1
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Thakuria S, Paul S. Salt-bridge mediated conformational dynamics in the figure-of-eight knotted ketol acid reductoisomerase (KARI). Phys Chem Chem Phys 2024; 26:24963-24974. [PMID: 39297222 DOI: 10.1039/d4cp02677b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2024]
Abstract
The utility of knotted proteins in biological activities has been ambiguous since their discovery. From their evolutionary significance to their functionality in stabilizing the native protein structure, a unilateral conclusion hasn't been achieved yet. While most studies have been performed to understand the stabilizing effect of the knotted fold on the protein chain, more ideas are yet to emerge regarding the interactions in stabilizing the knot. Using classical molecular dynamics (MD) simulations, we have explored the dynamics of the figure-of-eight knotted domain present in ketol acid reductoisomerase (KARI). Our main focus was on the presence of a salt bridge network evident within the knotted region and its role in shaping the conformational dynamics of the knotted chain. Through the potential of mean forces (PMFs) calculation, we have also marked the specific salt bridges that are pivotal in stabilizing the knotted structure. The correlated motions have been further monitored with the help of principal component analysis (PCA) and dynamic cross-correlation maps (DCCM). Furthermore, mutation of the specific salt bridges led to a change in their conformational stability, vindicating their importance.
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Affiliation(s)
- Sanjib Thakuria
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam, 781039, India.
| | - Sandip Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam, 781039, India.
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2
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Ferreira SGF, Sriramoju MK, Hsu STD, Faísca PFN, Machuqueiro M. Is There a Functional Role for the Knotted Topology in Protein UCH-L1? J Chem Inf Model 2024; 64:6827-6837. [PMID: 39045738 PMCID: PMC11388461 DOI: 10.1021/acs.jcim.4c00880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2024]
Abstract
Knotted proteins are present in nature, but there is still an open issue regarding the existence of a universal role for these remarkable structures. To address this question, we used classical molecular dynamics (MD) simulations combined with in vitro experiments to investigate the role of the Gordian knot in the catalytic activity of UCH-L1. To create an unknotted form of UCH-L1, we modified its amino acid sequence by truncating several residues from its N-terminus. Remarkably, we find that deleting the first two N-terminal residues leads to a partial loss of enzyme activity with conservation of secondary structural content and knotted topological state. This happens because the integrity of the N-terminus is critical to ensure the correct alignment of the catalytic triad. However, the removal of five residues from the N-terminus, which significantly disrupts the native structure and the topological state, leads to a complete loss of enzymatic activity. Overall, our findings indicate that UCH-L1's catalytic activity depends critically on the integrity of the N-terminus and the secondary structure content, with the latter being strongly coupled with the knotted topological state.
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Affiliation(s)
- Sara G F Ferreira
- BioISI - Instituto de Biossistemas e Ciências Integrativas, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Manoj K Sriramoju
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Shang-Te Danny Hsu
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM2), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Institute of Biochemical Sciences, National Taiwan University, Taipei 11529, Taiwan
| | - Patrícia F N Faísca
- BioISI - Instituto de Biossistemas e Ciências Integrativas, Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Miguel Machuqueiro
- BioISI - Instituto de Biossistemas e Ciências Integrativas, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
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3
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Hsu MF, Sriramoju MK, Lai CH, Chen YR, Huang JS, Ko TP, Huang KF, Hsu STD. Structure, dynamics, and stability of the smallest and most complex 7 1 protein knot. J Biol Chem 2024; 300:105553. [PMID: 38072060 PMCID: PMC10840475 DOI: 10.1016/j.jbc.2023.105553] [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: 06/29/2023] [Revised: 11/21/2023] [Accepted: 12/04/2023] [Indexed: 12/29/2023] Open
Abstract
Proteins can spontaneously tie a variety of intricate topological knots through twisting and threading of the polypeptide chains. Recently developed artificial intelligence algorithms have predicted several new classes of topological knotted proteins, but the predictions remain to be authenticated experimentally. Here, we showed by X-ray crystallography and solution-state NMR spectroscopy that Q9PR55, an 89-residue protein from Ureaplasma urealyticum, possesses a novel 71 knotted topology that is accurately predicted by AlphaFold 2, except for the flexible N terminus. Q9PR55 is monomeric in solution, making it the smallest and most complex knotted protein known to date. In addition to its exceptional chemical stability against urea-induced unfolding, Q9PR55 is remarkably robust to resist the mechanical unfolding-coupled proteolysis by a bacterial proteasome, ClpXP. Our results suggest that the mechanical resistance against pulling-induced unfolding is determined by the complexity of the knotted topology rather than the size of the molecule.
