1
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Tavili E, Aziziyan F, Dabirmanesh B. Pathways of amyloid fibril formation and protein aggregation. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2024; 206:11-54. [PMID: 38811078 DOI: 10.1016/bs.pmbts.2024.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
The main cause of many neurodegenerative diseases and systemic amyloidoses is protein and peptide aggregation and the formation of amyloid fibrils. The study of aggregation mechanisms, the discovery and description of aggregate structures, and a comprehensive understanding of the molecular mechanisms of amyloid formation are of great importance for the diagnostic processes at the molecular level and for the development of therapeutic strategies to counter aggregation-associated disorders. Given that understanding protein misfolding phenomena is directly related to the protein folding process, we will briefly explain the protein folding mechanism and then discuss the important factors involved in protein aggregation. In the following, we review different mechanisms of amyloid formation and finally represent the current knowledge on how amyloid fibrils are formed based on kinetic and thermodynamic factors.
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Affiliation(s)
- Elaheh Tavili
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | - Fatemeh Aziziyan
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | - Bahareh Dabirmanesh
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
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2
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Becht DC, Leavens MJ, Zeng B, Rothfuss MT, Briknarová K, Bowler BE. Residual Structure in the Denatured State of the Fast-Folding UBA(1) Domain from the Human DNA Excision Repair Protein HHR23A. Biochemistry 2022; 61:767-784. [PMID: 35430812 PMCID: PMC9150713 DOI: 10.1021/acs.biochem.2c00011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The structure of the first ubiquitin-associated domain from HHR23A, UBA(1), was determined by X-ray crystallography at a 1.60 Å resolution, and its stability, folding kinetics, and residual structure under denaturing conditions have been investigated. The concentration dependence of thermal denaturation and size-exclusion chromatography indicate that UBA(1) is monomeric. Guanidine hydrochloride (GdnHCl) denaturation experiments reveal that the unfolding free energy, ΔGu°'(H2O), of UBA(1) is 2.4 kcal mol-1. Stopped-flow folding kinetics indicates sub-millisecond folding with only proline isomerization phases detectable at 25 °C. The full folding kinetics are observable at 4 °C, yielding a folding rate constant, kf, in the absence of a denaturant of 13,000 s-1 and a Tanford β-value of 0.80, consistent with a compact transition state. Evaluation of the secondary structure via circular dichroism shows that the residual helical structure in the denatured state is replaced by polyproline II structure as the GdnHCl concentration increases. Analysis of NMR secondary chemical shifts for backbone 15NH, 13CO, and 13Cα atoms between 4 and 7 M GdnHCl shows three islands of residual helical secondary structure that align in sequence with the three native-state helices. Extrapolation of the NMR data to 0 M GdnHCl demonstrates that helical structure would populate to 17-33% in the denatured state under folding conditions. Comparison with NMR data for a peptide corresponding to helix 1 indicates that this helix is stabilized by transient tertiary interactions in the denatured state of UBA(1). The high helical content in the denatured state, which is enhanced by transient tertiary interactions, suggests a diffusion-collision folding mechanism.
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Affiliation(s)
- Dustin C Becht
- Department of Chemistry & Biochemistry, University of Montana, Missoula, Montana 59812, United States
- Center for Biomolecular Structure & Dynamics, University of Montana, Missoula, Montana 59812, United States
| | - Moses J Leavens
- Department of Chemistry & Biochemistry, University of Montana, Missoula, Montana 59812, United States
- Center for Biomolecular Structure & Dynamics, University of Montana, Missoula, Montana 59812, United States
| | - Baisen Zeng
- Department of Chemistry & Biochemistry, University of Montana, Missoula, Montana 59812, United States
- Center for Biomolecular Structure & Dynamics, University of Montana, Missoula, Montana 59812, United States
| | - Michael T Rothfuss
- Department of Chemistry & Biochemistry, University of Montana, Missoula, Montana 59812, United States
- Center for Biomolecular Structure & Dynamics, University of Montana, Missoula, Montana 59812, United States
| | - Klára Briknarová
- Department of Chemistry & Biochemistry, University of Montana, Missoula, Montana 59812, United States
- Center for Biomolecular Structure & Dynamics, University of Montana, Missoula, Montana 59812, United States
| | - Bruce E Bowler
- Department of Chemistry & Biochemistry, University of Montana, Missoula, Montana 59812, United States
- Center for Biomolecular Structure & Dynamics, University of Montana, Missoula, Montana 59812, United States
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3
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Leavens MJ, Spang LE, Cherney MM, Bowler BE. Denatured State Conformational Biases in Three-Helix Bundles Containing Divergent Sequences Localize near Turns and Helix Capping Residues. Biochemistry 2021; 60:3071-3085. [PMID: 34606713 PMCID: PMC8751257 DOI: 10.1021/acs.biochem.1c00400] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rhodopseudomonas palustris cytochrome c', a four-helix bundle, and the second ubiquitin-associated domain, UBA(2), a three-helix bundle from the human homologue of yeast Rad23, HHR23A, deviate from random coil behavior under denaturing conditions in a fold-specific manner. The random coil deviations in each of these folds occur near interhelical turns and loops in their tertiary structures. Here, we examine an additional three-helix bundle with an identical fold to UBA(2), but a highly divergent sequence, the first ubiquitin-associated domain, UBA(1), of HHR23A. We use histidine-heme loop formation methods, employing eight single histidine variants, to probe for denatured state conformational bias of a UBA(1) domain fused to the N-terminus of iso-1-cytochrome c (iso-1-Cytc). Guanidine hydrochloride (GuHCl) denaturation shows that the iso-1-Cytc domain unfolds first, followed by the UBA(1) domain. Denatured state (4 and 6 M GuHCl) histidine-heme loop formation studies show that as the size of the histidine-heme loop increases, loop stability decreases, as expected for the Jacobson-Stockmayer relationship. However, loops formed with His35, His31, and His15, of UBA(1), are 0.6-1.1 kcal/mol more stable than expected from the Jacobson-Stockmayer relationship, confirming the importance of deviations of the denatured state from random coil behavior near interhelical turns of helical domains for facilitating folding to the correct topology. For UBA(1) and UBA(2), hydrophobic clusters on either side of the turns partially explain deviations from random coil behavior; however, helix capping also appears to be important.
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Affiliation(s)
- Moses J. Leavens
- Department of Chemistry & Biochemistry, University of Montana, Missoula, Montana 59812, United States
- Center for Biomolecular Structure & Dynamics, University of Montana, Missoula, Montana 59812, United States
| | - Lisa E. Spang
- Department of Chemistry & Biochemistry, University of Montana, Missoula, Montana 59812, United States
- Center for Biomolecular Structure & Dynamics, University of Montana, Missoula, Montana 59812, United States
| | - Melisa M. Cherney
- Department of Chemistry & Biochemistry, University of Montana, Missoula, Montana 59812, United States
- Center for Biomolecular Structure & Dynamics, University of Montana, Missoula, Montana 59812, United States
| | - Bruce E. Bowler
- Department of Chemistry & Biochemistry, University of Montana, Missoula, Montana 59812, United States
- Center for Biomolecular Structure & Dynamics, University of Montana, Missoula, Montana 59812, United States
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4
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Zou J, Xiao S, Simmerling C, Raleigh DP. Quantitative Analysis of Protein Unfolded State Energetics: Experimental and Computational Studies Demonstrate That Non-Native Side-Chain Interactions Stabilize Local Native Backbone Structure. J Phys Chem B 2021; 125:3269-3277. [PMID: 33779182 DOI: 10.1021/acs.jpcb.0c08922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Proteins fold on relatively smooth free energy landscapes which are biased toward the native state, but even simple topologies which fold rapidly can experience roughness on their free energy landscape. The details of these interactions are difficult to elucidate experimentally. Closely related to the problem of deciphering the details of the free energy landscape is the problem of defining the interactions in the denatured state ensemble (DSE) which is populated under native conditions, that is, under conditions where the native state is stable. The DSE of many proteins deviates from random coil models, but quantifying and defining the energetics of the transiently populated interactions in this ensemble is extremely challenging. Characterization of the DSE of proteins which fold to compact structures is also relevant to studies of intrinsically disordered proteins (IDPs) since interactions in the dynamic ensemble populated by IDPs can modulate their behavior. Here we show how experimental thermodynamic and pKa measurements can be combined with computational thermodynamic integration to quantify interactions in the DSE. We show that non-native side chain interactions can stabilize native backbone structure in the DSE and demonstrate that that even rapidly folding proteins can form energetically significant non-native interactions in their DSE. As an example, we characterize a non-native salt bridge that stabilizes local native backbone structure in the DSE of a widely studied fast-folding protein, the villin headpiece helical domain. The combined computational experimental approach is applicable to other protein unfolded states and provides insight that is impossible to obtain with either method alone.
