conditions where the protein is unfolded, Förster resonance energy transfer measurements reveal that in the presence of dextran, the unfolded ensemble is more compact and there is residual structure left as probed by far-ultraviolet circular dichroism. In the presence of a crowding agent, folding rates are faster in the two-state regime, and at low denaturant concentrations, a kinetic intermediate is favored. Our study provides direct evidence for protein unfolded-state compaction in the presence of macromolecular crowding along with its energetic and kinetic consequences.
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90
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Akabayov SR, Akabayov B, Richardson CC, Wagner G. Molecular crowding enhanced ATPase activity of the RNA helicase eIF4A correlates with compaction of its quaternary structure and association with eIF4G. J Am Chem Soc 2013; 135:10040-7. [PMID: 23767688 DOI: 10.1021/ja404404h] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Enzymatic reactions occur in a crowded and confined environment in vivo, containing proteins, RNA and DNA. Previous reports have shown that interactions between macromolecules, and reactions rates differ significantly between crowded environments and dilute buffers. However, the direct effect of crowding on the level of high-resolution structures of macromolecules has not been extensively analyzed and is not well understood. Here we analyze the effect of macromolecular crowding on structure and function of the human translation initiation factors eIF4A, a two-domain DEAD-Box helicase, the HEAT-1 domain of eIF4G, and their complex. We find that crowding enhances the ATPase activity of eIF4A, which correlates with a shift to a more compact structure as revealed with small-angle X-ray scattering. However, the individual domains of eIF4A, or the eIF4G-HEAT-1 domain alone show little structural changes due to crowding except for flexible regions. Thus, the effect of macromolecular crowding on activity and structure need to be taken into account when evaluating enzyme activities and structures of multidomain proteins, proteins with flexible regions, or protein complexes obtained by X-ray crystallography, NMR, or other structural methods.
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Affiliation(s)
- Sabine R Akabayov
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA
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91
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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]
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92
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Wang MX. Effect of coil-globule transition on the single-chain crystallization. J Phys Chem B 2013; 117:6541-6. [PMID: 23646890 DOI: 10.1021/jp3120397] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The folding process of a single chain including coil-globule transition and crystallization has been investigated through dynamic Monte Carlo simulations. The results based upon ensemble averaging illustrated three distinct states: coil, molten globule, and globule states. Furthermore, the crystallization process from these collapsed states demonstrated various characteristics and it also verified the thermodynamic partitions. The isothermal crystallization in the three states showed the folding rates, and the final crystallite morphologies strongly depended on the collapsed states. Especially, the onset temperature of crystallization in the intermediate molten globule state demonstrated the strongest sensitivity to the solvent qualities in the three different states. Moreover, the crystallization in this intermediate state illustrated a two-step folding mechanism with the prior dense core serving as a precursor to induce the subsequent crystallization. Our observations would help in understanding the thermodynamics and kinetics of phase transition of a single macromolecule. Possible relations to the protein folding were also discussed.
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Affiliation(s)
- Mao-Xiang Wang
- School of Science, Nanjing University of Science and Technology, Nanjing 210094, China.
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93
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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.
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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
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94
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Ultrafast electron transfer in riboflavin binding protein in macromolecular crowding of nano-sized micelle. Biochimie 2012; 94:2673-80. [DOI: 10.1016/j.biochi.2012.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Accepted: 08/06/2012] [Indexed: 11/20/2022]
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95
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Arviv O, Levy Y. Folding of multidomain proteins: Biophysical consequences of tethering even in apparently independent folding. Proteins 2012; 80:2780-98. [DOI: 10.1002/prot.24161] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2012] [Revised: 07/11/2012] [Accepted: 07/16/2012] [Indexed: 01/09/2023]
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96
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Zhang DL, Wu LJ, Chen J, Liang Y. Effects of macromolecular crowding on the structural stability of human α-lactalbumin. Acta Biochim Biophys Sin (Shanghai) 2012; 44:703-11. [PMID: 22735492 DOI: 10.1093/abbs/gms052] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The folding of protein, an important process for protein to fulfill normal functions, takes place in crowded physiological environments. α-Lactalbumin, as a model system for protein-folding studies, has been used extensively because it can form stable molten globule states under a range of conditions. Here we report that the crowding agents Ficoll 70, dextran 70, and polyethylene glycol (PEG) 2000 have different effects on the structural stability of human α-lactalbumin (HLA) represented by the transition to a molten globule state: dextran 70 dramatically enhances the thermal stability of Ca(2+)-depleted HLA (apo-HLA) and Ficoll 70 enhances the thermal stability of apo-HLA to some extent, while PEG 2000 significantly decreases the thermal stability of apo-HLA. Ficoll 70 and dextran 70 have no obvious effects on trypsin degradation of apo-HLA but PEG 2000 accelerates apo-HLA degradation by trypsin and destabilizes the native conformation of apo-HLA. Furthermore, no interaction is observed between apo-HLA and Ficoll 70 or dextran 70, but a weak, non-specific interaction between the apo form of the protein and PEG 2000 is detected, and such a weak, non-specific interaction could overcome the excluded-volume effect of PEG 2000. Our data are consistent with the results of protein stability studies in cells and suggest that stabilizing excluded-volume effects of crowding agents can be ameliorated by non-specific interactions between proteins and crowders.