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Affiliation(s)
- Min-Feng Hsu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | | | - Chih-Hsuan Lai
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yun-Ru Chen
- Academia Sinica Protein Clinic, Academia Sinica, Taipei, Taiwan
| | - Jing-Siou Huang
- Academia Sinica Protein Clinic, Academia Sinica, Taipei, Taiwan
| | - Tzu-Ping Ko
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Kai-Fa Huang
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Academia Sinica Protein Clinic, Academia Sinica, Taipei, Taiwan
| | - Shang-Te Danny Hsu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Academia Sinica Protein Clinic, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan; International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM(2)), Hiroshima University, Higashihiroshima, Japan.
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4
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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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5
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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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6
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Halder R, Nissley DA, Sitarik I, Jiang Y, Rao Y, Vu QV, Li MS, Pritchard J, O'Brien EP. How soluble misfolded proteins bypass chaperones at the molecular level. Nat Commun 2023; 14:3689. [PMID: 37344452 DOI: 10.1038/s41467-023-38962-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 05/24/2023] [Indexed: 06/23/2023] Open
Abstract
Subpopulations of soluble, misfolded proteins can bypass chaperones within cells. The extent of this phenomenon and how it happens at the molecular level are unknown. Through a meta-analysis of the experimental literature we find that in all quantitative protein refolding studies there is always a subpopulation of soluble but misfolded protein that does not fold in the presence of one or more chaperones, and can take days or longer to do so. Thus, some misfolded subpopulations commonly bypass chaperones. Using multi-scale simulation models we observe that the misfolded structures that bypass various chaperones can do so because their structures are highly native like, leading to a situation where chaperones do not distinguish between the folded and near-native-misfolded states. More broadly, these results provide a mechanism by which long-time scale changes in protein structure and function can persist in cells because some misfolded states can bypass components of the proteostasis machinery.
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Affiliation(s)
- Ritaban Halder
- Department of Chemistry, Pennsylvania State University, University Park, PA, 16802, USA
| | - Daniel A Nissley
- Department of Chemistry, Pennsylvania State University, University Park, PA, 16802, USA
- Department of Statistics, University of Oxford, Oxford, OX1 3LB, UK
| | - Ian Sitarik
- Department of Chemistry, Pennsylvania State University, University Park, PA, 16802, USA
| | - Yang Jiang
- Department of Chemistry, Pennsylvania State University, University Park, PA, 16802, USA
| | - Yiyun Rao
- Molecular, Cellular and Integrative Biosciences Program, The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - Quyen V Vu
- Institute of Physics, Polish Academy of Sciences; Al. Lotnikow 32/46, 02-668, Warsaw, Poland
| | - Mai Suan Li
- Institute of Physics, Polish Academy of Sciences; Al. Lotnikow 32/46, 02-668, Warsaw, Poland
- Institute for Computational Sciences and Technology; Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi Minh City, Vietnam
| | - Justin Pritchard
- Department of Biomedical Engineering, Pennsylvania State University, State College, PA, 16802, USA
- Huck Institute for the Life Sciences, Pennsylvania State University, State College, PA, 16802, USA
| | - Edward P O'Brien
- Department of Chemistry, Pennsylvania State University, University Park, PA, 16802, USA.
- Bioinformatics and Genomics Graduate Program, The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA.
- Institute for Computational and Data Sciences, Pennsylvania State University, University Park, PA, 16802, USA.
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7
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Chen Y, Zhou J, Wu S, Wang L, Chen G, Chen D, Peng X, Miao YL, Mei S, Li F. ISG15 suppresses ovulation and female fertility by ISGylating ADAMTS1. Cell Biosci 2023; 13:84. [PMID: 37170317 PMCID: PMC10176748 DOI: 10.1186/s13578-023-01024-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 03/31/2023] [Indexed: 05/13/2023] Open
Abstract
BACKGROUND ISGylation is a post-translational protein modification that regulates many life activities, including immunomodulation, antiviral responses, and embryo implantation. The exact contribution of ISGylation to folliculogenesis remains largely undefined. RESULTS Here, Isg15 knockout in mice causes hyperfertility along with sensitive ovarian responses to gonadotropin, such as increases in cumulus expansion and ovulation rate. Moreover, ISG15 represses the expression of ovulation-related genes in an ISGylation-dependent manner. Mechanistically, ISG15 binds to ADAMTS1 via the ISG15-conjugating system (UBA7, UBE2L6, and HERC6), ISGylating ADAMTS1 at the binding sites Lys309, Lys593, Lys597, and Lys602, resulting in ADAMTS1 degradation via a 20S proteasome-dependent pathway. CONCLUSION Taken together, the present study demonstrates that covalent ISG15 conjugation produces a novel regulatory axis of ISG15-ADAMTS1 that enhances the degradation of ADAMTS1, thereby compromising ovulation and female fertility.
