1
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Hsu STD. Folding and functions of knotted proteins. Curr Opin Struct Biol 2023; 83:102709. [PMID: 37778185 DOI: 10.1016/j.sbi.2023.102709] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 09/02/2023] [Accepted: 09/05/2023] [Indexed: 10/03/2023]
Abstract
Topologically knotted proteins have entangled structural elements within their native structures that cannot be disentangled simply by pulling from the N- and C-termini. Systematic surveys have identified different types of knotted protein structures, constituting as much as 1% of the total entries within the Protein Data Bank. Many knotted proteins rely on their knotted structural elements to carry out evolutionarily conserved biological functions. Being knotted may also provide mechanical stability to withstand unfolding-coupled proteolysis. Reconfiguring a knotted protein topology by circular permutation or cyclization provides insights into the importance of being knotted in the context of folding and functions. With the explosion of predicted protein structures by artificial intelligence, we are now entering a new era of exploring the entangled protein universe.
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Affiliation(s)
- Shang-Te Danny Hsu
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei 10617, Taiwan; International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM(2)), Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan.
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2
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Imamura H, Ooishi A, Honda S. Getting Smaller by Denaturation: Acid-Induced Compaction of Antibodies. J Phys Chem Lett 2023; 14:3898-3906. [PMID: 37093025 PMCID: PMC10150727 DOI: 10.1021/acs.jpclett.3c00258] [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: 01/29/2023] [Accepted: 04/07/2023] [Indexed: 05/03/2023]
Abstract
Protein denaturation is a ubiquitous process that occurs both in vitro and in vivo. While our molecular understanding of the denatured structures of proteins is limited, it is commonly accepted that the loss of unique intramolecular contacts makes proteins larger. Herein, we report compaction of the immunoglobulin G1 (IgG1) protein upon acid denaturation. Small-angle X-ray scattering coupled with size exclusion chromatography revealed that IgG1 radii of gyration at pH 2 were ∼75% of those at a neutral pH. Scattering profiles showed a compact globular shape, supported by analytical ultracentrifugation. The acid denaturation of proteins with a decrease in size is energetically costly, and acid-induced compaction requires an attractive force for domain reorientation. Such intramolecular aggregation may be widespread in immunoglobulin proteins as noncanonical structures. Herein, we discuss the potential biological significance of these noncanonical structures of antibodies.
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Affiliation(s)
- Hiroshi Imamura
- Biomedical
Research Institute, National Institute of
Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
- Department
of Applied Chemistry, College of Life Sciences, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577, Japan
- Department
of Bio-Science, Nagahama Institute of Bio-Science
and Technology, 1266 Tamura, Nagahama, Shiga 526-0829, Japan
| | - Ayako Ooishi
- Biomedical
Research Institute, National Institute of
Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Shinya Honda
- Biomedical
Research Institute, National Institute of
Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
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3
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Puri S, Hsu STD. Elucidation of folding pathways of knotted proteins. Methods Enzymol 2022; 675:275-297. [DOI: 10.1016/bs.mie.2022.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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4
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Xu Y, Kang R, Ren L, Yang L, Yue T. Revealing Topological Barriers against Knot Untying in Thermal and Mechanical Protein Unfolding by Molecular Dynamics Simulations. Biomolecules 2021; 11:1688. [PMID: 34827686 PMCID: PMC8615548 DOI: 10.3390/biom11111688] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/20/2021] [Accepted: 10/21/2021] [Indexed: 11/16/2022] Open
Abstract
The knot is one of the most remarkable topological features identified in an increasing number of proteins with important functions. However, little is known about how the knot is formed during protein folding, and untied or maintained in protein unfolding. By means of all-atom molecular dynamics simulation, here we employ methyltransferase YbeA as the knotted protein model to analyze changes of the knotted conformation coupled with protein unfolding under thermal and mechanical denaturing conditions. Our results show that the trefoil knot in YbeA is occasionally untied via knot loosening rather than sliding under enhanced thermal fluctuations. Through correlating protein unfolding with changes in the knot position and size, several aspects of barriers that jointly suppress knot untying are revealed. In particular, protein unfolding is always prior to knot untying and starts preferentially from separation of two α-helices (α1 and α5), which protect the hydrophobic core consisting of β-sheets (β1-β4) from exposure to water. These β-sheets form a loop through which α5 is threaded to form the knot. Hydrophobic and hydrogen bonding interactions inside the core stabilize the loop against loosening. In addition, residues at N-terminal of α5 define a rigid turning to impede α5 from sliding out of the loop. Site mutations are designed to specifically eliminate these barriers, and easier knot untying is achieved under the same denaturing conditions. These results provide new molecular level insights into the folding/unfolding of knotted proteins.