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Affiliation(s)
- Junjie Zou
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States.,Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Shifeng Xiao
- Shenzhen Key Laboratory of Marine Biotechnology and Ecology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China
| | - Carlos Simmerling
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States.,Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Daniel P Raleigh
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States.,Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, New York 11794-3400, United States
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5
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Chen J, Liu X, Chen J. Atomistic Peptide Folding Simulations Reveal Interplay of Entropy and Long-Range Interactions in Folding Cooperativity. Sci Rep 2018; 8:13668. [PMID: 30209295 PMCID: PMC6135771 DOI: 10.1038/s41598-018-32028-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 08/30/2018] [Indexed: 11/23/2022] Open
Abstract
Understanding how proteins fold has remained a problem of great interest in biophysical research. Atomistic computer simulations using physics-based force fields can provide important insights on the interplay of different interactions and energetics and their roles in governing the folding thermodynamics and mechanism. In particular, generalized Born (GB)-based implicit solvent force fields can be optimized to provide an appropriate balance between solvation and intramolecular interactions and successfully recapitulate experimental conformational equilibria for a set of helical and β-hairpin peptides. Here, we further demonstrate that key thermodynamic properties and their temperature dependence obtained from replica exchange molecular dynamics simulations of these peptides are in quantitative agreement with experimental results. Useful lessons can be learned on how the interplay of entropy and sequentially long-range interactions governs the mechanism and cooperativity of folding. These results highlight the great potential of high-quality implicit solvent force fields for studying protein folding and large-scale conformational transitions.
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Affiliation(s)
- Jianlin Chen
- Department of Hematology, The Central Hospital of Taizhou, Taizhou, Zhejiang, 318000, P.R. China
| | - Xiaorong Liu
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA, 01003, USA. .,Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA.
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6
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Nagarajan S, Xiao S, Raleigh DP, Dyer RB. Heterogeneity in the Folding of Villin Headpiece Subdomain HP36. J Phys Chem B 2018; 122:11640-11648. [PMID: 30118232 DOI: 10.1021/acs.jpcb.8b07683] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Small single domain proteins that fold on the microsecond time scale have been the subject of intense interest as models for probing the complexity of folding energy landscapes. The villin headpiece subdomain (HP36) has been extensively studied because of its simple three helix structure, ultrafast folding lifetime of a few microseconds, and stable native fold. We have previously shown that folding as measured by a single 13C═18O isotopic label on residue A57 in helix 2 occurs at a different rate than that measured by global probes of folding, indicating noncooperative complexity in the folding of HP36. In order to determine whether this complexity reflects intermediates or parallel pathways over a small activation barrier, 13C═18O labels were individually incorporated at six different positions in HP36, including into all 3 helices. The equilibrium thermal unfolding transitions and the folding/unfolding dynamics were monitored using the unique IR signature of the 13C═18O label by temperature dependent FTIR and temperature jump IR spectroscopy, respectively. Equilibrium experiments reveal that the 13C═18O labels at different positions in HP36 show drastic differences in the midpoint of their transitions ( Tm), ranging from 45 to 67 °C. Heterogeneity is also observed in the relaxation kinetics; there are differences in the microsecond phase when different labeled positions are probed. At a final temperature of 45 °C, the relaxation rate for 13C═18O A57 is 2.4e + 05 s-1 whereas for 13C═18O L69 HP36 the relaxation rate is 5.1e + 05 s-1, two times faster. The observation of site-dependent midpoints for the equilibrium unfolding transitions and differences in the relaxation rates of the labeled positions enables us to probe the progressive accumulation of the folded structure, providing insight into the microscopic details of the folding mechanism.
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Affiliation(s)
- Sureshbabu Nagarajan
- Department of Chemistry , Emory University , Atlanta , Georgia 30322 , United States
| | - Shifeng Xiao
- Shenzhen Key Laboratory of Marine Biotechnology and Ecology, College of Life Sciences and Oceanography , Shenzhen University , Shenzhen 518060 , China
| | - Daniel P Raleigh
- Department of Chemistry , State University of New York at Stony Brook , Stony Brook , New York 11794 , United States.,Institute of Structural and Molecular Biology , University College London , Gower Street , London WC1E 6BT , United Kingdom
| | - R Brian Dyer
- Department of Chemistry , Emory University , Atlanta , Georgia 30322 , United States
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7
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Abstract
In vitro, computational, and theoretical studies of protein folding have converged to paint a rich and complex energy landscape. This landscape is sensitively modulated by environmental conditions and subject to evolutionary pressure on protein function. Of these environments, none is more complex than the cell itself, where proteins function in the cytosol, in membranes, and in different compartments. A wide variety of kinetic and thermodynamics experiments, ranging from single-molecule studies to jump kinetics and from nuclear magnetic resonance to imaging on the microscope, have elucidated how protein energy landscapes facilitate folding and how they are subject to evolutionary constraints and environmental perturbation. Here we review some recent developments in the field and refer the reader to some original work and additional reviews that cover this broad topic in protein science.
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Affiliation(s)
- Martin Gruebele
- Center for Biophysics and Quantitative Biology, University of Illinois, Urbana, Illinois 61801; , .,Department of Chemistry, University of Illinois, Urbana, Illinois 61801; .,Department of Physics, University of Illinois, Urbana, Illinois 61801
| | - Kapil Dave
- Center for Biophysics and Quantitative Biology, University of Illinois, Urbana, Illinois 61801; ,
| | - Shahar Sukenik
- Department of Chemistry, University of Illinois, Urbana, Illinois 61801;
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8
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Davis CM, Reddish MJ, Dyer RB. Dual time-resolved temperature-jump fluorescence and infrared spectroscopy for the study of fast protein dynamics. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 178:185-191. [PMID: 28189834 PMCID: PMC5346054 DOI: 10.1016/j.saa.2017.01.069] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 01/27/2017] [Accepted: 01/31/2017] [Indexed: 05/30/2023]
Abstract
Time-resolved temperature-jump (T-jump) coupled with fluorescence and infrared (IR) spectroscopy is a powerful technique for monitoring protein dynamics. Although IR spectroscopy of the polypeptide amide I mode is more technically challenging, it offers complementary information because it directly probes changes in the protein backbone, whereas, fluorescence spectroscopy is sensitive to the environment of specific side chains. With the advent of widely tunable quantum cascade lasers (QCL) it is possible to efficiently probe multiple IR frequencies with high sensitivity and reproducibility. Here we describe a dual time-resolved T-jump fluorescence and IR spectrometer and its application to study protein folding dynamics. A Q-switched Ho:YAG laser provides the T-jump source for both time-resolved IR and fluorescence spectroscopy, which are probed by a QCL and Ti:Sapphire laser, respectively. The Ho:YAG laser simultaneously pumps the time-resolved IR and fluorescence spectrometers. The instrument has high sensitivity, with an IR absorbance detection limit of <0.2mOD and a fluorescence sensitivity of 2% of the overall fluorescence intensity. Using a computer controlled QCL to rapidly tune the IR frequency it is possible to create a T-jump induced difference spectrum from 50ns to 0.5ms. This study demonstrates the power of the dual time-resolved T-jump fluorescence and IR spectroscopy to resolve complex folding mechanisms by complementary IR absorbance and fluorescence measurements of protein dynamics.
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Affiliation(s)
- Caitlin M Davis
- Department of Chemistry, Emory University, Atlanta, GA 30322, United States
| | - Michael J Reddish
- Department of Chemistry, Emory University, Atlanta, GA 30322, United States
| | - R Brian Dyer
- Department of Chemistry, Emory University, Atlanta, GA 30322, United States.
