1
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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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2
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Gersteuer F, Morici M, Gabrielli S, Fujiwara K, Safdari HA, Paternoga H, Bock LV, Chiba S, Wilson DN. The SecM arrest peptide traps a pre-peptide bond formation state of the ribosome. Nat Commun 2024; 15:2431. [PMID: 38503753 PMCID: PMC10951299 DOI: 10.1038/s41467-024-46762-2] [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: 10/30/2023] [Accepted: 03/07/2024] [Indexed: 03/21/2024] Open
Abstract
Nascent polypeptide chains can induce translational stalling to regulate gene expression. This is exemplified by the E. coli secretion monitor (SecM) arrest peptide that induces translational stalling to regulate expression of the downstream encoded SecA, an ATPase that co-operates with the SecYEG translocon to facilitate insertion of proteins into or through the cytoplasmic membrane. Here we present the structure of a ribosome stalled during translation of the full-length E. coli SecM arrest peptide at 2.0 Å resolution. The structure reveals that SecM arrests translation by stabilizing the Pro-tRNA in the A-site, but in a manner that prevents peptide bond formation with the SecM-peptidyl-tRNA in the P-site. By employing molecular dynamic simulations, we also provide insight into how a pulling force on the SecM nascent chain can relieve the SecM-mediated translation arrest. Collectively, the mechanisms determined here for SecM arrest and relief are also likely to be applicable for a variety of other arrest peptides that regulate components of the protein localization machinery identified across a wide range of bacteria lineages.
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Affiliation(s)
- Felix Gersteuer
- Institute for Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King-Platz 6, 20146, Hamburg, Germany
| | - Martino Morici
- Institute for Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King-Platz 6, 20146, Hamburg, Germany
| | - Sara Gabrielli
- Theoretical and Computational Biophysics Department, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Keigo Fujiwara
- Faculty of Life Sciences and Institute for Protein Dynamics, Kyoto Sangyo University, Kamigamo, Motoyama, Kita-ku, Kyoto, 603-8555, Japan
| | - Haaris A Safdari
- Institute for Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King-Platz 6, 20146, Hamburg, Germany
| | - Helge Paternoga
- Institute for Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King-Platz 6, 20146, Hamburg, Germany
| | - Lars V Bock
- Theoretical and Computational Biophysics Department, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Shinobu Chiba
- Faculty of Life Sciences and Institute for Protein Dynamics, Kyoto Sangyo University, Kamigamo, Motoyama, Kita-ku, Kyoto, 603-8555, Japan
| | - Daniel N Wilson
- Institute for Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King-Platz 6, 20146, Hamburg, Germany.
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3
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Masse M, Hutchinson RB, Morgan CE, Allaman HJ, Guan H, Yu EW, Cavagnero S. Mapping Protein-Protein Interactions at Birth: Single-Particle Cryo-EM Analysis of a Ribosome-Nascent Globin Complex. ACS CENTRAL SCIENCE 2024; 10:385-401. [PMID: 38435509 PMCID: PMC10906257 DOI: 10.1021/acscentsci.3c00777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 12/29/2023] [Accepted: 01/03/2024] [Indexed: 03/05/2024]
Abstract
Interactions between ribosome-bound nascent chains (RNCs) and ribosomal components are critical to elucidate the mechanism of cotranslational protein folding. Nascent protein-ribosome contacts within the ribosomal exit tunnel were previously assessed mostly in the presence of C-terminal stalling sequences, yet little is known about contacts taking place in the absence of these strongly interacting motifs. Further, there is nearly no information about ribosomal proteins (r-proteins) interacting with nascent chains within the outer surface of the ribosome. Here, we combine chemical cross-linking, single-particle cryo-EM, and fluorescence anisotropy decays to determine the structural features of ribosome-bound apomyoglobin (apoMb). Within the ribosomal exit tunnel core, interactions are similar to those identified in previous reports. However, once the RNC enters the tunnel vestibule, it becomes more dynamic and interacts with ribosomal RNA (rRNA) and the L23 r-protein. Remarkably, on the outer surface of the ribosome, RNCs interact mainly with a highly conserved nonpolar patch of the L23 r-protein. RNCs also comprise a compact and dynamic N-terminal region lacking contact with the ribosome. In all, apoMb traverses the ribosome and interacts with it via its C-terminal region, while N-terminal residues sample conformational space and form a compact subdomain before the entire nascent protein sequence departs from the ribosome.
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Affiliation(s)
- Meranda
M. Masse
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Rachel B. Hutchinson
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Christopher E. Morgan
- Department
of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Heather J. Allaman
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Hongqing Guan
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Edward W. Yu
- Department
of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Silvia Cavagnero
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
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4
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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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5
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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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6
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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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7
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Wu H, Hegde RS. Mechanism of signal-anchor triage during early steps of membrane protein insertion. Mol Cell 2023; 83:961-973.e7. [PMID: 36764302 PMCID: PMC10155758 DOI: 10.1016/j.molcel.2023.01.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/08/2022] [Accepted: 01/18/2023] [Indexed: 02/11/2023]
Abstract
Most membrane proteins use their first transmembrane domain, known as a signal anchor (SA), for co-translational targeting to the endoplasmic reticulum (ER) via the signal recognition particle (SRP). The SA then inserts into the membrane using either the Sec61 translocation channel or the ER membrane protein complex (EMC) insertase. How EMC and Sec61 collaborate to ensure SA insertion in the correct topology is not understood. Using site-specific crosslinking, we detect a pre-insertion SA intermediate adjacent to EMC. This intermediate forms after SA release from SRP but before ribosome transfer to Sec61. The polypeptide's N-terminal tail samples a cytosolic vestibule bordered by EMC3, from where it can translocate across the membrane concomitant with SA insertion. The ribosome then docks on Sec61, which has an opportunity to insert those SAs skipped by EMC. These results suggest that EMC acts between SRP and Sec61 to triage SAs for insertion during membrane protein biogenesis.
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Affiliation(s)
- Haoxi Wu
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
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8
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Abstract
Copper is essential to most living beings but also highly toxic and as such is an important player at the host-pathogen interface. Bacteria have thus developed homeostatic mechanisms to tightly control its intracellular concentration. Known Cu export and import systems are under transcriptional control, whereas posttranscriptional regulatory mechanisms are yet to be characterized. We identified a three-gene operon, bp2923-bfrG-bp2921, downregulated by copper and notably encoding a TonB-dependent transporter in Bordetella pertussis. We show here that the protein encoded by the first gene, which is a member of the DUF2946 protein family, represents a new type of upstream Open Reading Frame (uORF) involved in posttranscriptional regulation of the downstream genes. In the absence of copper, the entire operon is transcribed and translated. Perception of copper by the nascent bp2923-coded protein via its conserved CXXC motif triggers Rho-dependent transcription termination between the first and second genes by relieving translation arrest on a conserved C-terminal RAPP motif. Homologs of bp2923 are widespread in bacterial genomes, where they head operons predicted to participate in copper homeostasis. This work has thus unveiled a new mode of genetic regulation by a transition metal and identified a regulatory function for a member of an uncharacterized family of bacterial proteins that we have named CruR, for copper-responsive upstream regulator.
