1
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Rubach P, Sikora M, Jarmolinska A, Perlinska A, Sulkowska J. AlphaKnot 2.0: a web server for the visualization of proteins' knotting and a database of knotted AlphaFold-predicted models. Nucleic Acids Res 2024; 52:W187-W193. [PMID: 38842945 PMCID: PMC11223836 DOI: 10.1093/nar/gkae443] [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: 03/16/2024] [Revised: 04/29/2024] [Accepted: 05/10/2024] [Indexed: 07/06/2024] Open
Abstract
The availability of 3D protein models is rapidly increasing with the development of structure prediction algorithms. With the expanding availability of data, new ways of analysis, especially topological analysis, of those predictions are becoming necessary. Here, we present the updated version of the AlphaKnot service that provides a straightforward way of analyzing structure topology. It was designed specifically to determine knot types of the predicted structure models, however, it can be used for all structures, including the ones solved experimentally. AlphaKnot 2.0 provides the user's ability to obtain the knowledge necessary to assess the topological correctness of the model. Both probabilistic and deterministic knot detection methods are available, together with various visualizations (including a trajectory of simplification steps to highlight the topological complexities). Moreover, the web server provides a list of proteins similar to the queried model within AlphaKnot's database and returns their knot types for direct comparison. We pre-calculated the topology of high-quality models from the AlphaFold Database (4th version) and there are now more than 680.000 knotted models available in the AlphaKnot database. AlphaKnot 2.0 is available at https://alphaknot.cent.uw.edu.pl/.
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Affiliation(s)
- Pawel Rubach
- Warsaw School of Economics, Al. Niepodleglosci 162, 02-554 Warsaw, Poland
| | - Maciej Sikora
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
| | | | - Agata P Perlinska
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
| | - Joanna I Sulkowska
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
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2
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Sikora M, Klimentova E, Uchal D, Sramkova D, Perlinska AP, Nguyen ML, Korpacz M, Malinowska R, Nowakowski S, Rubach P, Simecek P, Sulkowska JI. Knot or not? Identifying unknotted proteins in knotted families with sequence-based Machine Learning model. Protein Sci 2024; 33:e4998. [PMID: 38888487 PMCID: PMC11184937 DOI: 10.1002/pro.4998] [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: 12/04/2023] [Revised: 03/14/2024] [Accepted: 04/09/2024] [Indexed: 06/20/2024]
Abstract
Knotted proteins, although scarce, are crucial structural components of certain protein families, and their roles continue to be a topic of intense research. Capitalizing on the vast collection of protein structure predictions offered by AlphaFold (AF), this study computationally examines the entire UniProt database to create a robust dataset of knotted and unknotted proteins. Utilizing this dataset, we develop a machine learning (ML) model capable of accurately predicting the presence of knots in protein structures solely from their amino acid sequences. We tested the model's capabilities on 100 proteins whose structures had not yet been predicted by AF and found agreement with our local prediction in 92% cases. From the point of view of structural biology, we found that all potentially knotted proteins predicted by AF can be classified only into 17 families. This allows us to discover the presence of unknotted proteins in families with a highly conserved knot. We found only three new protein families: UCH, DUF4253, and DUF2254, that contain both knotted and unknotted proteins, and demonstrate that deletions within the knot core could potentially account for the observed unknotted (trivial) topology. Finally, we have shown that in the majority of knotted families (11 out of 15), the knotted topology is strictly conserved in functional proteins with very low sequence similarity. We have conclusively demonstrated that proteins AF predicts as unknotted are structurally accurate in their unknotted configurations. However, these proteins often represent nonfunctional fragments, lacking significant portions of the knot core (amino acid sequence).
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Affiliation(s)
- Maciej Sikora
- Centre of New Technologies, University of WarsawWarsawPoland
- Faculty of Mathematics, Informatics and Mechanics, University of WarsawWarsawPoland
| | - Eva Klimentova
- Central European Institute of Technology, Masaryk UniversityBrnoCzech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk UniversityBrnoCzech Republic
| | - Dawid Uchal
- Centre of New Technologies, University of WarsawWarsawPoland
- Faculty of Physics, University of WarsawWarsawPoland
| | - Denisa Sramkova
- Central European Institute of Technology, Masaryk UniversityBrnoCzech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk UniversityBrnoCzech Republic
| | | | - Mai Lan Nguyen
- Centre of New Technologies, University of WarsawWarsawPoland
| | - Marta Korpacz
- Centre of New Technologies, University of WarsawWarsawPoland
- Faculty of Mathematics, Informatics and Mechanics, University of WarsawWarsawPoland
| | - Roksana Malinowska
- Centre of New Technologies, University of WarsawWarsawPoland
- Faculty of Mathematics, Informatics and Mechanics, University of WarsawWarsawPoland
| | - Szymon Nowakowski
- Faculty of Mathematics, Informatics and Mechanics, University of WarsawWarsawPoland
- Faculty of Physics, University of WarsawWarsawPoland
| | - Pawel Rubach
- Centre of New Technologies, University of WarsawWarsawPoland
- Warsaw School of EconomicsWarsawPoland
| | - Petr Simecek
- Central European Institute of Technology, Masaryk UniversityBrnoCzech Republic
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3
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Gren BA, Antczak M, Zok T, Sulkowska JI, Szachniuk M. Knotted artifacts in predicted 3D RNA structures. PLoS Comput Biol 2024; 20:e1011959. [PMID: 38900780 PMCID: PMC11218946 DOI: 10.1371/journal.pcbi.1011959] [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: 03/08/2024] [Revised: 07/02/2024] [Accepted: 06/01/2024] [Indexed: 06/22/2024] Open
Abstract
Unlike proteins, RNAs deposited in the Protein Data Bank do not contain topological knots. Recently, admittedly, the first trefoil knot and some lasso-type conformations have been found in experimental RNA structures, but these are still exceptional cases. Meanwhile, algorithms predicting 3D RNA models have happened to form knotted structures not so rarely. Interestingly, machine learning-based predictors seem to be more prone to generate knotted RNA folds than traditional methods. A similar situation is observed for the entanglements of structural elements. In this paper, we analyze all models submitted to the CASP15 competition in the 3D RNA structure prediction category. We show what types of topological knots and structure element entanglements appear in the submitted models and highlight what methods are behind the generation of such conformations. We also study the structural aspect of susceptibility to entanglement. We suggest that predictors take care of an evaluation of RNA models to avoid publishing structures with artifacts, such as unusual entanglements, that result from hallucinations of predictive algorithms.
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Affiliation(s)
- Bartosz A. Gren
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
| | - Maciej Antczak
- Institute of Computing Science, Poznan University of Technology, Poznan, Poland
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
| | - Tomasz Zok
- Institute of Computing Science, Poznan University of Technology, Poznan, Poland
| | | | - Marta Szachniuk
- Institute of Computing Science, Poznan University of Technology, Poznan, Poland
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
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4
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Rana V, Sitarik I, Petucci J, Jiang Y, Song H, O'Brien EP. Non-covalent Lasso Entanglements in Folded Proteins: Prevalence, Functional Implications, and Evolutionary Significance. J Mol Biol 2024; 436:168459. [PMID: 38296158 DOI: 10.1016/j.jmb.2024.168459] [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: 09/03/2023] [Revised: 01/23/2024] [Accepted: 01/24/2024] [Indexed: 02/17/2024]
Abstract
One-third of protein domains in the CATH database contain a recently discovered tertiary topological motif: non-covalent lasso entanglements, in which a segment of the protein backbone forms a loop closed by non-covalent interactions between residues and is threaded one or more times by the N- or C-terminal backbone segment. Unknown is how frequently this structural motif appears across the proteomes of organisms. And the correlation of these motifs with various classes of protein function and biological processes have not been quantified. Here, using a combination of protein crystal structures, AlphaFold2 predictions, and Gene Ontology terms we show that in E. coli, S. cerevisiae and H. sapiens that 71%, 52% and 49% of globular proteins contain one-or-more non-covalent lasso entanglements in their native fold, and that some of these are highly complex with multiple threading events. Further, proteins containing these tertiary motifs are consistently enriched in certain functions and biological processes across these organisms and depleted in others, strongly indicating an influence of evolutionary selection pressures acting positively and negatively on the distribution of these motifs. Together, these results demonstrate that non-covalent lasso entanglements are widespread and indicate they may be extensively utilized for protein function and subcellular processes, thus impacting phenotype.
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Affiliation(s)
- Viraj Rana
- Department of Chemistry, Pennsylvania State University, University Park, PA, United States
| | - Ian Sitarik
- Department of Chemistry, Pennsylvania State University, University Park, PA, United States
| | - Justin Petucci
- Institute for Computational and Data Sciences, Pennsylvania State University, University Park, PA, United States
| | - Yang Jiang
- Department of Chemistry, Pennsylvania State University, University Park, PA, United States
| | - Hyebin Song
- Bioinformatics and Genomics Graduate Program, The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, United States; Department of Statistics, Pennsylvania State University, University Park, PA, United States.
| | - Edward P O'Brien
- Department of Chemistry, Pennsylvania State University, University Park, PA, United States; Institute for Computational and Data Sciences, Pennsylvania State University, University Park, PA, United States; Bioinformatics and Genomics Graduate Program, The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, United States.