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9
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NISHIMURA C. Folding of apomyoglobin: Analysis of transient intermediate structure during refolding using quick hydrogen deuterium exchange and NMR. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2017; 93:10-27. [PMID: 28077807 PMCID: PMC5406622 DOI: 10.2183/pjab.93.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 10/31/2016] [Indexed: 05/27/2023]
Abstract
The structures of apomyoglobin folding intermediates have been widely analyzed using physical chemistry methods including fluorescence, circular dichroism, small angle X-ray scattering, NMR, mass spectrometry, and rapid mixing. So far, at least two intermediates (on sub-millisecond- and millisecond-scales) have been demonstrated for apomyoglobin folding. The combination of pH-pulse labeling and NMR is a useful tool for analyzing the kinetic intermediates at the atomic level. Its use has revealed that the latter-phase kinetic intermediate of apomyoglobin (6 ms) was composed of helices A, B, G and H, whereas the equilibrium intermediate, called the pH 4 molten-globule intermediate, was composed mainly of helices A, G and H. The improved strategy for the analysis of the kinetic intermediate was developed to include (1) the dimethyl sulfoxide method, (2) data processing with the various labeling times, and (3) a new in-house mixer. Particularly, the rapid mixing revealed that helices A and G were significantly more protected at the earlier stage (400 µs) of the intermediate (former-phase intermediate) than the other helices. Mutation studies, where each hydrophobic residue was replaced with an alanine in helices A, B, E, F, G and H, indicated that both non-native and native-like structures exist in the latter-phase folding intermediate. The N-terminal part of helix B is a weak point in the intermediate, and the docking of helix E residues to the core of the A, B, G and H helices was interrupted by a premature helix B, resulting in the accumulation of the intermediate composed of helices A, B, G and H. The prediction-based protein engineering produced important mutants: Helix F in a P88K/A90L/S92K/A94L mutant folded in the latter-phase intermediate, although helix F in the wild type does not fold even at the native state. Furthermore, in the L11G/W14G/A70L/G73W mutant, helix A did not fold but helix E did, which is similar to what was observed in the kinetic intermediate of apoleghemoglobin. Thus, this protein engineering resulted in a changed structure for the apomyoglobin folding intermediate.
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Affiliation(s)
- Chiaki NISHIMURA
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano-ku, Tokyo, Japan
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10
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Gerig JT. Examination of Trifluoroethanol Interactions with Trp-Cage through MD Simulations and Intermolecular Nuclear Overhauser Effects. J Phys Chem B 2016; 120:11256-11265. [DOI: 10.1021/acs.jpcb.6b08430] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J. T. Gerig
- Department of Chemistry and
Biochemistry, University of California at Santa Barbara, Santa Barbara, California 93106, United States
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11
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Ono YI, Miyashita M, Ono Y, Okazaki H, Watanabe S, Tochio N, Kigawa T, Nishimura C. Comparison of residual alpha- and beta-structures between two intrinsically disordered proteins by using NMR. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1854:229-38. [PMID: 25523747 DOI: 10.1016/j.bbapap.2014.12.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Revised: 11/20/2014] [Accepted: 12/10/2014] [Indexed: 11/24/2022]
Abstract
Intrinsically disordered proteins contain some residual structures, which may fold further upon binding to the partner protein for function. The residual structures observed in two intrinsically disordered proteins, including the C-terminal segment of peripherin-2 (63 residues) and measles virus nucleocapsid protein Ntail (125 residues), were compared using NMR. Differences in the chemical shifts of alpha-, beta- and carbonyl carbons between the observed structure and calculated random coil revealed the existence of a helix and some possible beta-structures in both proteins. The intensity of signals in the C-terminal segment of peripherin-2 in NMR spectra was informative and locally low, particularly in the middle and N-terminal parts: this suggested the broadening of the signals caused by the formation of residual structures in those areas. Furthermore, the protection of exchange of amide protons was significantly observed at the N-terminus. Conversely, the intensities of signals for Ntail were random beyond the overall areas of protein, and indicated no characteristic pattern. Only a faint protection of amide-proton exchange in Ntail was observed in the C-terminus. It was concluded that Ntail was more intrinsically disordered than the C-terminal segment of peripherin-2. The combination of chemical shifts with the amide-proton exchanges and signal intensities was useful for the analyses of the remaining secondary structures. The beta-structure might be more detectable by the protection of amide-proton exchange than the helical structure, although the changes in chemical shifts were sensitive for the detection of elements of both secondary structures.
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Affiliation(s)
- Yu-ichi Ono
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano, Tokyo 164-8530, Japan
| | - Manami Miyashita
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano, Tokyo 164-8530, Japan
| | - Yumi Ono
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano, Tokyo 164-8530, Japan
| | - Honoka Okazaki
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano, Tokyo 164-8530, Japan
| | - Satoru Watanabe
- NMR Pipeline Methodology Team, RIKEN Systems and Structural Biology Center, Tsurumi, Yokohama 230-0045, Japan
| | - Naoya Tochio
- NMR Pipeline Methodology Team, RIKEN Systems and Structural Biology Center, Tsurumi, Yokohama 230-0045, Japan
| | - Takanori Kigawa
- NMR Pipeline Methodology Team, RIKEN Systems and Structural Biology Center, Tsurumi, Yokohama 230-0045, Japan
| | - Chiaki Nishimura
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano, Tokyo 164-8530, Japan.
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12
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Abstract
Folding may be described conceptually in terms of trajectories over a landscape of free energies corresponding to different molecular configurations. In practice, energy landscapes can be difficult to measure. Single-molecule force spectroscopy (SMFS), whereby structural changes are monitored in molecules subjected to controlled forces, has emerged as a powerful tool for probing energy landscapes. We summarize methods for reconstructing landscapes from force spectroscopy measurements under both equilibrium and nonequilibrium conditions. Other complementary, but technically less demanding, methods provide a model-dependent characterization of key features of the landscape. Once reconstructed, energy landscapes can be used to study critical folding parameters, such as the characteristic transition times required for structural changes and the effective diffusion coefficient setting the timescale for motions over the landscape. We also discuss issues that complicate measurement and interpretation, including the possibility of multiple states or pathways and the effects of projecting multiple dimensions onto a single coordinate.
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Affiliation(s)
- Michael T Woodside
- Department of Physics, University of Alberta, Edmonton, Alberta T6G2E1, Canada;
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13
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Mou L, Jia X, Gao Y, Li Y, Zhang JZH, Mei Y. Folding simulation of Trp-cage utilizing a new AMBER compatible force field with coupled main chain torsions. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2014. [DOI: 10.1142/s0219633614500266] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A newly developed AMBER compatible force field with coupled backbone torsion potential terms (AMBER032D) is utilized in a folding simulation of a mini-protein Trp-cage. Through replica exchange and direct molecular dynamics (MD) simulations, a multi-step folding mechanism with a synergetic folding of the hydrophobic core (HPC) and the α-helix in the final stage is suggested. The native structure has the lowest free energy and the melting temperature predicted from the specific heat capacity Cvis only 12 K higher than the experimental measurement. This study, together with our previous study, shows that AMBER032Dis an accurate force field that can be used for protein folding simulations.
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Affiliation(s)
- Lirong Mou
- Institute for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, P. R. China
| | - Xiangyu Jia
- Center for Laser and Computational Biophysics, State Key Laboratory of Precision Spectroscopy and Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062, P. R. China
| | - Ya Gao
- Center for Laser and Computational Biophysics, State Key Laboratory of Precision Spectroscopy and Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062, P. R. China
| | - Yongxiu Li
- Center for Laser and Computational Biophysics, State Key Laboratory of Precision Spectroscopy and Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062, P. R. China
| | - John Z. H. Zhang
- Center for Laser and Computational Biophysics, State Key Laboratory of Precision Spectroscopy and Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062, P. R. China
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062, P. R. China
| | - Ye Mei
- Center for Laser and Computational Biophysics, State Key Laboratory of Precision Spectroscopy and Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062, P. R. China
- NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062, P. R. China
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14
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Galzitskaya OV, Pereyaslavets LB, Glyakina AV. Folding of Right- and Left-Handed Three-Helix Proteins. Isr J Chem 2014. [DOI: 10.1002/ijch.201300146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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15
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Markiewicz BN, Yang L, Culik RM, Gao YQ, Gai F. How quickly can a β-hairpin fold from its transition state? J Phys Chem B 2014; 118:3317-25. [PMID: 24611730 PMCID: PMC3969101 DOI: 10.1021/jp500774q] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
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Understanding the structural nature
of the free energy bottleneck(s)
encountered in protein folding is essential to elucidating the underlying
dynamics and mechanism. For this reason, several techniques, including
Φ-value analysis, have previously been developed to infer the
structural characteristics of such high free-energy or transition
states. Herein we propose that one (or few) appropriately placed backbone
and/or side chain cross-linkers, such as disulfides, could be used
to populate a thermodynamically accessible conformational state that
mimics the folding transition state. Specifically, we test this hypothesis
on a model β-hairpin, Trpzip4, as its folding mechanism has
been extensively studied and is well understood. Our results show
that cross-linking the two β-strands near the turn region increases
the folding rate by an order of magnitude, to about (500 ns)−1, whereas cross-linking the termini results in a hyperstable β-hairpin
that has essentially the same folding rate as the uncross-linked peptide.
Taken together, these findings suggest that cross-linking is not only
a useful strategy to manipulate folding free energy barriers, as shown
in other studies, but also, in some cases, it can be used to stabilize
a folding transition state analogue and allow for direct assessment
of the folding process on the downhill side of the free energy barrier.
