1
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Komar AA, Samatova E, Rodnina MV. Translation Rates and Protein Folding. J Mol Biol 2024; 436:168384. [PMID: 38065274 DOI: 10.1016/j.jmb.2023.168384] [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: 10/20/2023] [Revised: 12/01/2023] [Accepted: 12/02/2023] [Indexed: 12/19/2023]
Abstract
The mRNA coding sequence defines not only the amino acid sequence of the protein, but also the speed at which the ribosomes move along the mRNA while making the protein. The non-uniform local kinetics - denoted as translational rhythm - is similar among mRNAs coding for related protein folds. Deviations from this conserved rhythm can result in protein misfolding. In this review we summarize the experimental evidence demonstrating how local translation rates affect cotranslational protein folding, with the focus on the synonymous codons and patches of charged residues in the nascent peptide as best-studied examples. Alterations in nascent protein conformations due to disturbed translational rhythm can persist off the ribosome, as demonstrated by the effects of synonymous codon variants of several disease-related proteins. Charged amino acid patches in nascent chains also modulate translation and cotranslational protein folding, and can abrogate translation when placed at the N-terminus of the nascent peptide. During cotranslational folding, incomplete nascent chains navigate through a unique conformational landscape in which earlier intermediate states become inaccessible as the nascent peptide grows. Precisely tuned local translation rates, as well as interactions with the ribosome, guide the folding pathway towards the native structure, whereas deviations from the natural translation rhythm may favor pathways leading to trapped misfolded states. Deciphering the 'folding code' of the mRNA will contribute to understanding the diseases caused by protein misfolding and to rational protein design.
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Affiliation(s)
- Anton A Komar
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological and Environmental Sciences, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA; Department of Biochemistry and Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Ekaterina Samatova
- Max Planck Department of Physical Biochemistry, Max Planck Institute for Multidisciplinary Sciences, 37077 Goettingen, Germany
| | - Marina V Rodnina
- Max Planck Department of Physical Biochemistry, Max Planck Institute for Multidisciplinary Sciences, 37077 Goettingen, Germany.
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2
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Roeselová A, Maslen SL, Shivakumaraswamy S, Pellowe GA, Howell S, Joshi D, Redmond J, Kjær S, Skehel JM, Balchin D. Mechanism of chaperone coordination during cotranslational protein folding in bacteria. Mol Cell 2024; 84:2455-2471.e8. [PMID: 38908370 DOI: 10.1016/j.molcel.2024.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 04/12/2024] [Accepted: 06/01/2024] [Indexed: 06/24/2024]
Abstract
Protein folding is assisted by molecular chaperones that bind nascent polypeptides during mRNA translation. Several structurally distinct classes of chaperones promote de novo folding, suggesting that their activities are coordinated at the ribosome. We used biochemical reconstitution and structural proteomics to explore the molecular basis for cotranslational chaperone action in bacteria. We found that chaperone binding is disfavored close to the ribosome, allowing folding to precede chaperone recruitment. Trigger factor recognizes compact folding intermediates that expose an extensive unfolded surface, and dictates DnaJ access to nascent chains. DnaJ uses a large surface to bind structurally diverse intermediates and recruits DnaK to sequence-diverse solvent-accessible sites. Neither Trigger factor, DnaJ, nor DnaK destabilize cotranslational folding intermediates. Instead, the chaperones collaborate to protect incipient structure in the nascent polypeptide well beyond the ribosome exit tunnel. Our findings show how the chaperone network selects and modulates cotranslational folding intermediates.
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Affiliation(s)
- Alžběta Roeselová
- Protein Biogenesis Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Sarah L Maslen
- Proteomics Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | | | - Grant A Pellowe
- Protein Biogenesis Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Steven Howell
- Proteomics Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | - Dhira Joshi
- Chemical Biology Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | - Joanna Redmond
- Chemical Biology Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | - Svend Kjær
- Structural Biology Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | - J Mark Skehel
- Proteomics Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK
| | - David Balchin
- Protein Biogenesis Laboratory, The Francis Crick Institute, London NW1 1AT, UK.
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3
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Rajasekaran N, Kaiser CM. Navigating the complexities of multi-domain protein folding. Curr Opin Struct Biol 2024; 86:102790. [PMID: 38432063 DOI: 10.1016/j.sbi.2024.102790] [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: 11/27/2023] [Revised: 02/11/2024] [Accepted: 02/12/2024] [Indexed: 03/05/2024]
Abstract
Proteome complexity has expanded tremendously over evolutionary time, enabling biological diversification. Much of this complexity is achieved by combining a limited set of structural units into long polypeptides. This widely used evolutionary strategy poses challenges for folding of the resulting multi-domain proteins. As a consequence, their folding differs from that of small single-domain proteins, which generally fold quickly and reversibly. Co-translational processes and chaperone interactions are important aspects of multi-domain protein folding. In this review, we discuss some of the recent experimental progress toward understanding these processes.
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Affiliation(s)
| | - Christian M Kaiser
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States; Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, Netherlands.
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4
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Masse MM, Guzman-Luna V, Varela AE, Mahfuza Shapla U, Hutchinson RB, Srivastava A, Wei W, Fuchs AM, Cavagnero S. Nascent chains derived from a foldable protein sequence interact with specific ribosomal surface sites near the exit tunnel. Sci Rep 2024; 14:12324. [PMID: 38811604 PMCID: PMC11137106 DOI: 10.1038/s41598-024-61274-1] [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: 03/25/2023] [Accepted: 05/03/2024] [Indexed: 05/31/2024] Open
Abstract
In order to become bioactive, proteins must be translated and protected from aggregation during biosynthesis. The ribosome and molecular chaperones play a key role in this process. Ribosome-bound nascent chains (RNCs) of intrinsically disordered proteins and RNCs bearing a signal/arrest sequence are known to interact with ribosomal proteins. However, in the case of RNCs bearing foldable protein sequences, not much information is available on these interactions. Here, via a combination of chemical crosslinking and time-resolved fluorescence-anisotropy, we find that nascent chains of the foldable globin apoHmp1-140 interact with ribosomal protein L23 and have a freely-tumbling non-interacting N-terminal compact region comprising 63-94 residues. Longer RNCs (apoHmp1-189) also interact with an additional yet unidentified ribosomal protein, as well as with chaperones. Surprisingly, the apparent strength of RNC/r-protein interactions does not depend on nascent-chain sequence. Overall, foldable nascent chains establish and expand interactions with selected ribosomal proteins and chaperones, as they get longer. These data are significant because they reveal the interplay between independent conformational sampling and nascent-protein interactions with the ribosomal surface.
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Affiliation(s)
- Meranda M Masse
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Valeria Guzman-Luna
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Angela E Varela
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Ummay Mahfuza Shapla
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Rachel B Hutchinson
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Department of Food Science, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Aniruddha Srivastava
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- McGaw Medical Center, Northwestern University, Chicago, IL, 60611, USA
| | - Wanting Wei
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- AIDS Vaccine Research Laboratory, University of Wisconsin-Madison, Madison, WI, 53711, USA
| | - Andrew M Fuchs
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Silvia Cavagnero
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA.
