1
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Chowdhury AR, Sapkota D, Girodat D. Conformational changes of ribosomes during translation elongation resolved by molecular dynamics simulations. Curr Opin Struct Biol 2024; 86:102804. [PMID: 38569462 DOI: 10.1016/j.sbi.2024.102804] [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: 10/02/2023] [Revised: 02/06/2024] [Accepted: 03/04/2024] [Indexed: 04/05/2024]
Abstract
Molecular dynamics simulations have emerged as a powerful set of tools to unravel the intricate dynamics of ribosomes during protein synthesis. Recent advancements in this field have enabled simulations to delve deep into the conformational rearrangements of ribosomes and associated factors, providing invaluable insights into the intricacies of translation. Emphasis on simulations has recently been on translation elongation, such as tRNA selection, translocation, and ribosomal head-swivel motions. These studies have offered crucial structural interpretations of how genetic information is faithfully translated into proteins. This review outlines recent discoveries concerning ribosome conformational changes occurring during translation elongation, as elucidated through molecular dynamics simulations.
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Affiliation(s)
- Anuradha Rai Chowdhury
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR, 72701, USA. https://twitter.com/atomcellplankl
| | - Divya Sapkota
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR, 72701, USA; Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Dylan Girodat
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR, 72701, USA.
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2
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Singh V, Itoh Y, Del'Olio S, Hassan A, Naschberger A, Flygaard RK, Nobe Y, Izumikawa K, Aibara S, Andréll J, Whitford PC, Barrientos A, Taoka M, Amunts A. Mitoribosome structure with cofactors and modifications reveals mechanism of ligand binding and interactions with L1 stalk. Nat Commun 2024; 15:4272. [PMID: 38769321 PMCID: PMC11106087 DOI: 10.1038/s41467-024-48163-x] [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: 08/07/2022] [Accepted: 04/19/2024] [Indexed: 05/22/2024] Open
Abstract
The mitoribosome translates mitochondrial mRNAs and regulates energy conversion that is a signature of aerobic life forms. We present a 2.2 Å resolution structure of human mitoribosome together with validated mitoribosomal RNA (rRNA) modifications, including aminoacylated CP-tRNAVal. The structure shows how mitoribosomal proteins stabilise binding of mRNA and tRNA helping to align it in the decoding center, whereas the GDP-bound mS29 stabilizes intersubunit communication. Comparison between different states, with respect to tRNA position, allowed us to characterize a non-canonical L1 stalk, and molecular dynamics simulations revealed how it facilitates tRNA transitions in a way that does not require interactions with rRNA. We also report functionally important polyamines that are depleted when cells are subjected to an antibiotic treatment. The structural, biochemical, and computational data illuminate the principal functional components of the translation mechanism in mitochondria and provide a description of the structure and function of the human mitoribosome.
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Affiliation(s)
- Vivek Singh
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165, Solna, Sweden
| | - Yuzuru Itoh
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165, Solna, Sweden
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, 113-0033, Tokyo, Japan
| | - Samuel Del'Olio
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Asem Hassan
- Department of Physics, Northeastern University, Boston, MA, 02115, USA
- Center for Theoretical Biological Physics, Northeastern University, Boston, MA, 02115, USA
| | - Andreas Naschberger
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165, Solna, Sweden
- King Abdullah University of Science and Technology, Thuwal, 23955, Saudi Arabia
| | - Rasmus Kock Flygaard
- Department of Molecular Biology and Genetics, Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic EMBL Partnership for Molecular Medicine, Aarhus University, 8000, Aarhus C, Denmark
| | - Yuko Nobe
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Keiichi Izumikawa
- Department of Molecular and Cellular Biochemistry, Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose-shi, Tokyo, 204-8588, Japan
| | - Shintaro Aibara
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165, Solna, Sweden
| | - Juni Andréll
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17177, Stockholm, Sweden
| | - Paul C Whitford
- Department of Physics, Northeastern University, Boston, MA, 02115, USA
- Center for Theoretical Biological Physics, Northeastern University, Boston, MA, 02115, USA
| | - Antoni Barrientos
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Masato Taoka
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Alexey Amunts
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165, Solna, Sweden.