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Affiliation(s)
- Yaru Chen
- Key Laboratory of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs & Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jiawei Zhou
- Key Laboratory of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs & Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China.
- Institute of Animal Science and Veterinary Medicine, Hubei Academy of Agricultural Sciences, Wuhan, 430064, China.
| | - Shang Wu
- Key Laboratory of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs & Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Lei Wang
- Key Laboratory of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs & Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Gaogui Chen
- Key Laboratory of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs & Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Dake Chen
- Key Laboratory of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs & Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xianwen Peng
- Institute of Animal Science and Veterinary Medicine, Hubei Academy of Agricultural Sciences, Wuhan, 430064, China
| | - Yi-Liang Miao
- Key Laboratory of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs & Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Shuqi Mei
- Institute of Animal Science and Veterinary Medicine, Hubei Academy of Agricultural Sciences, Wuhan, 430064, China
| | - Fenge Li
- Key Laboratory of Swine Genetics and Breeding of Ministry of Agriculture and Rural Affairs & Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China.
- The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, 430070, China.
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8
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Walker SD, Olivares AO. The activated ClpP peptidase forcefully grips a protein substrate. Biophys J 2022; 121:3907-3916. [PMID: 36045571 PMCID: PMC9674977 DOI: 10.1016/j.bpj.2022.08.042] [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: 04/29/2022] [Revised: 08/12/2022] [Accepted: 08/26/2022] [Indexed: 11/26/2022] Open
Abstract
ATPases associated with diverse cellular activities (AAA+) proteases power the maintenance of protein homeostasis by coupling ATP hydrolysis to mechanical protein unfolding, translocation, and ultimately degradation. Although ATPase activity drives a large portion of the mechanical work these molecular machines perform, how the peptidase contributes to the forceful denaturation and processive threading of substrates remains unknown. Here, using single-molecule optical trapping, we examine the mechanical activity of the caseinolytic peptidase P (ClpP) from Escherichia coli in the absence of a partner ATPase and in the presence of an activating small-molecule acyldepsipeptide. We demonstrate that ClpP grips protein substrate under mechanical loads exceeding 40 pN, which are greater than those observed for the AAA+ unfoldase ClpX and the AAA+ protease complexes ClpXP and ClpAP. We further characterize substrate-ClpP bond lifetimes and rupture forces under varying loads. We find that the resulting slip bond behavior does not depend on ClpP peptidase activity. In addition, we find that unloaded bond lifetimes between ClpP and protein substrate are on a timescale relevant to unfolding times (up to ∼160 s) for difficult to unfold model substrate proteins. These direct measurements of the substrate-peptidase bond under load define key properties required by AAA+ proteases to mechanically unfold and degrade protein substrates.
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Affiliation(s)
- Steven D Walker
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee; Chemical and Physical Biology Graduate Program, Vanderbilt University, Nashville, Tennessee
| | - Adrian O Olivares
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee.
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9
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Varikoti RA, Fonseka HYY, Kelly MS, Javidi A, Damre M, Mullen S, Nugent JL, Gonzales CM, Stan G, Dima RI. Exploring the Effect of Mechanical Anisotropy of Protein Structures in the Unfoldase Mechanism of AAA+ Molecular Machines. NANOMATERIALS 2022; 12:nano12111849. [PMID: 35683705 PMCID: PMC9182431 DOI: 10.3390/nano12111849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 05/25/2022] [Accepted: 05/25/2022] [Indexed: 02/06/2023]
Abstract
Essential cellular processes of microtubule disassembly and protein degradation, which span lengths from tens of μm to nm, are mediated by specialized molecular machines with similar hexameric structure and function. Our molecular simulations at atomistic and coarse-grained scales show that both the microtubule-severing protein spastin and the caseinolytic protease ClpY, accomplish spectacular unfolding of their diverse substrates, a microtubule lattice and dihydrofolate reductase (DHFR), by taking advantage of mechanical anisotropy in these proteins. Unfolding of wild-type DHFR requires disruption of mechanically strong β-sheet interfaces near each terminal, which yields branched pathways associated with unzipping along soft directions and shearing along strong directions. By contrast, unfolding of circular permutant DHFR variants involves single pathways due to softer mechanical interfaces near terminals, but translocation hindrance can arise from mechanical resistance of partially unfolded intermediates stabilized by β-sheets. For spastin, optimal severing action initiated by pulling on a tubulin subunit is achieved through specific orientation of the machine versus the substrate (microtubule lattice). Moreover, changes in the strength of the interactions between spastin and a microtubule filament, which can be driven by the tubulin code, lead to drastically different outcomes for the integrity of the hexameric structure of the machine.