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5
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McDonnell RT, Elcock AH. AutoRNC: An automated modeling program for building atomic models of ribosome-nascent chain complexes. Structure 2024; 32:621-629.e5. [PMID: 38428431 PMCID: PMC11073581 DOI: 10.1016/j.str.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 11/29/2023] [Accepted: 02/05/2024] [Indexed: 03/03/2024]
Abstract
The interpretation of experimental studies of co-translational protein folding often benefits from the use of computational methods that seek to model or simulate the nascent chain and its interactions with the ribosome. Building realistic 3D models of ribosome-nascent chain (RNC) constructs often requires expert knowledge, so to circumvent this issue, we describe here AutoRNC, an automated modeling program capable of constructing large numbers of plausible atomic models of RNCs within minutes. AutoRNC takes input from the user specifying any regions of the nascent chain that contain secondary or tertiary structure and attempts to build conformations compatible with those specifications-and with the constraints imposed by the ribosome-by sampling and progressively piecing together dipeptide conformations extracted from the Research Collaboratory for Structural Bioinformatics Protein Data Bank (RCSB). Despite using only modest computational resources, we show here that AutoRNC can build plausible conformations for a wide range of RNC constructs for which experimental data have already been reported.
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Affiliation(s)
- Robert T McDonnell
- Department of Biochemistry & Molecular Biology, University of Iowa, Iowa City, IA, USA
| | - Adrian H Elcock
- Department of Biochemistry & Molecular Biology, University of Iowa, Iowa City, IA, USA.
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6
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Samatova E, Komar AA, Rodnina MV. How the ribosome shapes cotranslational protein folding. Curr Opin Struct Biol 2024; 84:102740. [PMID: 38071940 DOI: 10.1016/j.sbi.2023.102740] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/15/2023] [Accepted: 11/16/2023] [Indexed: 02/09/2024]
Abstract
During protein synthesis, the growing nascent peptide chain moves inside the polypeptide exit tunnel of the ribosome from the peptidyl transferase center towards the exit port where it emerges into the cytoplasm. The ribosome defines the unique energy landscape of the pioneering round of protein folding. The spatial confinement and the interactions of the nascent peptide with the tunnel walls facilitate formation of secondary structures, such as α-helices. The vectorial nature of protein folding inside the tunnel favors local intra- and inter-molecular interactions, thereby inducing cotranslational folding intermediates that do not form upon protein refolding in solution. Tertiary structures start to fold in the lower part of the tunnel, where interactions with the ribosome destabilize native protein folds. The present review summarizes the recent progress in understanding the driving forces of nascent protein folding inside the tunnel and at the surface of the ribosome.
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Affiliation(s)
- Ekaterina Samatova
- Department of Physical Biochemistry, Max Planck Institute for Multidisciplinary Sciences, Goettingen 37077, Germany
| | - Anton A Komar
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological and Environmental Sciences, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA; Department of Biochemistry and Center for RNA Science and Therapeutics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Marina V Rodnina
- Department of Physical Biochemistry, Max Planck Institute for Multidisciplinary Sciences, Goettingen 37077, Germany.
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7
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Chen X, Kaiser CM. AP profiling resolves co-translational folding pathway and chaperone interactions in vivo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.01.555749. [PMID: 37693575 PMCID: PMC10491307 DOI: 10.1101/2023.09.01.555749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Natural proteins have evolved to fold robustly along specific pathways. Folding begins during synthesis, guided by interactions of the nascent protein with the ribosome and molecular chaperones. However, the timing and progression of co-translational folding remain largely elusive, in part because the process is difficult to measure in the natural environment of the cytosol. We developed a high-throughput method to quantify co-translational folding in live cells that we term Arrest Peptide profiling (AP profiling). We employed AP profiling to delineate co-translational folding for a set of GTPase domains with very similar structures, defining how topology shapes folding pathways. Genetic ablation of major nascent chain-binding chaperones resulted in localized folding changes that suggest how functional redundancies among chaperones are achieved by distinct interactions with the nascent protein. Collectively, our studies provide a window into cellular folding pathways of complex proteins and pave the way for systematic studies on nascent protein folding at unprecedented resolution and throughput.
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Affiliation(s)
- Xiuqi Chen
- CMDB Graduate Program, Johns Hopkins University, Baltimore, MD, United States
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States
- Present address: Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, the Netherlands
| | - Christian M. Kaiser
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, United States
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8
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Tan R, Hoare M, Welle KA, Swovick K, Hryhorenko JR, Ghaemmaghami S. Folding stabilities of ribosome-bound nascent polypeptides probed by mass spectrometry. Proc Natl Acad Sci U S A 2023; 120:e2303167120. [PMID: 37552756 PMCID: PMC10438377 DOI: 10.1073/pnas.2303167120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 07/11/2023] [Indexed: 08/10/2023] Open
Abstract
The folding of most proteins occurs during the course of their translation while their tRNA-bound C termini are embedded in the ribosome. How the close proximity of nascent proteins to the ribosome influences their folding thermodynamics remains poorly understood. Here, we have developed a mass spectrometry-based approach for determining the stabilities of nascent polypeptide chains using methionine oxidation as a folding probe. This approach enables quantitative measurement subglobal folding stabilities of ribosome nascent chains within complex protein mixtures and extracts. To validate the methodology, we analyzed the folding thermodynamics of three model proteins (dihydrofolate reductase, chemotaxis protein Y, and DNA polymerase IV) in soluble and ribosome-bound states. The data indicate that the ribosome can significantly alter the stability of nascent polypeptides. Ribosome-induced stability modulations were highly variable among different folding domains and were dependent on localized charge distributions within nascent polypeptides. The results implicated electrostatic interactions between the ribosome surface and nascent polypeptides as the cause of ribosome-induced stability modulations. The study establishes a robust proteomic methodology for analyzing localized stabilities within ribosome-bound nascent polypeptides and sheds light on how the ribosome influences the thermodynamics of protein folding.
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Affiliation(s)
- Ruiyue Tan
- Department of Biology, University of Rochester, Rochester, NY14627
| | - Margaret Hoare
- Department of Biology, University of Rochester, Rochester, NY14627
| | - Kevin A. Welle
- Mass Spectrometry Resource Laboratory, University of Rochester Medical Center, Rochester, NY14627
| | - Kyle Swovick
- Mass Spectrometry Resource Laboratory, University of Rochester Medical Center, Rochester, NY14627
| | - Jennifer R. Hryhorenko
- Mass Spectrometry Resource Laboratory, University of Rochester Medical Center, Rochester, NY14627
| | - Sina Ghaemmaghami
- Department of Biology, University of Rochester, Rochester, NY14627
- Mass Spectrometry Resource Laboratory, University of Rochester Medical Center, Rochester, NY14627
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9
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McDonnell RT, Elcock AH. AutoRNC: an automated modeling program for building atomic models of ribosome-nascent chain complexes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.14.544999. [PMID: 37398297 PMCID: PMC10312685 DOI: 10.1101/2023.06.14.544999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
The interpretation of experimental studies of co-translational protein folding often benefits from the use of computational methods that seek to model the nascent chain and its interactions with the ribosome. Ribosome-nascent chain (RNC) constructs studied experimentally can vary significantly in size and the extent to which they contain secondary and tertiary structure, and building realistic 3D models of them therefore often requires expert knowledge. To circumvent this issue, we describe here AutoRNC, an automated modeling program capable of constructing large numbers of plausible atomic models of RNCs within minutes. AutoRNC takes input from the user specifying any regions of the nascent chain that contain secondary or tertiary structure and attempts to build conformations compatible with those specifications - and with the constraints imposed by the ribosome - by sampling and progressively piecing together dipeptide conformations extracted from the RCSB. We first show that conformations of completely unfolded proteins built by AutoRNC in the absence of the ribosome have radii of gyration that match well with the corresponding experimental data. We then show that AutoRNC can build plausible conformations for a wide range of RNC constructs for which experimental data have already been reported. Since AutoRNC requires only modest computational resources, we anticipate that it will prove to be a useful hypothesis generator for experimental studies, for example, in providing indications of whether designed constructs are likely to be capable of folding, as well as providing useful starting points for downstream atomic or coarse-grained simulations of the conformational dynamics of RNCs.
