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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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Molecular and cellular dynamics of the 26S proteasome. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1869:140583. [PMID: 33321258 DOI: 10.1016/j.bbapap.2020.140583] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/07/2020] [Accepted: 12/09/2020] [Indexed: 01/16/2023]
Abstract
In eukaryotic cells, the ubiquitin-proteasome system serves to remove proteins that are either dysfunctional or no longer needed. The 26S proteasome is a 2.5 MDa multisubunit complex comprising the 20S core particle, where degradation is executed, and one or two regulatory particles which prepare substrates for degradation. Whereas the 20S core particles of several species had been studied extensively by X-ray crystallography, the 26S holocomplex structure had remained elusive for a long time. Recent advances in single-particle cryo-electron microscopy have changed the situation and provided atomic resolution models of this intriguing molecular machine and its dynamics. Besides, cryo-electron tomography enables structural studies in situ, providing molecular resolution images of macromolecules inside pristinely preserved cellular environments. This has greatly contributed to our understanding of proteasome dynamics in the context of cells.
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Avestan MS, Javidi A, Ganote LP, Brown JM, Stan G. Kinetic effects in directional proteasomal degradation of the green fluorescent protein. J Chem Phys 2020; 153:105101. [DOI: 10.1063/5.0015191] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
| | - Alex Javidi
- Data Sciences, Janssen Research and Development, Spring House, Pennsylvania 19477, USA
| | | | | | - George Stan
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, USA
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Transient knots in intrinsically disordered proteins and neurodegeneration. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 174:79-103. [PMID: 32828471 DOI: 10.1016/bs.pmbts.2020.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We provide a brief overview of the topological features found in structured proteins and of the dynamical processes that involve knots. We then discuss the knotted states that arise in the intrinsically disordered polyglutamine and α-synuclein. We argue that the existence of the knotted conformations stalls degradation by proteases and thus enhances aggregation. This mechanism works if the length of a peptide chain exceeds a threshold, as in the Huntington disease. We also study the cavities that form within the conformations of the disordered proteins. The volume of the cavities varies in time in a way that is different than that of the radius of gyration or the end-to-end distance. In addition, we study the traffic between the conformational basins and identify patterns associated with the deep and shallow knots. The results are obtained by molecular dynamics simulations that use coarse-grained and all-atom models (with and without the explicit solvent).
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Dima RI, Stan G. Computational Studies of Mechanical Remodeling of Substrate Proteins by AAA+ Biological Nanomachines. ACS SYMPOSIUM SERIES 2020. [DOI: 10.1021/bk-2020-1356.ch008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Ruxandra I. Dima
- Department of Chemistry, University of Cincinnati, P. O. Box 210172, Cincinnati, Ohio 45221, United States
| | - George Stan
- Department of Chemistry, University of Cincinnati, P. O. Box 210172, Cincinnati, Ohio 45221, United States
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Javidialesaadi A, Flournoy SM, Stan G. Role of Diffusion in Unfolding and Translocation of Multidomain Titin I27 Substrates by a Clp ATPase Nanomachine. J Phys Chem B 2019; 123:2623-2635. [DOI: 10.1021/acs.jpcb.8b10282] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
| | - Shanice M. Flournoy
- Department of Chemistry, Virginia State University, Petersburg, Virginia 23806, United States
| | - George Stan
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
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Javidialesaadi A, Stan G. Asymmetric Conformational Transitions in AAA+ Biological Nanomachines Modulate Direction-Dependent Substrate Protein Unfolding Mechanisms. J Phys Chem B 2017; 121:7108-7121. [DOI: 10.1021/acs.jpcb.7b05963] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
| | - George Stan
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
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An Arginine Finger Regulates the Sequential Action of Asymmetrical Hexameric ATPase in the Double-Stranded DNA Translocation Motor. Mol Cell Biol 2016; 36:2514-23. [PMID: 27457616 PMCID: PMC5021374 DOI: 10.1128/mcb.00142-16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 06/30/2016] [Indexed: 11/30/2022] Open
Abstract
Biological motors are ubiquitous in living systems. Currently, how the motor components coordinate the unidirectional motion is elusive in most cases. Here, we report that the sequential action of the ATPase ring in the DNA packaging motor of bacteriophage ϕ29 is regulated by an arginine finger that extends from one ATPase subunit to the adjacent unit to promote noncovalent dimer formation. Mutation of the arginine finger resulted in the interruption of ATPase oligomerization, ATP binding/hydrolysis, and DNA translocation. Dimer formation reappeared when arginine mutants were mixed with other ATPase subunits that can offer the arginine to promote their interaction. Ultracentrifugation and virion assembly assays indicated that the ATPase was presenting as monomers and dimer mixtures. The isolated dimer alone was inactive in DNA translocation, but the addition of monomer could restore the activity, suggesting that the hexameric ATPase ring contained both dimer and monomers. Moreover, ATP binding or hydrolysis resulted in conformation and entropy changes of the ATPase with high or low DNA affinity. Taking these observations together, we concluded that the arginine finger regulates sequential action of the motor ATPase subunit by promoting the formation of the dimer inside the hexamer. The finding of asymmetrical hexameric organization is supported by structural evidence of many other ATPase systems showing the presence of one noncovalent dimer and four monomer subunits. All of these provide clues for why the asymmetrical hexameric ATPase gp16 of ϕ29 was previously reported as a pentameric configuration by cryo-electron microscopy (cryo-EM) since the contact by the arginine finger renders two adjacent ATPase subunits closer than other subunits. Thus, the asymmetrical hexamer would appear as a pentamer by cryo-EM, a technology that acquires the average of many images.