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Affiliation(s)
- Rohith Anand Varikoti
- Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221, USA; (R.A.V.); (H.Y.Y.F.); (M.S.K.); (M.D.); (J.L.N.IV)
| | - Hewafonsekage Yasan Y. Fonseka
- Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221, USA; (R.A.V.); (H.Y.Y.F.); (M.S.K.); (M.D.); (J.L.N.IV)
| | - Maria S. Kelly
- Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221, USA; (R.A.V.); (H.Y.Y.F.); (M.S.K.); (M.D.); (J.L.N.IV)
| | - Alex Javidi
- Data Sciences, Janssen Research and Development, Spring House, PA 19477, USA;
| | - Mangesh Damre
- Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221, USA; (R.A.V.); (H.Y.Y.F.); (M.S.K.); (M.D.); (J.L.N.IV)
| | - Sarah Mullen
- Department of Chemistry, The College of Wooster, Wooster, OH 44691, USA;
| | - Jimmie L. Nugent
- Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221, USA; (R.A.V.); (H.Y.Y.F.); (M.S.K.); (M.D.); (J.L.N.IV)
| | | | - George Stan
- Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221, USA; (R.A.V.); (H.Y.Y.F.); (M.S.K.); (M.D.); (J.L.N.IV)
- Correspondence: (G.S.); (R.I.D.)
| | - Ruxandra I. Dima
- Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221, USA; (R.A.V.); (H.Y.Y.F.); (M.S.K.); (M.D.); (J.L.N.IV)
- Correspondence: (G.S.); (R.I.D.)
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10
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Lin J, Shorter J, Lucius AL. AAA+ proteins: one motor, multiple ways to work. Biochem Soc Trans 2022; 50:895-906. [PMID: 35356966 PMCID: PMC9115847 DOI: 10.1042/bst20200350] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 03/14/2022] [Accepted: 03/15/2022] [Indexed: 12/15/2022]
Abstract
Numerous ATPases associated with diverse cellular activities (AAA+) proteins form hexameric, ring-shaped complexes that function via ATPase-coupled translocation of substrates across the central channel. Cryo-electron microscopy of AAA+ proteins processing substrate has revealed non-symmetric, staircase-like hexameric structures that indicate a sequential clockwise/2-residue step translocation model for these motors. However, for many of the AAA+ proteins that share similar structural features, their translocation properties have not yet been experimentally determined. In the cases where translocation mechanisms have been determined, a two-residue translocation step-size has not been resolved. In this review, we explore Hsp104, ClpB, ClpA and ClpX as examples to review the experimental methods that have been used to examine, in solution, the translocation mechanisms employed by AAA+ motor proteins. We then ask whether AAA+ motors sharing similar structural features can have different translocation mechanisms. Finally, we discuss whether a single AAA+ motor can adopt multiple translocation mechanisms that are responsive to different challenges imposed by the substrate or the environment. We suggest that AAA+ motors adopt more than one translocation mechanism and are tuned to switch to the most energetically efficient mechanism when constraints are applied.
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Affiliation(s)
- JiaBei Lin
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, U.S.A
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, U.S.A
| | - Aaron L. Lucius
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, U.S.A
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11
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Sauer RT, Fei X, Bell TA, Baker TA. Structure and function of ClpXP, a AAA+ proteolytic machine powered by probabilistic ATP hydrolysis. Crit Rev Biochem Mol Biol 2022; 57:188-204. [PMID: 34923891 PMCID: PMC9871882 DOI: 10.1080/10409238.2021.1979461] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
ClpXP is an archetypical AAA+ protease, consisting of ClpX and ClpP. ClpX is an ATP-dependent protein unfoldase and polypeptide translocase, whereas ClpP is a self-compartmentalized peptidase. ClpXP is currently the only AAA+ protease for which high-resolution structures exist, the molecular basis of recognition for a protein substrate is understood, extensive biochemical and genetic analysis have been performed, and single-molecule optical trapping has allowed direct visualization of the kinetics of substrate unfolding and translocation. In this review, we discuss our current understanding of ClpXP structure and function, evaluate competing sequential and probabilistic mechanisms of ATP hydrolysis, and highlight open questions for future exploration.