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10
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Vu QV, Nissley DA, Jiang Y, O'Brien EP, Li MS. Is Posttranslational Folding More Efficient Than Refolding from a Denatured State: A Computational Study. J Phys Chem B 2023. [PMID: 37200608 DOI: 10.1021/acs.jpcb.3c01694] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The folding of proteins into their native conformation is a complex process that has been extensively studied over the past half-century. The ribosome, the molecular machine responsible for protein synthesis, is known to interact with nascent proteins, adding further complexity to the protein folding landscape. Consequently, it is unclear whether the folding pathways of proteins are conserved on and off the ribosome. The main question remains: to what extent does the ribosome help proteins fold? To address this question, we used coarse-grained molecular dynamics simulations to compare the mechanisms by which the proteins dihydrofolate reductase, type III chloramphenicol acetyltransferase, and d-alanine-d-alanine ligase B fold during and after vectorial synthesis on the ribosome to folding from the full-length unfolded state in bulk solution. Our results reveal that the influence of the ribosome on protein folding mechanisms varies depending on the size and complexity of the protein. Specifically, for a small protein with a simple fold, the ribosome facilitates efficient folding by helping the nascent protein avoid misfolded conformations. However, for larger and more complex proteins, the ribosome does not promote folding and may contribute to the formation of intermediate misfolded states cotranslationally. These misfolded states persist posttranslationally and do not convert to the native state during the 6 μs runtime of our coarse-grain simulations. Overall, our study highlights the complex interplay between the ribosome and protein folding and provides insight into the mechanisms of protein folding on and off the ribosome.
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Affiliation(s)
- Quyen V Vu
- Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
| | - Daniel A Nissley
- Department of Statistics, University of Oxford, Oxford OX1 3LB, U.K
| | - Yang Jiang
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Edward P O'Brien
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Bioinformatics and Genomics Graduate Program, The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Institute for Computational and Data Sciences, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - 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 700000, Vietnam
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11
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Rajasekaran N, Kaiser CM. Co-Translational Folding of Multi-Domain Proteins. Front Mol Biosci 2022; 9:869027. [PMID: 35517860 PMCID: PMC9065291 DOI: 10.3389/fmolb.2022.869027] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 03/21/2022] [Indexed: 12/24/2022] Open
Abstract
The majority of proteins in nature are composed of multiple domains connected in a single polypeptide. How these long sequences fold into functional structures without forming toxic misfolds or aggregates is poorly understood. Their folding is inextricably linked to protein synthesis and interactions with cellular machinery, making mechanistic studies challenging. Recent progress has revealed critical features of multi-domain protein folding in isolation and in the context of translation by the ribosome. In this review, we discuss challenges and progress in understanding multi-domain protein folding, and highlight how molecular interactions shape folding and misfolding pathways. With the development of new approaches and model systems, the stage is now set for mechanistically exploring the folding of large multi-domain proteins.
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Affiliation(s)
| | - Christian M. Kaiser
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States,Department of Biophysics, Johns Hopkins University, Baltimore, MD, United States,*Correspondence: Christian M. Kaiser,
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12
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Thermodynamics of co-translational folding and ribosome-nascent chain interactions. Curr Opin Struct Biol 2022; 74:102357. [PMID: 35390638 DOI: 10.1016/j.sbi.2022.102357] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 02/22/2022] [Accepted: 02/22/2022] [Indexed: 11/03/2022]
Abstract
Proteins can begin the conformational search for their native structure in parallel with biosynthesis on the ribosome, in a process termed co-translational folding. In contrast to the reversible folding of isolated domains, as a nascent chain emerges from the ribosome exit tunnel during translation the free energy landscape it explores also evolves as a function of chain length. While this presents a substantially more complex measurement problem, this review will outline the progress that has been made recently in understanding, quantitatively, the process by which a nascent chain attains its full native stability, as well as the mechanisms through which interactions with the nearby ribosome surface can perturb or modulate this process.
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13
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The folding and misfolding mechanisms of multidomain proteins. MEDICINE IN DRUG DISCOVERY 2022. [DOI: 10.1016/j.medidd.2022.100126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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14
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Plessa E, Chu LP, Chan SHS, Thomas OL, Cassaignau AME, Waudby CA, Christodoulou J, Cabrita LD. Nascent chains can form co-translational folding intermediates that promote post-translational folding outcomes in a disease-causing protein. Nat Commun 2021; 12:6447. [PMID: 34750347 PMCID: PMC8576036 DOI: 10.1038/s41467-021-26531-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 10/01/2021] [Indexed: 01/16/2023] Open
Abstract
During biosynthesis, proteins can begin folding co-translationally to acquire their biologically-active structures. Folding, however, is an imperfect process and in many cases misfolding results in disease. Less is understood of how misfolding begins during biosynthesis. The human protein, alpha-1-antitrypsin (AAT) folds under kinetic control via a folding intermediate; its pathological variants readily form self-associated polymers at the site of synthesis, leading to alpha-1-antitrypsin deficiency. We observe that AAT nascent polypeptides stall during their biosynthesis, resulting in full-length nascent chains that remain bound to ribosome, forming a persistent ribosome-nascent chain complex (RNC) prior to release. We analyse the structure of these RNCs, which reveals compacted, partially-folded co-translational folding intermediates possessing molten-globule characteristics. We find that the highly-polymerogenic mutant, Z AAT, forms a distinct co-translational folding intermediate relative to wild-type. Its very modest structural differences suggests that the ribosome uniquely tempers the impact of deleterious mutations during nascent chain emergence. Following nascent chain release however, these co-translational folding intermediates guide post-translational folding outcomes thus suggesting that Z's misfolding is initiated from co-translational structure. Our findings demonstrate that co-translational folding intermediates drive how some proteins fold under kinetic control, and may thus also serve as tractable therapeutic targets for human disease.
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Affiliation(s)
- Elena Plessa
- Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Lien P Chu
- Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Sammy H S Chan
- Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Oliver L Thomas
- Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Anaïs M E Cassaignau
- Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Christopher A Waudby
- Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - John Christodoulou
- Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK. .,School of Crystallography, Birkbeck College, University of London, Malet Street, London, WC1E 7HX, UK.
| | - Lisa D Cabrita
- Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, UK.