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5
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Zayats V, Sikora M, Perlinska AP, Stasiulewicz A, Gren BA, Sulkowska JI. Conservation of knotted and slipknotted topology in transmembrane transporters. Biophys J 2023; 122:4528-4541. [PMID: 37919904 PMCID: PMC10719070 DOI: 10.1016/j.bpj.2023.10.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 08/25/2023] [Accepted: 10/30/2023] [Indexed: 11/04/2023] Open
Abstract
The existence of nontrivial topology is well accepted in globular proteins but not in membrane proteins. Our comprehensive topological analysis of the Protein Data Bank structures reveals 18 families of transmembrane proteins with nontrivial topology, showing that they constitute a significant number of membrane proteins. Moreover, we found that they comprise one of the largest groups of secondary active transporters. We classified them based on their knotted fingerprint into four groups: three slipknotted and one knotted. Unexpectedly, we found that the same protein can possess two distinct slipknot motifs that correspond to its outward- and inward-open conformational state. Based on the analysis of structures and knotted fingerprints, we show that slipknot topology is directly involved in the conformational transition and substrate transfer. Therefore, entanglement can be used to classify proteins and to find their structure-function relationship. Furthermore, based on the topological analysis of the transmembrane protein structures predicted by AlphaFold, we identified new potentially slipknotted protein families.
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Affiliation(s)
- Vasilina Zayats
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
| | - Maciej Sikora
- Centre of New Technologies, University of Warsaw, Warsaw, Poland; Faculty of Mathematics, Informatics and Mechanics, University of Warsaw, Warsaw, Poland
| | | | - Adam Stasiulewicz
- Centre of New Technologies, University of Warsaw, Warsaw, Poland; Department of Drug Chemistry, Faculty of Pharmacy, Medical University of Warsaw, Warsaw, Poland
| | - Bartosz A Gren
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
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6
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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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7
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Tripathi P, Mehrafrooz B, Aksimentiev A, Jackson SE, Gruebele M, Wanunu M. A Marcus-Type Inverted Region in the Translocation Kinetics of a Knotted Protein. J Phys Chem Lett 2023; 14:10719-10726. [PMID: 38009629 PMCID: PMC11176711 DOI: 10.1021/acs.jpclett.3c02183] [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] [Indexed: 11/29/2023]
Abstract
Knotted proteins are rare but important species, yet how their complex topologies affect their physical properties is not fully understood. Here we combine single molecule nanopore experiments and all-atom MD simulations to study the electric-field-driven unfolding during the translocation through a model pore of individual protein knots important for methylating tRNA. One of these knots shows an unusual behavior that resembles the behavior of electrons hopping between two potential surfaces: as the electric potential driving the translocation reaction is increased, the rate eventually plateaus or slows back down in the "Marcus inverted regime". Our results shed light on the influence of topology in knotted proteins on their forced translocation through a pore connecting two electrostatic potential wells.
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Affiliation(s)
- Prabhat Tripathi
- Department of Chemistry, Indian Institute of Technology (Banaras Hindu University), Varanasi, UP-221005, India
| | - Behzad Mehrafrooz
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL-61801, USA
| | - Aleksei Aksimentiev
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL-61801, USA
| | - Sophie E. Jackson
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield `Road, Cambridge CB2 1EW, UK
| | - Martin Gruebele
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL-61801, USA
| | - Meni Wanunu
- Department of Physics, Northeastern University, Boston, MA-02115, USA
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8
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Bale A, Rambo R, Prior C. The SKMT Algorithm: A method for assessing and comparing underlying protein entanglement. PLoS Comput Biol 2023; 19:e1011248. [PMID: 38011290 PMCID: PMC10703313 DOI: 10.1371/journal.pcbi.1011248] [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: 06/08/2023] [Revised: 12/07/2023] [Accepted: 11/06/2023] [Indexed: 11/29/2023] Open
Abstract
We present fast and simple-to-implement measures of the entanglement of protein tertiary structures which are appropriate for highly flexible structure comparison. These are performed using the SKMT algorithm, a novel method of smoothing the Cα backbone to achieve a minimal complexity curve representation of the manner in which the protein's secondary structure elements fold to form its tertiary structure. Its subsequent complexity is characterised using measures based on the writhe and crossing number quantities heavily utilised in DNA topology studies, and which have shown promising results when applied to proteins recently. The SKMT smoothing is used to derive empirical bounds on a protein's entanglement relative to its number of secondary structure elements. We show that large scale helical geometries dominantly account for the maximum growth in entanglement of protein monomers, and further that this large scale helical geometry is present in a large array of proteins, consistent across a number of different protein structure types and sequences. We also show how these bounds can be used to constrain the search space of protein structure prediction from small angle x-ray scattering experiments, a method highly suited to determining the likely structure of proteins in solution where crystal structure or machine learning based predictions often fail to match experimental data. Finally we develop a structural comparison metric based on the SKMT smoothing which is used in one specific case to demonstrate significant structural similarity between Rossmann fold and TIM Barrel proteins, a link which is potentially significant as attempts to engineer the latter have in the past produced the former. We provide the SWRITHE interactive python notebook to calculate these metrics.
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Affiliation(s)
- Arron Bale
- Department of Mathematical Sciences, Durham University, Durham, United Kingdom
| | - Robert Rambo
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, United Kingdom
| | - Christopher Prior
- Department of Mathematical Sciences, Durham University, Durham, United Kingdom
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9
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Doyle LA, Takushi B, Kibler RD, Milles LF, Orozco CT, Jones JD, Jackson SE, Stoddard BL, Bradley P. De novo design of knotted tandem repeat proteins. Nat Commun 2023; 14:6746. [PMID: 37875492 PMCID: PMC10598012 DOI: 10.1038/s41467-023-42388-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 10/09/2023] [Indexed: 10/26/2023] Open
Abstract
De novo protein design methods can create proteins with folds not yet seen in nature. These methods largely focus on optimizing the compatibility between the designed sequence and the intended conformation, without explicit consideration of protein folding pathways. Deeply knotted proteins, whose topologies may introduce substantial barriers to folding, thus represent an interesting test case for protein design. Here we report our attempts to design proteins with trefoil (31) and pentafoil (51) knotted topologies. We extended previously described algorithms for tandem repeat protein design in order to construct deeply knotted backbones and matching designed repeat sequences (N = 3 repeats for the trefoil and N = 5 for the pentafoil). We confirmed the intended conformation for the trefoil design by X ray crystallography, and we report here on this protein's structure, stability, and folding behaviour. The pentafoil design misfolded into an asymmetric structure (despite a 5-fold symmetric sequence); two of the four repeat-repeat units matched the designed backbone while the other two diverged to form local contacts, leading to a trefoil rather than pentafoil knotted topology. Our results also provide insights into the folding of knotted proteins.
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Affiliation(s)
- Lindsey A Doyle
- Division of Basic Sciences, Fred Hutchinson Cancer Center, 1100 Fairview Ave. North, Seattle, WA, 98109, USA
| | - Brittany Takushi
- Division of Basic Sciences, Fred Hutchinson Cancer Center, 1100 Fairview Ave. North, Seattle, WA, 98109, USA
| | - Ryan D Kibler
- Department of Biochemistry, University of Washington, Seattle, WA, 98195, USA
| | - Lukas F Milles
- Department of Biochemistry, University of Washington, Seattle, WA, 98195, USA
| | - Carolina T Orozco
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Jonathan D Jones
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Sophie E Jackson
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Barry L Stoddard
- Division of Basic Sciences, Fred Hutchinson Cancer Center, 1100 Fairview Ave. North, Seattle, WA, 98109, USA.
| | - Philip Bradley
- Division of Basic Sciences, Fred Hutchinson Cancer Center, 1100 Fairview Ave. North, Seattle, WA, 98109, USA.
- Division of Public Health Sciences and Program in Computational Biology, Fred Hutchinson Cancer Center, 1100 Fairview Ave. N, Seattle, WA, 98009, USA.
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10
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Brems MA, Runkel R, Yeates TO, Virnau P. AlphaFold
predicts the most complex protein knot and composite protein knots. Protein Sci 2022; 31:e4380. [PMID: 35900026 PMCID: PMC9278004 DOI: 10.1002/pro.4380] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 06/09/2022] [Accepted: 06/11/2022] [Indexed: 11/06/2022]
Abstract
The computer artificial intelligence system AlphaFold has recently predicted previously unknown three‐dimensional structures of thousands of proteins. Focusing on the subset with high‐confidence scores, we algorithmically analyze these predictions for cases where the protein backbone exhibits rare topological complexity, that is, knotting. Amongst others, we discovered a 71‐knot, the most topologically complex knot ever found in a protein, as well several six‐crossing composite knots comprised of two methyltransferase or carbonic anhydrase domains, each containing a simple trefoil knot. These deeply embedded composite knots occur evidently by gene duplication and interconnection of knotted dimers. Finally, we report two new five‐crossing knots including the first 51‐knot. Our list of analyzed structures forms the basis for future experimental studies to confirm these novel‐knotted topologies and to explore their complex folding mechanisms.
