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Bolonova EI, Melnik TN, Potekhin SA. Inside of the burst-phase intermediate of a protein folding. Hydration of hydrophobic groups. Biophys Chem 2024; 312:107268. [PMID: 38843749 DOI: 10.1016/j.bpc.2024.107268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Revised: 05/07/2024] [Accepted: 05/20/2024] [Indexed: 07/22/2024]
Abstract
The thermal effect of the formation of the "burst-phase" folding intermediate has been studied using a titration calorimeter. It is shown that, unlike the total thermal effect of native structure formation, it can be both positive and negative depending on the temperature. The reasons for this paradoxical behavior are analyzed. A conclusion is drawn about the leading role of dehydration of non-polar groups in the first stage of folding.
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Affiliation(s)
- Elena I Bolonova
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia; Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region, China
| | - Tatiana N Melnik
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Sergey A Potekhin
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia.
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2
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Thomas S, Schulz AM, Leong JM, Zeczycki TN, Garcia BL. The molecular determinants of classical pathway complement inhibition by OspEF-related proteins of Borrelia burgdorferi. J Biol Chem 2024; 300:107236. [PMID: 38552741 PMCID: PMC11066524 DOI: 10.1016/j.jbc.2024.107236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 03/18/2024] [Accepted: 03/22/2024] [Indexed: 04/04/2024] Open
Abstract
The complement system serves as the first line of defense against invading pathogens by promoting opsonophagocytosis and bacteriolysis. Antibody-dependent activation of complement occurs through the classical pathway and relies on the activity of initiating complement proteases of the C1 complex, C1r and C1s. The causative agent of Lyme disease, Borrelia burgdorferi, expresses two paralogous outer surface lipoproteins of the OspEF-related protein family, ElpB and ElpQ, that act as specific inhibitors of classical pathway activation. We have previously shown that ElpB and ElpQ bind directly to C1r and C1s with high affinity and specifically inhibit C2 and C4 cleavage by C1s. To further understand how these novel protease inhibitors function, we carried out a series of hydrogen-deuterium exchange mass spectrometry (HDX-MS) experiments using ElpQ and full-length activated C1s as a model of Elp-protease interaction. Comparison of HDX-MS profiles between unbound ElpQ and the ElpQ/C1s complex revealed a putative C1s-binding site on ElpQ. HDX-MS-guided, site-directed ElpQ mutants were generated and tested for direct binding to C1r and C1s using surface plasmon resonance. Several residues within the C-terminal region of ElpQ were identified as important for protease binding, including a single conserved tyrosine residue that was required for ElpQ- and ElpB-mediated complement inhibition. Collectively, our study identifies key molecular determinants for classical pathway protease recognition by Elp proteins. This investigation improves our understanding of the unique complement inhibitory mechanism employed by Elp proteins which serve as part of a sophisticated complement evasion system present in Lyme disease spirochetes.
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Affiliation(s)
- Sheila Thomas
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Anna M Schulz
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - John M Leong
- Department of Molecular Biology and Microbiology, Tufts School of Medicine, Tufts University, Boston, Massachusetts, USA
| | - Tonya N Zeczycki
- Department of Biochemistry & Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Brandon L Garcia
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA.
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3
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Zhang L, Brown MC, Mutter AC, Greenland KN, Cooley JW, Koder RL. Protein dynamics govern the oxyferrous state lifetime of an artificial oxygen transport protein. Biophys J 2023; 122:4440-4450. [PMID: 37865818 PMCID: PMC10698322 DOI: 10.1016/j.bpj.2023.10.022] [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] [Received: 06/09/2023] [Revised: 09/26/2023] [Accepted: 10/19/2023] [Indexed: 10/23/2023] Open
Abstract
It has long been known that the alteration of protein side chains that occlude or expose the heme cofactor to water can greatly affect the stability of the oxyferrous heme state. Here, we demonstrate that the rate of dynamically driven water penetration into the core of an artificial oxygen transport protein also correlates with oxyferrous state lifetime by reducing global dynamics, without altering the structure of the active site, via the simple linking of the two monomers in a homodimeric artificial oxygen transport protein using a glycine-rich loop. The tethering of these two helices does not significantly affect the active site structure, pentacoordinate heme-binding affinity, reduction potential, or gaseous ligand affinity. It does, however, significantly reduce the hydration of the protein core, as demonstrated by resonance Raman spectroscopy, backbone amide hydrogen exchange, and pKa shifts in buried histidine side chains. This further destabilizes the charge-buried entatic state and nearly triples the oxyferrous state lifetime. These data are the first direct evidence that dynamically driven water penetration is a rate-limiting step in the oxidation of these complexes. It furthermore demonstrates that structural rigidity that limits water penetration is a critical design feature in metalloenzyme construction and provides an explanation for both the failures and successes of earlier attempts to create oxygen-binding proteins.
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Affiliation(s)
- Lei Zhang
- Department of Physics, The City College of New York, New York, New York
| | - Mia C Brown
- Department of Chemistry, University of Missouri, Columbia, Missouri
| | - Andrew C Mutter
- Department of Biochemistry, The City College of New York, New York, New York
| | - Kelly N Greenland
- Department of Physics, The City College of New York, New York, New York
| | - Jason W Cooley
- Department of Chemistry, University of Missouri, Columbia, Missouri
| | - Ronald L Koder
- Department of Physics, The City College of New York, New York, New York; Graduate Programs of Physics, Biology, Chemistry and Biochemistry, The Graduate Center of CUNY, New York, New York.
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4
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Vila JA. Protein folding rate evolution upon mutations. Biophys Rev 2023; 15:661-669. [PMID: 37681091 PMCID: PMC10480377 DOI: 10.1007/s12551-023-01088-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 06/24/2023] [Indexed: 09/09/2023] Open
Abstract
Despite the spectacular success of cutting-edge protein fold prediction methods, many critical questions remain unanswered, including why proteins can reach their native state in a biologically reasonable time. A satisfactory answer to this simple question could shed light on the slowest folding rate of proteins as well as how mutations-amino-acid substitutions and/or post-translational modifications-might affect it. Preliminary results indicate that (i) Anfinsen's dogma validity ensures that proteins reach their native state on a reasonable timescale regardless of their sequence or length, and (ii) it is feasible to determine the evolution of protein folding rates without accounting for epistasis effects or the mutational trajectories between the starting and target sequences. These results have direct implications for evolutionary biology because they lay the groundwork for a better understanding of why, and to what extent, mutations-a crucial element of evolution and a factor influencing it-affect protein evolvability. Furthermore, they may spur significant progress in our efforts to solve crucial structural biology problems, such as how a sequence encodes its folding.
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Affiliation(s)
- Jorge A. Vila
- IMASL-CONICET, Universidad Nacional de San Luis, Ejército de Los Andes 950, 5700 San Luis, Argentina
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5
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Wand AJ. Deep mining of the protein energy landscape. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2023; 10:020901. [PMID: 37124940 PMCID: PMC10147411 DOI: 10.1063/4.0000180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 03/30/2023] [Indexed: 05/03/2023]
Abstract
For over half a century, it has been known that protein molecules naturally undergo extensive structural fluctuations, and that these internal motions are intimately related to their functional properties. The energy landscape view has provided a powerful framework for describing the various physical states that proteins visit during their lifetimes. This Perspective focuses on the commonly neglected and often disparaged axis of the protein energy landscape: entropy. Initially seen largely as a barrier to functionally relevant states of protein molecules, it has recently become clear that proteins retain considerable conformational entropy in the "native" state, and that this entropy can and often does contribute significantly to the free energy of fundamental protein properties, processes, and functions. NMR spectroscopy, molecular dynamics simulations, and emerging crystallographic views have matured in parallel to illuminate dynamic disorder of the "ground state" of proteins and their importance in not only transiting between biologically interesting structures but also greatly influencing their stability, cooperativity, and contribution to critical properties such as allostery.
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6
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Jain S, Sekhar A. Elucidating the mechanisms underlying protein conformational switching using NMR spectroscopy. JOURNAL OF MAGNETIC RESONANCE OPEN 2022; 10-11:100034. [PMID: 35586549 PMCID: PMC7612731 DOI: 10.1016/j.jmro.2022.100034] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
How proteins switch between various ligand-free and ligand-bound structures has been a key biophysical question ever since the postulation of the Monod-Wyman-Changeux and Koshland-Nemethy-Filmer models over six decades ago. The ability of NMR spectroscopy to provide structural and kinetic information on biomolecular conformational exchange places it in a unique position as an analytical tool to interrogate the mechanisms of biological processes such as protein folding and biomolecular complex formation. In addition, recent methodological developments in the areas of saturation transfer and relaxation dispersion have expanded the scope of NMR for probing the mechanics of transitions in systems where one or more states constituting the exchange process are sparsely populated and 'invisible' in NMR spectra. In this review, we highlight some of the strategies available from NMR spectroscopy for examining the nature of multi-site conformational exchange, using five case studies that have employed NMR, either in isolation, or in conjunction with other biophysical tools.