The calculated free energy landscape of the cross-linked Trpzip4 also
supports this picture. An empirical analysis further suggests, when
folding of β-hairpins does not involve a significant free energy
barrier, the folding time (τ) follows a power law dependence
on the number of hydrogen bonds to be formed (nH), namely, τ = τ0nHα, with
τ0 = 20 ns and α = 2.3.
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Affiliation(s)
- Beatrice N Markiewicz
- Department of Chemistry and ‡Department of Biochemistry and Biophysics, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
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16
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Davis CM, Dyer RB. Dynamics of an ultrafast folding subdomain in the context of a larger protein fold. J Am Chem Soc 2013; 135:19260-7. [PMID: 24320936 PMCID: PMC3949483 DOI: 10.1021/ja409608r] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Small fast folding subdomains with low contact order have been postulated to facilitate the folding of larger proteins. We have tested this idea by determining how the fastest folding linear β-hairpin, CLN025, which folds on the nanosecond time scale, folds within the context of a two-hairpin WW domain system, which folds on the microsecond time scale. The folding of the wild type FBP28 WW domain was compared to constructs in which each of the loops was replaced by CLN025. A combination of FTIR spectroscopy and laser-induced temperature-jump coupled with infrared spectroscopy was used to probe changes in the peptide backbone. The relaxation dynamics of the β-sheets and β-turn were measured independently by probing the corresponding bands assigned in the amide I region. The folding rate of the CLN025 β-hairpin is unchanged within the larger protein. Insertion of the β-hairpin into the second loop results in an overall stabilization of the WW domain and a relaxation lifetime five times faster than the parent WW domain. In both mutants, folding is initiated in the turns and the β-sheets form last. These results demonstrate that fast folding subdomains can be used to speed the folding of more complex proteins, and that the folding dynamics of the subdomain is unchanged within the context of the larger protein.
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Affiliation(s)
- Caitlin M. Davis
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - R. Brian Dyer
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
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17
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Glyakina AV, Likhachev IV, Balabaev NK, Galzitskaya OV. Right- and left-handed three-helix proteins. II. Similarity and differences in mechanical unfolding of proteins. Proteins 2013; 82:90-102. [PMID: 23873665 DOI: 10.1002/prot.24373] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 06/26/2013] [Accepted: 07/09/2013] [Indexed: 11/11/2022]
Abstract
Here, we study mechanical properties of eight 3-helix proteins (four right-handed and four left-handed ones), which are similar in size under stretching at a constant speed and at a constant force on the atomic level using molecular dynamics simulations. The analysis of 256 trajectories from molecular dynamics simulations with explicit water showed that the right-handed three-helix domains are more mechanically resistant than the left-handed domains. Such results are observed at different extension velocities studied (192 trajectories obtained at the following conditions: v = 0.1, 0.05, and 0.01 Å ps(-1) , T = 300 K) and under constant stretching force (64 trajectories, F = 800 pN, T = 300 K). We can explain this by the fact, at least in part, that the right-handed domains have a larger number of contacts per residue and the radius of cross section than the left-handed domains.
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Affiliation(s)
- Anna V Glyakina
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia; Institute of Mathematical Problems of Biology, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
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18
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Burke KS, Parul D, Reddish MJ, Dyer RB. A simple three-dimensional-focusing, continuous-flow mixer for the study of fast protein dynamics. LAB ON A CHIP 2013; 13:2912-21. [PMID: 23760106 PMCID: PMC3733270 DOI: 10.1039/c3lc50497b] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We present a simple, yet flexible microfluidic mixer with a demonstrated mixing time as short as 80 μs that is widely accessible because it is made of commercially available parts. To simplify the study of fast protein dynamics, we have developed an inexpensive continuous-flow microfluidic mixer, requiring no specialized equipment or techniques. The mixer uses three-dimensional, hydrodynamic focusing of a protein sample stream by a surrounding sheath solution to achieve rapid diffusional mixing between the sample and sheath. Mixing initiates the reaction of interest. Reactions can be spatially observed by fluorescence or absorbance spectroscopy. We characterized the pixel-to-time calibration and diffusional mixing experimentally. We achieved a mixing time as short as 80 μs. We studied the kinetics of horse apomyoglobin (apoMb) unfolding from the intermediate (I) state to its completely unfolded (U) state, induced by a pH jump from the initial pH of 4.5 in the sample stream to a final pH of 2.0 in the sheath solution. The reaction time was probed using the fluorescence of 1-anilinonaphthalene-8-sulfonate (1,8-ANS) bound to the folded protein. We observed unfolding of apoMb within 760 μs, without populating additional intermediate states under these conditions. We also studied the reaction kinetics of the conversion of pyruvate to lactate catalyzed by lactate dehydrogenase using the intrinsic tryptophan emission of the enzyme. We observe sub-millisecond kinetics that we attribute to Michaelis complex formation and loop domain closure. These results demonstrate the utility of the three-dimensional focusing mixer for biophysical studies of protein dynamics.
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Affiliation(s)
- Kelly S. Burke
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91106
| | | | - Michael J. Reddish
- Emory University, 1515 Dickey Drive, Atlanta, GA 30322, United States of America
| | - R. Brian Dyer
- Emory University, 1515 Dickey Drive, Atlanta, GA 30322, United States of America
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19
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Glyakina AV, Pereyaslavets LB, Galzitskaya OV. Right- and left-handed three-helix proteins. I. Experimental and simulation analysis of differences in folding and structure. Proteins 2013; 81:1527-41. [DOI: 10.1002/prot.24301] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 03/27/2013] [Accepted: 03/28/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Anna V. Glyakina
- Institute of Protein Research; Russian Academy of Sciences; Pushchino, Moscow Region 142290 Russia
- Institute of Mathematical Problems of Biology; Russian Academy of Sciences; Pushchino, Moscow Region 142290 Russia
| | - Leonid B. Pereyaslavets
- Institute of Protein Research; Russian Academy of Sciences; Pushchino, Moscow Region 142290 Russia
| | - Oxana V. Galzitskaya
- Institute of Protein Research; Russian Academy of Sciences; Pushchino, Moscow Region 142290 Russia
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20
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Lin C, Culik RM, Gai F. Using VIPT-jump to distinguish between different folding mechanisms: application to BBL and a Trpzip. J Am Chem Soc 2013; 135:7668-73. [PMID: 23642153 PMCID: PMC3706100 DOI: 10.1021/ja401473m] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein folding involves a large number of sequential molecular steps or conformational substates. Thus, experimental characterization of the underlying folding energy landscape for any given protein is difficult. Herein, we present a new method that can be used to determine the major characteristics of the folding energy landscape in question, e.g., to distinguish between activated and barrierless downhill folding scenarios. This method is based on the idea that the conformational relaxation kinetics of different folding mechanisms at a given final condition will show different dependences on the initial condition. We show, using both simulation and experiment, that it is possible to differentiate between disparate kinetic folding models by comparing temperature jump (T-jump) relaxation traces obtained with a fixed final temperature and varied initial temperatures, which effectively varies the initial potential (VIP) of the system of interest. We apply this method (hereafter refer to as VIPT-jump) to two model systems, tryptophan zipper (Trpzip)-2c and BBL, and our results show that BBL exhibits characteristics of barrierless downhill folding, whereas Trpzip-2c folding encounters a free energy barrier. In addition, using the T-jump data of BBL we are able to provide, via Langevin dynamics simulations, a realistic estimate of its conformational diffusion coefficient.
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Affiliation(s)
- Chun–Wei Lin
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - Robert M. Culik
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
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21
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Scian M, Shu I, Olsen KA, Hassam K, Andersen NH. Mutational effects on the folding dynamics of a minimized hairpin. Biochemistry 2013; 52:2556-64. [PMID: 23521619 DOI: 10.1021/bi400146c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The fold stabilities and folding dynamics of a series of mutants of a model hairpin, KTW-NPATGK-WTE (HP7), are reported. The parent system and the corresponding DPATGK loop species display submicrosecond folding time constants. The mutational studies revealed that ultrafast folding requires both some prestructuring of the loop and a favorable interaction between the chain termini in the transition state. In the case of YY-DPETGT-WY, another submicrosecond folding species [Davis, C. M., Xiao, S., Raleigh, D. P., and Dyer, R. B. (2012) J. Am. Chem. Soc. 134, 14476-14482], a hydrophobic cluster provides the latter. In the case of HP7, the Coulombic interaction between the terminal NH3(+) and CO2(-) units provides this; a C-terminal Glu to amidated Ala mutation results in a 5-fold retardation of the folding rate. The effects of mutations within the reversing loop indicate the balance between loop flexibility (favoring fast conformational searching) and turn formation in the unfolded state is a major factor in determining the folding dynamics. The -NAAAKX- loops examined display no detectable turn formation propensity in other hairpin constructs but do result in stable analogues of HP7. Peptide KTW-NAAAKK-WTE displays the same fold stability as HP7, but both the folding and unfolding time constants are greater by a factor of 20.