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Affiliation(s)
- Maarten A. Brems
- Department of Physics Johannes Gutenberg University Mainz Mainz Germany
| | - Robert Runkel
- Department of Physics Johannes Gutenberg University Mainz Mainz Germany
| | - Todd O. Yeates
- UCLA‐DOE Institute for Genomics and Proteomics University of California Los Angeles Los Angeles California USA
- UCLA Department of Chemistry and Biochemistry University of California Los Angeles Los Angeles California USA
| | - Peter Virnau
- Department of Physics Johannes Gutenberg University Mainz Mainz Germany
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11
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The protein folding rate and the geometry and topology of the native state. Sci Rep 2022; 12:6384. [PMID: 35430582 PMCID: PMC9013383 DOI: 10.1038/s41598-022-09924-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 03/21/2022] [Indexed: 11/08/2022] Open
Abstract
AbstractProteins fold in 3-dimensional conformations which are important for their function. Characterizing the global conformation of proteins rigorously and separating secondary structure effects from topological effects is a challenge. New developments in applied knot theory allow to characterize the topological characteristics of proteins (knotted or not). By analyzing a small set of two-state and multi-state proteins with no knots or slipknots, our results show that 95.4% of the analyzed proteins have non-trivial topological characteristics, as reflected by the second Vassiliev measure, and that the logarithm of the experimental protein folding rate depends on both the local geometry and the topology of the protein’s native state.
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12
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Blackholly LR, Harris NJ, Findlay HE, Booth PJ. Cell-Free Expression to Probe Co-Translational Insertion of an Alpha Helical Membrane Protein. Front Mol Biosci 2022; 9:795212. [PMID: 35187078 PMCID: PMC8847741 DOI: 10.3389/fmolb.2022.795212] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 01/11/2022] [Indexed: 01/23/2023] Open
Abstract
The majority of alpha helical membrane proteins fold co-translationally during their synthesis on the ribosome. In contrast, most mechanistic folding studies address refolding of full-length proteins from artificially induced denatured states that are far removed from the natural co-translational process. Cell-free translation of membrane proteins is emerging as a useful tool to address folding during translation by a ribosome. We summarise the benefits of this approach and show how it can be successfully extended to a membrane protein with a complex topology. The bacterial leucine transporter, LeuT can be synthesised and inserted into lipid membranes using a variety of in vitro transcription translation systems. Unlike major facilitator superfamily transporters, where changes in lipids can optimise the amount of correctly inserted protein, LeuT insertion yields are much less dependent on the lipid composition. The presence of a bacterial translocon either in native membrane extracts or in reconstituted membranes also has little influence on the yield of LeuT incorporated into the lipid membrane, except at high reconstitution concentrations. LeuT is considered a paradigm for neurotransmitter transporters and possesses a knotted structure that is characteristic of this transporter family. This work provides a method in which to probe the formation of a protein as the polypeptide chain is being synthesised on a ribosome and inserting into lipids. We show that in comparison with the simpler major facilitator transporter structures, LeuT inserts less efficiently into membranes when synthesised cell-free, suggesting that more of the protein aggregates, likely as a result of the challenging formation of the knotted topology in the membrane.
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Affiliation(s)
| | | | | | - Paula J. Booth
- Department of Chemistry, King’s College London, London, United Kingdom
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13
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Slipknot or Crystallographic Error: A Computational Analysis of the Plasmodium falciparum DHFR Structural Folds. Int J Mol Sci 2022; 23:ijms23031514. [PMID: 35163439 PMCID: PMC8835989 DOI: 10.3390/ijms23031514] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/21/2022] [Accepted: 01/25/2022] [Indexed: 01/12/2023] Open
Abstract
The presence of protein structures with atypical folds in the Protein Data Bank (PDB) is rare and may result from naturally occurring knots or crystallographic errors. Proper characterisation of such folds is imperative to understanding the basis of naturally existing knots and correcting crystallographic errors. If left uncorrected, such errors can frustrate downstream experiments that depend on the structures containing them. An atypical fold has been identified in P. falciparum dihydrofolate reductase (PfDHFR) between residues 20–51 (loop 1) and residues 191–205 (loop 2). This enzyme is key to drug discovery efforts in the parasite, necessitating a thorough characterisation of these folds. Using multiple sequence alignments (MSA), a unique insert was identified in loop 1 that exacerbates the appearance of the atypical fold-giving it a slipknot-like topology. However, PfDHFR has not been deposited in the knotted proteins database, and processing its structure failed to identify any knots within its folds. The application of protein homology modelling and molecular dynamics simulations on the DHFR domain of P. falciparum and those of two other organisms (E. coli and M. tuberculosis) that were used as molecular replacement templates in solving the PfDHFR structure revealed plausible unentangled or open conformations of these loops. These results will serve as guides for crystallographic experiments to provide further insights into the atypical folds identified.
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14
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Slipknotted and unknotted monovalent cation-proton antiporters evolved from a common ancestor. PLoS Comput Biol 2021; 17:e1009502. [PMID: 34648493 PMCID: PMC8562792 DOI: 10.1371/journal.pcbi.1009502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 11/02/2021] [Accepted: 09/28/2021] [Indexed: 11/20/2022] Open
Abstract
While the slipknot topology in proteins has been known for over a decade, its evolutionary origin is still a mystery. We have identified a previously overlooked slipknot motif in a family of two-domain membrane transporters. Moreover, we found that these proteins are homologous to several families of unknotted membrane proteins. This allows us to directly investigate the evolution of the slipknot motif. Based on our comprehensive analysis of 17 distantly related protein families, we have found that slipknotted and unknotted proteins share a common structural motif. Furthermore, this motif is conserved on the sequential level as well. Our results suggest that, regardless of topology, the proteins we studied evolved from a common unknotted ancestor single domain protein. Our phylogenetic analysis suggests the presence of at least seven parallel evolutionary scenarios that led to the current diversity of proteins in question. The tools we have developed in the process can now be used to investigate the evolution of other repeated-domain proteins. In proteins with the slipknot topology, the polypeptide chain forms a slipknot—a structure that is not necessarily manifest to a naked eye, but it can be detected using mathematical methods. Slipknots are conserved motifs often found at catalytic sites and are directly involved in molecular transport. Although the first proteins with slipknots were found in 2007, many questions remain unanswered, e.g. how these proteins appeared, or whether the slipknotted proteins evolved from unknotted ones or vice versa. Here we provide the first analysis of homologous slipknotted and unknotted transmembrane proteins in order to elucidate their evolutionary relationship. We show that two-domain slipknotted and unknotted membrane transporters share the same one-domain unknotted protein as an ancestor. The ancestor gene duplicated and underwent various diversification and fusion events during the evolution, which have led to the appearance of a large superfamily of secondary active transporters. The slipknot motif seems to have been created by chance after a fusion of two single domain genes. Therefore, we show here that the slipknotted transporter evolved from an unknotted one-domain protein and that there are at least seven different evolutionary scenarios that gave rise to this large superfamily of transporters.
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15
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A Topological Selection of Folding Pathways from Native States of Knotted Proteins. Symmetry (Basel) 2021. [DOI: 10.3390/sym13091670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Understanding how knotted proteins fold is a challenging problem in biology. Researchers have proposed several models for their folding pathways, based on theory, simulations and experiments. The geometry of proteins with the same knot type can vary substantially and recent simulations reveal different folding behaviour for deeply and shallow knotted proteins. We analyse proteins forming open-ended trefoil knots by introducing a topologically inspired statistical metric that measures their entanglement. By looking directly at the geometry and topology of their native states, we are able to probe different folding pathways for such proteins. In particular, the folding pathway of shallow knotted carbonic anhydrases involves the creation of a double-looped structure, contrary to what has been observed for other knotted trefoil proteins. We validate this with Molecular Dynamics simulations. By leveraging the geometry and local symmetries of knotted proteins’ native states, we provide the first numerical evidence of a double-loop folding mechanism in trefoil proteins.
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16
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Especial JNC, Faísca PFN. A Specific Set of Heterogeneous Native Interactions Yields Efficient Knotting in Protein Folding. J Phys Chem B 2021; 125:7359-7367. [PMID: 34197706 DOI: 10.1021/acs.jpcb.1c03127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Native interactions are crucial for folding, and non-native interactions appear to be critical for efficiently knotting proteins. Therefore, it is important to understand both their roles in the folding of knotted proteins. It has been proposed that non-native interactions drive the correct order of contact formation, which is essential to avoid backtracking and efficiently self-tie. In this study, we ask if non-native interactions are strictly necessary to tangle a protein or if the correct order of contact formation can be assured by a specific set of native, but otherwise heterogeneous (i.e., having distinct energies), interactions. In order to address this problem, we conducted extensive Monte Carlo simulations of lattice models of protein-like sequences designed to fold into a preselected knotted conformation embedding a trefoil knot. We were able to identify a specific set of heterogeneous native interactions that drives efficient knotting and is able to fold the protein when combined with the remaining native interactions modeled as homogeneous. This specific set of heterogeneous native interactions is strictly enough to efficiently self-tie. A distinctive feature of these native interactions is that they do not backtrack because their energies ensure the correct order of contact formation. Furthermore, they stabilize a knotted intermediate state, which is en route to the native structure. Our results thus show that-at least in the context of the adopted model-non-native interactions are not necessary to knot a protein. However, when they are taken into account in protein energetics, it is possible to find specific, nonlocal non-native interactions that operate as a scaffold that assists the knotting step.