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Affiliation(s)
- Yan Xu
- College of Electronic Engineering and Automation, Shandong University of Science and Technology, Qingdao 266590, China;
- College of Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China;
| | - Runshan Kang
- College of Chemical Engineering, China University of Petroleum (East China), Qingdao 266580, China;
| | - Luyao Ren
- Key Laboratory of Marine Environment and Ecology, Institute of Coastal Environmental Pollution Control, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; (L.R.); (L.Y.)
| | - Lin Yang
- Key Laboratory of Marine Environment and Ecology, Institute of Coastal Environmental Pollution Control, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; (L.R.); (L.Y.)
| | - Tongtao Yue
- Key Laboratory of Marine Environment and Ecology, Institute of Coastal Environmental Pollution Control, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; (L.R.); (L.Y.)
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
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5
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Hsu STD, Lee YTC, Mikula KM, Backlund SM, Tascón I, Goldman A, Iwaï H. Tying up the Loose Ends: A Mathematically Knotted Protein. Front Chem 2021; 9:663241. [PMID: 34109153 PMCID: PMC8182377 DOI: 10.3389/fchem.2021.663241] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 04/20/2021] [Indexed: 11/23/2022] Open
Abstract
Knots have attracted scientists in mathematics, physics, biology, and engineering. Long flexible thin strings easily knot and tangle as experienced in our daily life. Similarly, long polymer chains inevitably tend to get trapped into knots. Little is known about their formation or function in proteins despite >1,000 knotted proteins identified in nature. However, these protein knots are not mathematical knots with their backbone polypeptide chains because of their open termini, and the presence of a “knot” depends on the algorithm used to create path closure. Furthermore, it is generally not possible to control the topology of the unfolded states of proteins, therefore making it challenging to characterize functional and physicochemical properties of knotting in any polymer. Covalently linking the amino and carboxyl termini of the deeply trefoil-knotted YibK from Pseudomonas aeruginosa allowed us to create the truly backbone knotted protein by enzymatic peptide ligation. Moreover, we produced and investigated backbone cyclized YibK without any knotted structure. Thus, we could directly probe the effect of the backbone knot and the decrease in conformational entropy on protein folding. The backbone cyclization did not perturb the native structure and its cofactor binding affinity, but it substantially increased the thermal stability and reduced the aggregation propensity. The enhanced stability of a backbone knotted YibK could be mainly originated from an increased ruggedness of its free energy landscape and the destabilization of the denatured state by backbone cyclization with little contribution from a knot structure. Despite the heterogeneity in the side-chain compositions, the chemically unfolded cyclized YibK exhibited several macroscopic physico-chemical attributes that agree with theoretical predictions derived from polymer physics.
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Affiliation(s)
- Shang-Te Danny Hsu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.,Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Yun-Tzai Cloud Lee
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.,Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Kornelia M Mikula
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Sofia M Backlund
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Igor Tascón
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Adrian Goldman
- Division of Biochemistry, Department of Biosciences, University of Helsinki, Helsinki, Finland.,Astbury Centre for Structural Molecular Biology, School of Biomedical Sciences, University of Leeds, West Yorkshire, United Kingdom
| | - Hideo Iwaï
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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6
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Shibuya R, Miyafusa T, Imamura H, Ooishi A, Honda S. Effect of backbone circularization on colloidal stability: Compaction of unfolded structures improves aggregation resistance of granulocyte colony-stimulating factor. Int J Pharm 2021; 605:120774. [PMID: 34116181 DOI: 10.1016/j.ijpharm.2021.120774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 05/29/2021] [Accepted: 06/02/2021] [Indexed: 10/21/2022]
Abstract
Aggregation of protein therapeutics can lead to immunogenicity and loss of function in vivo. Its effective prevention requires an understanding of the conformational and colloidal stability of protein and the improvement of both. Granulocyte colony-stimulating factor (G-CSF), which is one of the most widely used protein therapeutics, was previously shown to be conformationally stabilized by connecting its N- and C-termini with amide bonds (backbone circularization). In this study, we investigated whether circularization affects the colloidal stability of proteins. Colloidal stability was indirectly assessed by analyzing the aggregation behavior of G-CSF variants using analytical ultracentrifugation (AUC) and small-angle X-ray scattering (SAXS). Consequently, we found that the unfolded structure of circularized G-CSF was more compact than non-circularized G-CSF, and that backbone circularization improved its aggregation resistance against chemical denaturation by guanidine hydrochloride (GdnHCl). The improved aggregation resistance suggests that the expansion tolerance of circularized G-CSF in the unfolded state increased its colloidal stability. Thus, backbone circularization is an excellent method for enhancing the colloidal and the conformational stability of protein with minimal sequence changes. It is therefore expected to be effective in extending the storage stability of protein therapeutics, enhancing their biological stability.