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9
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Mercier E, Wang X, Bögeholz LAK, Wintermeyer W, Rodnina MV. Cotranslational Biogenesis of Membrane Proteins in Bacteria. Front Mol Biosci 2022; 9:871121. [PMID: 35573737 PMCID: PMC9099147 DOI: 10.3389/fmolb.2022.871121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 04/12/2022] [Indexed: 12/26/2022] Open
Abstract
Nascent polypeptides emerging from the ribosome during translation are rapidly scanned and processed by ribosome-associated protein biogenesis factors (RPBs). RPBs cleave the N-terminal formyl and methionine groups, assist cotranslational protein folding, and sort the proteins according to their cellular destination. Ribosomes translating inner-membrane proteins are recognized and targeted to the translocon with the help of the signal recognition particle, SRP, and SRP receptor, FtsY. The growing nascent peptide is then inserted into the phospholipid bilayer at the translocon, an inner-membrane protein complex consisting of SecY, SecE, and SecG. Folding of membrane proteins requires that transmembrane helices (TMs) attain their correct topology, the soluble domains are inserted at the correct (cytoplasmic or periplasmic) side of the membrane, and – for polytopic membrane proteins – the TMs find their interaction partner TMs in the phospholipid bilayer. This review describes the recent progress in understanding how growing nascent peptides are processed and how inner-membrane proteins are targeted to the translocon and find their correct orientation at the membrane, with the focus on biophysical approaches revealing the dynamics of the process. We describe how spontaneous fluctuations of the translocon allow diffusion of TMs into the phospholipid bilayer and argue that the ribosome orchestrates cotranslational targeting not only by providing the binding platform for the RPBs or the translocon, but also by helping the nascent chains to find their correct orientation in the membrane. Finally, we present the auxiliary role of YidC as a chaperone for inner-membrane proteins. We show how biophysical approaches provide new insights into the dynamics of membrane protein biogenesis and raise new questions as to how translation modulates protein folding.
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10
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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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11
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Protein folding in vitro and in the cell: From a solitary journey to a team effort. Biophys Chem 2022; 287:106821. [PMID: 35667131 PMCID: PMC9636488 DOI: 10.1016/j.bpc.2022.106821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 04/18/2022] [Accepted: 04/21/2022] [Indexed: 12/22/2022]
Abstract
Correct protein folding is essential for the health and function of living organisms. Yet, it is not well understood how unfolded proteins reach their native state and avoid aggregation, especially within the cellular milieu. Some proteins, especially small, single-domain and apparent two-state folders, successfully attain their native state upon dilution from denaturant. Yet, many more proteins undergo misfolding and aggregation during this process, in a concentration-dependent fashion. Once formed, native and aggregated states are often kinetically trapped relative to each other. Hence, the early stages of protein life are absolutely critical for proper kinetic channeling to the folded state and for long-term solubility and function. This review summarizes current knowledge on protein folding/aggregation mechanisms in buffered solution and within the bacterial cell, highlighting early stages. Remarkably, teamwork between nascent chain, ribosome, trigger factor and Hsp70 molecular chaperones enables all proteins to overcome aggregation propensities and reach a long-lived bioactive state.
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12
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Agirrezabala X, Samatova E, Macher M, Liutkute M, Maiti M, Gil-Carton D, Novacek J, Valle M, Rodnina MV. A switch from α-helical to β-strand conformation during co-translational protein folding. EMBO J 2022; 41:e109175. [PMID: 34994471 PMCID: PMC8844987 DOI: 10.15252/embj.2021109175] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 11/30/2021] [Accepted: 12/06/2021] [Indexed: 11/09/2022] Open
Abstract
Cellular proteins begin to fold as they emerge from the ribosome. The folding landscape of nascent chains is not only shaped by their amino acid sequence but also by the interactions with the ribosome. Here, we combine biophysical methods with cryo‐EM structure determination to show that folding of a β‐barrel protein begins with formation of a dynamic α‐helix inside the ribosome. As the growing peptide reaches the end of the tunnel, the N‐terminal part of the nascent chain refolds to a β‐hairpin structure that remains dynamic until its release from the ribosome. Contacts with the ribosome and structure of the peptidyl transferase center depend on nascent chain conformation. These results indicate that proteins may start out as α‐helices inside the tunnel and switch into their native folds only as they emerge from the ribosome. Moreover, the correlation of nascent chain conformations with reorientation of key residues of the ribosomal peptidyl‐transferase center suggest that protein folding could modulate ribosome activity.
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Affiliation(s)
| | - Ekaterina Samatova
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Gottingen, Germany
| | - Meline Macher
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Gottingen, Germany
| | - Marija Liutkute
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Gottingen, Germany
| | - Manisankar Maiti
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Gottingen, Germany
| | - David Gil-Carton
- CIC bioGUNE, Basque Research and Technology Alliance (BRTA), Derio, Spain.,IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Jiri Novacek
- CEITEC, Masaryk University, Brno, Czech Republic
| | - Mikel Valle
- CIC bioGUNE, Basque Research and Technology Alliance (BRTA), Derio, Spain
| | - Marina V Rodnina
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Gottingen, Germany
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13
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Tirincsi A, Sicking M, Hadzibeganovic D, Haßdenteufel S, Lang S. The Molecular Biodiversity of Protein Targeting and Protein Transport Related to the Endoplasmic Reticulum. Int J Mol Sci 2021; 23:143. [PMID: 35008565 PMCID: PMC8745461 DOI: 10.3390/ijms23010143] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/19/2021] [Accepted: 12/20/2021] [Indexed: 12/15/2022] Open
Abstract
Looking at the variety of the thousands of different polypeptides that have been focused on in the research on the endoplasmic reticulum from the last five decades taught us one humble lesson: no one size fits all. Cells use an impressive array of components to enable the safe transport of protein cargo from the cytosolic ribosomes to the endoplasmic reticulum. Safety during the transit is warranted by the interplay of cytosolic chaperones, membrane receptors, and protein translocases that together form functional networks and serve as protein targeting and translocation routes. While two targeting routes to the endoplasmic reticulum, SRP (signal recognition particle) and GET (guided entry of tail-anchored proteins), prefer targeting determinants at the N- and C-terminus of the cargo polypeptide, respectively, the recently discovered SND (SRP-independent) route seems to preferentially cater for cargos with non-generic targeting signals that are less hydrophobic or more distant from the termini. With an emphasis on targeting routes and protein translocases, we will discuss those functional networks that drive efficient protein topogenesis and shed light on their redundant and dynamic nature in health and disease.
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Affiliation(s)
- Andrea Tirincsi
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
| | - Mark Sicking
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
| | - Drazena Hadzibeganovic
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
| | - Sarah Haßdenteufel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Sven Lang
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
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14
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Leininger SE, Rodriguez J, Vu QV, Jiang Y, Li MS, Deutsch C, O'Brien EP. Ribosome Elongation Kinetics of Consecutively Charged Residues Are Coupled to Electrostatic Force. Biochemistry 2021; 60:3223-3235. [PMID: 34652913 DOI: 10.1021/acs.biochem.1c00507] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The speed of protein synthesis can dramatically change when consecutively charged residues are incorporated into an elongating nascent protein by the ribosome. The molecular origins of this class of allosteric coupling remain unknown. We demonstrate, using multiscale simulations, that positively charged residues generate large forces that move the P-site amino acid away from the A-site amino acid. Negatively charged residues generate forces of similar magnitude but move the A- and P-sites closer together. These conformational changes, respectively, increase and decrease the transition state barrier height to peptide bond formation, explaining how charged residues mechanochemically alter translation speed. This mechanochemical mechanism is consistent with in vivo ribosome profiling data exhibiting proportionality between translation speed and the number of charged residues, experimental data characterizing nascent chain conformations, and a previously published cryo-EM structure of a ribosome-nascent chain complex containing consecutive lysines. These results expand the role of mechanochemistry in translation and provide a framework for interpreting experimental results on translation speed.