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Affiliation(s)
- João N C Especial
- Departamento de Física, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa, Portugal.,BioISI-Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa, Portugal
| | - Patrícia F N Faísca
- Departamento de Física, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa, Portugal.,BioISI-Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa, Portugal
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17
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Dabrowski-Tumanski P, Rubach P, Niemyska W, Gren BA, Sulkowska JI. Topoly: Python package to analyze topology of polymers. Brief Bioinform 2021; 22:bbaa196. [PMID: 32935829 PMCID: PMC8138882 DOI: 10.1093/bib/bbaa196] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/15/2020] [Accepted: 07/29/2020] [Indexed: 12/27/2022] Open
Abstract
The increasing role of topology in (bio)physical properties of matter creates a need for an efficient method of detecting the topology of a (bio)polymer. However, the existing tools allow one to classify only the simplest knots and cannot be used in automated sample analysis. To answer this need, we created the Topoly Python package. This package enables the distinguishing of knots, slipknots, links and spatial graphs through the calculation of different topological polynomial invariants. It also enables one to create the minimal spanning surface on a given loop, e.g. to detect a lasso motif or to generate random closed polymers. It is capable of reading various file formats, including PDB. The extensive documentation along with test cases and the simplicity of the Python programming language make it a very simple to use yet powerful tool, suitable even for inexperienced users. Topoly can be obtained from https://topoly.cent.uw.edu.pl.
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Affiliation(s)
| | | | | | | | - Joanna Ida Sulkowska
- Corresponding author: Joanna Ida Sulkowska, Centre of New Technologies, University of Warsaw, Warsaw, 02-097, Poland; Faculty of Chemistry, University of Warsaw, 02-093, Warsaw, Poland. Tel.: +48-22-55-43678 E-mail:
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18
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Caraglio M, Marcone B, Baldovin F, Orlandini E, Stella AL. Topological Disentanglement of Linear Polymers under Tension. Polymers (Basel) 2020; 12:E2580. [PMID: 33153057 PMCID: PMC7692779 DOI: 10.3390/polym12112580] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 10/30/2020] [Accepted: 10/30/2020] [Indexed: 01/01/2023] Open
Abstract
We develop a theoretical description of the topological disentanglement occurring when torus knots reach the ends of a semiflexible polymer under tension. These include decays into simpler knots and total unknotting. The minimal number of crossings and the minimal knot contour length are the topological invariants playing a key role in the model. The crossings behave as particles diffusing along the chain and the application of appropriate boundary conditions at the ends of the chain accounts for the knot disentanglement. Starting from the number of particles and their positions, suitable rules allow reconstructing the type and location of the knot moving on the chain Our theory is extensively benchmarked with corresponding molecular dynamics simulations and the results show a remarkable agreement between the simulations and the theoretical predictions of the model.
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Affiliation(s)
- Michele Caraglio
- Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 21A, A-6020 Innsbruck, Austria
| | - Boris Marcone
- Istituto Tecnico Economico Tecnologico Statale ‘L. Einaudi’, via Tommaso D’Aquino 8, I-36061 Bassano del Grappa, Italy;
| | - Fulvio Baldovin
- Dipartimento di Fisica e Astronomia and Sezione INFN Università di Padova, Via Marzolo 8, I-35131 Padova, Italy; (F.B.); (E.O.); (A.L.S.)
| | - Enzo Orlandini
- Dipartimento di Fisica e Astronomia and Sezione INFN Università di Padova, Via Marzolo 8, I-35131 Padova, Italy; (F.B.); (E.O.); (A.L.S.)
| | - Attilio L. Stella
- Dipartimento di Fisica e Astronomia and Sezione INFN Università di Padova, Via Marzolo 8, I-35131 Padova, Italy; (F.B.); (E.O.); (A.L.S.)
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19
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Niemyska W, Millett KC, Sulkowska JI. GLN: a method to reveal unique properties of lasso type topology in proteins. Sci Rep 2020; 10:15186. [PMID: 32938999 PMCID: PMC7494857 DOI: 10.1038/s41598-020-71874-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 08/17/2020] [Indexed: 02/02/2023] Open
Abstract
Geometry and topology are the main factors that determine the functional properties of proteins. In this work, we show how to use the Gauss linking integral (GLN) in the form of a matrix diagram-for a pair of a loop and a tail-to study both the geometry and topology of proteins with closed loops e.g. lassos. We show that the GLN method is a significantly faster technique to detect entanglement in lasso proteins in comparison with other methods. Based on the GLN technique, we conduct comprehensive analysis of all proteins deposited in the PDB and compare it to the statistical properties of the polymers. We show how high and low GLN values correlate with the internal exibility of proteins, and how the GLN in the form of a matrix diagram can be used to study folding and unfolding routes. Finally, we discuss how the GLN method can be applied to study entanglement between two structures none of which are closed loops. Since this approach is much faster than other linking invariants, the next step will be evaluation of lassos in much longer molecules such as RNA or loops in a single chromosome.
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Affiliation(s)
- Wanda Niemyska
- Faculty of Mathematics, Informatics and Mechanics, University of Warsaw, Banacha 2, 02-097, Warsaw, Poland
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097, Warsaw, Poland
| | - Kenneth C Millett
- Department of Mathematics, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Joanna I Sulkowska
- 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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20
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Liu Y, Duan Z, Fang J, Zhang F, Xiao J, Zhang WB. Cellular Synthesis and X-ray Crystal Structure of a Designed Protein Heterocatenane. Angew Chem Int Ed Engl 2020; 59:16122-16127. [PMID: 32506656 DOI: 10.1002/anie.202005490] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Indexed: 01/24/2023]
Abstract
Herein, we report the biosynthesis of protein heterocatenanes using a programmed sequence of multiple post-translational processing events including intramolecular chain entanglement, in situ backbone cleavage, and spontaneous cyclization. The approach is general, autonomous, and can obviate the need for any additional enzymes. The catenane topology was convincingly proven using a combination of SDS-PAGE, LC-MS, size exclusion chromatography, controlled proteolytic digestion, and protein crystallography. The X-ray crystal structure clearly shows two mechanically interlocked protein rings with intact folded domains. It opens new avenues in the nascent field of protein-topology engineering.
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Affiliation(s)
- Yajie Liu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry &, Physics of Ministry of Education, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
| | - Zelin Duan
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, P. R. China
| | - Jing Fang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry &, Physics of Ministry of Education, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
| | - Fan Zhang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry &, Physics of Ministry of Education, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
| | - Junyu Xiao
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, P. R. China
| | - Wen-Bin Zhang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry &, Physics of Ministry of Education, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China
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21
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Liu Y, Duan Z, Fang J, Zhang F, Xiao J, Zhang W. Cellular Synthesis and X‐ray Crystal Structure of a Designed Protein Heterocatenane. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202005490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Yajie Liu
- Beijing National Laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry &, Physics of Ministry of Education Center for Soft Matter Science and Engineering College of Chemistry and Molecular Engineering Peking University Beijing 100871 P. R. China
| | - Zelin Duan
- State Key Laboratory of Protein and Plant Gene Research School of Life Sciences Peking-Tsinghua Center for Life Sciences Peking University Beijing 100871 P. R. China
| | - Jing Fang
- Beijing National Laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry &, Physics of Ministry of Education Center for Soft Matter Science and Engineering College of Chemistry and Molecular Engineering Peking University Beijing 100871 P. R. China
| | - Fan Zhang
- Beijing National Laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry &, Physics of Ministry of Education Center for Soft Matter Science and Engineering College of Chemistry and Molecular Engineering Peking University Beijing 100871 P. R. China
| | - Junyu Xiao
- State Key Laboratory of Protein and Plant Gene Research School of Life Sciences Peking-Tsinghua Center for Life Sciences Peking University Beijing 100871 P. R. China
| | - Wen‐Bin Zhang
- Beijing National Laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry &, Physics of Ministry of Education Center for Soft Matter Science and Engineering College of Chemistry and Molecular Engineering Peking University Beijing 100871 P. R. China
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22
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Michieletto D, Orlandini E, Turner MS, Micheletti C. Separation of Geometrical and Topological Entanglement in Confined Polymers Driven out of Equilibrium. ACS Macro Lett 2020; 9:1081-1085. [PMID: 35653213 DOI: 10.1021/acsmacrolett.0c00366] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We use Brownian dynamics simulations and advanced topological profiling methods to characterize the out-of-equilibrium evolution of self-entanglement in linear polymers confined into nanochannels and under periodic compression. By introducing suitable observables, we can distinguish two main forms of entanglement that we term geometrical and topological. The latter is measured by the number of (essential) crossings of the physical knot detected after a suitable bridging of the chain termini. The former is instead measured as the average number of times a linear chain appears to cross itself when viewed under all projections and is irrespective of the physical knotted state. The key discovery of our work is that these two forms of entanglement are uncoupled and evolve with distinct dynamics. While geometrical entanglement is typically in phase with the compression-elongation cycles and it is primarily sensitive to its force f, the topological measure is mildly sensitive to cyclic modulation but strongly depends on both compression force f and duration k. The findings could assist the interpretation of experiments using fluorescence molecular tracers to track physical knots in polymers. Furthermore, we identify optimal regions in the experimentally controllable parameter space in which to obtain more/less topological and geometrical entanglement; this may help designing polymers with targeted topology.