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15
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Petrosyan R, Narayan A, Woodside MT. Single-Molecule Force Spectroscopy of Protein Folding. J Mol Biol 2021; 433:167207. [PMID: 34418422 DOI: 10.1016/j.jmb.2021.167207] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/11/2021] [Accepted: 08/11/2021] [Indexed: 10/20/2022]
Abstract
The use of force probes to induce unfolding and refolding of single molecules through the application of mechanical tension, known as single-molecule force spectroscopy (SMFS), has proven to be a powerful tool for studying the dynamics of protein folding. Here we provide an overview of what has been learned about protein folding using SMFS, from small, single-domain proteins to large, multi-domain proteins. We highlight the ability of SMFS to measure the energy landscapes underlying folding, to map complex pathways for native and non-native folding, to probe the mechanisms of chaperones that assist with native folding, to elucidate the effects of the ribosome on co-translational folding, and to monitor the folding of membrane proteins.
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Affiliation(s)
- Rafayel Petrosyan
- Department of Physics, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - Abhishek Narayan
- Department of Physics, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - Michael T Woodside
- Department of Physics, University of Alberta, Edmonton, AB T6G 2E1, Canada
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16
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Vu QV, Jiang Y, Li MS, O'Brien EP. The driving force for co-translational protein folding is weaker in the ribosome vestibule due to greater water ordering. Chem Sci 2021; 12:11851-11857. [PMID: 34659725 PMCID: PMC8442680 DOI: 10.1039/d1sc01008e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 08/02/2021] [Indexed: 01/12/2023] Open
Abstract
Interactions between the ribosome and nascent chain can destabilize folded domains in the ribosome exit tunnel's vestibule, the last 3 nm of the exit tunnel where tertiary folding can occur. Here, we test if a contribution to this destabilization is a weakening of hydrophobic association, the driving force for protein folding. Using all-atom molecular dynamics simulations, we calculate the potential-of-mean force between two methane molecules along the center line of the ribosome exit tunnel and in bulk solution. Associated methanes, we find, are half as stable in the ribosome's vestibule as compared to bulk solution, demonstrating that the hydrophobic effect is weakened by the presence of the ribosome. This decreased stability arises from a decrease in the amount of water entropy gained upon the association of the methanes. And this decreased entropy gain originates from water molecules being more ordered in the vestibule as compared to bulk solution. Therefore, the hydrophobic effect is weaker in the vestibule because waters released from the first solvation shell of methanes upon association do not gain as much entropy in the vestibule as they do upon release in bulk solution. These findings mean that nascent proteins pass through a ribosome vestibule environment that can destabilize folded structures, which has the potential to influence co-translational protein folding pathways, energetics, and kinetics.
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Affiliation(s)
- Quyen V. Vu
- Institute of Physics, Polish Academy of SciencesAl. Lotnikow 32/4602-668 WarsawPoland
| | - Yang Jiang
- Department of Chemistry, Penn State UniversityUniversity ParkPennsylvaniaUSA
| | - Mai Suan Li
- Institute of Physics, Polish Academy of SciencesAl. Lotnikow 32/4602-668 WarsawPoland,Institute for Computational Sciences and TechnologyQuang Trung Software City, Tan Chanh Hiep Ward, District 12Ho Chi Minh CityVietnam
| | - Edward P. O'Brien
- Department of Chemistry, Penn State UniversityUniversity ParkPennsylvaniaUSA,Bioinformatics and Genomics Graduate Program, The Huck Institutes of the Life Sciences, Penn State UniversityUniversity ParkPennsylvaniaUSA,Institute for Computational and Data Sciences, Penn State UniversityUniversity ParkPennsylvaniaUSA
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17
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Abstract
Folding of polypeptides begins during their synthesis on ribosomes. This process has evolved as a means for the cell to maintain proteostasis, by mitigating the risk of protein misfolding and aggregation. The capacity to now depict this cellular feat at increasingly higher resolution is providing insight into the mechanistic determinants that promote successful folding. Emerging from these studies is the intimate interplay between protein translation and folding, and within this the ribosome particle is the key player. Its unique structural properties provide a specialized scaffold against which nascent polypeptides can begin to form structure in a highly coordinated, co-translational manner. Here, we examine how, as a macromolecular machine, the ribosome modulates the intrinsic dynamic properties of emerging nascent polypeptide chains and guides them toward their biologically active structures.
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Affiliation(s)
- Anaïs M E Cassaignau
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, London WC1E 7HX, United Kingdom; , ,
| | - Lisa D Cabrita
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, London WC1E 7HX, United Kingdom; , ,
| | - John Christodoulou
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, London WC1E 7HX, United Kingdom; , ,
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18
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Koubek J, Schmitt J, Galmozzi CV, Kramer G. Mechanisms of Cotranslational Protein Maturation in Bacteria. Front Mol Biosci 2021; 8:689755. [PMID: 34113653 PMCID: PMC8185961 DOI: 10.3389/fmolb.2021.689755] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 05/10/2021] [Indexed: 01/05/2023] Open
Abstract
Growing cells invest a significant part of their biosynthetic capacity into the production of proteins. To become functional, newly-synthesized proteins must be N-terminally processed, folded and often translocated to other cellular compartments. A general strategy is to integrate these protein maturation processes with translation, by cotranslationally engaging processing enzymes, chaperones and targeting factors with the nascent polypeptide. Precise coordination of all factors involved is critical for the efficiency and accuracy of protein synthesis and cellular homeostasis. This review provides an overview of the current knowledge on cotranslational protein maturation, with a focus on the production of cytosolic proteins in bacteria. We describe the role of the ribosome and the chaperone network in protein folding and how the dynamic interplay of all cotranslationally acting factors guides the sequence of cotranslational events. Finally, we discuss recent data demonstrating the coupling of protein synthesis with the assembly of protein complexes and end with a brief discussion of outstanding questions and emerging concepts in the field of cotranslational protein maturation.
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Affiliation(s)
- Jiří Koubek
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Jaro Schmitt
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Carla Veronica Galmozzi
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Günter Kramer
- Center for Molecular Biology of Heidelberg University (ZMBH) and German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany
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19
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Maciuba K, Rajasekaran N, Chen X, Kaiser CM. Co-translational folding of nascent polypeptides: Multi-layered mechanisms for the efficient biogenesis of functional proteins. Bioessays 2021; 43:e2100042. [PMID: 33987870 PMCID: PMC8262109 DOI: 10.1002/bies.202100042] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 04/02/2021] [Accepted: 04/07/2021] [Indexed: 11/09/2022]
Abstract
The coupling of protein synthesis and folding is a crucial yet poorly understood aspect of cellular protein folding. Over the past few years, it has become possible to experimentally follow and define protein folding on the ribosome, revealing principles that shape co-translational folding and distinguish it from refolding in solution. Here, we highlight some of these recent findings from biochemical and biophysical studies and their potential significance for cellular protein biogenesis. In particular, we focus on nascent chain interactions with the ribosome, interactions within the nascent protein, modulation of translation elongation rates, and the role of mechanical force that accompanies nascent protein folding. The ability to obtain mechanistic insight in molecular detail has set the stage for exploring the intricate process of nascent protein folding. We believe that the aspects discussed here will be generally important for understanding how protein synthesis and folding are coupled and regulated.
