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Zhang N, Sood D, Guo SC, Chen N, Antoszewski A, Marianchuk T, Chavan A, Dey S, Xiao Y, Hong L, Peng X, Baxa M, Partch C, Wang LP, Sosnick TR, Dinner AR, LiWang A. Temperature-Dependent Fold-Switching Mechanism of the Circadian Clock Protein KaiB. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.21.594594. [PMID: 38826295 PMCID: PMC11142059 DOI: 10.1101/2024.05.21.594594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
The oscillator of the cyanobacterial circadian clock relies on the ability of the KaiB protein to switch reversibly between a stable ground-state fold (gsKaiB) and an unstable fold-switched fold (fsKaiB). Rare fold-switching events by KaiB provide a critical delay in the negative feedback loop of this post-translational oscillator. In this study, we experimentally and computationally investigate the temperature dependence of fold switching and its mechanism. We demonstrate that the stability of gsKaiB increases with temperature compared to fsKaiB and that the Q10 value for the gsKaiB → fsKaiB transition is nearly three times smaller than that for the reverse transition. Simulations and native-state hydrogen-deuterium exchange NMR experiments suggest that fold switching can involve both subglobally and near-globally unfolded intermediates. The simulations predict that the transition state for fold switching coincides with isomerization of conserved prolines in the most rapidly exchanging region, and we confirm experimentally that proline isomerization is a rate-limiting step for fold switching. We explore the implications of our results for temperature compensation, a hallmark of circadian clocks, through a kinetic model.
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Adhikari U, Mostofian B, Copperman J, Subramanian SR, Petersen AA, Zuckerman DM. Computational Estimation of Microsecond to Second Atomistic Folding Times. J Am Chem Soc 2019; 141:6519-6526. [PMID: 30892023 PMCID: PMC6660137 DOI: 10.1021/jacs.8b10735] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Despite the development of massively parallel computing hardware including inexpensive graphics processing units (GPUs), it has remained infeasible to simulate the folding of atomistic proteins at room temperature using conventional molecular dynamics (MD) beyond the microsecond scale. Here, we report the folding of atomistic, implicitly solvated protein systems with folding times τ ranging from ∼10 μs to ∼100 ms using the weighted ensemble (WE) strategy in combination with GPU computing. Starting from an initial structure or set of structures, WE organizes an ensemble of GPU-accelerated MD trajectory segments via intermittent pruning and replication events to generate statistically unbiased estimates of rate constants for rare events such as folding; no biasing forces are used. Although the variance among atomistic WE folding runs is significant, multiple independent runs are used to reduce and quantify statistical uncertainty. Folding times are estimated directly from WE probability flux and from history-augmented Markov analysis of the WE data. Three systems were examined: NTL9 at low solvent viscosity (yielding τf = 0.8-9 μs), NTL9 at water-like viscosity (τf = 0.2-2 ms), and Protein G at low viscosity (τf = 3-200 ms). In all cases, the folding time, uncertainty, and ensemble properties could be estimated from WE simulation; for Protein G, this characterization required significantly less overall computing than would be required to observe a single folding event with conventional MD simulations. Our results suggest that the use and calibration of force fields and solvent models for precise estimation of kinetic quantities is becoming feasible.
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Affiliation(s)
- Upendra Adhikari
- Department of Biomedical Engineering, School of Medicine, Oregon Health & Science University, Portland, OR 97239
| | - Barmak Mostofian
- Department of Biomedical Engineering, School of Medicine, Oregon Health & Science University, Portland, OR 97239
| | - Jeremy Copperman
- Department of Biomedical Engineering, School of Medicine, Oregon Health & Science University, Portland, OR 97239
| | | | - Andrew A. Petersen
- NCSU Data Science Resources, North Carolina State University, Raleigh, NC 27695
| | - Daniel M. Zuckerman
- Department of Biomedical Engineering, School of Medicine, Oregon Health & Science University, Portland, OR 97239
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Moulick R, Goluguri RR, Udgaonkar JB. Ruggedness in the Free Energy Landscape Dictates Misfolding of the Prion Protein. J Mol Biol 2019; 431:807-824. [DOI: 10.1016/j.jmb.2018.12.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 11/15/2018] [Accepted: 12/16/2018] [Indexed: 12/12/2022]
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Zhang H, Jackson SE. Characterization of the Folding of a 5 2-Knotted Protein Using Engineered Single-Tryptophan Variants. Biophys J 2017; 111:2587-2599. [PMID: 28002735 DOI: 10.1016/j.bpj.2016.10.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 10/20/2016] [Accepted: 10/20/2016] [Indexed: 11/16/2022] Open
Abstract
An increasing number of proteins that contain topological knots have been identified over the past two decades; however, their folding mechanisms are still not well understood. UCH-L1 has a 52-knotted topology. Here, we constructed a series of variants that contain a single tryptophan at different locations along the polypeptide chain. A study of the thermodynamic properties of the variants shows that the structure of UCH-L1 is remarkably tolerant to incorporation of bulky tryptophan side chains. Comprehensive kinetic studies of the variants reveal that they fold via parallel pathways on which there are two intermediate states very similar to wild-type UCH-L1. The structures of the intermediate states do not change significantly with mutation and therefore occupy local minima on the energy landscape that have relatively narrow basins. The kinetic studies also establish that there are considerably more tertiary interactions in the intermediate states than results from previous NMR studies suggested. The two intermediates differ from each other in the extent to which tertiary interactions between the highly stable central β-sheet and flanking α-helices and loop regions are formed. There is strong evidence that these states are aggregation prone. The transition states from both I1 and I2 to the native state are plastic and change with mutation and denaturant concentration. Previous studies indicated that the threading event that creates the 52 knot occurs during these steps, suggesting that there is a broad energy barrier consistent with the chain undergoing some searching of conformational space as the threading takes place.