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7
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Mohanty S, Dabburu GR, Kumar M, Khasa YP. Heterologous expression of novel SUMO proteases from Schizosaccharomyces pombe in E. coli: Catalytic domain identification and optimization of product yields. Int J Biol Macromol 2022; 209:1001-1019. [PMID: 35447271 DOI: 10.1016/j.ijbiomac.2022.04.078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 04/01/2022] [Accepted: 04/11/2022] [Indexed: 11/19/2022]
Abstract
Small ubiquitin-related modifier (SUMO) proteins are efficiently used to target the soluble expression of various difficult-to-express proteins in E. coli. However, its utilization in large scale protein production is restricted by the higher cost of Ulp, which is required to cleave SUMO fusion tag from protein-of-interest to generate an authentic N-terminus. This study identified and characterized two novel SUMO proteases i.e., Ulp1 and Ulp2 from Schizosaccharomyces pombe. Codon-optimized gene sequences were cloned and expressed in E. coli. The sequence and structure of SpUlp1 and SpUlp2 catalytic domains were deduced using bioinformatics tools. Protein-protein interaction studies predicted the higher affinity of SpUlp1 towards SUMO compared to its counterpart from Saccharomyces cerevisiae (ScUlp1). The catalytic domain of SpUlp1 was purified using Ni-NTA chromatography with 83.33% recovery yield. Moreover, In vitro activity data further confirmed the fast-acting nature of SpUlp1 catalytic domain, where a 90% cleavage of fusion proteins was obtained within 1 h of incubation, indicating novelty and commercial relevance of S. pombe Ulp1. Biophysical characterization showed 8.8% α-helices, 36.7% β-sheets in SpUlp1SD. From thermal CD and fluorescence data, SpUlp1SD Tm was found to be 45 °C. Further, bioprocess optimization using fed-batch cultivation resulted in 3.5 g/L of SpUlp1SD production with YP/X of 77.26 mg/g DCW and volumetric productivity of 205.88 mg/L/h.
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Affiliation(s)
- Shilpa Mohanty
- Department of Microbiology, University of Delhi South Campus, New Delhi 110021, India
| | - Govinda Rao Dabburu
- Department of Biophysics, University of Delhi South Campus, New Delhi 110021, India
| | - Manish Kumar
- Department of Biophysics, University of Delhi South Campus, New Delhi 110021, India
| | - Yogender Pal Khasa
- Department of Microbiology, University of Delhi South Campus, New Delhi 110021, India.
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8
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Protein folding in vitro and in the cell: From a solitary journey to a team effort. Biophys Chem 2022; 287:106821. [PMID: 35667131 PMCID: PMC9636488 DOI: 10.1016/j.bpc.2022.106821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 04/18/2022] [Accepted: 04/21/2022] [Indexed: 12/22/2022]
Abstract
Correct protein folding is essential for the health and function of living organisms. Yet, it is not well understood how unfolded proteins reach their native state and avoid aggregation, especially within the cellular milieu. Some proteins, especially small, single-domain and apparent two-state folders, successfully attain their native state upon dilution from denaturant. Yet, many more proteins undergo misfolding and aggregation during this process, in a concentration-dependent fashion. Once formed, native and aggregated states are often kinetically trapped relative to each other. Hence, the early stages of protein life are absolutely critical for proper kinetic channeling to the folded state and for long-term solubility and function. This review summarizes current knowledge on protein folding/aggregation mechanisms in buffered solution and within the bacterial cell, highlighting early stages. Remarkably, teamwork between nascent chain, ribosome, trigger factor and Hsp70 molecular chaperones enables all proteins to overcome aggregation propensities and reach a long-lived bioactive state.
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9
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Probing biomolecular structure, dynamics, and function using hydrogen exchange. Arch Biochem Biophys 2022; 726:109185. [DOI: 10.1016/j.abb.2022.109185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 03/13/2022] [Indexed: 11/22/2022]
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10
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Native State Hydrogen Exchange-Mass Spectrometry Methods to Probe Protein Folding and Unfolding. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2022; 2376:143-159. [PMID: 34845608 DOI: 10.1007/978-1-0716-1716-8_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Native state hydrogen exchange (HX) methods provide high-resolution structural data on the rare and transient opening motions in proteins under native conditions. Mass spectrometry-based HX methods (HX-MS) have gained popularity because of their ability to delineate population distributions, which allow a direct determination of the mechanism of inter conversion of the partially folded states under native conditions. Various technological advancements have provided further impetus to the development of HX-MS-based experiments to study protein folding. Classical HX-MS studies use proteolytic digestion to produce fragments of the protein subsequent to HX in solution, in order to obtain structural data. New chemical fragmentation methods, which achieve the same result as proteolysis and cause minimal change to the HX pattern in the protein, provide an attractive alternative to proteolysis. Moreover, when used in conjunction with proteolysis, chemical fragmentation methods have significantly increased the structural resolution afforded by HX-MS studies, even bringing them at par with the single amino acid resolution observed in NMR-based measurements. Experiments based on one such chemical fragmentation method, electron transfer dissociation (ETD), are described in this chapter. The ETD HX-MS method is introduced using data from a protein which is inherently resistant to proteolytic digestion as example of how such an experiment can provide high-resolution structural data on the folding-unfolding transitions of the protein under native conditions.
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11
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The native state conformational heterogeneity in the energy landscape of protein folding. Biophys Chem 2022; 283:106761. [DOI: 10.1016/j.bpc.2022.106761] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/10/2022] [Accepted: 01/14/2022] [Indexed: 11/18/2022]
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12
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Komives EA. Achieving a realistic native protein ensemble by HDX-MS and computational modeling. Biophys J 2021; 120:5139-5140. [PMID: 34742401 DOI: 10.1016/j.bpj.2021.10.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 10/21/2021] [Accepted: 10/27/2021] [Indexed: 11/18/2022] Open
Affiliation(s)
- Elizabeth A Komives
- Department of Chemistry and Biochemistry, University of California, San Diego, California.
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13
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Naganathan AN, Dani R, Gopi S, Aranganathan A, Narayan A. Folding Intermediates, Heterogeneous Native Ensembles and Protein Function. J Mol Biol 2021; 433:167325. [PMID: 34695380 DOI: 10.1016/j.jmb.2021.167325] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 10/17/2021] [Accepted: 10/18/2021] [Indexed: 01/01/2023]
Abstract
Single domain proteins fold via diverse mechanisms emphasizing the intricate relationship between energetics and structure, which is a direct consequence of functional constraints and demands imposed at the level of sequence. On the other hand, elucidating the interplay between folding mechanisms and function is challenging in large proteins, given the inherent shortcomings in identifying metastable states experimentally and the sampling limitations associated with computational methods. Here, we show that free energy profiles and surfaces of large systems (>150 residues), as predicted by a statistical mechanical model, display a wide array of folding mechanisms with ubiquitous folding intermediates and heterogeneous native ensembles. Importantly, residues around the ligand binding or enzyme active site display a larger tendency to partially unfold and this manifests as intermediates or excited states along the folding coordinate in ligand binding domains, transcription repressors, and representative enzymes from all the six classes, including the SARS-CoV-2 receptor binding domain (RBD) of the spike protein and the protease Mpro. It thus appears that it is relatively easier to distill the imprints of function on the folding landscape of larger proteins as opposed to smaller systems. We discuss how an understanding of energetic-entropic features in ordered proteins can pinpoint specific avenues through which folding mechanisms, populations of partially structured states and function can be engineered.
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Affiliation(s)
- Athi N Naganathan
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
| | - Rahul Dani
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Soundhararajan Gopi
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India. https://twitter.com/Soundha
| | - Akashnathan Aranganathan
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Abhishek Narayan
- Department of Physics, University of Alberta, Edmonton, AB T6G 2E1, Canada
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14
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Bhattacharjee R, Udgaonkar JB. Structural Characterization of the Cooperativity of Unfolding of a Heterodimeric Protein using Hydrogen Exchange-Mass Spectrometry. J Mol Biol 2021; 433:167268. [PMID: 34563547 DOI: 10.1016/j.jmb.2021.167268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 09/03/2021] [Accepted: 09/16/2021] [Indexed: 10/20/2022]
Abstract
Little is known about how the sequence of structural changes in one chain of a heterodimeric protein is coupled to those in the other chain during protein folding and unfolding reactions, and whether individual secondary structural changes in the two chains occur in one or many coordinated steps. Here, the unfolding mechanism of a small heterodimeric protein, double chain monellin, has been characterized using hydrogen exchange-mass spectrometry. Transient structure opening, which enables HX, was found to be describable by a five state N ↔ I1 ↔ I2 ↔ I3 ↔ U mechanism. Structural changes occur gradually in the first three steps, and cooperatively in the last step. β strands 2, 4 and 5, as well as the α-helix undergo transient unfolding during all three non-cooperative steps, while β1 and the two loops on both sides of the helix undergo transient unfolding during the first two steps. In the absence of GdnHCl, only β3 in chain A of the protein unfolds during the last cooperative step, while in the presence of 1 M GdnHCl, not only β3, but also β2 in chain B unfolds cooperatively. Hence, the extent of cooperative structural change and size of the cooperative unfolding unit increase when the protein is destabilized by denaturant. The naturally evolved two-chain variant of monellin folds and unfolds in a more cooperative manner than does a single chain variant created artificially, suggesting that increasing folding cooperativity, even at the cost of decreasing stability, may be a driving force in the evolution of proteins.
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Affiliation(s)
- Rupam Bhattacharjee
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India; Indian Institute of Science Education and Research, Pune, India. https://twitter.com/Rupam_B01
| | - Jayant B Udgaonkar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India; Indian Institute of Science Education and Research, Pune, India.
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15
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Nassar R, Dignon GL, Razban RM, Dill KA. The Protein Folding Problem: The Role of Theory. J Mol Biol 2021; 433:167126. [PMID: 34224747 PMCID: PMC8547331 DOI: 10.1016/j.jmb.2021.167126] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/21/2021] [Accepted: 06/26/2021] [Indexed: 10/20/2022]
Abstract
The protein folding problem was first articulated as question of how order arose from disorder in proteins: How did the various native structures of proteins arise from interatomic driving forces encoded within their amino acid sequences, and how did they fold so fast? These matters have now been largely resolved by theory and statistical mechanics combined with experiments. There are general principles. Chain randomness is overcome by solvation-based codes. And in the needle-in-a-haystack metaphor, native states are found efficiently because protein haystacks (conformational ensembles) are funnel-shaped. Order-disorder theory has now grown to encompass a large swath of protein physical science across biology.