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Affiliation(s)
- Sarah E Leininger
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Judith Rodriguez
- Bioinformatics and Genomics Graduate Program, Huck Institutes of the Life Sciences, Penn State University, University Park, Pennsylvania 16802, United States
| | - Quyen V Vu
- Institute of Physics, Polish Academy of Sciences, Warsaw 02-668, Poland
| | - Yang Jiang
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Mai Suan Li
- Institute of Physics, Polish Academy of Sciences, Warsaw 02-668, Poland.,Institute for Computational Sciences and Technology, Ho Chi Minh City 700000, Vietnam
| | - Carol Deutsch
- Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Edward P O'Brien
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States.,Bioinformatics and Genomics Graduate Program, Huck Institutes of the Life Sciences, Penn State University, University Park, Pennsylvania 16802, United States.,Institute for Computational and Data Sciences, Penn State University, University Park, Pennsylvania 16802, United States
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15
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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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16
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Jiang Y, O'Brien EP. Mechanical Forces Have a Range of Effects on the Rate of Ribosome Catalyzed Peptidyl Transfer Depending on Direction. J Phys Chem B 2021; 125:7128-7136. [PMID: 34166592 PMCID: PMC8291131 DOI: 10.1021/acs.jpcb.1c02263] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mechanical forces acting on the nascent chain residue located at the P-site of the ribosome can influence codon translation rates. Most observations to date involve force vectors aligned collinear with the long axis of the ribosome exit tunnel. What is poorly understood is how force applied in other directions will impact the rate of peptide bond formation catalyzed by the ribosome. Here, we utilize quantum mechanical/molecular mechanics simulations to estimate the changes in the activation free energy as a consequence of applying a constant force in various directions on the C-terminal residue at the P-site. Qualitatively consistent with the Bell model, we find this force can either accelerate, decelerate, or not alter the reaction rate depending on the force direction. A force in the average direction between the P-site 3' O-C ester bond that breaks and the peptide bond that forms accelerates the reaction. A force in the opposite direction slows down the reaction as it opposes these bonds breaking and forming, but surprisingly it does not do so to the maximum extent possible. In this case, there is a counterbalancing trend; the force in this direction brings the A-site amino nitrogen and the P-site tRNA A76 3' oxygen groups closer together, which promotes one of the proton shuttling steps of the reaction. We find the maximum force-induced slowdown occurs 37° off this axis. If force is applied in orthogonal directions to the reaction coordinates, there is no significant change in the reaction speed. These results indicate that there is a richer set of scenarios of force effects on translation speed that have yet to be experimentally explored and raise the possibility that cells could use these mechanochemical effects to modulate and regulate protein synthesis.
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Affiliation(s)
- Yang Jiang
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
| | - Edward P O'Brien
- Department of Chemistry, Penn State University, University Park, Pennsylvania 16802, United States
- Bioinformatics and Genomics Graduate Program, The Huck Institutes of the Life Sciences, Penn State University, University Park, Pennsylvania 16802, United States
- Institute for Computational and Data Sciences, Penn State University, University Park, Pennsylvania 16802, United States
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17
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Hutchinson RB, Chen X, Zhou N, Cavagnero S. Fluorescence Anisotropy Decays and Microscale-Volume Viscometry Reveal the Compaction of Ribosome-Bound Nascent Proteins. J Phys Chem B 2021; 125:6543-6558. [PMID: 34110829 PMCID: PMC8741338 DOI: 10.1021/acs.jpcb.1c04473] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
This work introduces a technology that combines fluorescence anisotropy decay with microscale-volume viscometry to investigate the compaction and dynamics of ribosome-bound nascent proteins. Protein folding in the cell, especially when nascent chains emerge from the ribosomal tunnel, is poorly understood. Previous investigations based on fluorescence anisotropy decay determined that a portion of the ribosome-bound nascent protein apomyoglobin (apoMb) forms a compact structure. This work, however, could not assess the size of the compact region. The combination of fluorescence anisotropy with microscale-volume viscometry, presented here, enables identifying the size of compact nascent-chain subdomains using a single fluorophore label. Our results demonstrate that the compact region of nascent apoMb contains 57-83 amino acids and lacks residues corresponding to the two native C-terminal helices. These amino acids are necessary for fully burying the nonpolar residues in the native structure, yet they are not available for folding before ribosome release. Therefore, apoMb requires a significant degree of post-translational folding for the generation of its native structure. In summary, the combination of fluorescence anisotropy decay and microscale-volume viscometry is a powerful approach to determine the size of independently tumbling compact regions of biomolecules. This technology is of general applicability to compact macromolecules linked to larger frameworks.
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Affiliation(s)
| | - Xi Chen
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706
| | - Ningkun Zhou
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706
| | - Silvia Cavagnero
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706
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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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Urrutia J, Aguado A, Gomis-Perez C, Muguruza-Montero A, Ballesteros OR, Zhang J, Nuñez E, Malo C, Chung HJ, Leonardo A, Bergara A, Villarroel A. An epilepsy-causing mutation leads to co-translational misfolding of the Kv7.2 channel. BMC Biol 2021; 19:109. [PMID: 34020651 PMCID: PMC8138981 DOI: 10.1186/s12915-021-01040-1] [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: 08/21/2020] [Accepted: 04/29/2021] [Indexed: 12/21/2022] Open
Abstract
Background The amino acid sequence of proteins generally carries all the necessary information for acquisition of native conformations, but the vectorial nature of translation can additionally determine the folding outcome. Such consideration is particularly relevant in human diseases associated to inherited mutations leading to structural instability, aggregation, and degradation. Mutations in the KCNQ2 gene associated with human epilepsy have been suggested to cause misfolding of the encoded Kv7.2 channel. Although the effect on folding of mutations in some domains has been studied, little is known of the way pathogenic variants located in the calcium responsive domain (CRD) affect folding. Here, we explore how a Kv7.2 mutation (W344R) located in helix A of the CRD and associated with hereditary epilepsy interferes with channel function. Results We report that the epilepsy W344R mutation within the IQ motif of CRD decreases channel function, but contrary to other mutations at this site, it does not impair the interaction with Calmodulin (CaM) in vitro, as monitored by multiple in vitro binding assays. We find negligible impact of the mutation on the structure of the complex by molecular dynamic computations. In silico studies revealed two orientations of the side chain, which are differentially populated by WT and W344R variants. Binding to CaM is impaired when the mutated protein is produced in cellulo but not in vitro, suggesting that this mutation impedes proper folding during translation within the cell by forcing the nascent chain to follow a folding route that leads to a non-native configuration, and thereby generating non-functional ion channels that fail to traffic to proper neuronal compartments. Conclusions Our data suggest that the key pathogenic mechanism of Kv7.2 W344R mutation involves the failure to adopt a configuration that can be recognized by CaM in vivo but not in vitro. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01040-1.
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Affiliation(s)
- Janire Urrutia
- Instituto Biofisika, CSIC-UPV/EHU, 48940, Leioa, Spain.,Present address: Department of Physiology, Faculty of Medicine and Nursery, UPV/EHU, 48940, Leioa, Spain
| | | | - Carolina Gomis-Perez
- Instituto Biofisika, CSIC-UPV/EHU, 48940, Leioa, Spain.,Present address: Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA
| | | | | | - Jiaren Zhang
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Eider Nuñez
- Instituto Biofisika, CSIC-UPV/EHU, 48940, Leioa, Spain
| | | | - Hee Jung Chung
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Aritz Leonardo
- Departamento de Física Aplicada II, Universidad del País Vasco, UPV/EHU, 48940, Leioa, Spain.,Donostia International Physics Center, 20018, Donostia, Spain
| | - Aitor Bergara
- Centro de Física de Materiales CFM, CSIC-UPV/EHU, 20018, Donostia, Spain.,Donostia International Physics Center, 20018, Donostia, Spain.,Departmento de Materia Condensada, Universidad del País Vasco, UPV/EHU, 48940, Leioa, Spain
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20
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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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21
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Cruzeiro L, Gill AC, Eilbeck JC. Statistical Evidence for a Helical Nascent Chain. Biomolecules 2021; 11:biom11030357. [PMID: 33652806 PMCID: PMC7996779 DOI: 10.3390/biom11030357] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/15/2021] [Accepted: 02/20/2021] [Indexed: 01/15/2023] Open
Abstract
We investigate the hypothesis that protein folding is a kinetic, non-equilibrium process, in which the structure of the nascent chain is crucial. We compare actual amino acid frequencies in loops, α-helices and β-sheets with the frequencies that would arise in the absence of any amino acid bias for those secondary structures. The novel analysis suggests that while specific amino acids exist to drive the formation of loops and sheets, none stand out as drivers for α-helices. This favours the idea that the α-helix is the initial structure of most proteins before the folding process begins.