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Affiliation(s)
- Michele Scian
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
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22
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Davis CM, Xiao S, Raleigh DP, Dyer RB. Raising the speed limit for β-hairpin formation. J Am Chem Soc 2012; 134:14476-82. [PMID: 22873643 DOI: 10.1021/ja3046734] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Understanding the folding of the β-hairpin is a crucial step in studying how β-rich proteins fold. We have studied CLN025, an optimized ten residue synthetic peptide, which adopts a compact, well-structured β-hairpin conformation. Formation of the component β-sheet and β-turn structures of CLN025 was probed independently using a combination of equilibrium Fourier transform infrared spectroscopy and laser-induced temperature jump coupled with time-resolved infrared and fluorescence spectroscopies. We find that CLN025 is an ultrafast folder due to its small free energy barrier to folding and that it exceeds the predicted speed limit for β-hairpin formation by an order of magnitude. We also find that the folding mechanism cannot be described by a simple two-state model, but rather is a heterogeneous process involving two independent parallel processes. Formation of stabilizing cross-strand hydrophobic interactions and turn alignment occur competitively, with relaxation lifetimes of 82 ± 10 and 124 ± 10 ns, respectively, at the highest probed temperature. The ultrafast and heterogeneous folding kinetics observed for CLN025 provide evidence for folding on a nearly barrierless free energy landscape, and recalibrate the speed limit for the formation of a β-hairpin.
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Affiliation(s)
- Caitlin M Davis
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA
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23
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Rogne P, Ozdowy P, Richter C, Saxena K, Schwalbe H, Kuhn LT. Atomic-level structure characterization of an ultrafast folding mini-protein denatured state. PLoS One 2012; 7:e41301. [PMID: 22848459 PMCID: PMC3407199 DOI: 10.1371/journal.pone.0041301] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 06/19/2012] [Indexed: 11/18/2022] Open
Abstract
Atomic-level analyses of non-native protein ensembles constitute an important aspect of protein folding studies to reach a more complete understanding of how proteins attain their native form exhibiting biological activity. Previously, formation of hydrophobic clusters in the 6 M urea-denatured state of an ultrafast folding mini-protein known as TC5b from both photo-CIDNP NOE transfer studies and FCS measurements was observed. Here, we elucidate the structural properties of this mini-protein denatured in 6 M urea performing (15)N NMR relaxation studies together with a thorough NOE analysis. Even though our results demonstrate that no elements of secondary structure persist in the denatured state, the heterogeneous distribution of R(2) rate constants together with observing pronounced heteronuclear NOEs along the peptide backbone reveals specific regions of urea-denatured TC5b exhibiting a high degree of structural rigidity more frequently observed for native proteins. The data are complemented with studies on two TC5b point mutants to verify the importance of hydrophobic interactions for fast folding. Our results corroborate earlier findings of a hydrophobic cluster present in urea-denatured TC5b comprising both native and non-native contacts underscoring their importance for ultra rapid folding. The data assist in finding ways of interpreting the effects of pre-existing native and/or non-native interactions on the ultrafast folding of proteins; a fact, which might have to be considered when defining the starting conditions for molecular dynamics simulation studies of protein folding.
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Affiliation(s)
- Per Rogne
- European Neuroscience Institute Göttingen (ENI-G), Göttingen, Germany
- DFG Research Center Molecular Physiology of the Brain (CMPB)/EXC 171 “Microscopy at the Nanometer Range”, Göttingen, Germany
| | - Przemysław Ozdowy
- European Neuroscience Institute Göttingen (ENI-G), Göttingen, Germany
- DFG Research Center Molecular Physiology of the Brain (CMPB)/EXC 171 “Microscopy at the Nanometer Range”, Göttingen, Germany
| | - Christian Richter
- Institute for Organic Chemistry and Chemical Biology and Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt, Frankfurt am Main, Germany
| | - Krishna Saxena
- Institute for Organic Chemistry and Chemical Biology and Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt, Frankfurt am Main, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology and Center for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt, Frankfurt am Main, Germany
| | - Lars T. Kuhn
- European Neuroscience Institute Göttingen (ENI-G), Göttingen, Germany
- DFG Research Center Molecular Physiology of the Brain (CMPB)/EXC 171 “Microscopy at the Nanometer Range”, Göttingen, Germany
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24
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Hałabis A, Żmudzińska W, Liwo A, Ołdziej S. Conformational Dynamics of the Trp-Cage Miniprotein at Its Folding Temperature. J Phys Chem B 2012; 116:6898-907. [DOI: 10.1021/jp212630y] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Anna Hałabis
- Laboratory of Biopolymer Structure,
Intercollegiate Faculty of Biotechnology, University of Gdańsk and Medical University of Gdańsk, Kładki 24, 80-922 Gdańsk, Poland
| | - Wioletta Żmudzińska
- Laboratory of Biopolymer Structure,
Intercollegiate Faculty of Biotechnology, University of Gdańsk and Medical University of Gdańsk, Kładki 24, 80-922 Gdańsk, Poland
| | - Adam Liwo
- Faculty of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952
Gdańsk, Poland
| | - Stanisław Ołdziej
- Laboratory of Biopolymer Structure,
Intercollegiate Faculty of Biotechnology, University of Gdańsk and Medical University of Gdańsk, Kładki 24, 80-922 Gdańsk, Poland
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25
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Denos S, Dhar A, Gruebele M. Crowding effects on the small, fast-folding protein lambda6-85. Faraday Discuss 2012; 157:451-500. [PMID: 23230782 PMCID: PMC3834863 DOI: 10.1039/c2fd20009k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2024]
Abstract
The microsecond folder lambda6-85 is a small (9.2 kDa = 9200 amu) five helix bundle protein. We investigated the stability of lambda6-85 in two different low-fluorescence crowding matrices: the large 70 kDa carbohydrate Ficoll 70, and the small 14 kDa thermophilic protein SubL. The same thermal stability of secondary structure was measured by circular dichroism in aqueous buffer, and at a crowding fraction phi = 15 +/- 1% of Ficoll 70. Tryptophan fluorescence detection (probing a tertiary contact) yielded the same thermal stability in Ficoll, but 4 degrees C lower in aqueous buffer. Temperature-jump kinetics revealed that the relaxation rate, corrected for bulk viscosity, was very similar in Ficoll and in aqueous buffer. Thus viscosity, hydrodynamics and crowding seem to compensate one another. However, a new fast phase was observed in Ficoll, attributed to crowding-induced downhill folding. We also measured the stability of lambda6-85 in phi = 14 +/- 1% SubL, which acts as a smaller more rigid crowder. Significantly greater stabilization (7 to 13 degrees C depending on probe) was observed than in the Ficoll matrix. The results highlight the importance of crowding agent choice for studies of small, fast-folding proteins amenable to comparison with molecular dynamics simulations.
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Affiliation(s)
- Sharlene Denos
- Center for Biophysics and Computational Biology, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
| | - Apratim Dhar
- Department of Chemistry, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
| | - Martin Gruebele
- Center for Biophysics and Computational Biology, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
- Department of Chemistry, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
- Department of Physics, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
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26
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Nagarajan S, Taskent-Sezgin H, Parul D, Carrico I, Raleigh DP, Dyer RB. Differential ordering of the protein backbone and side chains during protein folding revealed by site-specific recombinant infrared probes. J Am Chem Soc 2011; 133:20335-40. [PMID: 22039909 PMCID: PMC3241911 DOI: 10.1021/ja2071362] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The time scale for ordering of the polypeptide backbone relative to the side chains is a critical issue in protein folding. The interplay between ordering of the backbone and ordering of the side chains is particularly important for the formation of β-sheet structures, as the polypeptide chain searches for the native stabilizing cross-strand interactions. We have studied these issues in the N-terminal domain of protein L9 (NTL9), a model protein with mixed α/β structure. We have developed a general approach for introducing site-specific IR probes for the side chains (azide) and backbone ((13)C═(18)O) using recombinant protein expression. Temperature-jump time-resolved IR spectroscopy combined with site-specific labeling enables independent measurement of the respective backbone and side-chain dynamics with single residue resolution. We have found that side-chain ordering in a key region of the β-sheet structure occurs on a slower time scale than ordering of the backbone during the folding of NTL9, likely as a result of the transient formation of non-native side-chain interactions.