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Affiliation(s)
- Risa Shibuya
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan; Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
| | - Takamitsu Miyafusa
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan; Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Hiroshi Imamura
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan; Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan
| | - Ayako Ooishi
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Shinya Honda
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan; Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
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7
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Piejko M, Niewieczerzal S, Sulkowska JI. The Folding of Knotted Proteins: Distinguishing the Distinct Behavior of Shallow and Deep Knots. Isr J Chem 2020. [DOI: 10.1002/ijch.202000036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Maciej Piejko
- Faculty of ChemistryUniversity of Warsaw Pasteura 1 Warsaw 02-093 Poland
- Centre of New TechnologiesUniversity of Warsaw Banacha 2c Warsaw 02-097 Poland
| | | | - Joanna I. Sulkowska
- Faculty of ChemistryUniversity of Warsaw Pasteura 1 Warsaw 02-093 Poland
- Centre of New TechnologiesUniversity of Warsaw Banacha 2c Warsaw 02-097 Poland
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8
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Sulkowska JI. On folding of entangled proteins: knots, lassos, links and θ-curves. Curr Opin Struct Biol 2020; 60:131-141. [PMID: 32062143 DOI: 10.1016/j.sbi.2020.01.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 01/02/2020] [Accepted: 01/12/2020] [Indexed: 12/15/2022]
Abstract
Around 6% of protein structures deposited in the PDB are entangled, forming knots, slipknots, lassos, links, and θ-curves. In each of these cases, the protein backbone weaves through itself in a complex way, and at some point passes through a closed loop, formed by other regions of the protein structure. Such a passing can be interpreted as crossing a topological barrier. How proteins overcome such barriers, and therefore different degrees of frustration, challenged scientists and has shed new light on the field of protein folding. In this review, we summarize the current knowledge about the free energy landscape of proteins with non-trivial topology. We describe identified mechanisms which lead proteins to self-tying. We discuss the influence of excluded volume, such as crowding and chaperones, on tying, based on available data. We briefly discuss the diversity of topological complexity of proteins and their evolution. We also list available tools to investigate non-trivial topology. Finally, we formulate intriguing and challenging questions at the boundary of biophysics, bioinformatics, biology, and mathematics, which arise from the discovery of entangled proteins.
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Affiliation(s)
- Joanna Ida Sulkowska
- Centre of New Technologies, University of Warsaw, Warsaw, Poland; Faculty of Chemistry, University of Warsaw, Warsaw, Poland.
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9
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Ko KT, Hu IC, Huang KF, Lyu PC, Hsu STD. Untying a Knotted SPOUT RNA Methyltransferase by Circular Permutation Results in a Domain-Swapped Dimer. Structure 2019; 27:1224-1233.e4. [DOI: 10.1016/j.str.2019.04.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 03/01/2019] [Accepted: 04/05/2019] [Indexed: 11/28/2022]
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10
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Untying a Protein Knot by Circular Permutation. J Mol Biol 2019; 431:857-863. [DOI: 10.1016/j.jmb.2019.01.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Revised: 01/02/2019] [Accepted: 01/02/2019] [Indexed: 01/13/2023]
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11
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Lee YTC, Hsu STD. A Natively Monomeric Deubiquitinase UCH-L1 Forms Highly Dynamic but Defined Metastable Oligomeric Folding Intermediates. J Phys Chem Lett 2018; 9:2433-2437. [PMID: 29688017 DOI: 10.1021/acs.jpclett.8b00815] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Oligomerization of misfolded protein species is implicated in many human disorders. Here we showed by size-exclusion chromatography-coupled multiangle light scattering (SEC-MALS) and small-angle X-ray scattering (SEC-SAXS) that urea-induced folding intermediate of human ubiquitin C-terminal hydrolase, UCH-L1, can form well-defined dimers and tetramers under denaturing conditions despite being highly disordered. Introduction of a Parkinson disease-associated mutation, I93M, resulted in increased aggregation propensity and formation of irreversible precipitants in the presence of a moderate amount of urea. Since UCH-L1 exhibits highly populated partially unfolded forms under native conditions that resemble urea-induced folding intermediates, it is likely that these metastable dimers and tetramers can form under physiological conditions. Our findings highlighted the unique strength of integrated SEC-MALS/SAXS in quantitative analyses of the structure and dynamics of oligomeric folding intermediates that enabled us to extract information that is inaccessible to conventional biophysical techniques.