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Affiliation(s)
- Leonor Cruzeiro
- CCMAR/CIMAR - Centro de Ciências do Mar, FCT, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | - Andrew C Gill
- School of Chemistry, Joseph Banks Laboratories, University of Lincoln, Green Lane, Lincoln LN67DL, UK
| | - J Chris Eilbeck
- Department of Mathematics and Maxwell Institute, Heriot-Watt University, Edinburgh EH14 4AS, Scotland, UK
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22
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Kubyshkin V, Davis R, Budisa N. Biochemistry of fluoroprolines: the prospect of making fluorine a bioelement. Beilstein J Org Chem 2021; 17:439-460. [PMID: 33727970 PMCID: PMC7934785 DOI: 10.3762/bjoc.17.40] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/22/2021] [Indexed: 12/12/2022] Open
Abstract
Due to the heterocyclic structure and distinct conformational profile, proline is unique in the repertoire of the 20 amino acids coded into proteins. Here, we summarize the biochemical work on the replacement of proline with (4R)- and (4S)-fluoroproline as well as 4,4-difluoroproline in proteins done mainly in the last two decades. We first recapitulate the complex position and biochemical fate of proline in the biochemistry of a cell, discuss the physicochemical properties of fluoroprolines, and overview the attempts to use these amino acids as proline replacements in studies of protein production and folding. Fluorinated proline replacements are able to elevate the protein expression speed and yields and improve the thermodynamic and kinetic folding profiles of individual proteins. In this context, fluoroprolines can be viewed as useful tools in the biotechnological toolbox. As a prospect, we envision that proteome-wide proline-to-fluoroproline substitutions could be possible. We suggest a hypothetical scenario for the use of laboratory evolutionary methods with fluoroprolines as a suitable vehicle to introduce fluorine into living cells. This approach may enable creation of synthetic cells endowed with artificial biodiversity, containing fluorine as a bioelement.
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Affiliation(s)
- Vladimir Kubyshkin
- Department of Chemistry, University of Manitoba, 144 Dysart Rd., Winnipeg, R3T 2N2, Canada
| | - Rebecca Davis
- Department of Chemistry, University of Manitoba, 144 Dysart Rd., Winnipeg, R3T 2N2, Canada
| | - Nediljko Budisa
- Department of Chemistry, University of Manitoba, 144 Dysart Rd., Winnipeg, R3T 2N2, Canada.,Institute of Chemistry, Technical University of Berlin, Müller-Breslau-Str. 10, 10623 Berlin, Germany
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23
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Li F, Egea PF, Vecchio AJ, Asial I, Gupta M, Paulino J, Bajaj R, Dickinson MS, Ferguson-Miller S, Monk BC, Stroud RM. Highlighting membrane protein structure and function: A celebration of the Protein Data Bank. J Biol Chem 2021; 296:100557. [PMID: 33744283 PMCID: PMC8102919 DOI: 10.1016/j.jbc.2021.100557] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 02/10/2021] [Accepted: 03/16/2021] [Indexed: 12/13/2022] Open
Abstract
Biological membranes define the boundaries of cells and compartmentalize the chemical and physical processes required for life. Many biological processes are carried out by proteins embedded in or associated with such membranes. Determination of membrane protein (MP) structures at atomic or near-atomic resolution plays a vital role in elucidating their structural and functional impact in biology. This endeavor has determined 1198 unique MP structures as of early 2021. The value of these structures is expanded greatly by deposition of their three-dimensional (3D) coordinates into the Protein Data Bank (PDB) after the first atomic MP structure was elucidated in 1985. Since then, free access to MP structures facilitates broader and deeper understanding of MPs, which provides crucial new insights into their biological functions. Here we highlight the structural and functional biology of representative MPs and landmarks in the evolution of new technologies, with insights into key developments influenced by the PDB in magnifying their impact.
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Affiliation(s)
- Fei Li
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA; Department of Neurology, University of California San Francisco, San Francisco, California, USA
| | - Pascal F Egea
- Department of Biological Chemistry, School of Medicine, University of California Los Angeles, Los Angeles, California, USA
| | - Alex J Vecchio
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | | | - Meghna Gupta
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA
| | - Joana Paulino
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA
| | - Ruchika Bajaj
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, USA
| | - Miles Sasha Dickinson
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA
| | - Shelagh Ferguson-Miller
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
| | - Brian C Monk
- Sir John Walsh Research Institute and Department of Oral Sciences, University of Otago, North Dunedin, Dunedin, New Zealand
| | - Robert M Stroud
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA.
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24
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Schulte L, Mao J, Reitz J, Sreeramulu S, Kudlinzki D, Hodirnau VV, Meier-Credo J, Saxena K, Buhr F, Langer JD, Blackledge M, Frangakis AS, Glaubitz C, Schwalbe H. Cysteine oxidation and disulfide formation in the ribosomal exit tunnel. Nat Commun 2020; 11:5569. [PMID: 33149120 PMCID: PMC7642426 DOI: 10.1038/s41467-020-19372-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 10/08/2020] [Indexed: 12/20/2022] Open
Abstract
Understanding the conformational sampling of translation-arrested ribosome nascent chain complexes is key to understand co-translational folding. Up to now, coupling of cysteine oxidation, disulfide bond formation and structure formation in nascent chains has remained elusive. Here, we investigate the eye-lens protein γB-crystallin in the ribosomal exit tunnel. Using mass spectrometry, theoretical simulations, dynamic nuclear polarization-enhanced solid-state nuclear magnetic resonance and cryo-electron microscopy, we show that thiol groups of cysteine residues undergo S-glutathionylation and S-nitrosylation and form non-native disulfide bonds. Thus, covalent modification chemistry occurs already prior to nascent chain release as the ribosome exit tunnel provides sufficient space even for disulfide bond formation which can guide protein folding.
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Affiliation(s)
- Linda Schulte
- Institute of Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University of Frankfurt, Frankfurt, Germany
| | - Jiafei Mao
- Institute of Biophysical Chemistry, Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Frankfurt, Germany
| | - Julian Reitz
- Institute for Biophysics, Buchmann Institute for Molecular Life Science, Goethe University Frankfurt, Frankfurt, Germany
| | - Sridhar Sreeramulu
- Institute of Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University of Frankfurt, Frankfurt, Germany
| | - Denis Kudlinzki
- Institute of Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University of Frankfurt, Frankfurt, Germany
| | - Victor-Valentin Hodirnau
- Institute for Biophysics, Buchmann Institute for Molecular Life Science, Goethe University Frankfurt, Frankfurt, Germany.,Institute of Science and Technology Austria, Klosterneuburg, Austria
| | | | - Krishna Saxena
- Institute of Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University of Frankfurt, Frankfurt, Germany
| | - Florian Buhr
- Institute of Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University of Frankfurt, Frankfurt, Germany.,Centre for Misfolding Diseases, University of Cambridge, Cambridge, UK
| | | | | | - Achilleas S Frangakis
- Institute for Biophysics, Buchmann Institute for Molecular Life Science, Goethe University Frankfurt, Frankfurt, Germany.
| | - Clemens Glaubitz
- Institute of Biophysical Chemistry, Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Frankfurt, Germany.
| | - Harald Schwalbe
- Institute of Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University of Frankfurt, Frankfurt, Germany.