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Affiliation(s)
| | - Humeyra Taskent-Sezgin
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York, 11794, USA
| | - Dzmitry Parul
- Department of Chemistry, Emory University, Atlanta, Georgia, 30322, USA
| | - Isaac Carrico
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York, 11794, USA
| | - Daniel P. Raleigh
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York, 11794, USA
| | - R. Brian Dyer
- Department of Chemistry, Emory University, Atlanta, Georgia, 30322, USA
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27
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Roterman I, Konieczny L, Jurkowski W, Prymula K, Banach M. Two-intermediate model to characterize the structure of fast-folding proteins. J Theor Biol 2011; 283:60-70. [PMID: 21635900 DOI: 10.1016/j.jtbi.2011.05.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2010] [Revised: 05/17/2011] [Accepted: 05/18/2011] [Indexed: 01/15/2023]
Abstract
This paper introduces a new model that enables researchers to conduct protein folding simulations. A two-step in silico process is used in the course of structural analysis of a set of fast-folding proteins. The model assumes an early stage (ES) that depends solely on the backbone conformation, as described by its geometrical properties--specifically, by the V-angle between two sequential peptide bond planes (which determines the radius of curvature, also called R-radius, according to a second-degree polynomial form). The agreement between the structure under consideration and the assumed model is measured in terms of the magnitude of dispersion of both parameters with respect to idealized values. The second step, called late-stage folding (LS), is based on the "fuzzy oil drop" model, which involves an external hydrophobic force field described by a three-dimensional Gauss function. The degree of conformance between the structure under consideration and its idealized model is expressed quantitatively by means of the Kullback-Leibler entropy, which is a measure of disparity between the observed and expected hydrophobicity distributions. A set of proteins, representative of the fast-folding group - specifically, cold shock proteins - is shown to agree with the proposed model.
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Affiliation(s)
- I Roterman
- Department of Bioinformatics and Telemedicine, Jagiellonian University-Medical College, Lazarza 16, 31-530 Krakow, Poland.
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28
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Making connections between ultrafast protein folding kinetics and molecular dynamics simulations. Proc Natl Acad Sci U S A 2011; 108:6103-8. [PMID: 21441105 DOI: 10.1073/pnas.1019552108] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Determining the rate of forming the truly folded conformation of ultrafast folding proteins is an important issue for both experiments and simulations. The double-norleucine mutant of the 35-residue villin subdomain is the focus of recent computer simulations with atomistic molecular dynamics because it is currently the fastest folding protein. The folding kinetics of this protein have been measured in laser temperature-jump experiments using tryptophan fluorescence as a probe of overall folding. The conclusion from the simulations, however, is that the rate determined by fluorescence is significantly larger than the rate of overall folding. We have therefore employed an independent experimental method to determine the folding rate. The decay of the tryptophan triplet-state in photoselection experiments was used to monitor the change in the unfolded population for a sequence of the villin subdomain with one amino acid difference from that of the laser temperature-jump experiments, but with almost identical equilibrium properties. Folding times obtained in a two-state analysis of the results from the two methods at denaturant concentrations varying from 1.5-6.0 M guanidinium chloride are in excellent agreement, with an average difference of only 20%. Polynomial extrapolation of all the data to zero denaturant yields a folding time of 220 (+100,-70) ns at 283 K, suggesting that under these conditions the barrier between folded and unfolded states has effectively disappeared--the so-called "downhill scenario."
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29
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Gao J, Zhang T, Zhang H, Shen S, Ruan J, Kurgan L. Accurate prediction of protein folding rates from sequence and sequence-derived residue flexibility and solvent accessibility. Proteins 2010; 78:2114-30. [PMID: 20455267 DOI: 10.1002/prot.22727] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Protein folding rates vary by several orders of magnitude and they depend on the topology of the fold and the size and composition of the sequence. Although recent works show that the rates can be predicted from the sequence, allowing for high-throughput annotations, they consider only the sequence and its predicted secondary structure. We propose a novel sequence-based predictor, PFR-AF, which utilizes solvent accessibility and residue flexibility predicted from the sequence, to improve predictions and provide insights into the folding process. The predictor includes three linear regressions for proteins with two-state, multistate, and unknown (mixed-state) folding kinetics. PFR-AF on average outperforms current methods when tested on three datasets. The proposed approach provides high-quality predictions in the absence of similarity between the predicted and the training sequences. The PFR-AF's predictions are characterized by high (between 0.71 and 0.95, depending on the dataset) correlation and the lowest (between 0.75 and 0.9) mean absolute errors with respect to the experimental rates, as measured using out-of-sample tests. Our models reveal that for the two-state chains inclusion of solvent-exposed Ala may accelerate the folding, while increased content of Ile may reduce the folding speed. We also demonstrate that increased flexibility of coils facilitates faster folding and that proteins with larger content of solvent-exposed strands may fold at a slower pace. The increased flexibility of the solvent-exposed residues is shown to elongate folding, which also holds, with a lower correlation, for buried residues. Two case studies are included to support our findings.
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Affiliation(s)
- Jianzhao Gao
- College of Mathematics and LPMC, Nankai University, Tianjin, People's Republic of China
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30
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Piana S, Sarkar K, Lindorff-Larsen K, Guo M, Gruebele M, Shaw DE. Computational design and experimental testing of the fastest-folding β-sheet protein. J Mol Biol 2010; 405:43-8. [PMID: 20974152 DOI: 10.1016/j.jmb.2010.10.023] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 10/14/2010] [Accepted: 10/14/2010] [Indexed: 11/30/2022]
Abstract
One of the most important and elusive goals of molecular biology is the formulation of a detailed, atomic-level understanding of the process of protein folding. Fast-folding proteins with low free-energy barriers have proved to be particularly productive objects of investigation in this context, but the design of fast-folding proteins was previously driven largely by experiment. Dramatic advances in the attainable length of molecular dynamics simulations have allowed us to characterize in atomic-level detail the folding mechanism of the fast-folding all-β WW domain FiP35. In the work reported here, we applied the biophysical insights gained from these studies to computationally design an even faster-folding variant of FiP35 containing only naturally occurring amino acids. The increased stability and high folding rate predicted by our simulations were subsequently validated by temperature-jump experiments. The experimentally measured folding time was 4.3 μs at 80 °C-about three times faster than the fastest previously known protein with β-sheet content and in good agreement with our prediction. These results provide a compelling demonstration of the potential utility of very long molecular dynamics simulations in redesigning proteins well beyond their evolved stability and folding speed.
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31
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Buchner GS, Murphy RD, Buchete NV, Kubelka J. Dynamics of protein folding: probing the kinetic network of folding-unfolding transitions with experiment and theory. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1814:1001-20. [PMID: 20883829 DOI: 10.1016/j.bbapap.2010.09.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 09/14/2010] [Accepted: 09/16/2010] [Indexed: 10/19/2022]
Abstract
The problem of spontaneous folding of amino acid chains into highly organized, biologically functional three-dimensional protein structures continues to challenge the modern science. Understanding how proteins fold requires characterization of the underlying energy landscapes as well as the dynamics of the polypeptide chains in all stages of the folding process. In recent years, important advances toward these goals have been achieved owing to the rapidly growing interdisciplinary interest and significant progress in both experimental techniques and theoretical methods. Improvements in the experimental time resolution led to determination of the timescales of the important elementary events in folding, such as formation of secondary structure and tertiary contacts. Sensitive single molecule methods made possible probing the distributions of the unfolded and folded states and following the folding reaction of individual protein molecules. Discovery of proteins that fold in microseconds opened the possibility of atomic-level theoretical simulations of folding and their direct comparisons with experimental data, as well as of direct experimental observation of the barrier-less folding transition. The ultra-fast folding also brought new questions, concerning the intrinsic limits of the folding rates and experimental signatures of barrier-less "downhill" folding. These problems will require novel approaches for even more detailed experimental investigations of the folding dynamics as well as for the analysis of the folding kinetic data. For theoretical simulations of folding, a main challenge is how to extract the relevant information from overwhelmingly detailed atomistic trajectories. New theoretical methods have been devised to allow a systematic approach towards a quantitative analysis of the kinetic network of folding-unfolding transitions between various configuration states of a protein, revealing the transition states and the associated folding pathways at multiple levels, from atomistic to coarse-grained representations. This article is part of a Special Issue entitled: Protein Dynamics: Experimental and Computational Approaches.