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Affiliation(s)
- Davide Michieletto
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, United Kingdom.,MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, North Crewe Road, Edinburgh, EH4 2XU, United Kingdom
| | - Enzo Orlandini
- Dipartimento di Fisica e Astronomia and Sezione INFN, Universitá degli Studi di Padova, I-35131 Padova, Italy
| | - Matthew S Turner
- Department of Physics and Centre for Complexity Science, University of Warwick, Coventry, CV4 7AL, U.K.,Department of Chemical Engineering, Kyoto University, Kyoto, Japan
| | - Cristian Micheletti
- SISSA (Scuola Internazionale Superiore di Studi Avanzati), Via Bonomea 265, 34136 Trieste, Italy
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23
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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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24
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Rivera M, Hao Y, Maillard RA, Baez M. Mechanical unfolding of a knotted protein unveils the kinetic and thermodynamic consequences of threading a polypeptide chain. Sci Rep 2020; 10:9562. [PMID: 32533020 PMCID: PMC7292828 DOI: 10.1038/s41598-020-66258-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 05/12/2020] [Indexed: 12/21/2022] Open
Abstract
Knots are remarkable topological features in nature. The presence of knots in crystallographic structures of proteins have stimulated considerable research to determine the kinetic and thermodynamic consequences of threading a polypeptide chain. By mechanically manipulating MJ0366, a small single domain protein harboring a shallow trefoil knot, we allow the protein to refold from either the knotted or the unknotted denatured state to characterize the free energy profile associated to both folding pathways. By comparing the stability of the native state with reference to the knotted and unknotted denatured state we find that knotting the polypeptide chain of MJ0366 increase the folding energy barrier in a magnitude close to the energy cost of forming a knot randomly in the denatured state. These results support that a protein knot can be formed during a single cooperative step of folding but occurs at the expenses of a large increment on the free energy barrier.
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Affiliation(s)
- Maira Rivera
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Yuxin Hao
- Department of Chemistry, Georgetown University, Washington, DC, 20057, USA
| | - Rodrigo A Maillard
- Department of Chemistry, Georgetown University, Washington, DC, 20057, USA.
| | - Mauricio Baez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.
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25
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Grønbæk C, Hamelryck T, Røgen P. GISA: using Gauss Integrals to identify rare conformations in protein structures. PeerJ 2020; 8:e9159. [PMID: 32566389 PMCID: PMC7293858 DOI: 10.7717/peerj.9159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 04/18/2020] [Indexed: 12/13/2022] Open
Abstract
The native structure of a protein is important for its function, and therefore methods for exploring protein structures have attracted much research. However, rather few methods are sensitive to topologic-geometric features, the examples being knots, slipknots, lassos, links, and pokes, and with each method aimed only for a specific set of such configurations. We here propose a general method which transforms a structure into a ”fingerprint of topological-geometric values” consisting in a series of real-valued descriptors from mathematical Knot Theory. The extent to which a structure contains unusual configurations can then be judged from this fingerprint. The method is not confined to a particular pre-defined topology or geometry (like a knot or a poke), and so, unlike existing methods, it is general. To achieve this our new algorithm, GISA, as a key novelty produces the descriptors, so called Gauss integrals, not only for the full chains of a protein but for all its sub-chains. This allows fingerprinting on any scale from local to global. The Gauss integrals are known to be effective descriptors of global protein folds. Applying GISA to sets of several thousand high resolution structures, we first show how the most basic Gauss integral, the writhe, enables swift identification of pre-defined geometries such as pokes and links. We then apply GISA with no restrictions on geometry, to show how it allows identifying rare conformations by finding rare invariant values only. In this unrestricted search, pokes and links are still found, but also knotted conformations, as well as more highly entangled configurations not previously described. Thus, an application of the basic scan method in GISA’s tool-box revealed 10 known cases of knots as the top positive writhe cases, while placing at the top of the negative writhe 14 cases in cis-trans isomerases sharing a spatial motif of little secondary structure content, which possibly has gone unnoticed. Possible general applications of GISA are fold classification and structural alignment based on local Gauss integrals. Others include finding errors in protein models and identifying unusual conformations that might be important for protein folding and function. By its broad potential, we believe that GISA will be of general benefit to the structural bioinformatics community. GISA is coded in C and comes as a command line tool. Source and compiled code for GISA plus read-me and examples are publicly available at GitHub (https://github.com).
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Affiliation(s)
- Christian Grønbæk
- Department of Biology, University of Copenhagen, Copenhagen, Denmark.,Current affiliation: Department of Biology, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Hamelryck
- Department of Biology, Department of Computer Science, University of Copenhagen, Copenhagen, Denmark
| | - Peter Røgen
- DTU COMPUTE, Technical University of Denmark, Kgs. Lyngby, Denmark
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26
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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: 36] [Impact Index Per Article: 9.0] [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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27
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Caprice K, Aster A, Cougnon FBL, Kumpulainen T. Untying the Photophysics of Quinolinium-Based Molecular Knots and Links. Chemistry 2020; 26:1576-1587. [PMID: 31670851 DOI: 10.1002/chem.201904456] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 10/30/2019] [Indexed: 01/08/2023]
Abstract
Complex molecular knots and links are still difficult to synthesize and the properties arising from their topology are mostly unknown. Here, we report on a comparative photophysical study carried out on a family of closely related quinolinium-based knots and links to determine the impact exerted by topology on the molecular backbone. Our results indicate that topology has a negligible influence on the behavior of loosely braided molecules, which mostly behave like their unbraided equivalents. On the other hand, tightly braided molecules display distinct features. Their higher packing density results in a pronounced ability to resist deformation, a significant reduction in the solvent-accessible surface area and favors close-range π-π interactions between the quinolinium units and neighboring aromatics. Finally, the sharp alteration in behavior between loosely and tightly braided molecules sheds light on the factors contributing to braiding tightness.
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Affiliation(s)
- Kenji Caprice
- Department of Organic Chemistry, University of Geneva, 30 Quai Ernest Ansermet, Geneva, Switzerland
| | - Alexander Aster
- Department of Physical Chemistry, University of Geneva, 30 Quai Ernest Ansermet, Geneva, Switzerland
| | - Fabien B L Cougnon
- Department of Organic Chemistry, University of Geneva, 30 Quai Ernest Ansermet, Geneva, Switzerland
| | - Tatu Kumpulainen
- Department of Physical Chemistry, University of Geneva, 30 Quai Ernest Ansermet, Geneva, Switzerland
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28
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Chromatin Is Frequently Unknotted at the Megabase Scale. Biophys J 2019; 118:2268-2279. [PMID: 31818464 PMCID: PMC7202934 DOI: 10.1016/j.bpj.2019.11.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/03/2019] [Accepted: 11/05/2019] [Indexed: 11/20/2022] Open
Abstract
Knots in the human genome would greatly impact diverse cellular processes ranging from transcription to gene regulation. To date, it has not been possible to directly examine the genome in vivo for the presence of knots. Recently, methods for serial fluorescent in situ hybridization have made it possible to measure the three-dimensional position of dozens of consecutive genomic loci in vivo. However, the determination of whether genomic trajectories are knotted remains challenging because small errors in the localization of a single locus can transform an unknotted trajectory into a highly knotted trajectory and vice versa. Here, we use stochastic closure analysis to determine if a genomic trajectory is knotted in the setting of experimental noise. We analyze 4727 deposited genomic trajectories of a 2-Mb-long chromatin interval from human chromosome 21. For 243 of these trajectories, their knottedness could be reliably determined despite the possibility of localization errors. Strikingly, in each of these 243 cases, the trajectory was unknotted. We note a potential source of bias insofar as knotted contours may be more difficult to reliably resolve. Nevertheless, our data are consistent with a model in which, at the scales probed, the human genome is often free of knots.