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25
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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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26
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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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27
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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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Abstract
As the influence of translation rates on protein folding and function has come to light, the mechanisms by which translation speed is modulated have become an important issue. One mechanism entails the generation of force by the nascent protein. Cotranslational processes, such as nascent protein folding, the emergence of unfolded nascent chain segments from the ribosome's exit tunnel, and insertion of the nascent chain into or translocation of the nascent chain through membranes, can generate forces that are transmitted back to the peptidyl transferase center and affect translation rates. In this Perspective, we examine the processes that generate these forces, the mechanisms of transmission along the ribosomal exit tunnel to the peptidyl transferase center, and the effects of force on the ribosome's catalytic cycle. We also discuss the physical models that have been developed to predict and explain force generation for individual processes and speculate about other processes that may generate forces that have yet to be tested.
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Affiliation(s)
- Sarah Leininger
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Karthik Narayan
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Carol Deutsch
- Department of Physiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, 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 CyberScience, Pennsylvania State University, University Park, Pennsylvania 16802, United States
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29
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Dao Duc K, Batra SS, Bhattacharya N, Cate JHD, Song YS. Differences in the path to exit the ribosome across the three domains of life. Nucleic Acids Res 2019; 47:4198-4210. [PMID: 30805621 PMCID: PMC6486554 DOI: 10.1093/nar/gkz106] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 02/22/2019] [Indexed: 01/07/2023] Open
Abstract
The ribosome exit tunnel is an important structure involved in the regulation of translation and other essential functions such as protein folding. By comparing 20 recently obtained cryo-EM and X-ray crystallography structures of the ribosome from all three domains of life, we here characterize the key similarities and differences of the tunnel across species. We first show that a hierarchical clustering of tunnel shapes closely reflects the species phylogeny. Then, by analyzing the ribosomal RNAs and proteins, we explain the observed geometric variations and show direct association between the conservations of the geometry, structure and sequence. We find that the tunnel is more conserved in the upper part close to the polypeptide transferase center, while in the lower part, it is substantially narrower in eukaryotes than in bacteria. Furthermore, we provide evidence for the existence of a second constriction site in eukaryotic exit tunnels. Overall, these results have several evolutionary and functional implications, which explain certain differences between eukaryotes and prokaryotes in their translation mechanisms. In particular, they suggest that major co-translational functions of bacterial tunnels were externalized in eukaryotes, while reducing the tunnel size provided some other advantages, such as facilitating the nascent chain elongation and enabling antibiotic resistance.
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Affiliation(s)
- Khanh Dao Duc
- Computer Science Division, University of California, Berkeley, CA 94720, USA
| | - Sanjit S Batra
- Computer Science Division, University of California, Berkeley, CA 94720, USA
| | | | - Jamie H D Cate
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.,Department of Chemistry, University of California, Berkeley, CA 94720, USA.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Yun S Song
- Computer Science Division, University of California, Berkeley, CA 94720, USA.,Department of Statistics, University of California, Berkeley, CA 94720, USA.,Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
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30
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Ito K, Mori H, Chiba S. Monitoring substrate enables real-time regulation of a protein localization pathway. FEMS Microbiol Lett 2019; 365:4983124. [PMID: 29790986 DOI: 10.1093/femsle/fny109] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 04/23/2018] [Indexed: 12/20/2022] Open
Abstract
Protein localization machinery supports cell survival and physiology, suggesting the potential importance of its expression regulation. Here, we summarize a remarkable scheme of regulation, which allows real-time feedback regulation of the machinery expression. A class of regulatory nascent polypeptides, called monitoring substrates, undergoes force-sensitive translation arrest. The resulting ribosome stalling on the mRNA then affects mRNA folding to expose the ribosome-binding site of the downstream target gene and upregulate its translation. The target gene encodes a component of the localization machinery, whose physical action against the monitoring substrate leads to arrest cancellation. Thus, this scheme of feedback loop allows the cell to adjust the amount of the machinery to correlate inversely with the effectiveness of the process at a given moment. The system appears to have emerged late in evolution, in which a narrow range of organisms selected a distinct monitoring substrate-machinery combination. Currently, regulatory systems of SecM-SecA, VemP-SecDF2 and MifM-YidC2 are known to occur in different bacterial species.
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Affiliation(s)
- Koreaki Ito
- Faculty of Life Sciences and Institute for Protein Dynamics, Kyoto Sangyo University, Kita-Ku, Kyoto 603-8555, Japan
| | - Hiroyuki Mori
- Japan and Institute for Frontier Life and Medical Sciences, Kyoto University, Sakyo-Ku, Kyoto, 606-8507, Japan
| | - Shinobu Chiba
- Faculty of Life Sciences and Institute for Protein Dynamics, Kyoto Sangyo University, Kita-Ku, Kyoto 603-8555, Japan
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31
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Waudby CA, Dobson CM, Christodoulou J. Nature and Regulation of Protein Folding on the Ribosome. Trends Biochem Sci 2019; 44:914-926. [PMID: 31301980 PMCID: PMC7471843 DOI: 10.1016/j.tibs.2019.06.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 06/10/2019] [Accepted: 06/14/2019] [Indexed: 12/23/2022]
Abstract
Co-translational protein folding is an essential process by which cells ensure the safe and efficient production and assembly of new proteins in their functional native states following biosynthesis on the ribosome. In this review, we describe recent progress in probing the changes during protein synthesis of the free energy landscapes that underlie co-translational folding and discuss the critical coupling between these landscapes and the rate of translation that ultimately determines the success or otherwise of the folding process. Recent developments have revealed a variety of mechanisms by which both folding and translation can be modulated or regulated, and we discuss how these effects are utilised by the cell to optimise the outcome of protein biosynthesis.
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Affiliation(s)
- Christopher A Waudby
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, London, UK
| | - Christopher M Dobson
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, UK
| | - John Christodoulou
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, London, UK.
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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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33
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Leininger SE, Trovato F, Nissley DA, O'Brien EP. Domain topology, stability, and translation speed determine mechanical force generation on the ribosome. Proc Natl Acad Sci U S A 2019; 116:5523-5532. [PMID: 30824598 PMCID: PMC6431206 DOI: 10.1073/pnas.1813003116] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The concomitant folding of a nascent protein domain with its synthesis can generate mechanical forces that act on the ribosome and alter translation speed. Such changes in speed can affect the structure and function of the newly synthesized protein as well as cellular phenotype. The domain properties that govern force generation have yet to be identified and understood, and the influence of translation speed is unknown because all reported measurements have been carried out on arrested ribosomes. Here, using coarse-grained molecular simulations and statistical mechanical modeling of protein synthesis, we demonstrate that force generation is determined by a domain's stability and topology, as well as translation speed. The statistical mechanical models we create predict how force profiles depend on these properties. These results indicate that force measurements on arrested ribosomes will not always accurately reflect what happens in a cell, especially for slow-folding domains, and suggest the possibility that certain domain properties may be enriched or depleted across the structural proteome of organisms through evolutionary selection pressures to modulate protein synthesis speed and posttranslational protein behavior.