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Affiliation(s)
- De-Lin Zhang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
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97
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Protein crowding impedes pressure-induced unfolding of staphylococcal nuclease. Biochim Biophys Acta Gen Subj 2012; 1820:957-61. [DOI: 10.1016/j.bbagen.2012.03.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 03/29/2012] [Accepted: 03/30/2012] [Indexed: 11/17/2022]
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98
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Damodaran S. On the molecular mechanism of stabilization of proteins by cosolvents: role of Lifshitz electrodynamic forces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:9475-9486. [PMID: 22646139 DOI: 10.1021/la300953n] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Several ionic and nonionic additives are known to affect structural stability of proteins in aqueous solutions. At a fundamental level, the mechanism of stabilization or destabilization of proteins by cosolvents must be related to three-body interactions between the protein, additive, and the water medium. In this study, the role of the Lifshitz-van der Waals electrodynamic interaction between various additives (sucrose, glycerol, urea, poly(ethylene glycol)-200, betaine, taurine, proline, and valine) and bovine serum albumin (BSA) in water medium was examined. The electrodynamic interaction energy was attractive for all of the additives studied here when both far ultraviolet and infrared relaxations of the additives were included in their dielectric susceptibility representations. However, when only the infrared contribution was included for structure stabilizers and both far ultraviolet and infrared contributions for the structure destabilizers, the resulting electrodynamic interaction energy (E/kT) followed the structure stabilizing and/or destabilizing behavior of the additives; that is, the interaction was attractive for urea and PEG200 (structure destabilizers), whereas it was repulsive for sucrose, glycerol, betaine, taurine, alanine, valine, and proline (structure stabilizers). The electrodynamic interaction energy E/kT at any given surface-to-surface separation distance between the additives and BSA was positively correlated (r(2) = 0.92) with the experimental thermal denaturation temperature (T(d)) of BSA in 1 M solutions of the additives. These analyses provided a mechanistic basis for the experimental observations of exclusion of the structure-stabilizing additives from the protein-water interface and binding of the structure-destabilizing additives to the protein surface. The role of water structure in the three-body electrodynamic interaction is discussed. It is hypothesized that in the case of additives that enhance water structure the hydration shells formed around the additives effectively dampen the contribution of ultraviolet frequencies to the dielectric susceptibility of the additives and thus impart repulsive electrodyanamic interaction between the additive and the protein, whereas the opposite occurs in the case of additives that breakdown the hydrogen-bonded structure of water.
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Affiliation(s)
- Srinivasan Damodaran
- Department of Food Science, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States.
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99
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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
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100
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Three-dimensional stochastic off-lattice model of binding chemistry in crowded environments. PLoS One 2012; 7:e30131. [PMID: 22272286 PMCID: PMC3260218 DOI: 10.1371/journal.pone.0030131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 12/14/2011] [Indexed: 01/01/2023] Open
Abstract
Molecular crowding is one of the characteristic features of the intracellular environment, defined by a dense mixture of varying kinds of proteins and other molecules. Interaction with these molecules significantly alters the rates and equilibria of chemical reactions in the crowded environment. Numerous fundamental activities of a living cell are strongly influenced by the crowding effect, such as protein folding, protein assembly and disassembly, enzyme activity, and signal transduction. Quantitatively predicting how crowding will affect any particular process is, however, a very challenging problem because many physical and chemical parameters act synergistically in ways that defy easy analysis. To build a more realistic model for this problem, we extend a prior stochastic off-lattice model from two-dimensional (2D) to three-dimensional (3D) space and examine how the 3D results compare to those found in 2D. We show that both models exhibit qualitatively similar crowding effects and similar parameter dependence, particularly with respect to a set of parameters previously shown to act linearly on total reaction equilibrium. There are quantitative differences between 2D and 3D models, although with a generally gradual nonlinear interpolation as a system is extended from 2D to 3D. However, the additional freedom of movement allowed to particles as thickness of the simulation box increases can produce significant quantitative change as a system moves from 2D to 3D. Simulation results over broader parameter ranges further show that the impact of molecular crowding is highly dependent on the specific reaction system examined.
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