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Affiliation(s)
- Robert T. Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Xue Fei
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Tristan A. Bell
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Tania A. Baker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
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12
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Investigation of the structural dynamics of a knotted protein and its unknotted analog using molecular dynamics. J Mol Model 2022; 28:108. [PMID: 35357594 DOI: 10.1007/s00894-022-05094-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 03/12/2022] [Indexed: 10/18/2022]
Abstract
The role of knots in proteins remains elusive. Some studies suggest an impact on stability; the difficulty in comparing systems to assess this effect, however, has been a significant challenge. In this study, we produced and analyzed molecular dynamic trajectories considering three different temperatures of two variants of ornithine transcarbamylase (OTC), only one of which has a 31 knot, in order to evaluate the relative stability of the two molecules. RMSD showed equilibrated structures for the produced trajectories, and RMSF showed subtle differences in flexibility. In the knot moiety, the knotted protein did not show a great deal of fluctuation at any temperature. For the unknotted protein, the residue GLY243 showed a high fluctuation in the corresponding moiety. The fraction of native contacts (Q) showed a similar profile at all temperatures, with the greatest decrease by 436 K. The investigation of conformational behavior with principal component analysis (PCA) and dynamic cross-correlation map (DCCM) showed that knotted protein is less likely to undergo changes in its conformation under the conditions employed compared to unknotted. PCA data showed that the unknotted protein had greater dispersion in its conformations, which suggests that it has a greater capacity for conformation transitions in response to thermal changes. DCCM graphs comparing the 310 K and 436 K temperatures showed that the knotted protein had less change in its correlation and anti-correlation movements, indicating stability compared to the unknotted.
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13
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Mabanglo MF, Houry WA. Recent structural insights into the mechanism of ClpP protease regulation by AAA+ chaperones and small molecules. J Biol Chem 2022; 298:101781. [PMID: 35245501 PMCID: PMC9035409 DOI: 10.1016/j.jbc.2022.101781] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 11/19/2022] Open
Abstract
ClpP is a highly conserved serine protease that is a critical enzyme in maintaining protein homeostasis and is an important drug target in pathogenic bacteria and various cancers. In its functional form, ClpP is a self-compartmentalizing protease composed of two stacked heptameric rings that allow protein degradation to occur within the catalytic chamber. ATPase chaperones such as ClpX and ClpA are hexameric ATPases that form larger complexes with ClpP and are responsible for the selection and unfolding of protein substrates prior to their degradation by ClpP. Although individual structures of ClpP and ATPase chaperones have offered mechanistic insights into their function and regulation, their structures together as a complex have only been recently determined to high resolution. Here, we discuss the cryoelectron microscopy structures of ClpP-ATPase complexes and describe findings previously inaccessible from individual Clp structures, including how a hexameric ATPase and a tetradecameric ClpP protease work together in a functional complex. We then discuss the consensus mechanism for substrate unfolding and translocation derived from these structures, consider alternative mechanisms, and present their strengths and limitations. Finally, new insights into the allosteric control of ClpP gained from studies using small molecules and gain or loss-of-function mutations are explored. Overall, this review aims to underscore the multilayered regulation of ClpP that may present novel ideas for structure-based drug design.
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Affiliation(s)
- Mark F Mabanglo
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Walid A Houry
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Department of Chemistry, University of Toronto, Toronto, Ontario, Canada.
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14
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Wang J, Peng X. In silico method for identifying the key residues in a knotted protein: with MJ0366 as an example. Phys Chem Chem Phys 2022; 24:27495-27504. [DOI: 10.1039/d2cp03589h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A simple in silico method for predicting the key residues for knotting and unknotting a knotted protein is put forward, with the residues ranked by the relevance to knotting and unknotting in the annealing molecular dynamics simulations.