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Affiliation(s)
- Yun-Tzai Cloud Lee
- Institute of Biological Chemistry , Academia Sinica , Taipei 11529 , Taiwan
- Institute of Biochemical Sciences , National Taiwan University , Taipei 10617 , Taiwan
| | - Shang-Te Danny Hsu
- Institute of Biological Chemistry , Academia Sinica , Taipei 11529 , Taiwan
- Institute of Biochemical Sciences , National Taiwan University , Taipei 10617 , Taiwan
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12
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The energy cost of polypeptide knot formation and its folding consequences. Nat Commun 2017; 8:1581. [PMID: 29146980 PMCID: PMC5691195 DOI: 10.1038/s41467-017-01691-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 10/09/2017] [Indexed: 11/08/2022] Open
Abstract
Knots are natural topologies of chains. Yet, little is known about spontaneous knot formation in a polypeptide chain—an event that can potentially impair its folding—and about the effect of a knot on the stability and folding kinetics of a protein. Here we used optical tweezers to show that the free energy cost to form a trefoil knot in the denatured state of a polypeptide chain of 120 residues is 5.8 ± 1 kcal mol−1. Monte Carlo dynamics of random chains predict this value, indicating that the free energy cost of knot formation is of entropic origin. This cost is predicted to remain above 3 kcal mol−1 for denatured proteins as large as 900 residues. Therefore, we conclude that naturally knotted proteins cannot attain their knot randomly in the unfolded state but must pay the cost of knotting through contacts along their folding landscape. The effect of knots on protein stability and folding kinetics is not well understood. Here the authors combine optical tweezer experiments and calculations to experimentally determine the energy cost for knot formation, which indicates that knotted proteins evolved specific folding pathways because knot formation in unfolded chains is unfavorable.
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13
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Lee YTC, Chang CY, Chen SY, Pan YR, Ho MR, Hsu STD. Entropic stabilization of a deubiquitinase provides conformational plasticity and slow unfolding kinetics beneficial for functioning on the proteasome. Sci Rep 2017; 7:45174. [PMID: 28338014 PMCID: PMC5364529 DOI: 10.1038/srep45174] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 02/20/2017] [Indexed: 02/07/2023] Open
Abstract
Human ubiquitin C-terminal hydrolyase UCH-L5 is a topologically knotted deubiquitinase that is activated upon binding to the proteasome subunit Rpn13. The length of its intrinsically disordered cross-over loop is essential for substrate recognition. Here, we showed that the catalytic domain of UCH-L5 exhibits higher equilibrium folding stability with an unfolding rate on the scale of 10−8 s−1, over four orders of magnitudes slower than its paralogs, namely UCH-L1 and -L3, which have shorter cross-over loops. NMR relaxation dynamics analysis confirmed the intrinsic disorder of the cross-over loop. Hydrogen deuterium exchange analysis further revealed a positive correlation between the length of the cross-over loop and the degree of local fluctuations, despite UCH-L5 being thermodynamically and kinetically more stable than the shorter UCHs. Considering the role of UCH-L5 in removing K48-linked ubiquitin to prevent proteasomal degradation of ubiquitinated substrates, our findings offered mechanistic insights into the evolution of UCH-L5. Compared to its paralogs, it is entropically stabilized to withstand mechanical unfolding by the proteasome while maintaining structural plasticity. It can therefore accommodate a broad range of substrate geometries at the cost of unfavourable entropic loss.