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Perego C, Potestio R. Computational methods in the study of self-entangled proteins: a critical appraisal. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:443001. [PMID: 31269476 DOI: 10.1088/1361-648x/ab2f19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The existence of self-entangled proteins, the native structure of which features a complex topology, unveils puzzling, and thus fascinating, aspects of protein biology and evolution. The discovery that a polypeptide chain can encode the capability to self-entangle in an efficient and reproducible way during folding, has raised many questions, regarding the possible function of these knots, their conservation along evolution, and their role in the folding paradigm. Understanding the function and origin of these entanglements would lead to deep implications in protein science, and this has stimulated the scientific community to investigate self-entangled proteins for decades by now. In this endeavour, advanced experimental techniques are more and more supported by computational approaches, that can provide theoretical guidelines for the interpretation of experimental results, and for the effective design of new experiments. In this review we provide an introduction to the computational study of self-entangled proteins, focusing in particular on the methodological developments related to this research field. A comprehensive collection of techniques is gathered, ranging from knot theory algorithms, that allow detection and classification of protein topology, to Monte Carlo or molecular dynamics strategies, that constitute crucial instruments for investigating thermodynamics and kinetics of this class of proteins.
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Affiliation(s)
- Claudio Perego
- Max Panck Institute for Polymer Research, Ackermannweg 10, Mainz 55128, Germany
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30
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Dorier J, Goundaroulis D, Benedetti F, Stasiak A. Knoto-ID: a tool to study the entanglement of open protein chains using the concept of knotoids. Bioinformatics 2019; 34:3402-3404. [PMID: 29722808 DOI: 10.1093/bioinformatics/bty365] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 05/01/2018] [Indexed: 11/13/2022] Open
Abstract
Summary The backbone of most proteins forms an open curve. To study their entanglement, a common strategy consists in searching for the presence of knots in their backbones using topological invariants. However, this approach requires to close the curve into a loop, which alters the geometry of curve. Knoto-ID allows evaluating the entanglement of open curves without the need to close them, using the recent concept of knotoids which is a generalization of the classical knot theory to open curves. Knoto-ID can analyse the global topology of the full chain as well as the local topology by exhaustively studying all subchains or only determining the knotted core. Knoto-ID permits to localize topologically non-trivial protein folds that are not detected by informatics tools detecting knotted protein folds. Availability and implementation Knoto-ID is written in C++ and includes R (www.R-project.org) scripts to generate plots of projections maps, fingerprint matrices and disk matrices. Knoto-ID is distributed under the GNU General Public License (GPL), version 2 or any later version and is available at https://github.com/sib-swiss/Knoto-ID. A binary distribution for Mac OS X, Linux and Windows with detailed user guide and examples can be obtained from https://www.vital-it.ch/software/Knoto-ID.
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Affiliation(s)
- Julien Dorier
- Vital-IT, SIB Swiss Institute of Bioinformatics, Lausanne, Switzerland.,Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Dimos Goundaroulis
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland.,SIB Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Fabrizio Benedetti
- Vital-IT, SIB Swiss Institute of Bioinformatics, Lausanne, Switzerland.,Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Andrzej Stasiak
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland.,SIB Swiss Institute of Bioinformatics, Lausanne, Switzerland
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31
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Xu Y, Li S, Yan Z, Ge B, Huang F, Yue T. Revealing Cooperation between Knotted Conformation and Dimerization in Protein Stabilization by Molecular Dynamics Simulations. J Phys Chem Lett 2019; 10:5815-5822. [PMID: 31525988 DOI: 10.1021/acs.jpclett.9b02209] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The topological knot is thought to play a stabilizing role in maintaining the global fold and nature of proteins with the underlying mechanism yet to be elucidated. Given that most proteins containing trefoil knots exist and function as homodimers with a large part of the dimer interface occupied by the knotted region, we reason that the knotted conformation cooperates with dimerization in protein stabilization. Here, we take YbeA from Escherichia coli as the knotted protein model, using molecular dynamics (MD) simulations to compare the stability of two pairs of dimeric proteins having the same sequence and secondary structures but differing in the presence or absence of a trefoil knot in each subunit. The dimer interface of YbeA is identified to involve favorable contacts among three α-helices (α1, α3, and α5), one of which (α5) is threaded through a loop connected with α3 to form the knot. Upon removal of the knot by appropriate change of the knot-making crossing of the polypeptide chain, relevant domains are less constrained and exhibit enhanced fluctuations to decrease contacts at the interface. Unknotted subunits are less compact and undergo structural changes to ease the dimer separation. Such a stabilizing effect is evidenced by steered MD simulations, showing that the mechanical force required for dimer separation is significantly reduced by removing the knot. In addition to the knotted conformation, dimerization further improves the protein stability by restricting the α1-α5 separation, which is defined as a leading step for protein unfolding. These results provide important insights into the structure-function relationship of dimerization in knotted proteins.
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Affiliation(s)
- Yan Xu
- State Key Laboratory of Heavy Oil Processing, Center for Bioengineering and Biotechnology, College of Chemical Engineering , China University of Petroleum (East China) , Qingdao 266580 , China
- College of Electronic Engineering and Automation , Shandong University of Science and Technology , Qingdao 266590 , China
| | - Shixin Li
- State Key Laboratory of Heavy Oil Processing, Center for Bioengineering and Biotechnology, College of Chemical Engineering , China University of Petroleum (East China) , Qingdao 266580 , China
| | - Zengshuai Yan
- State Key Laboratory of Heavy Oil Processing, Center for Bioengineering and Biotechnology, College of Chemical Engineering , China University of Petroleum (East China) , Qingdao 266580 , China
| | - Baosheng Ge
- State Key Laboratory of Heavy Oil Processing, Center for Bioengineering and Biotechnology, College of Chemical Engineering , China University of Petroleum (East China) , Qingdao 266580 , China
| | - Fang Huang
- State Key Laboratory of Heavy Oil Processing, Center for Bioengineering and Biotechnology, College of Chemical Engineering , China University of Petroleum (East China) , Qingdao 266580 , China
| | - Tongtao Yue
- State Key Laboratory of Heavy Oil Processing, Center for Bioengineering and Biotechnology, College of Chemical Engineering , China University of Petroleum (East China) , Qingdao 266580 , China
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32
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PconsFam: An Interactive Database of Structure Predictions of Pfam Families. J Mol Biol 2019; 431:2442-2448. [DOI: 10.1016/j.jmb.2019.01.047] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 01/30/2019] [Accepted: 01/31/2019] [Indexed: 11/17/2022]
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33
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Caraglio M, Baldovin F, Marcone B, Orlandini E, Stella AL. Topological Disentanglement Dynamics of Torus Knots on Open Linear Polymers. ACS Macro Lett 2019; 8:576-581. [PMID: 35619367 DOI: 10.1021/acsmacrolett.9b00055] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We simulate and study the topological disentanglement occurring when torus knots reach the ends of a semiflexible open polymer (decay into simpler knots or unknotting). Through a rescaling procedure and the application of appropriate boundary conditions, we show that the full unknotting process can be understood in terms of point-like particles representing essential crossings, diffusing on the support [0, 1]. We address the bending and configurational free energy drives on the diffusion process, together with the scaling properties of the effective diffusion and friction coefficients. Agreement with simulations suggests universal features for these two model parameters.
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Affiliation(s)
- Michele Caraglio
- KU Leuven, Soft Matter and Biophysics Section, Celestijnenlaan 200D, 3001 Leuven, Belgium
- Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 21A, A-6020 Innsbruck, Austria
| | - Fulvio Baldovin
- Department of Physics and Astronomy, University of Padova, Via Marzolo 8, I-35131 Padova, Italy
- INFN, Sezione di Padova, Via Marzolo 8, I-35131 Padova, Italy
| | - Boris Marcone
- Center of Excellence for Stability Police Units, via Medici 87, 36100 Vicenza, Italy
| | - Enzo Orlandini
- Department of Physics and Astronomy, University of Padova, Via Marzolo 8, I-35131 Padova, Italy
- INFN, Sezione di Padova, Via Marzolo 8, I-35131 Padova, Italy
| | - Attilio L. Stella
- Department of Physics and Astronomy, University of Padova, Via Marzolo 8, I-35131 Padova, Italy
- INFN, Sezione di Padova, Via Marzolo 8, I-35131 Padova, Italy
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34
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Abstract
How knotted proteins fold has remained controversial since the identification of deeply knotted proteins nearly two decades ago. Both computational and experimental approaches have been used to investigate protein knot formation. Motivated by the computer simulations of Bölinger et al. [Bölinger D, et al. (2010) PLoS Comput Biol 6:e1000731] for the folding of the [Formula: see text]-knotted α-haloacid dehalogenase (DehI) protein, we introduce a topological description of knot folding that could describe pathways for the formation of all currently known protein knot types and predicts knot types that might be identified in the future. We analyze fingerprint data from crystal structures of protein knots as evidence that particular protein knots may fold according to specific pathways from our theory. Our results confirm Taylor's twisted hairpin theory of knot folding for the [Formula: see text]-knotted proteins and the [Formula: see text]-knotted ketol-acid reductoisomerases and present alternative folding mechanisms for the [Formula: see text]-knotted phytochromes and the [Formula: see text]- and [Formula: see text]-knotted proteins.