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Luan B, Huynh T, Li J, Zhou R. Nanomechanics of Protein Unfolding Outside a Generic Nanopore. ACS NANO 2016; 10:317-323. [PMID: 26655061 DOI: 10.1021/acsnano.5b04557] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Protein folding and unfolding have been the subject of active research for decades. Most of previous studies in protein unfolding were focused on temperature, chemical, and/or force (such as in atomic force microscopy (AFM)) induced denaturations. Recent studies on the functional roles of proteasomes (such as ClpXP) revealed a different unfolding process in cell, during which a target protein is mechanically unfolded and pulled into a confined, pore-like geometry for degradation. While the proteasome nanomachine has been extensively studied, the mechanism for unfolding proteins with the proteasome pore is still poorly understood. Here, we investigate the mechanical unfolding process of ubiquitin with (or really outside) a generic nanopore, and compare such process with that in the AFM pulling experiment. Unexpectedly, the required force for protein unfolding through a pore can be much smaller than that by the AFM. Simulation results also unveiled different nanomechanics, tearing fracture vs shearing friction, in these two distinct types of mechanical unfoldings.
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Affiliation(s)
- Binquan Luan
- Computational Biological Center, IBM Thomas J. Watson Research , Yorktown Heights, New York 10598, United States
| | - Tien Huynh
- Computational Biological Center, IBM Thomas J. Watson Research , Yorktown Heights, New York 10598, United States
| | - Jingyuan Li
- Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049, China
| | - Ruhong Zhou
- Computational Biological Center, IBM Thomas J. Watson Research , Yorktown Heights, New York 10598, United States
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Kravats AN, Tonddast-Navaei S, Stan G. Coarse-Grained Simulations of Topology-Dependent Mechanisms of Protein Unfolding and Translocation Mediated by ClpY ATPase Nanomachines. PLoS Comput Biol 2016; 12:e1004675. [PMID: 26734937 PMCID: PMC4703411 DOI: 10.1371/journal.pcbi.1004675] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 11/25/2015] [Indexed: 01/30/2023] Open
Abstract
Clp ATPases are powerful ring shaped nanomachines which participate in the degradation pathway of the protein quality control system, coupling the energy from ATP hydrolysis to threading substrate proteins (SP) through their narrow central pore. Repetitive cycles of sequential intra-ring ATP hydrolysis events induce axial excursions of diaphragm-forming central pore loops that effect the application of mechanical forces onto SPs to promote unfolding and translocation. We perform Langevin dynamics simulations of a coarse-grained model of the ClpY ATPase-SP system to elucidate the molecular details of unfolding and translocation of an α/β model protein. We contrast this mechanism with our previous studies which used an all-α SP. We find conserved aspects of unfolding and translocation mechanisms by allosteric ClpY, including unfolding initiated at the tagged C-terminus and translocation via a power stroke mechanism. Topology-specific aspects include the time scales, the rate limiting steps in the degradation pathway, the effect of force directionality, and the translocase efficacy. Mechanisms of ClpY-assisted unfolding and translocation are distinct from those resulting from non-allosteric mechanical pulling. Bulk unfolding simulations, which mimic Atomic Force Microscopy-type pulling, reveal multiple unfolding pathways initiated at the C-terminus, N-terminus, or simultaneously from both termini. In a non-allosteric ClpY ATPase pore, mechanical pulling with constant velocity yields larger effective forces for SP unfolding, while pulling with constant force results in simultaneous unfolding and translocation. Cell survival is critically dependent on tightly regulated protein quality control, which includes chaperone-mediated folding and degradation. In the degradation pathway, AAA+ nanomachines, such as bacterial Clp proteases, use ATP-driven mechanisms to mechanically unfold, translocate, and destroy excess or defective proteins. Understanding these remodeling mechanisms is of central importance for deciphering the details of essential cellular processes. We perform coarse-grained computer simulations to extensively probe the effect of substrate protein topology on unfolding and translocation actions of the ClpY ATPase nanomachine. We find that, independent of SP topology, unfolding proceeds from the tagged C-terminus, which is engaged by the ATPase, and translocation involves coordinated steps. Topology-specific aspects include more complex unfolding and translocation pathways of the α/β SP compared with the all-α SP due to high stability of β-hairpins and interplay of tertiary contacts. In addition, directionality of the mechanical force applied by the Clp ATPase gives rise to distinct unfolding pathways.