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Affiliation(s)
- Sarah E Leininger
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802
| | - Fabio Trovato
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802
| | - Daniel A Nissley
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802
| | - Edward P O'Brien
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802;
- Bioinformatics and Genomics Graduate Program, The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802
- Institute for CyberScience, Pennsylvania State University, University Park, PA 16802
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34
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Cherry JK, Woolhead CA. Hydrophobicity, rather than secondary structure, is essential for the SRP dependent targeting of GPR35 to the ER membrane. J Bioenerg Biomembr 2019; 51:137-150. [PMID: 30706279 PMCID: PMC6439181 DOI: 10.1007/s10863-019-9785-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 01/15/2019] [Indexed: 01/21/2023]
Abstract
The folding and targeting of hydrophobic transmembrane domains poses a major challenge to the cell. Several membrane proteins have been shown to gain some degree of secondary structure within the ribosome tunnel and to retain this conformation throughout maturation. However, there is little information on one of the largest classes of eukaryotic membrane proteins; the G protein-coupled receptors (GPCRs). In this study we show that the signal anchor domain of GPR35 remains in an extended conformation whilst exiting the ribosome tunnel, the polypeptide chain then forms interactions with components of the SRP targeting pathway, and the Sec61 translocon, resulting in a compacted conformation prior to integration into the ER membrane. We conclude that transmembrane structure is most likely adopted after the domain leaves the ribosome tunnel and that the interaction of the signal anchor with SRP is dependent on the native levels of hydrophobicity within the first transmembrane domain. Therefore, we propose a mechanism by which the first transmembrane domains of multi-spanning membrane proteins adopt compacted structures following SRP targeting but before insertion into the ER membrane.
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Affiliation(s)
- Jon K Cherry
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
- The Centre for Bacterial Cell Biology, Medical School, Newcastle University, Newcastle upon Tyne, NE2 4AX, UK
| | - Cheryl A Woolhead
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
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35
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Stein KC, Frydman J. The stop-and-go traffic regulating protein biogenesis: How translation kinetics controls proteostasis. J Biol Chem 2018; 294:2076-2084. [PMID: 30504455 DOI: 10.1074/jbc.rev118.002814] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Generating a functional proteome requires the ribosome to carefully regulate disparate co-translational processes that determine the fate of nascent polypeptides. With protein synthesis being energetically expensive, the ribosome must balance the costs of efficiently making a protein with those of properly folding it. Emerging as a primary means of regulating this trade-off is the nonuniform rate of translation elongation that defines translation kinetics. The varying speeds with which the ribosome progresses along a transcript have been implicated in several aspects of protein biogenesis, including co-translational protein folding and translational fidelity, as well as gene expression by mediating mRNA decay and protein quality control pathways. The optimal translation kinetics required to efficiently execute these processes can be distinct. Thus, the ribosome is tasked with tightly regulating translation kinetics to balance these processes while maintaining adaptability for changing cellular conditions. In this review, we first discuss the regulatory role of translation elongation in protein biogenesis and what factors influence elongation kinetics. We then describe how changes in translation kinetics signal downstream pathways that dictate the fate of nascent polypeptides. By regulating these pathways, the kinetics of translation elongation has emerged as a critical tool for driving gene expression and maintaining proteostasis through varied mechanisms, including nascent chain folding and binding different ribosome-associated machinery. Indeed, a growing number of examples demonstrate the important role of local changes in elongation kinetics in modulating the pathophysiology of human disease.
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Affiliation(s)
| | - Judith Frydman
- From the Departments of Biology and .,Genetics, Stanford University, Stanford, California 94305
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36
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Abstract
Most proteins need to fold into a specific 3D structure to function. The mechanism by which isolated proteins fold has been thoroughly studied by experiment and theory. However, in the cell proteins do not fold in isolation but are synthesized as linear chains by the ribosome during translation. It is therefore natural to ask at which point during synthesis proteins fold, and whether this differs from the folding of isolated protein molecules. By studying folding of a well-characterized protein domain, titin I27, stalled at different points during translation, we show that it already folds in the mouth of the ribosome exit tunnel and that the mechanism is almost identical to that of the isolated protein. Proteins that fold cotranslationally may do so in a restricted configurational space, due to the volume occupied by the ribosome. How does this environment, coupled with the close proximity of the ribosome, affect the folding pathway of a protein? Previous studies have shown that the cotranslational folding process for many proteins, including small, single domains, is directly affected by the ribosome. Here, we investigate the cotranslational folding of an all-β Ig domain, titin I27. Using an arrest peptide-based assay and structural studies by cryo-EM, we show that I27 folds in the mouth of the ribosome exit tunnel. Simulations that use a kinetic model for the force dependence of escape from arrest accurately predict the fraction of folded protein as a function of length. We used these simulations to probe the folding pathway on and off the ribosome. Our simulations—which also reproduce experiments on mutant forms of I27—show that I27 folds, while still sequestered in the mouth of the ribosome exit tunnel, by essentially the same pathway as free I27, with only subtle shifts of critical contacts from the C to the N terminus.
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37
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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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38
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Farías-Rico JA, Ruud Selin F, Myronidi I, Frühauf M, von Heijne G. Effects of protein size, thermodynamic stability, and net charge on cotranslational folding on the ribosome. Proc Natl Acad Sci U S A 2018; 115:E9280-E9287. [PMID: 30224455 PMCID: PMC6176590 DOI: 10.1073/pnas.1812756115] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
During the last five decades, studies of protein folding in dilute buffer solutions have produced a rich picture of this complex process. In the cell, however, proteins can start to fold while still attached to the ribosome (cotranslational folding) and it is not yet clear how the ribosome affects the folding of protein domains of different sizes, thermodynamic stabilities, and net charges. Here, by using arrest peptides as force sensors and on-ribosome pulse proteolysis, we provide a comprehensive picture of how the distance from the peptidyl transferase center in the ribosome at which proteins fold correlates with protein size. Moreover, an analysis of a large collection of mutants of the Escherichia coli ribosomal protein S6 shows that the force exerted on the nascent chain by protein folding varies linearly with the thermodynamic stability of the folded state, and that the ribosome environment disfavors folding of domains of high net-negative charge.
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Affiliation(s)
| | - Frida Ruud Selin
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Ioanna Myronidi
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Marie Frühauf
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Gunnar von Heijne
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden;
- Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden
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39
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Marino J, Buholzer KJ, Zosel F, Nettels D, Schuler B. Charge Interactions Can Dominate Coupled Folding and Binding on the Ribosome. Biophys J 2018; 115:996-1006. [PMID: 30173887 DOI: 10.1016/j.bpj.2018.07.037] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 07/20/2018] [Accepted: 07/30/2018] [Indexed: 12/29/2022] Open
Abstract
Interactions between emerging nascent polypeptide chains and the ribosome can modulate cotranslational protein folding. However, it has remained unclear how such interactions can affect the binding of nascent chains to their cellular targets. We thus investigated on the ribosome the interaction between two intrinsically disordered proteins of opposite charge, ACTR and NCBD, which form a high-affinity complex in a coupled folding-and-binding reaction. Using fluorescence correlation spectroscopy and arrest-peptide-mediated force measurements in vitro and in vivo, we find that the ACTR-NCBD complex can form cotranslationally but only with ACTR as the nascent chain and NCBD free in solution, not vice versa. We show that this surprising asymmetry in behavior is caused by pronounced charge interactions: attraction of the positively charged nascent chain of NCBD to the negatively charged ribosomal surface competes with complex formation and prevents ACTR binding. In contrast, the negatively charged nascent ACTR is repelled by the ribosomal surface and thus remains available for productively binding its partner. Electrostatic interactions may thus be more important for cotranslational folding and binding than previously thought.
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Affiliation(s)
- Jacopo Marino
- Department of Biochemistry, University of Zurich, Zurich, Switzerland; Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen PSI, Switzerland.
| | - Karin J Buholzer
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Franziska Zosel
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Daniel Nettels
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Benjamin Schuler
- Department of Biochemistry, University of Zurich, Zurich, Switzerland; Department of Physics, University of Zurich, Zurich, Switzerland.