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Affiliation(s)
- Kevin Maciuba
- CMDB Graduate Program, Johns Hopkins University, Baltimore, Maryland, USA
| | | | - Xiuqi Chen
- CMDB Graduate Program, Johns Hopkins University, Baltimore, Maryland, USA
| | - Christian M Kaiser
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA.,Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
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20
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Maciuba K, Zhang F, Kaiser CM. Facile tethering of stable and unstable proteins for optical tweezers experiments. Biophys J 2021; 120:2691-2700. [PMID: 33989618 DOI: 10.1016/j.bpj.2021.05.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 04/14/2021] [Accepted: 05/05/2021] [Indexed: 10/21/2022] Open
Abstract
Single-molecule force spectroscopy with optical tweezers has emerged as a powerful tool for dissecting protein folding. The requirement to stably attach "molecular handles" to specific points in the protein of interest by preparative biochemical techniques is a limiting factor in applying this methodology, especially for large or unstable proteins that are difficult to produce and isolate. Here, we present a streamlined approach for creating stable and specific attachments using autocatalytic covalent tethering. The high specificity of coupling allowed us to tether ribosome-nascent chain complexes, demonstrating its suitability for investigating complex macromolecular assemblies. We combined this approach with cell-free protein synthesis, providing a facile means of preparing samples for single-molecule force spectroscopy. The workflow eliminates the need for biochemical protein purification during sample preparation for single-molecule measurements, making structurally unstable proteins amenable to investigation by this powerful single-molecule technique. We demonstrate the capabilities of this approach by carrying out pulling experiments with an unstructured domain of elongation factor G that had previously been refractory to analysis. Our approach expands the pool of proteins amenable to folding studies, which should help to reduce existing biases in the currently available set of protein folding models.
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Affiliation(s)
- Kevin Maciuba
- Department of Biology, Johns Hopkins University, Baltimore, Maryland
| | - Fan Zhang
- Department of Biology, Johns Hopkins University, Baltimore, Maryland
| | - Christian M Kaiser
- Department of Biology, Johns Hopkins University, Baltimore, Maryland; Department of Biophysics, Johns Hopkins University, Baltimore, Maryland.
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21
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Bustamante CJ, Chemla YR, Liu S, Wang MD. Optical tweezers in single-molecule biophysics. NATURE REVIEWS. METHODS PRIMERS 2021; 1:25. [PMID: 34849486 PMCID: PMC8629167 DOI: 10.1038/s43586-021-00021-6] [Citation(s) in RCA: 112] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/12/2021] [Indexed: 12/15/2022]
Abstract
Optical tweezers have become the method of choice in single-molecule manipulation studies. In this Primer, we first review the physical principles of optical tweezers and the characteristics that make them a powerful tool to investigate single molecules. We then introduce the modifications of the method to extend the measurement of forces and displacements to torques and angles, and to develop optical tweezers with single-molecule fluorescence detection capabilities. We discuss force and torque calibration of these instruments, their various modes of operation and most common experimental geometries. We describe the type of data obtained in each experimental design and their analyses. This description is followed by a survey of applications of these methods to the studies of protein-nucleic acid interactions, protein/RNA folding and molecular motors. We also discuss data reproducibility, the factors that lead to the data variability among different laboratories and the need to develop field standards. We cover the current limitations of the methods and possible ways to optimize instrument operation, data extraction and analysis, before suggesting likely areas of future growth.
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Affiliation(s)
- Carlos J. Bustamante
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, CA, USA
- Department of Chemistry, University of California, Berkeley, CA, USA
- Kavli Energy NanoScience Institute, University of California, Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
| | - Yann R. Chemla
- Department of Physics, Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Shixin Liu
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY, USA
| | - Michelle D. Wang
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, NY, USA
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22
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Cassaignau AME, Włodarski T, Chan SHS, Woodburn LF, Bukvin IV, Streit JO, Cabrita LD, Waudby CA, Christodoulou J. Interactions between nascent proteins and the ribosome surface inhibit co-translational folding. Nat Chem 2021; 13:1214-1220. [PMID: 34650236 PMCID: PMC8627912 DOI: 10.1038/s41557-021-00796-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 08/24/2021] [Indexed: 11/19/2022]
Abstract
Most proteins begin to fold during biosynthesis on the ribosome. It has been suggested that interactions between the emerging polypeptide and the ribosome surface might allow the ribosome itself to modulate co-translational folding. Here we combine protein engineering and NMR spectroscopy to characterize a series of interactions between the ribosome surface and unfolded nascent chains of the immunoglobulin-like FLN5 filamin domain. The strongest interactions are found for a C-terminal segment that is essential for folding, and we demonstrate quantitative agreement between the strength of this interaction and the energetics of the co-translational folding process itself. Mutations in this region that reduce the extent of binding result in a shift in the co-translational folding equilibrium towards the native state. Our results therefore demonstrate that a competition between folding and binding provides a simple, dynamic mechanism for the modulation of co-translational folding by the ribosome.
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Affiliation(s)
- Anaïs M. E. Cassaignau
- grid.83440.3b0000000121901201Institute of Structural and Molecular Biology, University College London, London, UK
| | - Tomasz Włodarski
- grid.83440.3b0000000121901201Institute of Structural and Molecular Biology, University College London, London, UK
| | - Sammy H. S. Chan
- grid.83440.3b0000000121901201Institute of Structural and Molecular Biology, University College London, London, UK
| | - Lauren F. Woodburn
- grid.83440.3b0000000121901201Institute of Structural and Molecular Biology, University College London, London, UK
| | - Ivana V. Bukvin
- grid.83440.3b0000000121901201Institute of Structural and Molecular Biology, University College London, London, UK
| | - Julian O. Streit
- grid.83440.3b0000000121901201Institute of Structural and Molecular Biology, University College London, London, UK
| | - Lisa D. Cabrita
- grid.83440.3b0000000121901201Institute of Structural and Molecular Biology, University College London, London, UK
| | - Christopher A. Waudby
- grid.83440.3b0000000121901201Institute of Structural and Molecular Biology, University College London, London, UK
| | - John Christodoulou
- grid.83440.3b0000000121901201Institute of Structural and Molecular Biology, University College London, London, UK ,grid.4464.20000 0001 2161 2573Institute of Structural and Molecular Biology, Birkbeck College, University of London, London, UK
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23
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Liutkute M, Maiti M, Samatova E, Enderlein J, Rodnina MV. Gradual compaction of the nascent peptide during cotranslational folding on the ribosome. eLife 2020; 9:60895. [PMID: 33112737 PMCID: PMC7593090 DOI: 10.7554/elife.60895] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 10/16/2020] [Indexed: 12/21/2022] Open
Abstract
Nascent polypeptides begin to fold in the constrained space of the ribosomal peptide exit tunnel. Here we use force-profile analysis (FPA) and photo-induced energy-transfer fluorescence correlation spectroscopy (PET-FCS) to show how a small α-helical domain, the N-terminal domain of HemK, folds cotranslationally. Compaction starts vectorially as soon as the first α-helical segments are synthesized. As nascent chain grows, emerging helical segments dock onto each other and continue to rearrange at the vicinity of the ribosome. Inside or in the proximity of the ribosome, the nascent peptide undergoes structural fluctuations on the µs time scale. The fluctuations slow down as the domain moves away from the ribosome. Mutations that destabilize the packing of the domain's hydrophobic core have little effect on folding within the exit tunnel, but abolish the final domain stabilization. The results show the power of FPA and PET-FCS in solving the trajectory of cotranslational protein folding and in characterizing the dynamic properties of folding intermediates.