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35
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Zhang L, Lemonnier JF, Acocella A, Calvaresi M, Zerbetto F, Leigh DA. Effects of knot tightness at the molecular level. Proc Natl Acad Sci U S A 2019; 116:2452-2457. [PMID: 30683725 PMCID: PMC6377497 DOI: 10.1073/pnas.1815570116] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Three 819 knots in closed-loop strands of different lengths (∼20, 23, and 26 nm) were used to experimentally assess the consequences of knot tightness at the molecular level. Through the use of 1H NMR, diffusion-ordered spectroscopy (DOSY), circular dichroism (CD), collision-induced dissociation mass spectrometry (CID-MS) and molecular dynamics (MD) simulations on the different-sized knots, we find that the structure, dynamics, and reactivity of the molecular chains are dramatically affected by the tightness of the knotting. The tautness of entanglement causes differences in conformation, enhances the expression of topological chirality, weakens covalent bonds, inhibits decomplexation events, and changes absorption properties. Understanding the effects of tightening nanoscale knots may usefully inform the design of knotted and entangled molecular materials.
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Affiliation(s)
- Liang Zhang
- School of Chemistry and Molecular Engineering, East China Normal University, 200062 Shanghai, China
- School of Chemistry, University of Manchester, M13 9PL Manchester, United Kingdom
| | | | - Angela Acocella
- Dipartimento di Chimica "G. Ciamician", Università di Bologna, 40126 Bologna, Italy
| | - Matteo Calvaresi
- Dipartimento di Chimica "G. Ciamician", Università di Bologna, 40126 Bologna, Italy
| | - Francesco Zerbetto
- Dipartimento di Chimica "G. Ciamician", Università di Bologna, 40126 Bologna, Italy
| | - David A Leigh
- School of Chemistry and Molecular Engineering, East China Normal University, 200062 Shanghai, China;
- School of Chemistry, University of Manchester, M13 9PL Manchester, United Kingdom
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36
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Dabrowski-Tumanski P, Rubach P, Goundaroulis D, Dorier J, Sułkowski P, Millett KC, Rawdon EJ, Stasiak A, Sulkowska JI. KnotProt 2.0: a database of proteins with knots and other entangled structures. Nucleic Acids Res 2019; 47:D367-D375. [PMID: 30508159 PMCID: PMC6323932 DOI: 10.1093/nar/gky1140] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 10/24/2018] [Accepted: 11/30/2018] [Indexed: 01/08/2023] Open
Abstract
The KnotProt 2.0 database (the updated version of the KnotProt database) collects information about proteins which form knots and other entangled structures. New features in KnotProt 2.0 include the characterization of both probabilistic and deterministic entanglements which can be formed by disulfide bonds and interactions via ions, a refined characterization of entanglement in terms of knotoids, the identification of the so-called cysteine knots, the possibility to analyze all or a non-redundant set of proteins, and various technical updates. The KnotProt 2.0 database classifies all entangled proteins, represents their complexity in the form of a knotting fingerprint, and presents many biological and geometrical statistics based on these results. Currently the database contains >2000 entangled structures, and it regularly self-updates based on proteins deposited in the Protein Data Bank (PDB).
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Affiliation(s)
- Pawel Dabrowski-Tumanski
- Faculty of Chemistry, University of Warsaw, Pasteura 1, Warsaw, Poland
- Centre of New Technologies, University of Warsaw, Banacha 2c, Warsaw, Poland
| | - Pawel Rubach
- Centre of New Technologies, University of Warsaw, Banacha 2c, Warsaw, Poland
- Warsaw School of Economics, Al. Niepodlegosci 162, Warsaw, Poland
| | - Dimos Goundaroulis
- Center for Integrative Genomics, University of Lausanne, 1015-Lausanne, Switzerland, SIB Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Julien Dorier
- Vital-IT, SIB Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Piotr Sułkowski
- Faculty of Physics, University of Warsaw, Pasteura 5, Warsaw, Poland
- Walter Burke Institute for Theoretical Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Kenneth C Millett
- Department of Mathematics, University of California, Santa Barbara, CA 93106, USA
| | - Eric J Rawdon
- Department of Mathematics, University of St. Thomas, Saint Paul, MN 55105, USA
| | - Andrzej Stasiak
- Center for Integrative Genomics, University of Lausanne, 1015-Lausanne, Switzerland, SIB Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Joanna I Sulkowska
- Faculty of Chemistry, University of Warsaw, Pasteura 1, Warsaw, Poland
- Centre of New Technologies, University of Warsaw, Banacha 2c, Warsaw, Poland
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37
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38
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Jarmolinska AI, Perlinska AP, Runkel R, Trefz B, Ginn HM, Virnau P, Sulkowska JI. Proteins' Knotty Problems. J Mol Biol 2018; 431:244-257. [PMID: 30391297 DOI: 10.1016/j.jmb.2018.10.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 10/17/2018] [Accepted: 10/17/2018] [Indexed: 12/20/2022]
Abstract
Knots in proteins are increasingly being recognized as an important structural concept, and the folding of these peculiar structures still poses considerable challenges. From a functional point of view, most protein knots discovered so far are either enzymes or DNA-binding proteins. Our comprehensive topological analysis of the Protein Data Bank reveals several novel structures including knotted mitochondrial proteins and the most deeply embedded protein knot discovered so far. For the latter, we propose a novel folding pathway based on the idea that a loose knot forms at a terminus and slides to its native position. For the mitochondrial proteins, we discuss the folding problem from the perspective of transport and suggest that they fold inside the mitochondria. We also discuss the evolutionary origin of a novel class of knotted membrane proteins and argue that a novel knotted DNA-binding protein constitutes a new fold. Finally, we have also discovered a knot in an artificially designed protein structure.
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Affiliation(s)
- Aleksandra I Jarmolinska
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland; College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, Banacha 2c, 02-097 Warsaw, Poland
| | - Agata P Perlinska
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland; College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, Banacha 2c, 02-097 Warsaw, Poland
| | - Robert Runkel
- Department of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - Benjamin Trefz
- Department of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany; Graduate School Material Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany
| | - Helen M Ginn
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Peter Virnau
- Department of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - Joanna I Sulkowska
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland.
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39
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Dabrowski-Tumanski P, Piejko M, Niewieczerzal S, Stasiak A, Sulkowska JI. Protein Knotting by Active Threading of Nascent Polypeptide Chain Exiting from the Ribosome Exit Channel. J Phys Chem B 2018; 122:11616-11625. [PMID: 30198720 DOI: 10.1021/acs.jpcb.8b07634] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The mechanism of folding of deeply knotted proteins into their native structure is still not understood. Current thinking about protein folding is dominated by the Anfinsen dogma, stating that the structure of the folded proteins is uniquely dictated by the amino acid sequence of a given protein and that the folding is driven uniquely by the energy gained from interactions between amino acids that contact each other in the native structure of the protein. The role of ribosomes in protein folding was only seen as permitting the folding to progress from the N-terminal part of nascent protein chains. We propose here that ribosomes can participate actively in the folding of knotted proteins by actively threading nascent chains emerging from the ribosome exit channels through loops formed by a synthesized earlier portion of the same protein. Our simulations of folding of deeply knotted protein Tp0624 positively verify the proposed ribosome-driven active threading mechanism leading to the formation of deeply knotted proteins.
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Affiliation(s)
- Pawel Dabrowski-Tumanski
- Faculty of Chemistry , University of Warsaw , Pasteura 1 , 02-093 , Warsaw , Poland.,Centre of New Technologies , University of Warsaw , Banacha 2c , 02-097 , Warsaw , Poland
| | - Maciej Piejko
- Faculty of Chemistry , University of Warsaw , Pasteura 1 , 02-093 , Warsaw , Poland.,Centre of New Technologies , University of Warsaw , Banacha 2c , 02-097 , Warsaw , Poland
| | - Szymon Niewieczerzal
- Centre of New Technologies , University of Warsaw , Banacha 2c , 02-097 , Warsaw , Poland
| | - Andrzej Stasiak
- Center for Integrative Genomics , University of Lausanne , 1015 Lausanne , Switzerland.,Swiss Institute of Bioinformatics , 1015 Lausanne , Switzerland
| | - Joanna I Sulkowska
- Faculty of Chemistry , University of Warsaw , Pasteura 1 , 02-093 , Warsaw , Poland.,Centre of New Technologies , University of Warsaw , Banacha 2c , 02-097 , Warsaw , Poland
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40
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41
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Wang XW, Zhang WB. Chemical Topology and Complexity of Protein Architectures. Trends Biochem Sci 2018; 43:806-817. [DOI: 10.1016/j.tibs.2018.07.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 07/01/2018] [Accepted: 07/03/2018] [Indexed: 12/16/2022]
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42
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Sulkowska JI, Niewieczerzal S, Jarmolinska AI, Siebert JT, Virnau P, Niemyska W. KnotGenome: a server to analyze entanglements of chromosomes. Nucleic Acids Res 2018; 46:W17-W24. [PMID: 29905836 PMCID: PMC6030981 DOI: 10.1093/nar/gky511] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 05/05/2018] [Accepted: 05/23/2018] [Indexed: 02/03/2023] Open
Abstract
The KnotGenome server enables the topological analysis of chromosome model data using three-dimensional coordinate files of chromosomes as input. In particular, it detects prime and composite knots in single chromosomes, and links between chromosomes. The knotting complexity of the chromosome is presented in the form of a matrix diagram that reveals the knot type of the entire polynucleotide chain and of each of its subchains. Links are determined by means of the Gaussian linking integral and the HOMFLY-PT polynomial. Entangled chromosomes are presented graphically in an intuitive way. It is also possible to relax structure with short molecular dynamics runs before the analysis. KnotGenome is freely available at http://knotgenom.cent.uw.edu.pl/.