- Westlake University, Hangzhou, China.
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3
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Byju S, Hassan A, Whitford PC. The energy landscape of the ribosome. Biopolymers 2024; 115:e23570. [PMID: 38051695 DOI: 10.1002/bip.23570] [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: 08/27/2023] [Revised: 10/17/2023] [Accepted: 11/08/2023] [Indexed: 12/07/2023]
Abstract
The ribosome is a prototypical assembly that can be used to establish general principles and techniques for the study of biological molecular machines. Motivated by the fact that the dynamics of every biomolecule is governed by an underlying energy landscape, there has been great interest to understand and quantify ribosome energetics. In the present review, we will focus on theoretical and computational strategies for probing the interactions that shape the energy landscape of the ribosome, with an emphasis on more recent studies of the elongation cycle. These efforts include the application of quantum mechanical methods for describing chemical kinetics, as well as classical descriptions to characterize slower (microsecond to millisecond) large-scale (10-100 Å) rearrangements, where motion is described in terms of diffusion across an energy landscape. Together, these studies provide broad insights into the factors that control a diverse range of dynamical processes in this assembly.
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Affiliation(s)
- Sandra Byju
- Center for Theoretical Biological Physics, Northeastern University, Boston, Massachusetts, USA
- Department of Physics, Northeastern University, Boston, Massachusetts, USA
| | - Asem Hassan
- Department of Chemistry, The University of Texas at Austin, Austin, Texas, United States
| | - Paul C Whitford
- Center for Theoretical Biological Physics, Northeastern University, Boston, Massachusetts, USA
- Department of Physics, Northeastern University, Boston, Massachusetts, USA
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4
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Zhou J, Wang A, Song Y, Liu N, Wang J, Li Y, Liang X, Li G, Chu H, Wang HW. Structural insights into the mechanism of GTP initiation of microtubule assembly. Nat Commun 2023; 14:5980. [PMID: 37749104 PMCID: PMC10519996 DOI: 10.1038/s41467-023-41615-w] [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: 11/06/2022] [Accepted: 09/08/2023] [Indexed: 09/27/2023] Open
Abstract
In eukaryotes, the dynamic assembly of microtubules (MT) plays an important role in numerous cellular processes. The underlying mechanism of GTP triggering MT assembly is still unknown. Here, we present cryo-EM structures of tubulin heterodimer at their GTP- and GDP-bound states, intermediate assembly states of GTP-tubulin, and final assembly stages of MT. Both GTP- and GDP-tubulin heterodimers adopt similar curved conformations with subtle flexibility differences. In head-to-tail oligomers of tubulin heterodimers, the inter-dimer interface of GDP-tubulin exhibits greater flexibility, particularly in tangential bending. Cryo-EM of the intermediate assembly states reveals two types of tubulin lateral contacts, "Tube-bond" and "MT-bond". Further, molecular dynamics (MD) simulations show that GTP triggers lateral contact formation in MT assembly in multiple sequential steps, gradually straightening the curved tubulin heterodimers. Therefore, we propose a flexible model of GTP-initiated MT assembly, including the formation of longitudinal and lateral contacts, to explain the nucleation and assembly of MT.
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Affiliation(s)
- Ju Zhou
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Beijing Frontier Research Center for Biological Structures, Tsinghua University, Beijing, 100084, China
- University of California Berkeley, Berkeley, CA, USA
| | - Anhui Wang
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian, 116023, China
| | - Yinlong Song
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Nan Liu
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Beijing Frontier Research Center for Biological Structures, Tsinghua University, Beijing, 100084, China
| | - Jia Wang
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Beijing Frontier Research Center for Biological Structures, Tsinghua University, Beijing, 100084, China
| | - Yan Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian, 116023, China
| | - Xin Liang
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Guohui Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian, 116023, China
| | - Huiying Chu
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian, 116023, China.
| | - Hong-Wei Wang
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing, 100084, China.