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Affiliation(s)
- Marija Liutkute
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Manisankar Maiti
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Ekaterina Samatova
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Jörg Enderlein
- III. Institute of Physics - Biophysics, Georg August University, Göttingen, Germany
| | - Marina V Rodnina
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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24
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Chen X, Rajasekaran N, Liu K, Kaiser CM. Synthesis runs counter to directional folding of a nascent protein domain. Nat Commun 2020; 11:5096. [PMID: 33037221 PMCID: PMC7547688 DOI: 10.1038/s41467-020-18921-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 09/18/2020] [Indexed: 12/18/2022] Open
Abstract
Folding of individual domains in large proteins during translation helps to avoid otherwise prevalent inter-domain misfolding. How folding intermediates observed in vitro for the majority of proteins relate to co-translational folding remains unclear. Combining in vivo and single-molecule experiments, we followed the co-translational folding of the G-domain, encompassing the first 293 amino acids of elongation factor G. Surprisingly, the domain remains unfolded until it is fully synthesized, without collapsing into molten globule-like states or forming stable intermediates. Upon fully emerging from the ribosome, the G-domain transitions to its stable native structure via folding intermediates. Our results suggest a strictly sequential folding pathway initiating from the C-terminus. Folding and synthesis thus proceed in opposite directions. The folding mechanism is likely imposed by the final structure and might have evolved to ensure efficient, timely folding of a highly abundant and essential protein. In vivo experiments and optical tweezers force-spectroscopy measurements assessing the co-translational folding of the G-domain from bacterial elongation factor G reveal a sequential folding pathway initiating from the C-terminus. These results suggest that protein folding and synthesis proceed in opposite directions.
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Affiliation(s)
- Xiuqi Chen
- CMDB Graduate Program, Johns Hopkins University, Baltimore, MD, USA
| | | | - Kaixian Liu
- CMDB Graduate Program, Johns Hopkins University, Baltimore, MD, USA.,Molecular Biology Program, Sloan Kettering Institute, New York, NY, USA
| | - Christian M Kaiser
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA. .,Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA.
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25
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The SecA motor generates mechanical force during protein translocation. Nat Commun 2020; 11:3802. [PMID: 32732903 PMCID: PMC7393111 DOI: 10.1038/s41467-020-17561-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 07/07/2020] [Indexed: 12/31/2022] Open
Abstract
The Sec translocon moves proteins across lipid bilayers in all cells. The Sec channel enables passage of unfolded proteins through the bacterial plasma membrane, driven by the cytosolic ATPase SecA. Whether SecA generates mechanical force to overcome barriers to translocation posed by structured substrate proteins is unknown. Here, we kinetically dissect Sec-dependent translocation by monitoring translocation of a folded substrate protein with tunable stability at high time resolution. We find that substrate unfolding constitutes the rate-limiting step during translocation. Using single-molecule force spectroscopy, we also define the response of the protein to mechanical force. Relating the kinetic and force measurements reveals that SecA generates at least 10 piconewtons of mechanical force to actively unfold translocating proteins, comparable to cellular unfoldases. Combining biochemical and single-molecule measurements thus allows us to define how the SecA motor ensures efficient and robust export of proteins that contain stable structure. The ATPase SecA drives Sec-dependent protein translocation across the bacterial plasma membrane. Here, the authors combine kinetic translocation measurements with single-molecule force spectroscopy and demonstrate that the SecA motor generates mechanical force to unfold and translocate preproteins.
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26
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Abstract
Manipulation of individual molecules with optical tweezers provides a powerful means of interrogating the structure and folding of proteins. Mechanical force is not only a relevant quantity in cellular protein folding and function, but also a convenient parameter for biophysical folding studies. Optical tweezers offer precise control in the force range relevant for protein folding and unfolding, from which single-molecule kinetic and thermodynamic information about these processes can be extracted. In this review, we describe both physical principles and practical aspects of optical tweezers measurements and discuss recent advances in the use of this technique for the study of protein folding. In particular, we describe the characterization of folding energy landscapes at high resolution, studies of structurally complex multidomain proteins, folding in the presence of chaperones, and the ability to investigate real-time cotranslational folding of a polypeptide.
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Affiliation(s)
- Carlos Bustamante
- Department of Molecular and Cell Biology, Department of Physics, Howard Hughes Medical Institute, and Kavli Energy NanoScience Institute, University of California, Berkeley, California 94720, USA;
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Lisa Alexander
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Kevin Maciuba
- Cell, Molecular, Developmental Biology, and Biophysics Graduate Program, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Christian M Kaiser
- Department of Biology and Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, USA;
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27
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Jensen MK, Samelson AJ, Steward A, Clarke J, Marqusee S. The folding and unfolding behavior of ribonuclease H on the ribosome. J Biol Chem 2020; 295:11410-11417. [PMID: 32527724 PMCID: PMC7450101 DOI: 10.1074/jbc.ra120.013909] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/04/2020] [Indexed: 11/24/2022] Open
Abstract
The health of a cell depends on accurate translation and proper protein folding, whereas misfolding can lead to aggregation and disease. The first opportunity for a protein to fold occurs during translation, when the ribosome and surrounding environment can affect the nascent chain energy landscape. However, quantifying these environmental effects is challenging because ribosomal proteins and rRNA preclude most spectroscopic measurements of protein energetics. Here, we have applied two gel-based approaches, pulse proteolysis and force-profile analysis, to probe the folding and unfolding pathways of RNase H (RNH) nascent chains stalled on the prokaryotic ribosome in vitro. We found that ribosome-stalled RNH has an increased unfolding rate compared with free RNH. Because protein stability is related to the ratio of the unfolding and folding rates, this increase completely accounts for the observed change in protein stability and indicates that the folding rate is unchanged. Using arrest peptide–based force-profile analysis, we assayed the force generated during the folding of RNH on the ribosome. Surprisingly, we found that population of the RNH folding intermediate is required to generate sufficient force to release a stall induced by the SecM stalling sequence and that readthrough of SecM directly correlates with the stability of the RNH folding intermediate. Together, these results imply that the folding pathway of RNH is unchanged on the ribosome. Furthermore, our findings indicate that the ribosome promotes RNH unfolding while the nascent chain is proximal to the ribosome, which may limit the deleterious effects of RNH misfolding and assist in folding fidelity.