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Affiliation(s)
- Hongyu Zhang
- Department of Chemistry, Cambridge University, Cambridge, United Kingdom; St. Edmund's College, Cambridge University, Cambridge, United Kingdom
| | - Sophie E Jackson
- Department of Chemistry, Cambridge University, Cambridge, United Kingdom.
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Zhang Y, Kitazawa S, Peran I, Stenzoski N, McCallum SA, Raleigh DP, Royer CA. High Pressure ZZ-Exchange NMR Reveals Key Features of Protein Folding Transition States. J Am Chem Soc 2016; 138:15260-15266. [PMID: 27781428 DOI: 10.1021/jacs.6b09887] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Understanding protein folding mechanisms and their sequence dependence requires the determination of residue-specific apparent kinetic rate constants for the folding and unfolding reactions. Conventional two-dimensional NMR, such as HSQC experiments, can provide residue-specific information for proteins. However, folding is generally too fast for such experiments. ZZ-exchange NMR spectroscopy allows determination of folding and unfolding rates on much faster time scales, yet even this regime is not fast enough for many protein folding reactions. The application of high hydrostatic pressure slows folding by orders of magnitude due to positive activation volumes for the folding reaction. We combined high pressure perturbation with ZZ-exchange spectroscopy on two autonomously folding protein domains derived from the ribosomal protein, L9. We obtained residue-specific apparent rates at 2500 bar for the N-terminal domain of L9 (NTL9), and rates at atmospheric pressure for a mutant of the C-terminal domain (CTL9) from pressure dependent ZZ-exchange measurements. Our results revealed that NTL9 folding is almost perfectly two-state, while small deviations from two-state behavior were observed for CTL9. Both domains exhibited large positive activation volumes for folding. The volumetric properties of these domains reveal that their transition states contain most of the internal solvent excluded voids that are found in the hydrophobic cores of the respective native states. These results demonstrate that by coupling it with high pressure, ZZ-exchange can be extended to investigate a large number of protein conformational transitions.
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Affiliation(s)
- Yi Zhang
- Department of Chemistry & Chemical Biology, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Soichiro Kitazawa
- Department of Biological Sciences, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Ivan Peran
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794, United States
| | - Natalie Stenzoski
- Graduate Program in Biochemistry and Structural Biology, Stony Brook University , Stony Brook, New York 11794, United States
| | - Scott A McCallum
- NMR Core Facility, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Daniel P Raleigh
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794, United States
| | - Catherine A Royer
- Department of Chemistry & Chemical Biology, Rensselaer Polytechnic Institute , Troy, New York 12180, United States.,Department of Biological Sciences, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
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Aghera N, Udgaonkar JB. The Utilization of Competing Unfolding Pathways of Monellin Is Dictated by Enthalpic Barriers. Biochemistry 2013; 52:5770-9. [DOI: 10.1021/bi400688w] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Nilesh Aghera
- 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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In vivo translation rates can substantially delay the cotranslational folding of the Escherichia coli cytosolic proteome. Proc Natl Acad Sci U S A 2012; 110:E132-40. [PMID: 23256155 DOI: 10.1073/pnas.1213624110] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A question of fundamental importance concerning protein folding in vivo is whether the kinetics of translation or the thermodynamics of the ribosome nascent chain (RNC) complex is the major determinant of cotranslational folding behavior. This is because translation rates can reduce the probability of cotranslational folding below that associated with arrested ribosomes, whose behavior is determined by the equilibrium thermodynamics of the RNC complex. Here, we combine a chemical kinetic equation with genomic and proteomic data to predict domain folding probabilities as a function of nascent chain length for Escherichia coli cytosolic proteins synthesized on both arrested and continuously translating ribosomes. Our results indicate that, at in vivo translation rates, about one-third of the Escherichia coli cytosolic proteins exhibit cotranslational folding, with at least one domain in each of these proteins folding into its stable native structure before the full-length protein is released from the ribosome. The majority of these cotranslational folding domains are influenced by translation kinetics which reduces their probability of cotranslational folding and consequently increases the nascent chain length at which they fold into their native structures. For about 20% of all cytosolic proteins this delay in folding can exceed the length of the completely synthesized protein, causing one or more of their domains to switch from co- to posttranslational folding solely as a result of the in vivo translation rates. These kinetic effects arise from the difference in time scales of folding and amino-acid addition, and they represent a source of metastability in Escherichia coli's proteome.