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Affiliation(s)
- Ginka S Buchner
- Department of Chemistry, University of Wyoming, Laramie, WY 82071, USA; Universität Würzbug, Würzburg, Germany
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32
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Gambin Y, Deniz AA. Multicolor single-molecule FRET to explore protein folding and binding. MOLECULAR BIOSYSTEMS 2010; 6:1540-7. [PMID: 20601974 PMCID: PMC3005188 DOI: 10.1039/c003024d] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Proper protein function in cells, tissues and organisms depends critically on correct protein folding or interaction with partners. Over the last decade, single-molecule FRET (smFRET) has emerged as a powerful tool to probe complex distributions, dynamics, pathways and landscapes in protein folding and binding reactions, leveraging its ability to avoid averaging over an ensemble of molecules. While smFRET was practiced in a two-color form until recently, the last few years have seen the development of enhanced multicolor smFRET methods that provide additional structural information permitting us to probe more complex mechanisms. In this review, we provide a brief introduction to the smFRET technique, then follow with advanced multicolor measurements and end with ongoing methodology developments in microfluidics and protein labeling that are beginning to make these techniques more broadly applicable to answering a number of key questions about folding and binding.
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Affiliation(s)
- Yann Gambin
- Department of Molecular Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla CA 92037, USA. Fax: +1 (858) 784-9067; Tel: +1 (858) 784-9192
| | - Ashok A. Deniz
- Department of Molecular Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla CA 92037, USA. Fax: +1 (858) 784-9067; Tel: +1 (858) 784-9192
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33
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Glyakina AV, Galzitskaya OV. Influence of organization of native protein structure on its folding: Modeling of the folding of α-helical proteins. BIOCHEMISTRY (MOSCOW) 2010; 75:995-1005. [DOI: 10.1134/s0006297910080079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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34
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Xiao S, Raleigh DP. A critical assessment of putative gatekeeper interactions in the villin headpiece helical subdomain. J Mol Biol 2010; 401:274-85. [PMID: 20570680 DOI: 10.1016/j.jmb.2010.05.070] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 05/26/2010] [Accepted: 05/28/2010] [Indexed: 10/19/2022]
Abstract
The helical subdomain of the villin headpiece (HP36) is one of the smallest naturally occurring proteins that folds cooperatively. Its small size, rapid folding, and simple three-helix topology have made it an extraordinary popular model system for computational, theoretical, and experimental studies of protein folding. Aromatic-proline interactions involving Trp64 and Pro62 have been proposed to play a critical role in specifying the subdomain fold by acting as gatekeeper residues. Note that the numbering corresponds to full-length headpiece. Mutation of Pro62 has been shown to lead to a protein that does not fold, but this may arise for two different reasons: The residue may make interactions that are critical for the specificity of the fold or the mutation may simply destabilize the domain. In the first case, the protein cannot fold, while in the second, the small fraction of molecules that do fold adopt the correct structure. The modest stability of the wild type prevents a critical analysis of these interactions because even moderately destabilizing mutations lead to a very small folded state population. Using a hyperstable variant of HP36, denoted DM HP36, as our new wild type, we characterized a set of mutants designed to assess the role of the putative gatekeeper interactions. Four single mutants, DM Pro62Ala, DM Trp64Leu, DM Trp64Lys, and DM Trp64Ala, and a double mutant, DM Pro62Ala Trp64Leu, were prepared. All mutants are less stable than DM HP36, but all are well folded as judged by CD and (1)H NMR. All of the mutants display sigmoidal thermal unfolding and urea-induced unfolding curves. Double-mutant cycle analysis shows that the interactions between Pro62 and Trp64 are weak but favorable. Interactions involving Pro62 and proline-aromatic interactions are, thus, not required for specifying the subdomain fold. The implications for the design and thermodynamics of miniature proteins are discussed.
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Affiliation(s)
- Shifeng Xiao
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, NY 11794-3400, USA
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35
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Li H, Xu YY, Weng YX. Infrared Absorption Intensity Analysis as a New Tool for Investigation of Salt Effect on Proteins. CHINESE J CHEM PHYS 2009. [DOI: 10.1088/1674-0068/22/06/556-562] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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36
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Zhdanov VP. Model of gene transcription including the return of a RNA polymerase to the beginning of a transcriptional cycle. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:051925. [PMID: 20365024 DOI: 10.1103/physreve.80.051925] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2009] [Revised: 10/10/2009] [Indexed: 05/29/2023]
Abstract
The gene transcription occurs via the RNA polymerase (RNAP) recruitment on the DNA promoter sequence, formation of a locally open DNA chain, promoter escape, steps of the RNA synthesis, and RNA and RNAP release after reading the final DNA base. Just after the end of the RNA synthesis, RNAP surrounds the closed DNA chain and may diffuse along DNA, desorb, or reach the promoter and start the RNA-synthesis cycle again. We present a generic kinetic model taking the latter steps into account and show analytically and by Monte Carlo simulations that it predicts transcriptional bursts even in the absence of explicit regulation of the transcription by master proteins.
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Affiliation(s)
- Vladimir P Zhdanov
- Division of Biological Physics, Department of Applied Physics, Chalmers University of Technology, S-41296 Göteborg, Sweden.
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37
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Taskent-Sezgin H, Chung J, Patsalo V, Miyake-Stoner SJ, Miller AM, Brewer SH, Mehl RA, Green DF, Raleigh DP, Carrico I. Interpretation of p-Cyanophenylalanine Fluorescence in Proteins in Terms of Solvent Exposure and Contribution of Side-Chain Quenchers: A Combined Fluorescence, IR and Molecular Dynamics Study. Biochemistry 2009; 48:9040-6. [DOI: 10.1021/bi900938z] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Humeyra Taskent-Sezgin
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794
| | - Juah Chung
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794
| | - Vadim Patsalo
- Department of Applied Mathematics and Statistics, State University of New York at Stony Brook, Stony Brook, New York 11794
| | | | - Andrew M. Miller
- Department of Chemistry, Franklin and Marshall College, Lancaster, Pennsylvania 17603
| | - Scott H. Brewer
- Department of Chemistry, Franklin and Marshall College, Lancaster, Pennsylvania 17603
| | - Ryan A. Mehl
- Department of Chemistry, Franklin and Marshall College, Lancaster, Pennsylvania 17603
| | - David F. Green
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794
- Department of Applied Mathematics and Statistics, State University of New York at Stony Brook, Stony Brook, New York 11794
- Institute of Chemical Biology and Drug Discovery at State University of New York at Stony Brook, Stony Brook, New York 11794
| | - Daniel P. Raleigh
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794
- Institute of Chemical Biology and Drug Discovery at State University of New York at Stony Brook, Stony Brook, New York 11794
| | - Isaac Carrico
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794
- Institute of Chemical Biology and Drug Discovery at State University of New York at Stony Brook, Stony Brook, New York 11794
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38
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An expanding arsenal of experimental methods yields an explosion of insights into protein folding mechanisms. Nat Struct Mol Biol 2009; 16:582-8. [DOI: 10.1038/nsmb.1592] [Citation(s) in RCA: 205] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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39
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Tang J, Kang SG, Saven JG, Gai F. Characterization of the cofactor-induced folding mechanism of a zinc-binding peptide using computationally designed mutants. J Mol Biol 2009; 389:90-102. [PMID: 19361525 DOI: 10.1016/j.jmb.2009.03.074] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Revised: 03/26/2009] [Accepted: 03/31/2009] [Indexed: 10/20/2022]
Abstract
Metals are the most commonly encountered protein cofactors, and they play important structural and functional roles in biology. In many cases, metal binding provides a major driving force for a polypeptide chain to fold. While there are many studies on the structure, stability, and function of metal-binding proteins, there are few studies focusing on understanding the kinetic mechanism of metal-induced folding. Herein, the Zn(2+)-induced folding kinetics of a small zinc-binding protein are studied; the CH1(1) peptide is derived from the first cysteine/histidine-rich region (CH1 domain) of the protein interaction domains of the transcriptional coregulator CREB-binding protein. Computational design is used to introduce tryptophan and histidine mutations that are structurally consistent with CH1(1); these mutants are studied using stopped-flow tryptophan fluorescence experiments. The Zn(2+)-induced CH1(1) folding kinetics are consistent with two parallel pathways, where the initial binding of Zn(2+) occurs at two sites. However, the initially formed Zn(2+)-bound complexes can proceed either directly to the folded state where zinc adopts a tetrahedral coordination or to an off-pathway misligated intermediate. While elimination of those ligands responsible for misligation simplifies the folding kinetics, it also leads to a decrease in the zinc binding constant. Therefore, these results suggest why these nonnative zinc ligands in the CH1(1) motif are conserved in several distantly related organisms and why the requirement for function can lead to kinetic frustration in folding. In addition, the loop closure rate of the CH1(1) peptide is determined based on the proposed model and temperature-dependent kinetic measurements.