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Affiliation(s)
- Madeleine K Jensen
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
| | - Avi J Samelson
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
| | - Annette Steward
- Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Jane Clarke
- Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Susan Marqusee
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA .,Institute for Quantitative Biosciences (QB3)-Berkeley, University of California, Berkeley, California, USA.,Department of Chemistry, University of California, Berkeley, California, USA
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28
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Simpson LJ, Tzima E, Reader JS. Mechanical Forces and Their Effect on the Ribosome and Protein Translation Machinery. Cells 2020; 9:cells9030650. [PMID: 32156009 PMCID: PMC7140433 DOI: 10.3390/cells9030650] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 03/03/2020] [Accepted: 03/04/2020] [Indexed: 12/12/2022] Open
Abstract
Mechanical forces acting on biological systems, at both the macroscopic and microscopic levels, play an important part in shaping cellular phenotypes. There is a growing realization that biomolecules that respond to force directly applied to them, or via mechano-sensitive signalling pathways, can produce profound changes to not only transcriptional pathways, but also in protein translation. Forces naturally occurring at the molecular level can impact the rate at which the bacterial ribosome translates messenger RNA (mRNA) transcripts and influence processes such as co-translational folding of a nascent protein as it exits the ribosome. In eukaryotes, force can also be transduced at the cellular level by the cytoskeleton, the cell’s internal filamentous network. The cytoskeleton closely associates with components of the translational machinery such as ribosomes and elongation factors and, as such, is a crucial determinant of localized protein translation. In this review we will give (1) a brief overview of protein translation in bacteria and eukaryotes and then discuss (2) how mechanical forces are directly involved with ribosomes during active protein synthesis and (3) how eukaryotic ribosomes and other protein translation machinery intimately associates with the mechanosensitive cytoskeleton network.
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29
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Cotranslational folding allows misfolding-prone proteins to circumvent deep kinetic traps. Proc Natl Acad Sci U S A 2020; 117:1485-1495. [PMID: 31911473 DOI: 10.1073/pnas.1913207117] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Many large proteins suffer from slow or inefficient folding in vitro. It has long been known that this problem can be alleviated in vivo if proteins start folding cotranslationally. However, the molecular mechanisms underlying this improvement have not been well established. To address this question, we use an all-atom simulation-based algorithm to compute the folding properties of various large protein domains as a function of nascent chain length. We find that for certain proteins, there exists a narrow window of lengths that confers both thermodynamic stability and fast folding kinetics. Beyond these lengths, folding is drastically slowed by nonnative interactions involving C-terminal residues. Thus, cotranslational folding is predicted to be beneficial because it allows proteins to take advantage of this optimal window of lengths and thus avoid kinetic traps. Interestingly, many of these proteins' sequences contain conserved rare codons that may slow down synthesis at this optimal window, suggesting that synthesis rates may be evolutionarily tuned to optimize folding. Using kinetic modeling, we show that under certain conditions, such a slowdown indeed improves cotranslational folding efficiency by giving these nascent chains more time to fold. In contrast, other proteins are predicted not to benefit from cotranslational folding due to a lack of significant nonnative interactions, and indeed these proteins' sequences lack conserved C-terminal rare codons. Together, these results shed light on the factors that promote proper protein folding in the cell and how biomolecular self-assembly may be optimized evolutionarily.
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30
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Cotranslational Folding of Proteins on the Ribosome. Biomolecules 2020; 10:biom10010097. [PMID: 31936054 PMCID: PMC7023365 DOI: 10.3390/biom10010097] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 12/20/2019] [Accepted: 12/25/2019] [Indexed: 02/04/2023] Open
Abstract
Many proteins in the cell fold cotranslationally within the restricted space of the polypeptide exit tunnel or at the surface of the ribosome. A growing body of evidence suggests that the ribosome can alter the folding trajectory in many different ways. In this review, we summarize the recent examples of how translation affects folding of single-domain, multiple-domain and oligomeric proteins. The vectorial nature of translation, the spatial constraints of the exit tunnel, and the electrostatic properties of the ribosome-nascent peptide complex define the onset of early folding events. The ribosome can facilitate protein compaction, induce the formation of intermediates that are not observed in solution, or delay the onset of folding. Examples of single-domain proteins suggest that early compaction events can define the folding pathway for some types of domain structures. Folding of multi-domain proteins proceeds in a domain-wise fashion, with each domain having its role in stabilizing or destabilizing neighboring domains. Finally, the assembly of protein complexes can also begin cotranslationally. In all these cases, the ribosome helps the nascent protein to attain a native fold and avoid the kinetic traps of misfolding.
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31
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Abstract
Large proteins composed of multiple domains are abundant in all proteomes, but their folding and structural dynamics remain poorly understood. Using single-molecule force spectroscopy, we have defined how stabilizing interfaces among the domains of elongation factor G (EF-G) shape its folding pathway. Contrary to the expectation that multidomain proteins fold sequentially as they emerge from the ribosome, we find that folding cannot be completed until the full protein has been synthesized. This posttranslational folding mechanism results in a propensity for misfolding. It is dictated by an energetic coupling among domains that enables conformational flexibility crucial for EF-G function. EF-G thus provides an example of how distinct biological ends—robust folding and functionally important flexibility—come into conflict during protein biogenesis. Large proteins with multiple domains are thought to fold cotranslationally to minimize interdomain misfolding. Once folded, domains interact with each other through the formation of extensive interfaces that are important for protein stability and function. However, multidomain protein folding and the energetics of domain interactions remain poorly understood. In elongation factor G (EF-G), a highly conserved protein composed of 5 domains, the 2 N-terminal domains form a stably structured unit cotranslationally. Using single-molecule optical tweezers, we have defined the steps leading to fully folded EF-G. We find that the central domain III of EF-G is highly dynamic and does not fold upon emerging from the ribosome. Surprisingly, a large interface with the N-terminal domains does not contribute to the stability of domain III. Instead, it requires interactions with its folded C-terminal neighbors to be stably structured. Because of the directionality of protein synthesis, this energetic dependency of domain III on its C-terminal neighbors disrupts cotranslational folding and imposes a posttranslational mechanism on the folding of the C-terminal part of EF-G. As a consequence, unfolded domains accumulate during synthesis, leading to the extensive population of misfolded species that interfere with productive folding. Domain III flexibility enables large-scale conformational transitions that are part of the EF-G functional cycle during ribosome translocation. Our results suggest that energetic tuning of domain stabilities, which is likely crucial for EF-G function, complicates the folding of this large multidomain protein.
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32
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Non-equilibrium dynamics of a nascent polypeptide during translation suppress its misfolding. Nat Commun 2019; 10:2709. [PMID: 31221966 PMCID: PMC6586675 DOI: 10.1038/s41467-019-10647-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 05/07/2019] [Indexed: 12/20/2022] Open
Abstract
Protein folding can begin co-translationally. Due to the difference in timescale between folding and synthesis, co-translational folding is thought to occur at equilibrium for fast-folding domains. In this scenario, the folding kinetics of stalled ribosome-bound nascent chains should match the folding of nascent chains in real time. To test if this assumption is true, we compare the folding of a ribosome-bound, multi-domain calcium-binding protein stalled at different points in translation with the nascent chain as is it being synthesized in real-time, via optical tweezers. On stalled ribosomes, a misfolded state forms rapidly (1.5 s). However, during translation, this state is only attained after a long delay (63 s), indicating that, unexpectedly, the growing polypeptide is not equilibrated with its ensemble of accessible conformations. Slow equilibration on the ribosome can delay premature folding until adequate sequence is available and/or allow time for chaperone binding, thus promoting productive folding. Co-translational protein folding is thought to occur at equilibrium for fast-folding domains. Here authors use optical tweezers to show that the folding kinetics of stalled ribosome-bound nascent chains do not match the folding of nascent chains in real time.