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Affiliation(s)
- Jianmei Wang
- Center for Quantum Technology Research, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements (MOE), School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Xubiao Peng
- Center for Quantum Technology Research, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements (MOE), School of Physics, Beijing Institute of Technology, Beijing 100081, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
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15
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Fonseka HYY, Javidi A, Oliveira LFL, Micheletti C, Stan G. Unfolding and Translocation of Knotted Proteins by Clp Biological Nanomachines: Synergistic Contribution of Primary Sequence and Topology Revealed by Molecular Dynamics Simulations. J Phys Chem B 2021; 125:7335-7350. [PMID: 34110163 DOI: 10.1021/acs.jpcb.1c00898] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We use Langevin dynamics simulations to model, at an atomistic resolution, how various natively knotted proteins are unfolded in repeated allosteric translocating cycles of the ClpY ATPase. We consider proteins representative of different topologies, from the simplest knot (trefoil 31), to the three-twist 52 knot, to the most complex stevedore, 61, knot. We harness the atomistic detail of the simulations to address aspects that have so far remained largely unexplored, such as sequence-dependent effects on the ruggedness of the landscape traversed during knot sliding. Our simulations reveal the combined effect on translocation of the knotted protein structure, i.e., backbone topology and geometry, and primary sequence, i.e., side chain size and interactions, and show that the latter can dominate translocation hindrance. In addition, we observe that due to the interplay between the knotted topology and intramolecular contacts the transmission of tension along the polypeptide chain occurs very differently from that of homopolymers. Finally, by considering native and non-native interactions, we examine how the disruption or formation of such contacts can affect the translocation processivity and concomitantly create multiple unfolding pathways with very different activation barriers.
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Affiliation(s)
| | - Alex Javidi
- Data Sciences, Janssen Research and Development, Spring House, Pennsylvania 19477, United States
| | - Luiz F L Oliveira
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Cristian Micheletti
- Molecular and Statistical Biophysics, Scuola Internazionale Superiore di Studi Avanzati (SISSA), 34136 Trieste, Italy
| | - George Stan
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
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16
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Becchi M, Chiarantoni P, Suma A, Micheletti C. RNA Pore Translocation with Static and Periodic Forces: Effect of Secondary and Tertiary Elements on Process Activation and Duration. J Phys Chem B 2021; 125:1098-1106. [PMID: 33497228 PMCID: PMC7875513 DOI: 10.1021/acs.jpcb.0c09966] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 01/19/2021] [Indexed: 11/28/2022]
Abstract
We use MD simulations to study the pore translocation properties of a pseudoknotted viral RNA. We consider the 71-nucleotide-long xrRNA from the Zika virus and establish how it responds when driven through a narrow pore by static or periodic forces applied to either of the two termini. Unlike the case of fluctuating homopolymers, the onset of translocation is significantly delayed with respect to the application of static driving forces. Because of the peculiar xrRNA architecture, activation times can differ by orders of magnitude at the two ends. Instead, translocation duration is much smaller than activation times and occurs on time scales comparable at the two ends. Periodic forces amplify significantly the differences at the two ends, for both activation times and translocation duration. Finally, we use a waiting-times analysis to examine the systematic slowing downs in xrRNA translocations and associate them to the hindrance of specific secondary and tertiary elements of xrRNA. The findings provide a useful reference to interpret and design future theoretical and experimental studies of RNA translocation.
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Affiliation(s)
- Matteo Becchi
- Physics
Area, Scuola Internazionale Superiore di
Studi Avanzati (SISSA), Via Bonomea 265, 34136 Trieste, Italy
| | - Pietro Chiarantoni
- Physics
Area, Scuola Internazionale Superiore di
Studi Avanzati (SISSA), Via Bonomea 265, 34136 Trieste, Italy
| | - Antonio Suma
- Dipartimento
di Fisica, Università di Bari and
Sezione INFN di Bari, via Amendola 173, 70126 Bari, Italy
| | - Cristian Micheletti
- Physics
Area, Scuola Internazionale Superiore di
Studi Avanzati (SISSA), Via Bonomea 265, 34136 Trieste, Italy
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17
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Kang ZH, Liu YT, Gou Y, Deng QR, Hu ZY, Li GR. Progress and prospect of single-molecular ClpX ATPase researching system-a mini-review. Gene 2021; 774:145420. [PMID: 33434627 DOI: 10.1016/j.gene.2021.145420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/04/2020] [Accepted: 01/05/2021] [Indexed: 11/28/2022]
Abstract
ClpXP in Escherichia coli is a proteasome degrading protein substrates. It consists of one hexamer of ATPase (ClpX) and two heptamers of peptidase (ClpP). The ClpX binds ATP and translocates the substrate protein into the ClpP chamber by binding and hydrolysis of ATP. At single molecular level, ClpX harnesses cycles of power stroke (dwell and burst) to unfold the substrates, then releases the ADP and Pi. Based on the construction and function of ClpXP, especially the recent progress on how ClpX unfold protein substrates, in this mini-review, a currently proposed single ClpX molecular model system detected by optical tweezers, and its prospective for the elucidation of the mechanism of force generation of ClpX in its power stroke and the subunit interaction with each other, were discussed in detail.