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40
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Luke GA, Ryan MD. "Therapeutic applications of the 'NPGP' family of viral 2As". Rev Med Virol 2018; 28:e2001. [PMID: 30094875 DOI: 10.1002/rmv.2001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 06/29/2018] [Accepted: 07/01/2018] [Indexed: 12/15/2022]
Abstract
Oligopeptide "2A" and "2A-like" sequences ("2As"; 18-25aa) are found in a range of RNA virus genomes controlling protein biogenesis through "recoding" of the host-cell translational apparatus. Insertion of multiple 2As within a single open reading frame (ORF) produces multiple proteins; hence, 2As have been used in a very wide range of biotechnological and biomedical applications. During translation, these 2A peptide sequences mediate a eukaryote-specific, self-"cleaving" event, termed "ribosome skipping" with very high efficiency. A particular advantage of using 2As is the ability to simultaneously translate a number of proteins at an equal level in all eukaryotic systems although, naturally, final steady-state levels depend upon other factors-notably protein stability. By contrast, the use of internal ribosome entry site elements for co-expression results in an unbalanced expression due to the relative inefficiency of internal initiation. For example, a 1:1 ratio is of particular importance for the biosynthesis of the heavy-chain and light-chain components of antibodies: highly valuable as therapeutic proteins. Furthermore, each component of these "artificial polyprotein" systems can be independently targeted to different sub-cellular sites. The potential of this system was vividly demonstrated by concatenating multiple gene sequences, linked via 2A sequences, into a single, long, ORF-a polycistronic construct. Here, ORFs comprising the biosynthetic pathways for violacein (five gene sequences) and β-carotene (four gene sequences) were concatenated into a single cistron such that all components were co-expressed in the yeast Pichia pastoris. In this review, we provide useful information on 2As to serve as a guide for future utilities of this co-expression technology in basic research, biotechnology, and clinical applications.
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Affiliation(s)
- Garry A Luke
- Centre for Biomolecular Sciences, School of Biology, University of St Andrews, St Andrews, UK
| | - Martin D Ryan
- Centre for Biomolecular Sciences, School of Biology, University of St Andrews, St Andrews, UK
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41
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Fujiwara K, Ito K, Chiba S. MifM-instructed translation arrest involves nascent chain interactions with the exterior as well as the interior of the ribosome. Sci Rep 2018; 8:10311. [PMID: 29985442 PMCID: PMC6037786 DOI: 10.1038/s41598-018-28628-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 06/25/2018] [Indexed: 11/09/2022] Open
Abstract
Bacillus subtilis MifM is a monitoring substrate of the YidC pathways of protein integration into the membrane and controls the expression of the YidC2 (YqjG) homolog by undergoing regulated translational elongation arrest. The elongation arrest requires interactions between the MifM nascent polypeptide and the ribosomal components near the peptidyl transferase center (PTC) as well as at the constriction site of the ribosomal exit tunnel. Here, we addressed the roles played by more N-terminal regions of MifM and found that, in addition to the previously-identified arrest-provoking elements, the MifM residues 41-60 likely located at the tunnel exit and outside the ribosome contribute to the full induction of elongation arrest. Mutational effects of the cytosolically exposed part of the ribosomal protein uL23 suggested its involvement in the elongation arrest, presumably by interacting with the extra-ribosomal portion of MifM. In vitro translation with reconstituted translation components recapitulated the effects of the mutations at the 41-60 segment, reinforcing the importance of direct molecular interactions between the nascent chain and the ribosome. These results indicate that the nascent MifM polypeptide interacts extensively with the ribosome both from within and without to direct the elongation halt and consequent up-regulation of YidC2.
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Affiliation(s)
- Keigo Fujiwara
- Faculty of Life Sciences and Institute for Protein Dynamics, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto, 603-8555, Japan
| | - Koreaki Ito
- Faculty of Life Sciences and Institute for Protein Dynamics, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto, 603-8555, Japan
| | - Shinobu Chiba
- Faculty of Life Sciences and Institute for Protein Dynamics, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto, 603-8555, Japan.
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42
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Schönfelder J, Alonso-Caballero A, De Sancho D, Perez-Jimenez R. The life of proteins under mechanical force. Chem Soc Rev 2018; 47:3558-3573. [PMID: 29473060 DOI: 10.1039/c7cs00820a] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Although much of our understanding of protein folding comes from studies of isolated protein domains in bulk, in the cellular environment the intervention of external molecular machines is essential during the protein life cycle. During the past decade single molecule force spectroscopy techniques have been extremely useful to deepen our understanding of these interventional molecular processes, as they allow for monitoring and manipulating mechanochemical events in individual protein molecules. Here, we review some of the critical steps in the protein life cycle, starting with the biosynthesis of the nascent polypeptide chain in the ribosome, continuing with the folding supported by chaperones and the translocation into different cell compartments, and ending with proteolysis in the proteasome. Along these steps, proteins experience molecular forces often combined with chemical transformations, affecting their folding and structure, which are measured or mimicked in the laboratory by the application of force with a single molecule apparatus. These mechanochemical reactions can potentially be used as targets for fighting against diseases. Inspired by these insightful experiments, we devise an outlook on the emerging field of mechanopharmacology, which reflects an alternative paradigm for drug design.
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43
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Fritch B, Kosolapov A, Hudson P, Nissley DA, Woodcock HL, Deutsch C, O'Brien EP. Origins of the Mechanochemical Coupling of Peptide Bond Formation to Protein Synthesis. J Am Chem Soc 2018; 140:5077-5087. [PMID: 29577725 DOI: 10.1021/jacs.7b11044] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Mechanical forces acting on the ribosome can alter the speed of protein synthesis, indicating that mechanochemistry can contribute to translation control of gene expression. The naturally occurring sources of these mechanical forces, the mechanism by which they are transmitted 10 nm to the ribosome's catalytic core, and how they influence peptide bond formation rates are largely unknown. Here, we identify a new source of mechanical force acting on the ribosome by using in situ experimental measurements of changes in nascent-chain extension in the exit tunnel in conjunction with all-atom and coarse-grained computer simulations. We demonstrate that when the number of residues composing a nascent chain increases, its unstructured segments outside the ribosome exit tunnel generate piconewtons of force that are fully transmitted to the ribosome's P-site. The route of force transmission is shown to be through the nascent polypetide's backbone, not through the wall of the ribosome's exit tunnel. Utilizing quantum mechanical calculations we find that a consequence of such a pulling force is to decrease the transition state free energy barrier to peptide bond formation, indicating that the elongation of a nascent chain can accelerate translation. Since nascent protein segments can start out as largely unfolded structural ensembles, these results suggest a pulling force is present during protein synthesis that can modulate translation speed. The mechanism of force transmission we have identified and its consequences for peptide bond formation should be relevant regardless of the source of the pulling force.
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Affiliation(s)
- Benjamin Fritch
- Department of Chemistry , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - Andrey Kosolapov
- Department of Physiology , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
| | - Phillip Hudson
- Department of Chemistry , University of South Florida , Tampa , Florida 33620 , United States.,Laboratory of Computational Biology , National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Daniel A Nissley
- Department of Chemistry , Pennsylvania State University , University Park , Pennsylvania 16802 , United States
| | - H Lee Woodcock
- Department of Chemistry , University of South Florida , Tampa , Florida 33620 , United States
| | - Carol Deutsch
- Department of Physiology , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , 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
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44
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Non-equilibrium coupling of protein structure and function to translation-elongation kinetics. Curr Opin Struct Biol 2018; 49:94-103. [PMID: 29414517 DOI: 10.1016/j.sbi.2018.01.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 12/21/2017] [Accepted: 01/02/2018] [Indexed: 01/23/2023]
Abstract
Protein folding research has been dominated by the assumption that thermodynamics determines protein structure and function. And that when the folding process is compromised in vivo the proteostasis machinery-chaperones, deaggregases, the proteasome-work to restore proteins to their soluble, functional form or degrade them to maintain the cellular pool of proteins in a quasi-equilibrium state. During the past decade, however, more and more proteins have been identified for which altering only their speed of synthesis alters their structure and function, the efficiency of the down-stream processes they take part in, and cellular phenotype. Indeed, evidence has emerged that evolutionary selection pressures have encoded translation-rate information into mRNA molecules to coordinate diverse co-translational processes. Thus, non-equilibrium physics can play a fundamental role in influencing nascent protein behavior, mRNA sequence evolution, and disease. Here, we discuss how our understanding of this phenomenon is being advanced by the application of theoretical tools from the physical sciences.