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Affiliation(s)
- Roy Nassar
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY, USA; Department of Chemistry, Stony Brook University, Stony Brook, NY, USA
| | - Gregory L Dignon
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY, USA
| | - Rostam M Razban
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY, USA
| | - Ken A Dill
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY, USA; Department of Chemistry, Stony Brook University, Stony Brook, NY, USA; Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, USA.
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16
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Lou X, Schoenmakers SMC, van Dongen JLJ, Garcia‐Iglesias M, Casellas NM, Fernández‐Castaño Romera M, Sijbesma RP, Meijer EW, Palmans ARA. Elucidating dynamic behavior of synthetic supramolecular polymers in water by hydrogen/deuterium exchange mass spectrometry. JOURNAL OF POLYMER SCIENCE 2021; 59:1151-1161. [PMID: 34223179 PMCID: PMC8247967 DOI: 10.1002/pol.20210011] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/03/2021] [Accepted: 02/04/2021] [Indexed: 01/31/2023]
Abstract
A comprehensive understanding of the structure, self-assembly mechanism, and dynamics of one-dimensional supramolecular polymers in water is essential for their application as biomaterials. Although a plethora of techniques are available to study the first two properties, there is a paucity in possibilities to study dynamic exchange of monomers between supramolecular polymers in solution. We recently introduced hydrogen/deuterium exchange mass spectrometry (HDX-MS) to characterize the dynamic nature of synthetic supramolecular polymers with only a minimal perturbation of the chemical structure. To further expand the application of this powerful technique some essential experimental aspects have been reaffirmed and the technique has been applied to a diverse library of assemblies. HDX-MS is widely applicable if there are exchangeable hydrogen atoms protected from direct contact with the solvent and if the monomer concentration is sufficiently high to ensure the presence of supramolecular polymers during dilution. In addition, we demonstrate that the kinetic behavior as probed by HDX-MS is influenced by the internal order within the supramolecular polymers and by the self-assembly mechanism.
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Affiliation(s)
- Xianwen Lou
- Department of Chemical Engineering and ChemistryInstitute for Complex Molecular Systems, Eindhoven University of TechnologyEindhovenThe Netherlands
| | - Sandra M. C. Schoenmakers
- Department of Chemical Engineering and ChemistryInstitute for Complex Molecular Systems, Eindhoven University of TechnologyEindhovenThe Netherlands
| | - Joost L. J. van Dongen
- Department of Chemical Engineering and ChemistryInstitute for Complex Molecular Systems, Eindhoven University of TechnologyEindhovenThe Netherlands
| | - Miguel Garcia‐Iglesias
- Department of Organic ChemistryUniversidad Autónoma de Madrid (UAM)MadridSpain
- Department of Chemistry and Process & Resource EngineeringUniversity of CantabriaSantanderSpain
| | - Nicolás M. Casellas
- Department of Organic ChemistryUniversidad Autónoma de Madrid (UAM)MadridSpain
| | - Marcos Fernández‐Castaño Romera
- Department of Chemical Engineering and ChemistryEindhoven University of TechnologyEindhovenThe Netherlands
- SupraPolix BVEindhovenThe Netherlands
| | - Rint P. Sijbesma
- Department of Chemical Engineering and ChemistryEindhoven University of TechnologyEindhovenThe Netherlands
| | - E. W. Meijer
- Department of Chemical Engineering and ChemistryInstitute for Complex Molecular Systems, Eindhoven University of TechnologyEindhovenThe Netherlands
| | - Anja R. A. Palmans
- Department of Chemical Engineering and ChemistryInstitute for Complex Molecular Systems, Eindhoven University of TechnologyEindhovenThe Netherlands
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17
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Kim J, Mandal R, Hilty C. 2D NMR spectroscopy of refolding RNase Sa using polarization transfer from hyperpolarized water. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 326:106942. [PMID: 33713971 DOI: 10.1016/j.jmr.2021.106942] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 06/12/2023]
Abstract
Polarization transfer from hyperpolarized water through proton exchange is used to enhance the NMR signals of amide protons of the Ribonuclease Sa protein. Spectra of the refolding protein are measured within 6 s after dilution of the denaturant urea, at urea-dependent folding rates adjusted in the range of 0.3-0.8 s-1. Peak patterns including a mixture of folded and unfolded protein at different ratios are observed. The changes in the observed signals indicate that each spectrum accesses a different point in the partial completion of the folding. A comparison to simulated 2D NMR spectra suggests a lower polarization transfer efficiency from water when the protein folds slowly, which may result from the molecular motions in the unfolded protein and the absence of long-range contacts. The ability to acquire 2D NMR spectra under different refolding conditions may open a new avenue for residue specific characterization of the folding process.
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Affiliation(s)
- Jihyun Kim
- Chemistry Department, Texas A&M University, 3255 TAMU, College Station, TX 77843, USA
| | - Ratnamala Mandal
- Chemistry Department, Texas A&M University, 3255 TAMU, College Station, TX 77843, USA
| | - Christian Hilty
- Chemistry Department, Texas A&M University, 3255 TAMU, College Station, TX 77843, USA.
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18
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Hirota S, Nagao S. New Aspects of Cytochromec: 3D Domain Swapping, Membrane Interaction, Peroxidase Activity, and Met80 Sulfoxide Modification. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2021. [DOI: 10.1246/bcsj.20200272] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Shun Hirota
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan
| | - Satoshi Nagao
- Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan
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19
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Bhattacharjee K, Gopi S, Naganathan AN. A Disordered Loop Mediates Heterogeneous Unfolding of an Ordered Protein by Altering the Native Ensemble. J Phys Chem Lett 2020; 11:6749-6756. [PMID: 32787218 DOI: 10.1021/acs.jpclett.0c01848] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The high flexibility of long disordered or partially structured loops in folded proteins allows for entropic stabilization of native ensembles. Destabilization of such loops could alter the native ensemble or promote alternate conformations within the native ensemble if the ordered regions themselves are held together weakly. This is particularly true of downhill folding systems that exhibit weak unfolding cooperativity. Here, we combine experimental and computational methods to probe the response of the native ensemble of a helical, downhill folding domain PDD, which harbors an 11-residue partially structured loop, to perturbations. Statistical mechanical modeling points to continuous structural changes on both temperature and mutational perturbations driven by entropic stabilization of partially structured conformations within the native ensemble. Long time-scale simulations of the wild-type protein and two mutants showcase a remarkable conformational switching behavior wherein the parallel helices in the wild-type protein sample an antiparallel orientation in the mutants, with the C-terminal helix and the loop connecting the helices displaying high flexibility, disorder, and non-native interactions. We validate these computational predictions via the anomalous fluorescence of a native tyrosine located at the interface of the helices. Our observations highlight the role of long loops in determining the unfolding mechanisms, sensitivity of the native ensembles to mutational perturbations and provide experimentally testable predictions that can be explored in even two-state folding systems.
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Affiliation(s)
- Kabita Bhattacharjee
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Soundhararajan Gopi
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Athi N Naganathan
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
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20
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Bhunia A, Ilyas H, Bhattacharjya S. Salt Dependence Conformational Stability of the Dimeric SAM Domain of MAPKKK Ste11 from Budding Yeast: A Native-State H/D Exchange NMR Study. Biochemistry 2020; 59:2849-2858. [PMID: 32667811 DOI: 10.1021/acs.biochem.0c00522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The sterile α motif, also called the SAM domain, is known to form homo or heterocomplexes that modulate diverse biological functions through the regulation of specific protein-protein interactions. The MAPK pathway of budding yeast Saccharomyces cerevisiae is comprised of a three-tier kinase system akin to mammals. The MAPKKK Ste11 protein of yeast contains a homodimer SAM domain, which is critical for transmitting cues to the downstream kinases. The structural stability of the dimeric Ste11 SAM is maintained by hydrophobic and ionic interactions at the interfacial amino acids. The urea-induced equilibrium-unfolding process of the Ste11 SAM domain is cooperative without evidence of any intermediate states. The native-state H/D exchange under subdenaturing conditions is a useful method for the detection of intermediate states of proteins. In the present study, we investigated the effect of ionic strength on the conformational stability of the dimer using the H/D exchange experiments. The hydrogen exchange behavior of the Ste11 dimer under physiological salt concentrations reveals two partially unfolded metastable intermediate states, which may be generated by a sequential and cooperative unfolding of the five helices present in the domain. These intermediates appear to be significant for the reversible unfolding kinetics via hydrophobic collapse. In contrast, higher ionic concentrations eliminate this cooperative interactions that stabilize the pairs of helices.
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Affiliation(s)
- Anirban Bhunia
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.,Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VII (M), Kolkata 700 054, India
| | - Humaira Ilyas
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VII (M), Kolkata 700 054, India
| | - Surajit Bhattacharjya
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
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21
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Szekely O, Olsen GL, Novakovic M, Rosenzweig R, Frydman L. Assessing Site-Specific Enhancements Imparted by Hyperpolarized Water in Folded and Unfolded Proteins by 2D HMQC NMR. J Am Chem Soc 2020; 142:9267-9284. [PMID: 32338002 PMCID: PMC7304870 DOI: 10.1021/jacs.0c00807] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
![]()
Hyperpolarized water
can be a valuable aid in protein NMR, leading
to amide group 1H polarizations that are orders of magnitude
larger than their thermal counterparts. Suitable procedures can exploit
this to deliver 2D 1H–15N correlations
with good resolution and enhanced sensitivity. These enhancements
depend on the exchange rates between the amides and the water, thereby
yielding diagnostic information about solvent accessibility. This
study applied this “HyperW” method to four proteins
exhibiting a gamut of exchange behaviors: PhoA(350–471), an unfolded 122-residue fragment; barstar, a fully folded ribonuclease
inhibitor; R17, a 13.3 kDa system possessing folded and unfolded forms
under slow interconversion; and drkN SH3, a protein domain whose folded
and unfolded forms interchange rapidly and with temperature-dependent
population ratios. For PhoA4(350–471) HyperW sensitivity
enhancements were ≥300×, as expected for an unfolded protein
sequence. Though fully folded, barstar also exhibited substantial
enhancements; these, however, were not uniform and, according to CLEANEX
experiments, reflected the solvent-exposed residues. R17 showed the
expected superposition of ≥100-fold enhancements for its unfolded
form, coexisting with more modest enhancements for their folded counterparts.