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Affiliation(s)
- Zhen-Hui Kang
- School of Bioengineering, Sichuan University of Science & Engineering, Yibin 644005, Sichuan, China.
| | - Yi-Ting Liu
- School of Bioengineering, Sichuan University of Science & Engineering, Yibin 644005, Sichuan, China
| | - Yang Gou
- School of Bioengineering, Sichuan University of Science & Engineering, Yibin 644005, Sichuan, China
| | - Qi-Rui Deng
- School of Bioengineering, Sichuan University of Science & Engineering, Yibin 644005, Sichuan, China
| | - Zi-Yu Hu
- School of Bioengineering, Sichuan University of Science & Engineering, Yibin 644005, Sichuan, China
| | - Guan-Rong Li
- Southwest University, Beibei 400716, Chongqing, China.
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18
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Simien JM, Haglund E. Topological Twists in Nature. Trends Biochem Sci 2021; 46:461-471. [PMID: 33419636 DOI: 10.1016/j.tibs.2020.12.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 11/24/2020] [Accepted: 12/03/2020] [Indexed: 11/25/2022]
Abstract
The first entangled protein was observed about 30 years ago, resulting in an increased interest for uncovering the biological functions and biophysical properties of these complex topologies. Recently, the Pierced Lasso Topology (PLT) was discovered in which a covalent bond forms an intramolecular loop, leaving one or both termini free to pierce the loop. This topology is related to knots and other entanglements. PLTs exist in many well-researched systems where the PLTs have previously been unnoticed. PLTs represents 18% of all disulfide containing proteins across all kingdoms of life. In this review, we investigate the biological implications of this specific topology in which the PLT-forming disulfide may act as a molecular switch for protein function and consequently human health.
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Affiliation(s)
| | - Ellinor Haglund
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI, USA.
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19
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Suma A, Coronel L, Bussi G, Micheletti C. Directional translocation resistance of Zika xrRNA. Nat Commun 2020; 11:3749. [PMID: 32719310 PMCID: PMC7385498 DOI: 10.1038/s41467-020-17508-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 06/29/2020] [Indexed: 12/14/2022] Open
Abstract
xrRNAs from flaviviruses survive in host cells because of their exceptional dichotomic response to the unfolding action of different enzymes. They can be unwound, and hence copied, by replicases, and yet can resist degradation by exonucleases. How the same stretch of xrRNA can encode such diverse responses is an open question. Here, by using atomistic models and translocation simulations, we uncover an elaborate and directional mechanism for how stress propagates when the two xrRNA ends, [Formula: see text] and [Formula: see text], are driven through a pore. Pulling the [Formula: see text] end, as done by replicases, elicits a progressive unfolding; pulling the [Formula: see text] end, as done by exonucleases, triggers a counterintuitive molecular tightening. Thus, in what appears to be a remarkable instance of intra-molecular tensegrity, the very pulling of the [Formula: see text] end is what boosts resistance to translocation and consequently to degradation. The uncovered mechanistic principle might be co-opted to design molecular meta-materials.
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Affiliation(s)
- Antonio Suma
- Dipartimento di Fisica, Università di Bari and INFN Sezione di Bari, via Amendola 173, 70126, Bari, Italy
- Institute for Computational Molecular Science (ICMS), Temple University, 19122, Philadelphia, PA, Italy
| | - Lucia Coronel
- Physics Area, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265, 34136, Trieste, Italy
| | - Giovanni Bussi
- Physics Area, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265, 34136, Trieste, Italy
| | - Cristian Micheletti
- Physics Area, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265, 34136, Trieste, Italy.