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
- Beijing Frontier Research Center for Biological Structures, Tsinghua University, Beijing, 100084, China.
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5
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Singh V, Itoh Y, Del'Olio S, Hassan A, Naschberger A, Flygaard RK, Nobe Y, Izumikawa K, Aibara S, Andréll J, Whitford PC, Barrientos A, Taoka M, Amunts A. Structure of mitoribosome reveals mechanism of mRNA binding, tRNA interactions with L1 stalk, roles of cofactors and rRNA modifications. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.24.542018. [PMID: 37503168 PMCID: PMC10369894 DOI: 10.1101/2023.05.24.542018] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
The mitoribosome translates mitochondrial mRNAs and regulates energy conversion that is a signature of aerobic life forms. We present a 2.2 Å resolution structure of human mitoribosome together with validated mitoribosomal RNA (rRNA) modifications, including aminoacylated CP-tRNA Val . The structure shows how mitoribosomal proteins stabilise binding of mRNA and tRNA helping to align it in the decoding center, whereas the GDP-bound mS29 stabilizes intersubunit communication. Comparison between different states, with respect to tRNA position, allowed to characterize a non-canonical L1 stalk, and molecular dynamics simulations revealed how it facilitates tRNA transition in a way that does not require interactions with rRNA. We also report functionally important polyamines that are depleted when cells are subjected to an antibiotic treatment. The structural, biochemical, and computational data illuminate the principal functional components of the translation mechanism in mitochondria and provide the most complete description so far of the structure and function of the human mitoribosome.
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6
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Yu J, Zhang ZW, Yang HY, Liu CJ, Lu WC. Study of fusion peptide release for the spike protein of SARS-CoV-2. RSC Adv 2023; 13:16970-16983. [PMID: 37288377 PMCID: PMC10242618 DOI: 10.1039/d3ra01764h] [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: 03/17/2023] [Accepted: 05/11/2023] [Indexed: 06/09/2023] Open
Abstract
The spike protein of SARS-CoV-2 can recognize the ACE2 membrane protein on the host cell and plays a key role in the membrane fusion process between the virus envelope and the host cell membrane. However, to date, the mechanism for the spike protein recognizing host cells and initiating membrane fusion remains unknown. In this study, based on the general assumption that all three S1/S2 junctions of the spike protein are cleaved, structures with different forms of S1 subunit stripping and S2' site cleavage were constructed. Then, the minimum requirement for the release of the fusion peptide was studied by all-atom structure-based MD simulations. The results from simulations showed that stripping an S1 subunit from the A-, B- or C-chain of the spike protein and cleaving the specific S2' site on the B-chain (C-chain or A-chain) may result in the release of the fusion peptide, suggesting that the requirement for the release of FP may be more relaxed than previously expected.
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Affiliation(s)
- Jie Yu
- College of Physics, Qingdao University Qingdao 266071 Shandong P. R. China
| | - Zhi-Wei Zhang
- College of Physics, Qingdao University Qingdao 266071 Shandong P. R. China
| | - Han-Yu Yang
- College of Physics, Qingdao University Qingdao 266071 Shandong P. R. China
| | - Chong-Jin Liu
- College of Physics, Qingdao University Qingdao 266071 Shandong P. R. China
| | - Wen-Cai Lu
- College of Physics, Qingdao University Qingdao 266071 Shandong P. R. China
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7
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Wang A, Levi M, Mohanty U, Whitford PC. Diffuse Ions Coordinate Dynamics in a Ribonucleoprotein Assembly. J Am Chem Soc 2022; 144:9510-9522. [PMID: 35593477 DOI: 10.1021/jacs.2c04082] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Proper ionic concentrations are required for the functional dynamics of RNA and ribonucleoprotein (RNP) assemblies. While experimental and computational techniques have provided many insights into the properties of chelated ions, less is known about the energetic contributions of diffuse ions to large-scale conformational rearrangements. To address this, we present a model that is designed to quantify the influence of diffuse monovalent and divalent ions on the dynamics of biomolecular assemblies. This model employs all-atom (non-H) resolution and explicit ions, where effective potentials account for hydration effects. We first show that the model accurately predicts the number of excess Mg2+ ions for prototypical RNA systems, at a level comparable to modern coarse-grained models. We then apply the model to a complete ribosome and show how the balance between diffuse Mg2+ and K+ ions can control the dynamics of tRNA molecules during translation. The model predicts differential effects of diffuse ions on the free-energy barrier associated with tRNA entry and the energy of tRNA binding to the ribosome. Together, this analysis reveals the direct impact of diffuse ions on the dynamics of an RNP assembly.