Unexpected, however, was the behavior of drkN SH3, for which HyperW
enhanced the unfolded but, surprisingly, enhanced even more certain folded protein sites. These preferential enhancements were
repeatedly and reproducibly observed. A number of explanations—including
three-site exchange magnetization transfers between water and the
unfolded and folded states; cross-correlated relaxation processes
from hyperpolarized “structural” waters and labile side-chain
protons; and the possibility that faster solvent exchange rates characterize
certain folded sites over their unfolded counterparts—are considered
to account for them.
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22
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Danielsson J, Noel JK, Simien JM, Duggan BM, Oliveberg M, Onuchic JN, Jennings PA, Haglund E. The Pierced Lasso Topology Leptin has a Bolt on Dynamic Domain Composed by the Disordered Loops I and III. J Mol Biol 2020; 432:3050-3063. [PMID: 32081588 DOI: 10.1016/j.jmb.2020.01.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 01/18/2020] [Accepted: 01/24/2020] [Indexed: 02/08/2023]
Abstract
Leptin is an important signaling hormone, mostly known for its role in energy expenditure and satiety. Furthermore, leptin plays a major role in other proteinopathies, such as cancer, marked hyperphagia, impaired immune function, and inflammation. In spite of its biological relevance in human health, there are no NMR resonance assignments of the human protein available, obscuring high-resolution characterization of the soluble protein and/or its conformational dynamics, suggested as being important for receptor interaction and biological activity. Here, we report the nearly complete backbone resonance assignments of human leptin. Chemical shift-based secondary structure prediction confirms that in solution leptin forms a four-helix bundle including a pierced lasso topology. The conformational dynamics, determined on several timescales, show that leptin is monomeric, has a rigid four-helix scaffold, and a dynamic domain, including a transiently formed helix. The dynamic domain is anchored to the helical scaffold by a secondary hydrophobic core, pinning down the long loops of leptin to the protein body, inducing motional restriction without a well-defined secondary or tertiary hydrogen bond stabilized structure. This dynamic region is well suited for and may be involved in functional allosteric dynamics upon receptor binding.
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Affiliation(s)
- Jens Danielsson
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
| | | | | | - Brendan Michael Duggan
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, USA
| | - Mikael Oliveberg
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - José Nelson Onuchic
- Center for Theoretical Biological Physics, Rice University, Houston, USA; Department of Physics and Astronomy, Department of Chemistry, And Department of Biosciences, Rice University, Houston, USA
| | - Patricia Ann Jennings
- Department of Chemistry and Biochemistry, The University of California at San Diego, La Jolla, USA
| | - Ellinor Haglund
- The Department of Chemistry, University of Hawaii, Manoa, Honolulu, USA.
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23
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Structural Characterization of an ACP from Thermotoga maritima: Insights into Hyperthermal Adaptation. Int J Mol Sci 2020; 21:ijms21072600. [PMID: 32283632 PMCID: PMC7178038 DOI: 10.3390/ijms21072600] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 04/06/2020] [Accepted: 04/07/2020] [Indexed: 12/30/2022] Open
Abstract
Thermotoga maritima, a deep-branching hyperthermophilic bacterium, expresses an extraordinarily stable Thermotoga maritima acyl carrier protein (Tm-ACP) that functions as a carrier in the fatty acid synthesis system at near-boiling aqueous environments. Here, to understand the hyperthermal adaptation of Tm-ACP, we investigated the structure and dynamics of Tm-ACP by nuclear magnetic resonance (NMR) spectroscopy. The melting temperature of Tm-ACP (101.4 °C) far exceeds that of other ACPs, owing to extensive ionic interactions and tight hydrophobic packing. The D59 residue, which replaces Pro/Ser of other ACPs, mediates ionic clustering between helices III and IV. This creates a wide pocket entrance to facilitate the accommodation of long acyl chains required for hyperthermal adaptation of the T. maritima cell membrane. Tm-ACP is revealed to be the first ACP that harbor an amide proton hyperprotected against hydrogen/deuterium exchange for I15. The hydrophobic interactions mediated by I15 appear to be the key driving forces of the global folding process of Tm-ACP. Our findings provide insights into the structural basis of the hyperthermal adaptation of ACP, which might have allowed T. maritima to survive in hot ancient oceans.
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24
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Hodge EA, Benhaim MA, Lee KK. Bridging protein structure, dynamics, and function using hydrogen/deuterium-exchange mass spectrometry. Protein Sci 2020; 29:843-855. [PMID: 31721348 PMCID: PMC7096709 DOI: 10.1002/pro.3790] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 11/08/2019] [Accepted: 11/11/2019] [Indexed: 12/21/2022]
Abstract
Much of our understanding of protein structure and mechanistic function has been derived from static high-resolution structures. As structural biology has continued to evolve it has become clear that high-resolution structures alone are unable to fully capture the mechanistic basis for protein structure and function in solution. Recently Hydrogen/Deuterium-exchange Mass Spectrometry (HDX-MS) has developed into a powerful and versatile tool for structural biologists that provides novel insights into protein structure and function. HDX-MS enables direct monitoring of a protein's structural fluctuations and conformational changes under native conditions in solution even as it is carrying out its functions. In this review, we focus on the use of HDX-MS to monitor these dynamic changes in proteins. We examine how HDX-MS has been applied to study protein structure and function in systems ranging from large, complex assemblies to intrinsically disordered proteins, and we discuss its use in probing conformational changes during protein folding and catalytic function. STATEMENT FOR A BROAD AUDIENCE: The biophysical and structural characterization of proteins provides novel insight into their functionalities. Protein motions, ranging from small scale local fluctuations to larger concerted structural rearrangements, often determine protein function. Hydrogen/Deuterium-exchange Mass Spectrometry (HDX-MS) has proven a powerful biophysical tool capable of probing changes in protein structure and dynamic protein motions that are often invisible to most other techniques.
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Affiliation(s)
- Edgar A. Hodge
- Department of Medicinal ChemistryUniversity of WashingtonSeattleWashington
| | - Mark A. Benhaim
- Department of Medicinal ChemistryUniversity of WashingtonSeattleWashington
| | - Kelly K. Lee
- Department of Medicinal ChemistryUniversity of WashingtonSeattleWashington
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25
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Abstract
Infrared difference spectroscopy probes vibrational changes of proteins upon their perturbation. Compared with other spectroscopic methods, it stands out by its sensitivity to the protonation state, H-bonding, and the conformation of different groups in proteins, including the peptide backbone, amino acid side chains, internal water molecules, or cofactors. In particular, the detection of protonation and H-bonding changes in a time-resolved manner, not easily obtained by other techniques, is one of the most successful applications of IR difference spectroscopy. The present review deals with the use of perturbations designed to specifically change the protein between two (or more) functionally relevant states, a strategy often referred to as reaction-induced IR difference spectroscopy. In the first half of this contribution, I review the technique of reaction-induced IR difference spectroscopy of proteins, with special emphasis given to the preparation of suitable samples and their characterization, strategies for the perturbation of proteins, and methodologies for time-resolved measurements (from nanoseconds to minutes). The second half of this contribution focuses on the spectral interpretation. It starts by reviewing how changes in H-bonding, medium polarity, and vibrational coupling affect vibrational frequencies, intensities, and bandwidths. It is followed by band assignments, a crucial aspect mostly performed with the help of isotopic labeling and site-directed mutagenesis, and complemented by integration and interpretation of the results in the context of the studied protein, an aspect increasingly supported by spectral calculations. Selected examples from the literature, predominately but not exclusively from retinal proteins, are used to illustrate the topics covered in this review.
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26
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Cohen NR, Kayatekin C, Zitzewitz JA, Bilsel O, Matthews CR. Friction-Limited Folding of Disulfide-Reduced Monomeric SOD1. Biophys J 2020; 118:1992-2000. [PMID: 32191862 DOI: 10.1016/j.bpj.2020.02.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 02/04/2020] [Accepted: 02/28/2020] [Indexed: 11/16/2022] Open
Abstract
The folding reaction of a stable monomeric variant of Cu/Zn superoxide dismutase (mSOD1), an enzyme responsible for the conversion of superoxide free radicals into hydrogen peroxide and oxygen, is known to be among the slowest folding processes that adhere to two-state behavior. The long lifetime, ∼10 s, of the unfolded state presents ample opportunities for the polypeptide chain to transiently sample nonnative structures before the formation of the productive folding transition state. We recently observed the formation of a nonnative structure in a peptide model of the C-terminus of SOD1, a sequence that might serve as a potential source of internal chain friction-limited folding. To test for friction-limited folding, we performed a comprehensive thermodynamic and kinetic analysis of the folding mechanism of mSOD1 in the presence of the viscogens glycerol and glucose. Using a, to our knowledge, novel analysis of the folding reactions, we found the disulfide-reduced form of the protein that exposes the C-terminal sequence, but not its disulfide-oxidized counterpart that protects it, experiences internal chain friction during folding. The sensitivity of the internal friction to the disulfide bond status suggests that one or both of the cross-linked regions play a critical role in driving the friction-limited folding. We speculate that the molecular mechanisms giving rise to the internal friction of disulfide-reduced mSOD1 might play a role in the amyotrophic lateral sclerosis-linked aggregation of SOD1.