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Using Single-Molecule Chemo-Mechanical Unfolding to Simultaneously Probe Multiple Structural Parameters in Protein Folding. Methods Protoc 2019; 2:mps2020032. [PMID: 31164612 PMCID: PMC6632164 DOI: 10.3390/mps2020032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 04/10/2019] [Accepted: 04/15/2019] [Indexed: 11/28/2022] Open
Abstract
While single-molecule force spectroscopy has greatly advanced the study of protein folding, there are limitations to what can be learned from studying the effect of force alone. We developed a novel technique, chemo-mechanical unfolding, that combines multiple perturbants—force and chemical denaturant—to more fully characterize the folding process by simultaneously probing multiple structural parameters—the change in end-to-end distance, and solvent accessible surface area. Here, we describe the theoretical background, experimental design, and data analysis for chemo-mechanical unfolding experiments probing protein folding thermodynamics and kinetics. This technique has been applied to characterize parallel protein folding pathways, the protein denatured state, protein folding on the ribosome, and protein folding intermediates.
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Liu K, Maciuba K, Kaiser CM. The Ribosome Cooperates with a Chaperone to Guide Multi-domain Protein Folding. Mol Cell 2019; 74:310-319.e7. [PMID: 30852061 DOI: 10.1016/j.molcel.2019.01.043] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 12/12/2018] [Accepted: 01/30/2019] [Indexed: 11/28/2022]
Abstract
Multi-domain proteins, containing several structural units within a single polypeptide, constitute a large fraction of all proteomes. Co-translational folding is assumed to simplify the conformational search problem for large proteins, but the events leading to correctly folded, functional structures remain poorly characterized. Similarly, how the ribosome and molecular chaperones promote efficient folding remains obscure. Using optical tweezers, we have dissected early folding events of nascent elongation factor G, a multi-domain protein that requires chaperones for folding. The ribosome and the chaperone trigger factor reduce inter-domain misfolding, permitting folding of the N-terminal G-domain. Successful completion of this step is a crucial prerequisite for folding of the next domain. Unexpectedly, co-translational folding does not proceed unidirectionally; emerging unfolded polypeptide can denature an already-folded domain. Trigger factor, but not the ribosome, protects against denaturation. The chaperone thus serves a previously unappreciated function, helping multi-domain proteins overcome inherent challenges during co-translational folding.
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Affiliation(s)
- Kaixian Liu
- CMDB Graduate Program, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Kevin Maciuba
- CMDB Graduate Program, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Christian M Kaiser
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA; T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA.
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35
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Kemp G, Kudva R, de la Rosa A, von Heijne G. Force-Profile Analysis of the Cotranslational Folding of HemK and Filamin Domains: Comparison of Biochemical and Biophysical Folding Assays. J Mol Biol 2019; 431:1308-1314. [DOI: 10.1016/j.jmb.2019.01.043] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 01/27/2019] [Accepted: 01/29/2019] [Indexed: 12/31/2022]
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36
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A small single-domain protein folds through the same pathway on and off the ribosome. Proc Natl Acad Sci U S A 2018; 115:12206-12211. [PMID: 30409803 DOI: 10.1073/pnas.1810517115] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In vivo, proteins fold and function in a complex environment subject to many stresses that can modulate a protein's energy landscape. One aspect of the environment pertinent to protein folding is the ribosome, since proteins have the opportunity to fold while still bound to the ribosome during translation. We use a combination of force and chemical denaturant (chemomechanical unfolding), as well as point mutations, to characterize the folding mechanism of the src SH3 domain both as a stalled ribosome nascent chain and free in solution. Our results indicate that src SH3 folds through the same pathway on and off the ribosome. Molecular simulations also indicate that the ribosome does not affect the folding pathway for this small protein. Taken together, we conclude that the ribosome does not alter the folding mechanism of this small protein. These results, if general, suggest the ribosome may exert a bigger influence on the folding of multidomain proteins or protein domains that can partially fold before the entire domain sequence is outside the ribosome exit tunnel.
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Kaiser CM, Liu K. Folding up and Moving on-Nascent Protein Folding on the Ribosome. J Mol Biol 2018; 430:4580-4591. [PMID: 29981746 PMCID: PMC6384192 DOI: 10.1016/j.jmb.2018.06.050] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/26/2018] [Accepted: 06/28/2018] [Indexed: 01/01/2023]
Abstract
All cellular proteins are synthesized by the ribosome, an intricate molecular machine that translates the information of protein coding genes into the amino acid alphabet. The linear polypeptides synthesized by the ribosome must generally fold into specific three-dimensional structures to become biologically active. Folding has long been recognized to begin before synthesis is complete. Recently, biochemical and biophysical studies have shed light onto how the ribosome shapes the folding pathways of nascent proteins. Here, we discuss recent progress that is beginning to define the role of the ribosome in the folding of newly synthesized polypeptides.
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Affiliation(s)
- Christian M Kaiser
- Department of Biology, Johns Hopkins University, 3400 N Charles St., Baltimore, MD 21218, USA; Department of Biophysics, Johns Hopkins University, 3400 N Charles St., Baltimore, MD 21218, USA.
| | - Kaixian Liu
- Department of Biology, Johns Hopkins University, 3400 N Charles St., Baltimore, MD 21218, USA; CMDB Graduate Program, Johns Hopkins University, 3400 N Charles St., Baltimore, MD 21218, USA
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Komar AA. Unraveling co-translational protein folding: Concepts and methods. Methods 2017; 137:71-81. [PMID: 29221924 DOI: 10.1016/j.ymeth.2017.11.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 11/13/2017] [Indexed: 12/26/2022] Open
Abstract
Advances in techniques such as nuclear magnetic resonance spectroscopy, cryo-electron microscopy, and single-molecule and time-resolved fluorescent approaches are transforming our ability to study co-translational protein folding both in vivo in living cells and in vitro in reconstituted cell-free translation systems. These approaches provide comprehensive information on the spatial organization and dynamics of nascent polypeptide chains and the kinetics of co-translational protein folding. This information has led to an improved understanding of the process of protein folding in living cells and should allow remaining key questions in the field, such as what structures are formed within nascent chains during protein synthesis and when, to be answered. Ultimately, studies using these techniques will facilitate development of a unified concept of protein folding, a process that is essential for proper cell function and organism viability. This review describes current methods for analysis of co-translational protein folding with an emphasis on some of the recently developed techniques that allow monitoring of co-translational protein folding in real-time.
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Affiliation(s)
- Anton A Komar
- Center for Gene Regulation in Health and Disease and Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, OH 44115, USA; Department of Biochemistry and the Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH 44106, USA; Genomic Medicine Institute, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
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