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Affiliation(s)
- Ailun Wang
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States.,Center for Theoretical Biological Physics, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Mariana Levi
- Department of Physics, Northeastern University, Dana Research Center 111, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Udayan Mohanty
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Paul C Whitford
- Center for Theoretical Biological Physics, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, United States.,Department of Physics, Northeastern University, Dana Research Center 111, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
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8
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de Oliveira VM, Dias MMG, Avelino TM, Videira NB, da Silva FB, Doratioto TR, Whitford PC, Leite VBP, Figueira ACM. pH and the Breast Cancer Recurrent Mutation D538G Affect the Process of Activation of Estrogen Receptor α. Biochemistry 2022; 61:455-463. [PMID: 35238537 DOI: 10.1021/acs.biochem.1c00806] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Estrogen receptor α (ERα) is a regulatory protein that can access a set of distinct structural configurations. ERα undergoes extensive remodeling as it interacts with different agonists and antagonists, as well as transcription activation and repression factors. Moreover, breast cancer tumors resistant to hormone therapy have been associated with the imbalance between the active and inactive ERα states. Cancer-activating mutations in ERα play a crucial role in this imbalance and can promote the progression of cancer. However, the rate of this progression can also be increased by dysregulated pH in the tumor microenvironment. Many molecular aspects of the process of activation of ERα that can be affected by these pH changes and mutations are still unclear. Thus, we applied computational and experimental techniques to explore the activation process dynamics of ER for environments with different pHs and in the presence of one of the most recurrent cancer-activating mutations, D538G. Our results indicated that the effect of the pH increase associated with the D538G mutation promoted a robust stabilization of the active state of ER. We were also able to determine the main protein regions that have the most potential to influence the activation process under different pH conditions, which may provide targets of future therapeutics for the treatment of hormone-resistant breast cancer tumors. Finally, the approach used here can be applied for proteins associated with the proliferation of other cancer types, which can also have their function affected by small pH changes.
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Affiliation(s)
- Vinícius M de Oliveira
- Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, LNBio/CNPEM, Campinas 13083-970, SP, Brazil
| | - Marieli M G Dias
- Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, LNBio/CNPEM, Campinas 13083-970, SP, Brazil
| | - Thayná M Avelino
- Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, LNBio/CNPEM, Campinas 13083-970, SP, Brazil
| | - Natália B Videira
- Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, LNBio/CNPEM, Campinas 13083-970, SP, Brazil
| | - Fernando B da Silva
- Department of Physics, São Paulo State University (UNESP), Institute of Biosciences, Humanities and Exact Sciences, São José do Rio Preto 01140-070, SP, Brazil
| | - Tábata R Doratioto
- Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, LNBio/CNPEM, Campinas 13083-970, SP, Brazil
| | - Paul C Whitford
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States
| | - Vitor B P Leite
- Department of Physics, São Paulo State University (UNESP), Institute of Biosciences, Humanities and Exact Sciences, São José do Rio Preto 01140-070, SP, Brazil
| | - Ana Carolina M Figueira
- Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, LNBio/CNPEM, Campinas 13083-970, SP, Brazil
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9
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Hassan A, Byju S, Whitford PC. The energetics of subunit rotation in the ribosome. Biophys Rev 2021; 13:1029-1037. [PMID: 35059025 PMCID: PMC8724491 DOI: 10.1007/s12551-021-00877-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 10/26/2021] [Indexed: 12/12/2022] Open
Abstract
Protein synthesis in the cell is controlled by an elaborate sequence of conformational rearrangements in the ribosome. The composition of a ribosome varies by species, though they typically contain ∼ 50-100 RNA and protein molecules. While advances in structural techniques have revolutionized our understanding of long-lived conformational states, a vast range of transiently visited configurations can not be directly observed. In these cases, computational/simulation methods can be used to understand the mechanical properties of the ribosome. Insights from these approaches can then help guide next-generation experimental measurements. In this short review, we discuss theoretical strategies that have been deployed to quantitatively describe the energetics of collective rearrangements in the ribosome. We focus on efforts to probe large-scale subunit rotation events, which involve the coordinated displacement of large numbers of atoms (tens of thousands). These investigations are revealing how the molecular structure of the ribosome encodes the mechanical properties that control large-scale dynamics.