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Affiliation(s)
- Yun-Tzai Cloud Lee
- Institute of Biological Chemistry, Academia Sinica, Taipei, 11529, Taiwan.,Institute of Biochemical Sciences, National Taiwan University, 10617, Taiwan
| | - Chia-Yun Chang
- Institute of Biological Chemistry, Academia Sinica, Taipei, 11529, Taiwan.,Institute of Biochemical Sciences, National Taiwan University, 10617, Taiwan
| | - Szu-Yu Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, 11529, Taiwan
| | - Yun-Ru Pan
- Institute of Biological Chemistry, Academia Sinica, Taipei, 11529, Taiwan
| | - Meng-Ru Ho
- Institute of Biological Chemistry, Academia Sinica, Taipei, 11529, Taiwan
| | - Shang-Te Danny Hsu
- Institute of Biological Chemistry, Academia Sinica, Taipei, 11529, Taiwan.,Institute of Biochemical Sciences, National Taiwan University, 10617, Taiwan
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14
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Hsu STD. Protein knotting through concatenation significantly reduces folding stability. Sci Rep 2016; 6:39357. [PMID: 27982106 PMCID: PMC5159899 DOI: 10.1038/srep39357] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 11/22/2016] [Indexed: 12/24/2022] Open
Abstract
Concatenation by covalent linkage of two protomers of an intertwined all-helical HP0242 homodimer from Helicobacter pylori results in the first example of an engineered knotted protein. While concatenation does not affect the native structure according to X-ray crystallography, the folding kinetics is substantially slower compared to the parent homodimer. Using NMR hydrogen-deuterium exchange analysis, we showed here that concatenation destabilises significantly the knotted structure in solution, with some regions close to the covalent linkage being destabilised by as much as 5 kcal mol-1. Structural mapping of chemical shift perturbations induced by concatenation revealed a pattern that is similar to the effect induced by concentrated chaotrophic agent. Our results suggested that the design strategy of protein knotting by concatenation may be thermodynamically unfavourable due to covalent constrains imposed on the flexible fraying ends of the template structure, leading to rugged free energy landscape with increased propensity to form off-pathway folding intermediates.
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Affiliation(s)
- Shang-Te Danny Hsu
- Institute of Biological Chemistry, Academia Sinica, 128, Section 2, Academia Road, Taipei 11529, Taiwan
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15
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Jackson SE, Suma A, Micheletti C. How to fold intricately: using theory and experiments to unravel the properties of knotted proteins. Curr Opin Struct Biol 2016; 42:6-14. [PMID: 27794211 DOI: 10.1016/j.sbi.2016.10.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 09/06/2016] [Accepted: 10/03/2016] [Indexed: 11/15/2022]
Abstract
Over the years, advances in experimental and computational methods have helped us to understand the role of thermodynamic, kinetic and active (chaperone-aided) effects in coordinating the folding steps required to achieving a knotted native state. Here, we review such developments by paying particular attention to the complementarity of experimental and computational studies. Key open issues that could be tackled with either or both approaches are finally pointed out.
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Affiliation(s)
- Sophie E Jackson
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom.
| | - Antonio Suma
- SISSA, International School for Advanced Studies, via Bonomea 265, I-34136 Trieste, Italy
| | - Cristian Micheletti
- SISSA, International School for Advanced Studies, via Bonomea 265, I-34136 Trieste, Italy.
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16
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Folding analysis of the most complex Stevedore's protein knot. Sci Rep 2016; 6:31514. [PMID: 27527519 PMCID: PMC4985754 DOI: 10.1038/srep31514] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 07/21/2016] [Indexed: 12/21/2022] Open
Abstract
DehI is a homodimeric haloacid dehalogenase from Pseudomonas putida that contains the most complex 61 Stevedore's protein knot within its folding topology. To examine how DehI attains such an intricate knotted topology we combined far-UV circular dichroism (CD), intrinsic fluorescence spectroscopy and small angle X-ray scattering (SAXS) to investigate its folding mechanism. Equilibrium unfolding of DehI by chemical denaturation indicated the presence of two highly populated folding intermediates, I and I'. While the two intermediates vary in secondary structure contents and tertiary packing according to CD and intrinsic fluorescence, respectively, their overall dimension and compactness are similar according to SAXS. Three single-tryptophan variants (W34, W53, and W196) were generated to probe non-cooperative unfolding events localized around the three fluorophores. Kinetic fluorescence measurements indicated that the transition from the intermediate I' to the unfolded state is rate limiting. Our multiparametric folding analyses suggest that DehI unfolds through a linear folding pathway with two distinct folding intermediates by initial hydrophobic collapse followed by nucleation condensation, and that knotting precedes the formation of secondary structures.