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Periole X, Allen LR, Tamiola K, Mark AE, Paci E. Probing the free energy landscape of the FBP28WW domain using multiple techniques. J Comput Chem 2009; 30:1059-68. [PMID: 18942730 DOI: 10.1002/jcc.21128] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The free-energy landscape of a small protein, the FBP 28 WW domain, has been explored using molecular dynamics (MD) simulations with alternative descriptions of the molecule. The molecular models used range from coarse-grained to all-atom with either an implicit or explicit treatment of the solvent. Sampling of conformation space was performed using both conventional and temperature-replica exchange MD simulations. Experimental chemical shifts and NOEs were used to validate the simulations, and experimental phi values both for validation and as restraints. This combination of different approaches has provided insight into the free energy landscape and barriers encountered by the protein during folding and enabled the characterization of native, denatured and transition states which are compatible with the available experimental data. All the molecular models used stabilize well defined native and denatured basins; however, the degree of agreement with the available experimental data varies. While the most detailed, explicit solvent model predicts the data reasonably accurately, it does not fold despite a simulation time 10 times that of the experimental folding time. The less detailed models performed poorly relative to the explicit solvent model: an implicit solvent model stabilizes a ground state which differs from the experimental native state, and a structure-based model underestimates the size of the barrier between the two states. The use of experimental phi values both as restraints, and to extract structures from unfolding simulations, result in conformations which, although not necessarily true transition states, appear to share the geometrical characteristics of transition state structures. In addition to characterizing the native, transition and denatured states of this particular system in this work, the advantages and limitations of using varying levels of representation are discussed.
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Affiliation(s)
- Xavier Periole
- Department of Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
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Zoldák G, Carstensen L, Scholz C, Schmid FX. Consequences of domain insertion on the stability and folding mechanism of a protein. J Mol Biol 2008; 386:1138-52. [PMID: 19136015 DOI: 10.1016/j.jmb.2008.12.052] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 12/17/2008] [Accepted: 12/18/2008] [Indexed: 11/30/2022]
Abstract
SlyD, the sensitive-to-lysis protein from Escherichia coli, consists of two domains. They are not arranged successively along the protein chain, but one domain, the "insert-in-flap" (IF) domain, is inserted internally as a guest into a surface loop of the host domain, which is a prolyl isomerase of the FK506 binding protein (FKBP) type. We used SlyD as a model to elucidate how such a domain insertion affects the stability and folding mechanism of the host and the guest domain. For these studies, the two-domain protein was compared with a single-domain variant SlyDDeltaIF, SlyD* without the chaperone domain (residues 1-69 and 130-165) in which the IF domain was removed and replaced by a short loop, as present in human FKBP12. Equilibrium unfolding and folding kinetics followed an apparent two-state mechanism in the absence and in the presence of the IF domain. The inserted domain decreased, however, the stability of the host domain in the transition region and decelerated its refolding reaction by about 10-fold. This originates from the interruption of the chain connectivity by the IF domain and its inherent instability. To monitor folding processes in this domain selectively, a Trp residue was introduced as fluorescent probe. Kinetic double-mixing experiments revealed that, in intact SlyD, the IF domain folds and unfolds about 1000-fold more rapidly than the FKBP domain, and that it is strongly stabilized when linked with the folded FKBP domain. The unfolding limbs of the kinetic chevrons of SlyD show a strong downward curvature. This deviation from linearity is not caused by a transition-state movement, as often assumed, but by the accumulation of a silent unfolding intermediate at high denaturant concentrations. In this kinetic intermediate, the FKBP domain is still folded, whereas the IF domain is already unfolded.
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Affiliation(s)
- Gabriel Zoldák
- Laboratorium für Biochemie und Bayreuther Zentrum für Molekulare Biowissenschaften, Universität Bayreuth, D-95440 Bayreuth, Germany
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