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Affiliation(s)
- Noah R Cohen
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Can Kayatekin
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts; Rare and Neurological Therapeutic Area, Sanofi, Framingham, Massachusetts
| | - Jill A Zitzewitz
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Osman Bilsel
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - C R Matthews
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts.
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27
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Structure of an Unfolding Intermediate of an RRM Domain of ETR-3 Reveals Its Native-like Fold. Biophys J 2020; 118:352-365. [PMID: 31866002 DOI: 10.1016/j.bpj.2019.11.3392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 11/24/2019] [Accepted: 11/25/2019] [Indexed: 11/22/2022] Open
Abstract
Prevalence of one or more partially folded intermediates during protein unfolding with different secondary and ternary conformations has been identified as an integral character of protein unfolding. These transition-state species need to be characterized structurally for elucidation of their folding pathways. We have determined the three-dimensional structure of an intermediate state with increased conformational space sampling under urea-denaturing condition. The protein unfolds completely at 10 M urea but retains residual secondary structural propensities with restricted motion. Here, we describe the native state, observable intermediate state, and unfolded state for ETR-3 RRM-3, which has canonical RRM fold. These observations can shed more light on unfolding events for RRM-containing proteins.
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28
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Theoretical and computational advances in protein misfolding. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2020; 118:1-31. [PMID: 31928722 DOI: 10.1016/bs.apcsb.2019.08.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
Misfolded proteins escape the cellular quality control mechanism and fail to fold properly or remain correctly folded leading to a loss in their functional specificity. Thus misfolding of proteins cause a large number of very different diseases ranging from errors in metabolism to various types of complex neurodegenerative diseases. A theoretical and computational perspective of protein misfolding is presented with a special emphasis on its salient features, mechanism and consequences. These insights quantitatively analyze different determinants of misfolding, that may be applied to design disease specific molecular targets.
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29
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Troilo F, Malagrinò F, Visconti L, Toto A, Gianni S. The Effect of Proline cis- trans Isomerization on the Folding of the C-Terminal SH2 Domain from p85. Int J Mol Sci 2019; 21:E125. [PMID: 31878075 PMCID: PMC6982175 DOI: 10.3390/ijms21010125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 12/20/2019] [Accepted: 12/20/2019] [Indexed: 11/17/2022] Open
Abstract
SH2 domains are protein domains that modulate protein-protein interactions through a specific interaction with sequences containing phosphorylated tyrosines. In this work, we analyze the folding pathway of the C-terminal SH2 domain of the p85 regulatory subunit of the protein PI3K, which presents a proline residue in a cis configuration in the loop between the βE and βF strands. By employing single and double jump folding and unfolding experiments, we demonstrate the presence of an on-pathway intermediate that transiently accumulates during (un)folding. By comparing the kinetics of folding of the wild-type protein to that of a site-directed variant of C-SH2 in which the proline was replaced with an alanine, we demonstrate that this intermediate is dictated by the peptidyl prolyl cis-trans isomerization. The results are discussed in the light of previous work on the effect of peptidyl prolyl cis-trans isomerization on folding events.
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Affiliation(s)
- Francesca Troilo
- Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, 00161 Roma, Italy; (F.T.); (F.M.); (L.V.); (A.T.)
- Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy
| | - Francesca Malagrinò
- Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, 00161 Roma, Italy; (F.T.); (F.M.); (L.V.); (A.T.)
- Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy
| | - Lorenzo Visconti
- Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, 00161 Roma, Italy; (F.T.); (F.M.); (L.V.); (A.T.)
- Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy
| | - Angelo Toto
- Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, 00161 Roma, Italy; (F.T.); (F.M.); (L.V.); (A.T.)
- Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy
| | - Stefano Gianni
- Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, 00161 Roma, Italy; (F.T.); (F.M.); (L.V.); (A.T.)
- Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy
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30
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Uversky VN, Finkelstein AV. Life in Phases: Intra- and Inter- Molecular Phase Transitions in Protein Solutions. Biomolecules 2019; 9:E842. [PMID: 31817975 PMCID: PMC6995567 DOI: 10.3390/biom9120842] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 12/05/2019] [Accepted: 12/06/2019] [Indexed: 02/06/2023] Open
Abstract
Proteins, these evolutionarily-edited biological polymers, are able to undergo intramolecular and intermolecular phase transitions. Spontaneous intramolecular phase transitions define the folding of globular proteins, whereas binding-induced, intra- and inter- molecular phase transitions play a crucial role in the functionality of many intrinsically-disordered proteins. On the other hand, intermolecular phase transitions are the behind-the-scenes players in a diverse set of macrosystemic phenomena taking place in protein solutions, such as new phase nucleation in bulk, on the interface, and on the impurities, protein crystallization, protein aggregation, the formation of amyloid fibrils, and intermolecular liquid-liquid or liquid-gel phase transitions associated with the biogenesis of membraneless organelles in the cells. This review is dedicated to the systematic analysis of the phase behavior of protein molecules and their ensembles, and provides a description of the major physical principles governing intramolecular and intermolecular phase transitions in protein solutions.
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Affiliation(s)
- Vladimir N. Uversky
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- Laboratory of New Methods in Biology, Institute for Biological Instrumentation, Russian Academy of Sciences, Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, 142290 Pushchino, Moscow, Russia
| | - Alexei V. Finkelstein
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow, Russia
- Biology Department, Lomonosov Moscow State University, 119192 Moscow, Russia
- Bioltechnogy Department, Lomonosov Moscow State University, 142290 Pushchino, Moscow, Russia
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31
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Hudgens JW, Gallagher ES, Karageorgos I, Anderson KW, Filliben JJ, Huang RYC, Chen G, Bou-Assaf GM, Espada A, Chalmers MJ, Harguindey E, Zhang HM, Walters BT, Zhang J, Venable J, Steckler C, Park I, Brock A, Lu X, Pandey R, Chandramohan A, Anand GS, Nirudodhi SN, Sperry JB, Rouse JC, Carroll JA, Rand KD, Leurs U, Weis DD, Al-Naqshabandi MA, Hageman TS, Deredge D, Wintrode PL, Papanastasiou M, Lambris JD, Li S, Urata S. Interlaboratory Comparison of Hydrogen-Deuterium Exchange Mass Spectrometry Measurements of the Fab Fragment of NISTmAb. Anal Chem 2019; 91:7336-7345. [PMID: 31045344 PMCID: PMC6745711 DOI: 10.1021/acs.analchem.9b01100] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Hydrogen-deuterium exchange mass spectrometry (HDX-MS) is an established, powerful tool for investigating protein-ligand interactions, protein folding, and protein dynamics. However, HDX-MS is still an emergent tool for quality control of biopharmaceuticals and for establishing dynamic similarity between a biosimilar and an innovator therapeutic. Because industry will conduct quality control and similarity measurements over a product lifetime and in multiple locations, an understanding of HDX-MS reproducibility is critical. To determine the reproducibility of continuous-labeling, bottom-up HDX-MS measurements, the present interlaboratory comparison project evaluated deuterium uptake data from the Fab fragment of NISTmAb reference material (PDB: 5K8A ) from 15 laboratories. Laboratories reported ∼89 800 centroid measurements for 430 proteolytic peptide sequences of the Fab fragment (∼78 900 centroids), giving ∼100% coverage, and ∼10 900 centroid measurements for 77 peptide sequences of the Fc fragment. Nearly half of peptide sequences are unique to the reporting laboratory, and only two sequences are reported by all laboratories. The majority of the laboratories (87%) exhibited centroid mass laboratory repeatability precisions of ⟨ sLab⟩ ≤ (0.15 ± 0.01) Da (1σx̅). All laboratories achieved ⟨sLab⟩ ≤ 0.4 Da. For immersions of protein at THDX = (3.6 to 25) °C and for D2O exchange times of tHDX = (30 s to 4 h) the reproducibility of back-exchange corrected, deuterium uptake measurements for the 15 laboratories is σreproducibility15 Laboratories( tHDX) = (9.0 ± 0.9) % (1σ). A nine laboratory cohort that immersed samples at THDX = 25 °C exhibited reproducibility of σreproducibility25C cohort( tHDX) = (6.5 ± 0.6) % for back-exchange corrected, deuterium uptake measurements.