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17
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Lou SC, Wetzel S, Zhang H, Crone EW, Lee YT, Jackson SE, Hsu STD. The Knotted Protein UCH-L1 Exhibits Partially Unfolded Forms under Native Conditions that Share Common Structural Features with Its Kinetic Folding Intermediates. J Mol Biol 2016; 428:2507-2520. [PMID: 27067109 DOI: 10.1016/j.jmb.2016.04.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 03/22/2016] [Accepted: 04/02/2016] [Indexed: 10/22/2022]
Abstract
The human ubiquitin C-terminal hydrolase, UCH-L1, is an abundant neuronal deubiquitinase that is associated with Parkinson's disease. It contains a complex Gordian knot topology formed by the polypeptide chain alone. Using a combination of fluorescence-based kinetic measurements, we show that UCH-L1 has two distinct kinetic folding intermediates that are transiently populated on parallel pathways between the denatured and native states. NMR hydrogen-deuterium exchange (HDX) experiments indicate the presence of partially unfolded forms (PUFs) of UCH-L1 under native conditions. HDX measurements as a function of urea concentration were used to establish the structure of the PUFs and pulse-labelled HDX NMR was used to show that the PUFs and the folding intermediates are likely the same species. In both cases, a similar stable core encompassing most of the central β-sheet is highly structured and α-helix 3, which is partially formed, packs against it. In contrast to the stable β-sheet core, the peripheral α-helices display significant local fluctuations leading to rapid exchange. The results also suggest that the main difference between the two kinetic intermediates is structure and packing of α-helices 3 and 7 and the degree of structure in β-strand 5. Together, the fluorescence and NMR results establish that UCH-L1 neither folds through a continuum of pathways nor by a single discrete pathway. Its folding is complex, the β-sheet core forms early and is present in both intermediate states, and the rate-limiting step which is likely to involve the threading of the chain to form the 52-knot occurs late on the folding pathway.
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Affiliation(s)
- Shih-Chi Lou
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK; Institute of Biological Chemistry, Academia Sinica, 128, Section 2, Academia Road, Taipei 11529, Taiwan
| | - Svava Wetzel
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Hongyu Zhang
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Elizabeth W Crone
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Yun-Tzai Lee
- Institute of Biological Chemistry, Academia Sinica, 128, Section 2, Academia Road, Taipei 11529, Taiwan; Institute of Biochemical Sciences, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei 106, Taiwan
| | - Sophie E Jackson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Shang-Te Danny Hsu
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK; Institute of Biological Chemistry, Academia Sinica, 128, Section 2, Academia Road, Taipei 11529, Taiwan; Institute of Biochemical Sciences, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei 106, Taiwan.
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Dabrowski-Tumanski P, Jarmolinska AI, Sulkowska JI. Prediction of the optimal set of contacts to fold the smallest knotted protein. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:354109. [PMID: 26291339 DOI: 10.1088/0953-8984/27/35/354109] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Knotted protein chains represent a new motif in protein folds. They have been linked to various diseases, and recent extensive analysis of the Protein Data Bank shows that they constitute 1.5% of all deposited protein structures. Despite thorough theoretical and experimental investigations, the role of knots in proteins still remains elusive. Nonetheless, it is believed that knots play an important role in mechanical and thermal stability of proteins. Here, we perform a comprehensive analysis of native, shadow-specific and non-native interactions which describe free energy landscape of the smallest knotted protein (PDB id 2efv). We show that the addition of shadow-specific contacts in the loop region greatly enhances folding kinetics, while the addition of shadow-specific contacts along the C-terminal region (H3 or H4) results in a new folding route with slower kinetics. By means of direct coupling analysis (DCA) we predict non-native contacts which also can accelerate kinetics. Next, we show that the length of the C-terminal knot tail is responsible for the shape of the free energy barrier, while the influence of the elongation of the N-terminus is not significant. Finally, we develop a concept of a minimal contact map sufficient for 2efv protein to fold and analyze properties of this protein using this map.
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Affiliation(s)
- P Dabrowski-Tumanski
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland. Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
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