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Affiliation(s)
- Asem Hassan
- Center for Theoretical Biological Physics, 360 Huntington Ave, Boston, 02115 MA USA
- Physics Department, Northeastern University, 360 Huntington Ave, Boston, 02115 MA USA
| | - Sandra Byju
- Center for Theoretical Biological Physics, 360 Huntington Ave, Boston, 02115 MA USA
- Physics Department, Northeastern University, 360 Huntington Ave, Boston, 02115 MA USA
| | - Paul C. Whitford
- Center for Theoretical Biological Physics, 360 Huntington Ave, Boston, 02115 MA USA
- Physics Department, Northeastern University, 360 Huntington Ave, Boston, 02115 MA USA
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10
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Dodero-Rojas E, Onuchic JN, Whitford PC. Sterically confined rearrangements of SARS-CoV-2 Spike protein control cell invasion. eLife 2021; 10:70362. [PMID: 34463614 PMCID: PMC8456623 DOI: 10.7554/elife.70362] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 08/06/2021] [Indexed: 12/13/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly contagious, and transmission involves a series of processes that may be targeted by vaccines and therapeutics. During transmission, host cell invasion is controlled by a large-scale (200–300 Å) conformational change of the Spike protein. This conformational rearrangement leads to membrane fusion, which creates transmembrane pores through which the viral genome is passed to the host. During Spike-protein-mediated fusion, the fusion peptides must be released from the core of the protein and associate with the host membrane. While infection relies on this transition between the prefusion and postfusion conformations, there has yet to be a biophysical characterization reported for this rearrangement. That is, structures are available for the endpoints, though the intermediate conformational processes have not been described. Interestingly, the Spike protein possesses many post-translational modifications, in the form of branched glycans that flank the surface of the assembly. With the current lack of data on the pre-to-post transition, the precise role of glycans during cell invasion has also remained unclear. To provide an initial mechanistic description of the pre-to-post rearrangement, an all-atom model with simplified energetics was used to perform thousands of simulations in which the protein transitions between the prefusion and postfusion conformations. These simulations indicate that the steric composition of the glycans can induce a pause during the Spike protein conformational change. We additionally show that this glycan-induced delay provides a critical opportunity for the fusion peptides to capture the host cell. In contrast, in the absence of glycans, the viral particle would likely fail to enter the host. This analysis reveals how the glycosylation state can regulate infectivity, while providing a much-needed structural framework for studying the dynamics of this pervasive pathogen.