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Affiliation(s)
- Jeffrey W Hudgens
- Bioprocess Measurement Group, Biomolecular Measurements Division , National Institute of Standards and Technology , Rockville , Maryland 20850 , United States
- Institute for Bioscience and Biotechnology Research , 9600 Gudelsky Drive , Rockville , Maryland 20850 , United States
| | - Elyssia S Gallagher
- Bioprocess Measurement Group, Biomolecular Measurements Division , National Institute of Standards and Technology , Rockville , Maryland 20850 , United States
- Institute for Bioscience and Biotechnology Research , 9600 Gudelsky Drive , Rockville , Maryland 20850 , United States
| | - Ioannis Karageorgos
- Bioprocess Measurement Group, Biomolecular Measurements Division , National Institute of Standards and Technology , Rockville , Maryland 20850 , United States
- Institute for Bioscience and Biotechnology Research , 9600 Gudelsky Drive , Rockville , Maryland 20850 , United States
| | - Kyle W Anderson
- Bioprocess Measurement Group, Biomolecular Measurements Division , National Institute of Standards and Technology , Rockville , Maryland 20850 , United States
- Institute for Bioscience and Biotechnology Research , 9600 Gudelsky Drive , Rockville , Maryland 20850 , United States
| | - James J Filliben
- Statistical Engineering Division , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
| | - Richard Y-C Huang
- Pharmaceutical Candidate Optimization, Research and Development , Bristol-Myers Squibb Company , Princeton , New Jersey 08540 , United States
| | - Guodong Chen
- Pharmaceutical Candidate Optimization, Research and Development , Bristol-Myers Squibb Company , Princeton , New Jersey 08540 , United States
| | - George M Bou-Assaf
- Analytical Development , Biogen Inc. , 225 Binney Street , Cambridge , Massachusetts 02142 , United States
| | - Alfonso Espada
- Centro de Investigación Lilly S.A. , 28108 Alcobendas , Spain
| | - Michael J Chalmers
- Lilly Research Laboratories , Eli Lilly and Company , Indianapolis , Indiana 46285 , United States
| | | | - Hui-Min Zhang
- Protein Analytical Chemistry , Genentech, Inc. , 1 DNA Way , South San Francisco , California 94080 , United States
| | - Benjamin T Walters
- Protein Analytical Chemistry , Genentech, Inc. , 1 DNA Way , South San Francisco , California 94080 , United States
| | - Jennifer Zhang
- Protein Analytical Chemistry , Genentech, Inc. , 1 DNA Way , South San Francisco , California 94080 , United States
| | - John Venable
- Genomics Institute of the Novartis Research Foundation , 10675 John Jay Hopkins Drive , San Diego , California 92121 , United States
| | - Caitlin Steckler
- Genomics Institute of the Novartis Research Foundation , 10675 John Jay Hopkins Drive , San Diego , California 92121 , United States
- Joint Center for Structural Genomics , La Jolla , California 92037 , United States
| | - Inhee Park
- Genomics Institute of the Novartis Research Foundation , 10675 John Jay Hopkins Drive , San Diego , California 92121 , United States
| | - Ansgar Brock
- Genomics Institute of the Novartis Research Foundation , 10675 John Jay Hopkins Drive , San Diego , California 92121 , United States
| | - Xiaojun Lu
- MedImmune LLC , One MedImmune Way , Gaithersburg , Maryland 20878 , United States
| | - Ratnesh Pandey
- MedImmune LLC , One MedImmune Way , Gaithersburg , Maryland 20878 , United States
| | - Arun Chandramohan
- Department of Biological Sciences , National University of Singapore , 14, Science Drive 4 , Singapore 117543
| | - Ganesh Srinivasan Anand
- Department of Biological Sciences , National University of Singapore , 14, Science Drive 4 , Singapore 117543
| | - Sasidhar N Nirudodhi
- Vaccine R&D , Pfizer Inc. , 401 N Middletown Rd , Pearl River, New York 10965 , United States
| | - Justin B Sperry
- Analytical R&D , Pfizer Inc. , 700 Chesterfield Parkway West , Chesterfield , Missouri 63017 , United States
| | - Jason C Rouse
- Analytical R&D , Pfizer Inc. , 1 Burtt Road , Andover , Massachusetts 01810 , United States
| | - James A Carroll
- Analytical R&D , Pfizer Inc. , 700 Chesterfield Parkway West , Chesterfield , Missouri 63017 , United States
| | - Kasper D Rand
- Department of Pharmacy , University of Copenhagen , Universitetsparken 2 , DK-2100 Copenhagen , Denmark
| | - Ulrike Leurs
- Department of Pharmacy , University of Copenhagen , Universitetsparken 2 , DK-2100 Copenhagen , Denmark
| | - David D Weis
- Department of Chemistry , University of Kansas , 1567 Irving Hill Road , Lawrence , Kansas 66045 , United States
| | - Mohammed A Al-Naqshabandi
- Department of Chemistry , University of Kansas , 1567 Irving Hill Road , Lawrence , Kansas 66045 , United States
- Department of General Science , Soran University , Kawa Street , Soran , Kurdistan Region, Iraq
| | - Tyler S Hageman
- Department of Chemistry , University of Kansas , 1567 Irving Hill Road , Lawrence , Kansas 66045 , United States
| | - Daniel Deredge
- Department of Pharmaceutical Sciences , University of Maryland, Baltimore, School of Pharmacy , 20 North Pine Street , Baltimore , Maryland 21201 , United States
| | - Patrick L Wintrode
- Department of Pharmaceutical Sciences , University of Maryland, Baltimore, School of Pharmacy , 20 North Pine Street , Baltimore , Maryland 21201 , United States
| | - Malvina Papanastasiou
- Department of Pathology & Laboratory Medicine, Perelman School of Medicine, 402 Stellar-Chance Laboratories , University of Pennsylvania , 422 Curie Boulevard , Philadelphia , Pennsylvania 19104 , United States
| | - John D Lambris
- Department of Pathology & Laboratory Medicine, Perelman School of Medicine, 402 Stellar-Chance Laboratories , University of Pennsylvania , 422 Curie Boulevard , Philadelphia , Pennsylvania 19104 , United States
| | - Sheng Li
- Department of Medicine , University of California, San Diego , 9500 Gilman Drive , La Jolla , California 92093 , United States
| | - Sarah Urata
- Department of Medicine , University of California, San Diego , 9500 Gilman Drive , La Jolla , California 92093 , United States
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32
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Elmer-Dixon MM, Bowler BE. Electrostatic Constituents of the Interaction of Cardiolipin with Site A of Cytochrome c. Biochemistry 2018; 57:5683-5695. [DOI: 10.1021/acs.biochem.8b00704] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Margaret M. Elmer-Dixon
- Department of Chemistry and Biochemistry, Center for Bimolecular Structure and Dynamics, University of Montana, Missoula, Montana 59812, United States
| | - Bruce E. Bowler
- Department of Chemistry and Biochemistry, Center for Bimolecular Structure and Dynamics, University of Montana, Missoula, Montana 59812, United States
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33
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Holehouse AS, Pappu RV. Collapse Transitions of Proteins and the Interplay Among Backbone, Sidechain, and Solvent Interactions. Annu Rev Biophys 2018; 47:19-39. [PMID: 29345991 PMCID: PMC10740066 DOI: 10.1146/annurev-biophys-070317-032838] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Proteins can collapse into compact globules or form expanded, solvent-accessible, coil-like conformations. Additionally, they can fold into well-defined three-dimensional structures or remain partially or entirely disordered. Recent discoveries have shown that the tendency for proteins to collapse or remain expanded is not intrinsically coupled to their ability to fold. These observations suggest that proteins do not have to form compact globules in aqueous solutions. They can be intrinsically disordered, collapsed, or expanded, and even form well-folded, elongated structures. This ability to decouple collapse from folding is determined by the sequence details of proteins. In this review, we highlight insights gleaned from studies over the past decade. Using a polymer physics framework, we explain how the interplay among sidechains, backbone units, and solvent determines the driving forces for collapsed versus expanded states in aqueous solvents.
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Affiliation(s)
- Alex S Holehouse
- Department of Biomedical Engineering and Center for Biological Systems Engineering, Washington University in Saint Louis, Saint Louis, Missouri 63130, USA; ,
| | - Rohit V Pappu
- Department of Biomedical Engineering and Center for Biological Systems Engineering, Washington University in Saint Louis, Saint Louis, Missouri 63130, USA; ,
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34
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Wang G, Bondarenko PV, Kaltashov IA. Multi-step conformational transitions in heat-treated protein therapeutics can be monitored in real time with temperature-controlled electrospray ionization mass spectrometry. Analyst 2018; 143:670-677. [PMID: 29303166 DOI: 10.1039/c7an01655g] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Heat-induced conformational transitions are frequently used to probe the free energy landscapes of proteins. However, the extraction of information from thermal denaturation profiles pertaining to non-native protein conformations remains challenging due to their transient nature and significant conformational heterogeneity. Previously we developed a temperature-controlled electrospray ionization (ESI) source that allowed unfolding and association of biopolymers to be monitored by mass spectrometry (MS) in real time as a function of temperature. The scope of this technique is now extended to systems that undergo multi-step denaturation upon heat stress, as well as relatively small-scale conformational changes that are precursors to protein aggregation. The behavior of two therapeutic proteins (human antithrombin and an IgG1 monoclonal antibody) under heat-stress conditions is monitored in real time, providing evidence that relatively small-scale conformational changes in each system lead to protein oligomerization, followed by aggregation. Temperature-controlled ESI MS is particularly useful for the studies of heat-stressed multi-domain proteins such as IgG, where it allows distinct transitions to be observed. The ability of native temperature-controlled ESI MS to monitor both the conformational changes and oligomerization/degradation with high selectivity complements the classic calorimetric methods, lending itself as a powerful experimental tool for the thermostability studies of protein therapeutics.
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Affiliation(s)
- Guanbo Wang
- Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, and School of Chemistry and Materials Science, Nanjing Normal University, Nanjing, Jiangsu, China.
| | - Pavel V Bondarenko
- Attribute Sciences, Process Development, Amgen, Inc., Thousand Oaks, CA, USA
| | - Igor A Kaltashov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, USA
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35
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36
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Danielson TA, Stine JM, Dar TA, Briknarova K, Bowler BE. Effect of an Imposed Contact on Secondary Structure in the Denatured State of Yeast Iso-1-cytochrome c. Biochemistry 2017; 56:6662-6676. [PMID: 29148740 DOI: 10.1021/acs.biochem.7b01002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
There is considerable evidence that long-range interactions stabilize residual protein structure under denaturing conditions. However, evaluation of the effect of a specific contact on structure in the denatured state has been difficult. Iso-1-cytochrome c variants with a Lys54 → His mutation form a particularly stable His-heme loop in the denatured state, suggestive of loop-induced residual structure. We have used multidimensional nuclear magnetic resonance methods to assign 1H and 15N backbone amide and 13C backbone and side chain chemical shifts in the denatured state of iso-1-cytochrome c carrying the Lys54 → His mutation in 3 and 6 M guanidine hydrochloride and at both pH 6.4, where the His54-heme loop is formed, and pH 3.6, where the His54-heme loop is broken. Using the secondary structure propensity score, with the 6 M guanidine hydrochloride chemical shift data as a random coil reference state for data collected in 3 M guanidine hydrochloride, we found residual helical structure in the denatured state for the 60s helix and the C-terminal helix, but not in the N-terminal helix in the presence or absence of the His54-heme loop. Non-native helical structure is observed in two regions that form Ω-loops in the native state. There is more residual helical structure in the C-terminal helix at pH 6.4 when the loop is formed. Loop formation also appears to stabilize helical structure near His54, consistent with induction of helical structure observed when His-heme bonds form in heme-peptide model systems. The results are discussed in the context of the folding mechanism of cytochrome c.