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Affiliation(s)
- Andrea N. Kravats
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Sam Tonddast-Navaei
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - George Stan
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio, United States of America
- * E-mail:
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Wojciechowski M, Gómez-Sicilia À, Carrión-Vázquez M, Cieplak M. Unfolding knots by proteasome-like systems: simulations of the behaviour of folded and neurotoxic proteins. MOLECULAR BIOSYSTEMS 2016; 12:2700-12. [DOI: 10.1039/c6mb00214e] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Knots in proteins have been proposed to resist proteasomal degradation, thought in turn to be related to neurodegenerative diseases such as Huntington.
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Affiliation(s)
| | - Àngel Gómez-Sicilia
- Instituto Cajal
- Consejo Superior de Investigaciones Científicas
- (CSIC)
- 28002 Madrid
- Spain
| | | | - Marek Cieplak
- Institute of Physics
- Polish Academy of Sciences
- PL-02668 Warsaw
- Poland
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Wojciechowski M, Szymczak P, Carrión-Vázquez M, Cieplak M. Protein unfolding by biological unfoldases: insights from modeling. Biophys J 2015; 107:1661-8. [PMID: 25296319 DOI: 10.1016/j.bpj.2014.07.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 06/09/2014] [Accepted: 07/15/2014] [Indexed: 10/24/2022] Open
Abstract
The molecular determinants of the high efficiency of biological machines like unfoldases (e.g., the proteasome) are not well understood. We propose a model to study protein translocation into the chamber of biological unfoldases represented as a funnel. It is argued that translocation is a much faster way of unfolding a protein than end-to-end stretching, especially in a low-force regime, because it allows for a conformational freedom while concentrating local tension on consecutive regions of a protein chain and preventing refolding. This results in a serial unfolding of the protein structures dominated by unzipping. Thus, pulling against the unfoldase pore is an efficient catalyst of the unfolding reaction. We also show that the presence of the funnel makes the tension along the backbone of the substrate protein nonuniform even when the protein gets unfolded. Hence, the stalling force measured by single-molecule force spectroscopy techniques may be smaller than the traction force of the unfoldase motor.
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Affiliation(s)
| | - Piotr Szymczak
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - Mariano Carrión-Vázquez
- Instituto Cajal, Consejo Superior de Investigaciones Cientificas and Instituto Madrileño de Estudios Avanzados en Nanociencia, Madrid, Spain
| | - Marek Cieplak
- Institute of Physics, Polish Academy of Sciences, Warsaw, Poland.
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Gruebele M, Thirumalai D. Perspective: Reaches of chemical physics in biology. J Chem Phys 2013; 139:121701. [PMID: 24089712 PMCID: PMC5942441 DOI: 10.1063/1.4820139] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Accepted: 08/20/2013] [Indexed: 01/09/2023] Open
Abstract
Chemical physics as a discipline contributes many experimental tools, algorithms, and fundamental theoretical models that can be applied to biological problems. This is especially true now as the molecular level and the systems level descriptions begin to connect, and multi-scale approaches are being developed to solve cutting edge problems in biology. In some cases, the concepts and tools got their start in non-biological fields, and migrated over, such as the idea of glassy landscapes, fluorescence spectroscopy, or master equation approaches. In other cases, the tools were specifically developed with biological physics applications in mind, such as modeling of single molecule trajectories or super-resolution laser techniques. In this introduction to the special topic section on chemical physics of biological systems, we consider a wide range of contributions, all the way from the molecular level, to molecular assemblies, chemical physics of the cell, and finally systems-level approaches, based on the contributions to this special issue. Chemical physicists can look forward to an exciting future where computational tools, analytical models, and new instrumentation will push the boundaries of biological inquiry.
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Affiliation(s)
- Martin Gruebele
- Departments of Chemistry and Physics, and Center for Biophysics and Computational Biology, University of Illinois, Urbana, Illinois 61801, USA
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