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Affiliation(s)
- Esteban Dodero-Rojas
- Center for Theoretical Biological Physics, Rice University, Houston, United States
| | - Jose N Onuchic
- Center for Theoretical Biological Physics, Rice University, Houston, United States.,Department of Physics and Astronomy, Rice University, Houston, United States.,Department of Chemistry, Rice University, Houston, United States.,Department of Biosciences, Rice University, Houston, United States
| | - Paul Charles Whitford
- Center for Theoretical Biological Physics, Northeastern University, Boston, United States.,Department of Physics, Northeastern University, Boston, United States
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11
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Bheemireddy S, Sandhya S, Srinivasan N. Comparative Analysis of Structural and Dynamical Features of Ribosome Upon Association With mRNA Reveals Potential Role of Ribosomal Proteins. Front Mol Biosci 2021; 8:654164. [PMID: 34409066 PMCID: PMC8365230 DOI: 10.3389/fmolb.2021.654164] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 07/21/2021] [Indexed: 11/24/2022] Open
Abstract
Ribosomes play a critical role in maintaining cellular proteostasis. The binding of messenger RNA (mRNA) to the ribosome regulates kinetics of protein synthesis. To generate an understanding of the structural, mechanistic, and dynamical features of mRNA recognition in the ribosome, we have analysed mRNA-protein interactions through a structural comparison of the ribosomal complex in the presence and absence of mRNA. To do so, we compared the 3-Dimensional (3D) structures of components of the two assembly structures and analysed their structural differences because of mRNA binding, using elastic network models and structural network-based analysis. We observe that the head region of 30S ribosomal subunit undergoes structural displacement and subunit rearrangement to accommodate incoming mRNA. We find that these changes are observed in proteins that lie far from the mRNA-protein interface, implying allostery. Further, through perturbation response scanning, we show that the proteins S13, S19, and S20 act as universal sensors that are sensitive to changes in the inter protein network, upon binding of 30S complex with mRNA and other initiation factors. Our study highlights the significance of mRNA binding in the ribosome complex and identifies putative allosteric sites corresponding to alterations in structure and/or dynamics, in regions away from mRNA binding sites in the complex. Overall, our work provides fresh insights into mRNA association with the ribosome, highlighting changes in the interactions and dynamics of the ribosome assembly because of the binding.
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Affiliation(s)
- Sneha Bheemireddy
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, India
| | - Sankaran Sandhya
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, India
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12
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Freitas FC, Fuchs G, de Oliveira RJ, Whitford PC. The dynamics of subunit rotation in a eukaryotic ribosome. BIOPHYSICA 2021; 1:204-221. [PMID: 37484008 PMCID: PMC10361705 DOI: 10.3390/biophysica1020016] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Protein synthesis by the ribosome is coordinated by an intricate series of large-scale conformational rearrangements. Structural studies can provide information about long-lived states, however biological kinetics are controlled by the intervening free-energy barriers. While there has been progress describing the energy landscapes of bacterial ribosomes, very little is known about the energetics of large-scale rearrangements in eukaryotic systems. To address this topic, we constructed an all-atom model with simplified energetics and performed simulations of subunit rotation in the yeast ribosome. In these simulations, the small subunit (SSU; ~1MDa) undergoes spontaneous and reversible rotations (~8°). By enabling the simulation of this rearrangement under equilibrium conditions, these calculations provide initial insights into the molecular factors that control dynamics in eukaryotic ribosomes. Through this, we are able to identify specific inter-subunit interactions that have a pronounced influence on the rate-limiting free-energy barrier. We also show that, as a result of changes in molecular flexibility, the thermodynamic balance between the rotated and unrotated states is temperature-dependent. This effect may be interpreted in terms of differential molecular flexibility within the rotated and unrotated states. Together, these calculations provide a foundation, upon which the field may begin to dissect the energetics of these complex molecular machines.
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Affiliation(s)
- Frederico Campos Freitas
- Laboratório de Biofísica Teórica, Departamento de Física, Instituto de Ciências Exatas, Naturais e Educação, Universidade Federal do Triângulo Mineiro, Uberaba, MG, Brazil
| | - Gabriele Fuchs
- Department of Biological Sciences, The RNA Institute, University at Albany 1400 Washington Ave, Albany, NY,12222
| | - Ronaldo Junio de Oliveira
- Laboratório de Biofísica Teórica, Departamento de Física, Instituto de Ciências Exatas, Naturais e Educação, Universidade Federal do Triângulo Mineiro, Uberaba, MG, Brazil
| | - Paul Charles Whitford
- Department of Physics, Northeastern University, 360 Huntington Ave, Boston, MA 02115
- Center for Theoretical Biological Physics, Northeastern University, 360 Huntington Ave, Boston, MA 02115
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