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Affiliation(s)
- Travis A Danielson
- Department of Chemistry and Biochemistry, University of Montana , Missoula, Montana 59812, United States
| | - Jessica M Stine
- Department of Chemistry and Biochemistry, University of Montana , Missoula, Montana 59812, United States
| | - Tanveer A Dar
- Department of Chemistry and Biochemistry, University of Montana , Missoula, Montana 59812, United States
| | - Klara Briknarova
- Department of Chemistry and Biochemistry, University of Montana , Missoula, Montana 59812, United States.,Center for Biomolecular Structure and Dynamics, University of Montana , Missoula, Montana 59812, United States
| | - Bruce E Bowler
- Department of Chemistry and Biochemistry, University of Montana , Missoula, Montana 59812, United States.,Center for Biomolecular Structure and Dynamics, University of Montana , Missoula, Montana 59812, United States
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37
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Alvarez-Paggi D, Hannibal L, Castro MA, Oviedo-Rouco S, Demicheli V, Tórtora V, Tomasina F, Radi R, Murgida DH. Multifunctional Cytochrome c: Learning New Tricks from an Old Dog. Chem Rev 2017; 117:13382-13460. [DOI: 10.1021/acs.chemrev.7b00257] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Damián Alvarez-Paggi
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Luciana Hannibal
- Department
of Pediatrics, Universitätsklinikum Freiburg, Mathildenstrasse 1, Freiburg 79106, Germany
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - María A. Castro
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Santiago Oviedo-Rouco
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Veronica Demicheli
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Veronica Tórtora
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Florencia Tomasina
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Rafael Radi
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Daniel H. Murgida
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
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38
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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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39
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Malhotra P, Jethva PN, Udgaonkar JB. Chemical Denaturants Smoothen Ruggedness on the Free Energy Landscape of Protein Folding. Biochemistry 2017; 56:4053-4063. [DOI: 10.1021/acs.biochem.7b00367] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Pooja Malhotra
- National Centre for Biological Sciences, Tata Institute
of Fundamental Research, Bengaluru 560065, India
| | - Prashant N. Jethva
- National Centre for Biological Sciences, Tata Institute
of Fundamental Research, Bengaluru 560065, India
| | - Jayant B. Udgaonkar
- National Centre for Biological Sciences, Tata Institute
of Fundamental Research, Bengaluru 560065, India
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40
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Lou X, Lafleur RPM, Leenders CMA, Schoenmakers SMC, Matsumoto NM, Baker MB, van Dongen JLJ, Palmans ARA, Meijer EW. Dynamic diversity of synthetic supramolecular polymers in water as revealed by hydrogen/deuterium exchange. Nat Commun 2017; 8:15420. [PMID: 28504253 PMCID: PMC5440672 DOI: 10.1038/ncomms15420] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 03/29/2017] [Indexed: 02/02/2023] Open
Abstract
Numerous self-assembling molecules have been synthesized aiming at mimicking both the structural and dynamic properties found in living systems. Here we show the application of hydrogen/deuterium exchange (HDX) mass spectrometry (MS) to unravel the nanoscale organization and the structural dynamics of synthetic supramolecular polymers in water. We select benzene-1,3,5-tricarboxamide (BTA) derivatives that self-assemble in H2O to illustrate the strength of this technique for supramolecular polymers. The BTA structure has six exchangeable hydrogen atoms and we follow their exchange as a function of time after diluting the H2O solution with a 100-fold excess of D2O. The kinetic H/D exchange profiles reveal that these supramolecular polymers in water are dynamically diverse; a notion that has previously not been observed using other techniques. In addition, we report that small changes in the molecular structure can be used to control the dynamics of synthetic supramolecular polymers in water.
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Affiliation(s)
- Xianwen Lou
- Institute for Complex Molecular Systems, Eindhoven University of Technology, PO Box 513, Eindhoven 5600 MB, The Netherlands
| | - René P M Lafleur
- Institute for Complex Molecular Systems, Eindhoven University of Technology, PO Box 513, Eindhoven 5600 MB, The Netherlands
| | - Christianus M A Leenders
- Institute for Complex Molecular Systems, Eindhoven University of Technology, PO Box 513, Eindhoven 5600 MB, The Netherlands
| | - Sandra M C Schoenmakers
- Institute for Complex Molecular Systems, Eindhoven University of Technology, PO Box 513, Eindhoven 5600 MB, The Netherlands
| | - Nicholas M Matsumoto
- Institute for Complex Molecular Systems, Eindhoven University of Technology, PO Box 513, Eindhoven 5600 MB, The Netherlands
| | - Matthew B Baker
- Institute for Complex Molecular Systems, Eindhoven University of Technology, PO Box 513, Eindhoven 5600 MB, The Netherlands
| | - Joost L J van Dongen
- Institute for Complex Molecular Systems, Eindhoven University of Technology, PO Box 513, Eindhoven 5600 MB, The Netherlands
| | - Anja R A Palmans
- Institute for Complex Molecular Systems, Eindhoven University of Technology, PO Box 513, Eindhoven 5600 MB, The Netherlands
| | - E W Meijer
- Institute for Complex Molecular Systems, Eindhoven University of Technology, PO Box 513, Eindhoven 5600 MB, The Netherlands
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41
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Pakdaman Y, Sanchez-Guixé M, Kleppe R, Erdal S, Bustad HJ, Bjørkhaug L, Haugarvoll K, Tzoulis C, Heimdal K, Knappskog PM, Johansson S, Aukrust I. In vitro characterization of six STUB1 variants in spinocerebellar ataxia 16 reveals altered structural properties for the encoded CHIP proteins. Biosci Rep 2017; 37:BSR20170251. [PMID: 28396517 PMCID: PMC5408658 DOI: 10.1042/bsr20170251] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 04/07/2017] [Accepted: 04/10/2017] [Indexed: 11/24/2022] Open
Abstract
Spinocerebellar ataxia, autosomal recessive 16 (SCAR16) is caused by biallelic mutations in the STIP1 homology and U-box containing protein 1 (STUB1) gene encoding the ubiquitin E3 ligase and dimeric co-chaperone C-terminus of Hsc70-interacting protein (CHIP). It has been proposed that the disease mechanism is related to CHIP's impaired E3 ubiquitin ligase properties and/or interaction with its chaperones. However, there is limited knowledge on how these mutations affect the stability, folding, and protein structure of CHIP itself. To gain further insight, six previously reported pathogenic STUB1 variants (E28K, N65S, K145Q, M211I, S236T, and T246M) were expressed as recombinant proteins and studied using limited proteolysis, size-exclusion chromatography (SEC), and circular dichroism (CD). Our results reveal that N65S shows increased CHIP dimerization, higher levels of α-helical content, and decreased degradation rate compared with wild-type (WT) CHIP. By contrast, T246M demonstrates a strong tendency for aggregation, a more flexible protein structure, decreased levels of α-helical structures, and increased degradation rate compared with WT CHIP. E28K, K145Q, M211I, and S236T also show defects on structural properties compared with WT CHIP, although less profound than what observed for N65S and T246M. In conclusion, our results illustrate that some STUB1 mutations known to cause recessive SCAR16 have a profound impact on the protein structure, stability, and ability of CHIP to dimerize in vitro. These results add to the growing understanding on the mechanisms behind the disorder.
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Affiliation(s)
- Yasaman Pakdaman
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Monica Sanchez-Guixé
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Rune Kleppe
- K.G. Jebsen Centre for Neuropsychiatric Disorders, Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Sigrid Erdal
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
| | - Helene J Bustad
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Lise Bjørkhaug
- Department of Biomedical Laboratory Sciences and Chemical Engineering, Western Norway University of Applied Sciences, Bergen, Norway
| | - Kristoffer Haugarvoll
- Department of Neurology, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Charalampos Tzoulis
- Department of Neurology, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Ketil Heimdal
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Per M Knappskog
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
- K.G. Jebsen Centre for Neuropsychiatric Disorders, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Stefan Johansson
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
- K.G. Jebsen Centre for Neuropsychiatric Disorders, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Ingvild Aukrust
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Science, University of Bergen, Bergen, Norway
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42
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Gupta S, Sasidhar YU. Impact of Turn Propensity on the Folding Rates of Z34C Protein: Implications for the Folding of Helix-Turn-Helix Motif. J Phys Chem B 2017; 121:1268-1283. [PMID: 28094941 DOI: 10.1021/acs.jpcb.6b12219] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The rate-limiting step for the folding of the helix-turn-helix (HTH) protein, Z34C, involves β-turn region 20DPNL23. This reverse turn has been observed to be part of the transition state in the folding process for Z34C, influencing its folding rates. Molecular dynamics simulations were performed on this turn peptide and its two mutants, D20A and P21A, to study turn formation using GROMOS54A7 force field. We find that this region has a turn propensity of its own, and the highest turn propensity is observed for the wild-type, which correlates well with available experimental results. We also find that a slight unfavorable change in ΔG turn folding causes a drastic change in the folding rates of HTH motif and a mechanistic interpretation is given. Implications of these observations for the folding of the HTH protein Z34C are discussed.