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Affiliation(s)
- Joanna I Sulkowska
- 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
| | - Szymon Niewieczerzal
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
| | - Aleksandra I Jarmolinska
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
- College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
| | - Jonathan T Siebert
- Johannes Gutenberg-Universität Mainz, Institut für Physik, Staudingerweg 9, Mainz, 55128, Germany
| | - Peter Virnau
- Johannes Gutenberg-Universität Mainz, Institut für Physik, Staudingerweg 9, Mainz, 55128, Germany
| | - Wanda Niemyska
- Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
- Faculty of Mathematics, Informatics and Mechanics, University of Warsaw, Banacha 2, 02-097 Warsaw, Poland
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43
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Jarmolinska AI, Kadlof M, Dabrowski-Tumanski P, Sulkowska JI. GapRepairer: a server to model a structural gap and validate it using topological analysis. Bioinformatics 2018; 34:3300-3307. [DOI: 10.1093/bioinformatics/bty334] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 04/27/2018] [Indexed: 02/07/2023] Open
Affiliation(s)
- Aleksandra I Jarmolinska
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
- College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, Warsaw, Poland
| | - Michal Kadlof
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
- Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - Pawel Dabrowski-Tumanski
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
- Faculty of Chemistry, University of Warsaw, Warsaw, Poland
| | - Joanna I Sulkowska
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
- Faculty of Chemistry, University of Warsaw, Warsaw, Poland
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44
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Soler MA, Rey A, Faísca PFN. Steric confinement and enhanced local flexibility assist knotting in simple models of protein folding. Phys Chem Chem Phys 2018; 18:26391-26403. [PMID: 27722468 DOI: 10.1039/c6cp05086g] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The chaperonin complex GroEL-GroES is able to accelerate the folding process of knotted proteins considerably. However, the folding mechanism inside the chaperonin cage is elusive. Here we use a combination of lattice and off-lattice Monte Carlo simulations of simple Gō models to study the effect of physical confinement and local flexibility on the folding process of protein model systems embedding a trefoil knot in their native structure. This study predicts that steric confinement plays a specific role in the folding of knotted proteins by increasing the knotting probability for very high degrees of confinement. This effect is observed for protein MJ0366 even above the melting temperature for confinement sizes compatible with the size of the GroEL/GroES chaperonin cage. An enhanced local flexibility produces the same qualitative effects on the folding process. In particular, we observe that knotting probability increases up to 40% in the transition state of protein MJ0366 when flexibility is enhanced. This is underlined by a structural change in the transition state, which becomes devoid of helical content. No relation between the knotting mechanism and flexibility was found in the context of the off-lattice model adopted in this work.
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Affiliation(s)
- Miguel A Soler
- Dipartimento di Scienze Mediche e Biologiche, Universita' di Udine, Piazzale Kolbe 4, 33100 Udine, Italy
| | - Antonio Rey
- Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid, Spain.
| | - Patrícia F N Faísca
- Departamento de Física and BioISI - Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Ed. C8, 1749-016 Lisboa, Portugal.
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45
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Sulkowska JI, Sułkowski P. Entangled Proteins: Knots, Slipknots, Links, and Lassos. SPRINGER SERIES IN SOLID-STATE SCIENCES 2018. [DOI: 10.1007/978-3-319-76596-9_8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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46
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47
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Dabrowski-Tumanski P, Sulkowska JI. To Tie or Not to Tie? That Is the Question. Polymers (Basel) 2017; 9:E454. [PMID: 30965758 PMCID: PMC6418553 DOI: 10.3390/polym9090454] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Revised: 09/11/2017] [Accepted: 09/12/2017] [Indexed: 12/18/2022] Open
Abstract
In this review, we provide an overview of entangled proteins. Around 6% of protein structures deposited in the PBD are entangled, forming knots, slipknots, lassos and links. We present theoretical methods and tools that enabled discovering and classifying such structures. We discuss the advantages and disadvantages of the non-trivial topology in proteins, based on available data about folding, stability, biological properties and evolutionary conservation. We also formulate intriguing and challenging questions on the border of biophysics, bioinformatics, biology and mathematics, which arise from the discovery of an entanglement in proteins. Finally, we discuss possible applications of entangled proteins in medicine and nanotechnology, such as the chance to design super stable proteins, whose stability could be controlled by chemical potential.
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Affiliation(s)
- Pawel Dabrowski-Tumanski
- Centre of New Technologies, University of Warsaw, Warsaw 02-097, Poland.
- Faculty of Chemistry, University of Warsaw, Warsaw 02-093, Poland.
| | - Joanna I Sulkowska
- Centre of New Technologies, University of Warsaw, Warsaw 02-097, Poland.
- Faculty of Chemistry, University of Warsaw, Warsaw 02-093, Poland.
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Goundaroulis D, Dorier J, Benedetti F, Stasiak A. Studies of global and local entanglements of individual protein chains using the concept of knotoids. Sci Rep 2017; 7:6309. [PMID: 28740166 PMCID: PMC5524787 DOI: 10.1038/s41598-017-06649-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 06/20/2017] [Indexed: 11/23/2022] Open
Abstract
We study here global and local entanglements of open protein chains by implementing the concept of knotoids. Knotoids have been introduced in 2012 by Vladimir Turaev as a generalization of knots in 3-dimensional space. More precisely, knotoids are diagrams representing projections of open curves in 3D space, in contrast to knot diagrams which represent projections of closed curves in 3D space. The intrinsic difference with classical knot theory is that the generalization provided by knotoids admits non-trivial topological entanglement of the open curves provided that their geometry is frozen as it is the case for crystallized proteins. Consequently, our approach doesn’t require the closure of chains into loops which implies that the geometry of analysed chains does not need to be changed by closure in order to characterize their topology. Our study revealed that the knotoid approach detects protein regions that were classified earlier as knotted and also new, topologically interesting regions that we classify as pre-knotted.
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Affiliation(s)
- Dimos Goundaroulis
- Center for Integrative Genomics, University of Lausanne, 1015, Lausanne, Switzerland.,Swiss Institute of Bioinformatics, 1015, Lausanne, Switzerland
| | - Julien Dorier
- Center for Integrative Genomics, University of Lausanne, 1015, Lausanne, Switzerland.,Vital-IT, SIB Swiss Institute of Bioinformatics, 1015, Lausanne, Switzerland
| | - Fabrizio Benedetti
- Center for Integrative Genomics, University of Lausanne, 1015, Lausanne, Switzerland.,Vital-IT, SIB Swiss Institute of Bioinformatics, 1015, Lausanne, Switzerland
| | - Andrzej Stasiak
- Center for Integrative Genomics, University of Lausanne, 1015, Lausanne, Switzerland. .,Swiss Institute of Bioinformatics, 1015, Lausanne, Switzerland.
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Abstract
Twenty years after their discovery, knots in proteins are now quite well understood. They are believed to be functionally advantageous and provide extra stability to protein chains. In this work, we go one step further and search for links-entangled structures, more complex than knots, which consist of several components. We derive conditions that proteins need to meet to be able to form links. We search through the entire Protein Data Bank and identify several sequentially nonhomologous chains that form a Hopf link and a Solomon link. We relate topological properties of these proteins to their function and stability and show that the link topology is characteristic of eukaryotes only. We also explain how the presence of links affects the folding pathways of proteins. Finally, we define necessary conditions to form Borromean rings in proteins and show that no structure in the Protein Data Bank forms a link of this type.
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Affiliation(s)
- Pawel Dabrowski-Tumanski
- Faculty of Chemistry, University of Warsaw, 02-093, Warsaw, Poland
- Centre of New Technologies, University of Warsaw, 02-097, Warsaw, Poland
| | - Joanna I Sulkowska
- Faculty of Chemistry, University of Warsaw, 02-093, Warsaw, Poland;
- Centre of New Technologies, University of Warsaw, 02-097, Warsaw, Poland
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Cao PF, Rong LH, Mangadlao JD, Advincula RC. Synthesizing a Trefoil Knotted Block Copolymer via Ring-Expansion Strategy. Macromolecules 2017. [DOI: 10.1021/acs.macromol.6b02029] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Peng-Fei Cao
- Chemical
Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
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