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Affiliation(s)
- Jia Tang
- Department of Chemistry, University of Pennsylvania, Philadelphia, 19104, USA
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40
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Huang F, Lerner E, Sato S, Amir D, Haas E, Fersht AR. Time-Resolved Fluorescence Resonance Energy Transfer Study Shows a Compact Denatured State of the B Domain of Protein A. Biochemistry 2009; 48:3468-76. [DOI: 10.1021/bi801890w] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- F. Huang
- MRC Center for Protein Engineering, Hills Road, Cambridge CB2 0QH, United Kingdom, and The Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel 52900
| | - E. Lerner
- MRC Center for Protein Engineering, Hills Road, Cambridge CB2 0QH, United Kingdom, and The Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel 52900
| | - S. Sato
- MRC Center for Protein Engineering, Hills Road, Cambridge CB2 0QH, United Kingdom, and The Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel 52900
| | - D. Amir
- MRC Center for Protein Engineering, Hills Road, Cambridge CB2 0QH, United Kingdom, and The Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel 52900
| | - E. Haas
- MRC Center for Protein Engineering, Hills Road, Cambridge CB2 0QH, United Kingdom, and The Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel 52900
| | - A. R. Fersht
- MRC Center for Protein Engineering, Hills Road, Cambridge CB2 0QH, United Kingdom, and The Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel 52900
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41
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Kubelka J. Time-resolved methods in biophysics. 9. Laser temperature-jump methods for investigating biomolecular dynamics. Photochem Photobiol Sci 2009; 8:499-512. [DOI: 10.1039/b819929a] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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42
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Liu F, Nakaema M, Gruebele M. The transition state transit time of WW domain folding is controlled by energy landscape roughness. J Chem Phys 2009; 131:195101. [DOI: 10.1063/1.3262489] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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43
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Abstract
We investigate the structures of the major folding transition states of nine proteins by correlation of published Phi-values with inter-residue contact maps. Combined with previous studies on six proteins, the analysis suggests that at least 10 of the 15 small globular proteins fold via a nucleation-condensation mechanism with a concurrent build-up of secondary and tertiary structure contacts, but a structural consolidation that is clearly nonuniformly distributed over the molecule and most intense in a single structural region suggesting the occurrence of a single folding nucleus. However, on average helix- and sheet-forming residues show somewhat larger Phi-values in the major transition state, suggesting that secondary structure formation is one important driving force in the nucleation-condensation in many proteins and that secondary-structure forming residues tend to be more prominent in folding nuclei. We synthesize the combined information on these 10 of 15 proteins into a unified nucleation-condensation mechanism which also accounts for effects described by the framework, hydrophobic collapse, zipper, and funnel models.
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Affiliation(s)
- Bengt Nölting
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158-2517, USA
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44
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Tsai CJ, Sauna ZE, Kimchi-Sarfaty C, Ambudkar SV, Gottesman MM, Nussinov R. Synonymous mutations and ribosome stalling can lead to altered folding pathways and distinct minima. J Mol Biol 2008; 383:281-91. [PMID: 18722384 DOI: 10.1016/j.jmb.2008.08.012] [Citation(s) in RCA: 187] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Revised: 07/31/2008] [Accepted: 08/06/2008] [Indexed: 01/08/2023]
Abstract
How can we understand a case in which a given amino acid sequence folds into structurally and functionally distinct molecules? Synonymous single-nucleotide polymorphisms in the MDR1 (multidrug resistance 1 or ABCB1) gene involving frequent-to-rare codon substitutions lead to identical protein sequences. Remarkably, these alternative sequences give a protein product with similar but different structures and functions. Here, we propose that long-enough ribosomal pause time scales may lead to alternate folding pathways and distinct minima on the folding free energy surface. While the conformational and functional differences between the native and alternate states may be minor, the MDR1 case illustrates that the barriers may nevertheless constitute sufficiently high hurdles in physiological time scales, leading to kinetically trapped states with altered structures and functions. Different folding pathways leading to conformationally similar trapped states may be due to swapping of (fairly symmetric) segments. Domain swapping is more likely in the no-pause case in which the chain elongates and folds simultaneously; on the other hand, sufficiently long pause times between such segments may be expected to lessen the chances of swapping events. Here, we review the literature in this light.
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Affiliation(s)
- Chung-Jung Tsai
- Basic Research Program, SAIC-Frederick, Inc., Center for Cancer Research Nanobiology Program, NCI-Frederick, Frederick, MD 21702, USA
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45
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Mukherjee S, Chowdhury P, Bunagan MR, Gai F. Folding Kinetics of a Naturally Occurring Helical Peptide: Implication of the Folding Speed Limit of Helical Proteins. J Phys Chem B 2008; 112:9146-50. [DOI: 10.1021/jp801721p] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Smita Mukherjee
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Pramit Chowdhury
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Michelle R. Bunagan
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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46
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Amunson KE, Ackels L, Kubelka J. Site-Specific Unfolding Thermodynamics of a Helix-Turn-Helix Protein. J Am Chem Soc 2008; 130:8146-7. [DOI: 10.1021/ja802185e] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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47
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Sinha KK, Udgaonkar JB. Barrierless evolution of structure during the submillisecond refolding reaction of a small protein. Proc Natl Acad Sci U S A 2008; 105:7998-8003. [PMID: 18523007 PMCID: PMC2430349 DOI: 10.1073/pnas.0803193105] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Indexed: 11/18/2022] Open
Abstract
To determine whether a protein folding reaction can occur in the absence of a dominant barrier is crucial for understanding its complexity. Here direct ultrafast kinetic measurements have been used to study the initial submillisecond (sub-ms) folding reaction of the small protein barstar. The cooperativity of the initial folding reaction has been explored by using two probes: fluorescence resonance energy transfer, through which the contraction of two intramolecular distances is measured, and the binding of 8-anilino-1-naphthalene sulfonic acid, through which the formation of hydrophobic clusters is monitored. A fast chain contraction is shown to precede the formation of hydrophobic clusters, indicating that the sub-ms folding reaction is not cooperative. The observed rate constant of the sub-ms folding reaction monitored by 8-anilino-1-naphthalene sulfonic acid fluorescence has been found to be the same in stabilizing conditions (low urea concentrations), in which specific structure is formed, and in marginally stabilizing conditions (higher urea concentrations), where virtually no structure is formed in the product of the sub-ms folding reaction. The observation that the folding rate is independent of the folding conditions suggests that the initial folding reaction occurs in the absence of a dominant free energy barrier. These results provide kinetic evidence that the formation of specific structure need not be slowed down by any significant free energy barrier during the course of a very fast protein folding reaction.
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Affiliation(s)
- Kalyan K. Sinha
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India
| | - Jayant B. Udgaonkar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India
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48
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Zhang J, Li W, Wang J, Qin M, Wang W. All-atom replica exchange molecular simulation of protein BBL. Proteins 2008; 72:1038-47. [DOI: 10.1002/prot.22001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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49
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Prieto L, Rey A. Influence of the native topology on the folding barrier for small proteins. J Chem Phys 2007; 127:175101. [DOI: 10.1063/1.2780154] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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50
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Sato S, Fersht AR. Searching for Multiple Folding Pathways of a Nearly Symmetrical Protein: Temperature Dependent Φ-Value Analysis of the B Domain of Protein A. J Mol Biol 2007; 372:254-67. [PMID: 17628591 DOI: 10.1016/j.jmb.2007.06.043] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Revised: 05/25/2007] [Accepted: 06/15/2007] [Indexed: 11/19/2022]
Abstract
The B domain of protein A (BdpA) is a popular paradigm for simulating protein folding pathways. The discrepancies between so many simulations and subsequent experimental testing may be attributable to the protein being highly symmetrical: changing experimental conditions could perturb the subtle interplay between the effects of symmetry in the native structure and the effects of asymmetry from specific interactions in a given sequence. If the protein folds via multiple pathways, perturbations, such as temperature, denaturant concentration, and mutation, should change the flux of micro pathways, leading to changes in the bulk properties of the transition state. We tested this hypothesis by conducting a Phi-analysis of BdpA as a function of temperature from 25.0 degrees C to 60.0 degrees C. The Phi-values had no significant dependence on temperature and the values at 55.0 degrees C (denaturing conditions) are very similar to those at 25.0 degrees C (folding conditions), indicating the structure of the transition state does not significantly change although the experimental conditions are considerably altered. The results suggest that BdpA folds via a single dominant folding pathway.
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Affiliation(s)
- Satoshi Sato
- MRC Centre for Protein Engineering, Hills Road, Cambridge CB2 2QH, UK
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