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Affiliation(s)
- Shubhangi Gupta
- Department of Chemistry, Indian Institute of Technology Bombay , Powai, Mumbai 400 076, India
| | - Yellamraju U Sasidhar
- Department of Chemistry, Indian Institute of Technology Bombay , Powai, Mumbai 400 076, India
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43
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Gopi S, Singh A, Suresh S, Paul S, Ranu S, Naganathan AN. Toward a quantitative description of microscopic pathway heterogeneity in protein folding. Phys Chem Chem Phys 2017; 19:20891-20903. [DOI: 10.1039/c7cp03011h] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Experimentally consistent statistical modeling of protein folding thermodynamics reveals unprecedented complexity with numerous parallel folding routes in five different proteins.
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Affiliation(s)
- Soundhararajan Gopi
- Department of Biotechnology
- Bhupat & Jyoti Mehta School of Biosciences
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | - Animesh Singh
- Department of Computer Science and Engineering
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | | | - Suvadip Paul
- Department of Computer Science and Engineering
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | - Sayan Ranu
- Department of Computer Science and Engineering
- Indian Institute of Technology Madras
- Chennai 600036
- India
| | - Athi N. Naganathan
- Department of Biotechnology
- Bhupat & Jyoti Mehta School of Biosciences
- Indian Institute of Technology Madras
- Chennai 600036
- India
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44
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Robinson AC, Majumdar A, Schlessman JL, García-Moreno E B. Charges in Hydrophobic Environments: A Strategy for Identifying Alternative States in Proteins. Biochemistry 2016; 56:212-218. [DOI: 10.1021/acs.biochem.6b00843] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
| | | | - Jamie L. Schlessman
- Chemistry
Department, United States Naval Academy, 572M Holloway Rd MS 9B, Annapolis, Maryland 21402, United States
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45
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Ubiquitin utilizes an acidic surface patch to alter chromatin structure. Nat Chem Biol 2016; 13:105-110. [PMID: 27870837 PMCID: PMC5161692 DOI: 10.1038/nchembio.2235] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 09/07/2016] [Indexed: 02/06/2023]
Abstract
Ubiquitylation of histone H2B, associated with gene activation, leads to chromatin decompaction through an unknown mechanism. We used a hydrogen-deuterium exchange strategy coupled with nuclear magnetic resonance spectroscopy to map the ubiquitin surface responsible for its structural effects on chromatin. Our studies revealed that a previously uncharacterized acidic patch on ubiquitin comprising residues Glu16 and Glu18 is essential for decompaction. These residues mediate promiscuous electrostatic interactions with the basic histone proteins, potentially positioning the ubiquitin moiety as a dynamic “wedge” that prevents the intimate association of neighboring nucleosomes. Using two independent cross-linking strategies and an oligomerization assay, we also showed that ubiquitin-ubiquitin contacts occur in the chromatin environment and are important for the solubilization of the chromatin polymers. Our work highlights a novel, chromatin-related aspect of the “ubiquitin code”, and sheds light on how the information rich ubiquitin modification can orchestrate different biochemical outcomes using different surface features.
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46
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Malhotra P, Udgaonkar JB. How cooperative are protein folding and unfolding transitions? Protein Sci 2016; 25:1924-1941. [PMID: 27522064 PMCID: PMC5079258 DOI: 10.1002/pro.3015] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 08/09/2016] [Accepted: 08/09/2016] [Indexed: 11/12/2022]
Abstract
A thermodynamically and kinetically simple picture of protein folding envisages only two states, native (N) and unfolded (U), separated by a single activation free energy barrier, and interconverting by cooperative two-state transitions. The folding/unfolding transitions of many proteins occur, however, in multiple discrete steps associated with the formation of intermediates, which is indicative of reduced cooperativity. Furthermore, much advancement in experimental and computational approaches has demonstrated entirely non-cooperative (gradual) transitions via a continuum of states and a multitude of small energetic barriers between the N and U states of some proteins. These findings have been instrumental towards providing a structural rationale for cooperative versus noncooperative transitions, based on the coupling between interaction networks in proteins. The cooperativity inherent in a folding/unfolding reaction appears to be context dependent, and can be tuned via experimental conditions which change the stabilities of N and U. The evolution of cooperativity in protein folding transitions is linked closely to the evolution of function as well as the aggregation propensity of the protein. A large activation energy barrier in a fully cooperative transition can provide the kinetic control required to prevent the accumulation of partially unfolded forms, which may promote aggregation. Nevertheless, increasing evidence for barrier-less "downhill" folding, as well as for continuous "uphill" unfolding transitions, indicate that gradual non-cooperative processes may be ubiquitous features on the free energy landscape of protein folding.
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Affiliation(s)
- Pooja Malhotra
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, 560065, India
| | - Jayant B Udgaonkar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, 560065, India.
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Sacquin-Mora S. Fold and flexibility: what can proteins' mechanical properties tell us about their folding nucleus? J R Soc Interface 2016; 12:rsif.2015.0876. [PMID: 26577596 DOI: 10.1098/rsif.2015.0876] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The determination of a protein's folding nucleus, i.e. a set of native contacts playing an important role during its folding process, remains an elusive yet essential problem in biochemistry. In this work, we investigate the mechanical properties of 70 protein structures belonging to 14 protein families presenting various folds using coarse-grain Brownian dynamics simulations. The resulting rigidity profiles combined with multiple sequence alignments show that a limited set of rigid residues, which we call the consensus nucleus, occupy conserved positions along the protein sequence. These residues' side chains form a tight interaction network within the protein's core, thus making our consensus nuclei potential folding nuclei. A review of experimental and theoretical literature shows that most (above 80%) of these residues were indeed identified as folding nucleus member in earlier studies.
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Affiliation(s)
- Sophie Sacquin-Mora
- Laboratoire de Biochimie Théorique, CNRS UPR9080, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France
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48
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Heat- and pH-induced BSA conformational changes, hydrogel formation and application as 3D cell scaffold. Arch Biochem Biophys 2016; 606:134-42. [DOI: 10.1016/j.abb.2016.07.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 07/21/2016] [Accepted: 07/27/2016] [Indexed: 11/22/2022]
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49
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Contessoto VG, de Oliveira VM, de Carvalho SJ, Oliveira LC, Leite VBP. NTL9 Folding at Constant pH: The Importance of Electrostatic Interaction and pH Dependence. J Chem Theory Comput 2016; 12:3270-7. [PMID: 27327651 DOI: 10.1021/acs.jctc.6b00399] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The folding process of the N-terminal domain of ribosomal protein L9 (NTL9) was investigated at constant-pH computer simulations. Evaluation of the role of electrostatic interaction during folding was carried out by including a Debye-Hückel potential into a Cα structure-based model (SBM). In this study, the charges of the ionizable residues and the electrostatic potential are susceptible to the solution conditions, such as pH and ionic strength, as well as to the presence of charged groups. Simulations were performed under different pHs, and the results were validated by comparing them with experimental values of pKa and with denaturation experiment data. Also, the free energy profiles, Φ-values, and folding routes were calculated for each condition. It was shown how charges vary along the folding under different pH, which is subject to different scenarios. This study reveals how simplified models can capture essential physical features, reproducing experimental results, and presenting the role of electrostatic interactions before, during, and after the transition state.
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Affiliation(s)
- Vinícius G Contessoto
- Departamento de Física, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista (UNESP) , São José do Rio Preto, São Paulo 15054-000, Brazil
| | - Vinícius M de Oliveira
- Departamento de Física, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista (UNESP) , São José do Rio Preto, São Paulo 15054-000, Brazil
| | - Sidney J de Carvalho
- Departamento de Física, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista (UNESP) , São José do Rio Preto, São Paulo 15054-000, Brazil
| | - Leandro C Oliveira
- Departamento de Física, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista (UNESP) , São José do Rio Preto, São Paulo 15054-000, Brazil
| | - Vitor B P Leite
- Departamento de Física, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista (UNESP) , São José do Rio Preto, São Paulo 15054-000, Brazil
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50
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Chen C, Yun JH, Kim JH, Park C. Effect of circular permutations on transient partial unfolding in proteins. Protein Sci 2016; 25:1483-91. [PMID: 27164316 DOI: 10.1002/pro.2945] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 05/05/2016] [Accepted: 05/06/2016] [Indexed: 12/22/2022]
Abstract
Under native conditions, proteins can undergo transient partial unfolding, which may cause proteins to misfold or aggregate. A change in sequence connectivity by circular permutation may affect the energetics of transient partial unfolding in proteins without altering the three-dimensional structures. Using Escherichia coli dihydrofolate reductase (DHFR) as a model system, we investigated how circular permutation affects transient partial unfolding in proteins. We constructed three circular permutants, CP18, CP37, and CP87, with the new N-termini at residue 18, 37, and 87, respectively, and probed transient partial unfolding by native-state proteolysis. The new termini in CP18, CP37, and CP87 are within, near, and distal to the Met20 loop, which is known to be dynamic and also part of the region that undergoes transient unfolding in wild-type DHFR. The stabilities of both native and partially unfolded forms of CP18 are similar to those of wild-type DHFR, suggesting that the influence of introducing new termini in a dynamic region to the protein is minimal. CP37 has a significantly more accessible partially unfolded form than wild-type DHFR, demonstrating that introducing new termini near a dynamic region may promote transient partial unfolding. CP87 has significantly destabilized native and partially unfolded forms, confirming that modification of the folded region in a partially unfolded form destabilizes the partially unfolded form similar to the native form. Our findings provide valuable guidelines to control transient partial unfolding in designing circular permutants in proteins.
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Affiliation(s)
- Chen Chen
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, 47907
| | - Jung-Hun Yun
- Faculty of Biotechnology, College of Applied Life Science, SARI, Jeju National University, Jeju-Do, 690-756, Korea
| | - Jae-Hoon Kim
- Faculty of Biotechnology, College of Applied Life Science, SARI, Jeju National University, Jeju-Do, 690-756, Korea
| | - Chiwook Park
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, 47907
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