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20
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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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21
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Fei X, Bell TA, Jenni S, Stinson BM, Baker TA, Harrison SC, Sauer RT. Structures of the ATP-fueled ClpXP proteolytic machine bound to protein substrate. eLife 2020; 9:52774. [PMID: 32108573 PMCID: PMC7112951 DOI: 10.7554/elife.52774] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 02/27/2020] [Indexed: 01/11/2023] Open
Abstract
ClpXP is an ATP-dependent protease in which the ClpX AAA+ motor binds, unfolds, and translocates specific protein substrates into the degradation chamber of ClpP. We present cryo-EM studies of the E. coli enzyme that show how asymmetric hexameric rings of ClpX bind symmetric heptameric rings of ClpP and interact with protein substrates. Subunits in the ClpX hexamer assume a spiral conformation and interact with two-residue segments of substrate in the axial channel, as observed for other AAA+ proteases and protein-remodeling machines. Strictly sequential models of ATP hydrolysis and a power stroke that moves two residues of the substrate per translocation step have been inferred from these structural features for other AAA+ unfoldases, but biochemical and single-molecule biophysical studies indicate that ClpXP operates by a probabilistic mechanism in which five to eight residues are translocated for each ATP hydrolyzed. We propose structure-based models that could account for the functional results.
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Affiliation(s)
- Xue Fei
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Tristan A Bell
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Simon Jenni
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
| | - Benjamin M Stinson
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Tania A Baker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States.,Howard Hughes Medical Institute, Chevy Chase, United States
| | - Stephen C Harrison
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Chevy Chase, United States
| | - Robert T Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
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22
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Sulkowska JI. On folding of entangled proteins: knots, lassos, links and θ-curves. Curr Opin Struct Biol 2020; 60:131-141. [PMID: 32062143 DOI: 10.1016/j.sbi.2020.01.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 01/02/2020] [Accepted: 01/12/2020] [Indexed: 12/15/2022]
Abstract
Around 6% of protein structures deposited in the PDB are entangled, forming knots, slipknots, lassos, links, and θ-curves. In each of these cases, the protein backbone weaves through itself in a complex way, and at some point passes through a closed loop, formed by other regions of the protein structure. Such a passing can be interpreted as crossing a topological barrier. How proteins overcome such barriers, and therefore different degrees of frustration, challenged scientists and has shed new light on the field of protein folding. In this review, we summarize the current knowledge about the free energy landscape of proteins with non-trivial topology. We describe identified mechanisms which lead proteins to self-tying. We discuss the influence of excluded volume, such as crowding and chaperones, on tying, based on available data. We briefly discuss the diversity of topological complexity of proteins and their evolution. We also list available tools to investigate non-trivial topology. Finally, we formulate intriguing and challenging questions at the boundary of biophysics, bioinformatics, biology, and mathematics, which arise from the discovery of entangled proteins.
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Affiliation(s)
- Joanna Ida Sulkowska
- Centre of New Technologies, University of Warsaw, Warsaw, Poland; Faculty of Chemistry, University of Warsaw, Warsaw, Poland.
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23
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Sriramoju MK, Chen Y, Hsu STD. Protein knots provide mechano-resilience to an AAA+ protease-mediated proteolysis with profound ATP energy expenses. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1868:140330. [PMID: 31756432 DOI: 10.1016/j.bbapap.2019.140330] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Revised: 10/23/2019] [Accepted: 11/15/2019] [Indexed: 12/11/2022]
Abstract
Knotted proteins are some of the most fascinating examples of how linear polypeptide chains can achieve intricate topological arrangements efficiently and spontaneously. The entanglements of polypeptide chains could potentially enhance their folding stabilities. We recently reported the unprecedented mechanostability of the Gordian (52) knotted family of human ubiquitin C-terminal hydrolases (UCHs) in the context of withstanding the mechanical unfolding of the bacterial AAA+ proteasome, ClpXP; a green fluorescence protein (GFP) was fused to the N-terminus of various UCHs as a reporter of the unfolding and degradation of these topologically knotted substrates, but it also limited the ability to examine the effect of untying the knotted topology via N-terminal truncation. In this study, we directly monitored the ClpXP-mediated degradation of UCH variants by electrophoresis and quantitative imaging analyses. We demonstrated that untying of the 52 knot in UCHL1 via N-terminal truncation (UCHL1Δ11) significantly reduces its mechanostability. We further quantified the ATP expenditures of degrading different UCH variants by ClpXP. The unknotted UCHL1Δ11 underwent accelerated ClpXP-dependent proteolysis, with a 30-fold reduction in ATP consumption compared to the knotted wild type. Unlike all other known ClpXP substrates, UCHL5, which is the most resilient substrate known to date, significantly slowed down the ATP turnover rate by ClpXP. Furthermore, UCHL5 required 1000-fold more ATP to be fully degraded by ClpXP compared to GFP. Our results underscored how the complex, knotted folding topology in UCHs may interfere with the mechano-unfolding processes of the AAA+ unfoldase, ClpX.
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Affiliation(s)
| | - Yen Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Shang-Te Danny Hsu
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan.
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