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45
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46
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Klaips CL, Jayaraj GG, Hartl FU. Pathways of cellular proteostasis in aging and disease. J Cell Biol 2017; 217:51-63. [PMID: 29127110 PMCID: PMC5748993 DOI: 10.1083/jcb.201709072] [Citation(s) in RCA: 480] [Impact Index Per Article: 68.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 10/17/2017] [Accepted: 10/18/2017] [Indexed: 12/19/2022] Open
Abstract
Ensuring cellular protein homeostasis, or proteostasis, requires precise control of protein synthesis, folding, conformational maintenance, and degradation. A complex and adaptive proteostasis network coordinates these processes with molecular chaperones of different classes and their regulators functioning as major players. This network serves to ensure that cells have the proteins they need while minimizing misfolding or aggregation events that are hallmarks of age-associated proteinopathies, including neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. It is now clear that the capacity of cells to maintain proteostasis undergoes a decline during aging, rendering the organism susceptible to these pathologies. Here we discuss the major proteostasis pathways in light of recent research suggesting that their age-dependent failure can both contribute to and result from disease. We consider different strategies to modulate proteostasis capacity, which may help develop urgently needed therapies for neurodegeneration and other age-dependent pathologies.
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Affiliation(s)
- Courtney L Klaips
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | | | - F Ulrich Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
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47
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Sabi R, Tuller T. Computational analysis of nascent peptides that induce ribosome stalling and their proteomic distribution in Saccharomyces cerevisiae. RNA (NEW YORK, N.Y.) 2017; 23:983-994. [PMID: 28363900 PMCID: PMC5473148 DOI: 10.1261/rna.059188.116] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 03/24/2017] [Indexed: 05/14/2023]
Abstract
Interactions between the ribosomal exit tunnel and the nascent peptide can affect translation elongation rates. While previous studies have already demonstrated the feasibility of such interactions, little is known about the nature of the stalling peptide sequences and their distribution in the proteome. Here we ask which peptide sequences tend to occupy the tunnel of stalled ribosomes and how they are distributed in the proteome. Using computational analysis of ribosome profiling data from S. cerevisiae, we identified for the first time dozens of short stalling peptide sequences and studied their statistical properties. We found that short peptide sequences associated with ribosome stalling tend significantly to be either over- or underrepresented in the proteome. We then showed that the stalling interactions may occur at different positions along the length of the tunnel, prominently close to the P-site. Our findings throw light on the determinants of nascent peptide-mediated ribosome stalling during translation elongation and support the novel conjecture that mRNA translation affects the proteomic distribution of short peptide sequences.
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Affiliation(s)
- Renana Sabi
- Department of Biomedical Engineering, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Tamir Tuller
- Department of Biomedical Engineering, Tel Aviv University, Ramat Aviv 69978, Israel
- The Sagol School of Neuroscience, Tel Aviv University, Ramat Aviv 69978, Israel
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48
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Su T, Cheng J, Sohmen D, Hedman R, Berninghausen O, von Heijne G, Wilson DN, Beckmann R. The force-sensing peptide VemP employs extreme compaction and secondary structure formation to induce ribosomal stalling. eLife 2017; 6. [PMID: 28556777 PMCID: PMC5449182 DOI: 10.7554/elife.25642] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 05/22/2017] [Indexed: 12/29/2022] Open
Abstract
Interaction between the nascent polypeptide chain and the ribosomal exit tunnel can modulate the rate of translation and induce translational arrest to regulate expression of downstream genes. The ribosomal tunnel also provides a protected environment for initial protein folding events. Here, we present a 2.9 Å cryo-electron microscopy structure of a ribosome stalled during translation of the extremely compacted VemP nascent chain. The nascent chain forms two α-helices connected by an α-turn and a loop, enabling a total of 37 amino acids to be observed within the first 50-55 Å of the exit tunnel. The structure reveals how α-helix formation directly within the peptidyltransferase center of the ribosome interferes with aminoacyl-tRNA accommodation, suggesting that during canonical translation, a major role of the exit tunnel is to prevent excessive secondary structure formation that can interfere with the peptidyltransferase activity of the ribosome.
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Affiliation(s)
- Ting Su
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich, Ludwig Maximilian University of Munich, Munich, Germany
| | - Jingdong Cheng
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich, Ludwig Maximilian University of Munich, Munich, Germany
| | - Daniel Sohmen
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich, Ludwig Maximilian University of Munich, Munich, Germany
| | - Rickard Hedman
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Otto Berninghausen
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich, Ludwig Maximilian University of Munich, Munich, Germany
| | - Gunnar von Heijne
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.,Science for Life Laboratory Stockholm University, Solna, Sweden
| | - Daniel N Wilson
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich, Ludwig Maximilian University of Munich, Munich, Germany.,Institute for Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Roland Beckmann
- Gene Center, Department of Biochemistry and Center for integrated Protein Science Munich, Ludwig Maximilian University of Munich, Munich, Germany
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49
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Po P, Delaney E, Gamper H, Szantai-Kis DM, Speight L, Tu L, Kosolapov A, Petersson EJ, Hou YM, Deutsch C. Effect of Nascent Peptide Steric Bulk on Elongation Kinetics in the Ribosome Exit Tunnel. J Mol Biol 2017; 429:1873-1888. [PMID: 28483649 DOI: 10.1016/j.jmb.2017.04.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 04/18/2017] [Accepted: 04/28/2017] [Indexed: 12/17/2022]
Abstract
All proteins are synthesized by the ribosome, a macromolecular complex that accomplishes the life-sustaining tasks of faithfully decoding mRNA and catalyzing peptide bond formation at the peptidyl transferase center (PTC). The ribosome has evolved an exit tunnel to host the elongating new peptide, protect it from proteolytic digestion, and guide its emergence. It is here that the nascent chain begins to fold. This folding process depends on the rate of translation at the PTC. We report here that besides PTC events, translation kinetics depend on steric constraints on nascent peptide side chains and that confined movements of cramped side chains within and through the tunnel fine-tune elongation rates.
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Affiliation(s)
- Pengse Po
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erin Delaney
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Howard Gamper
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - D Miklos Szantai-Kis
- Department of Biochemistry and Molecular Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Lee Speight
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - LiWei Tu
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Andrey Kosolapov
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - E James Petersson
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ya-Ming Hou
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Carol Deutsch
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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50
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Tu L, Deutsch C. Determinants of Helix Formation for a Kv1.3 Transmembrane Segment inside the Ribosome Exit Tunnel. J Mol Biol 2017; 429:1722-1732. [PMID: 28478285 DOI: 10.1016/j.jmb.2017.04.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 04/26/2017] [Accepted: 04/30/2017] [Indexed: 11/17/2022]
Abstract
Proteins begin to fold in the ribosome, and misfolding has pathological consequences. Among the earliest folding events in biogenesis is the formation of a helix, an elementary structure that is ubiquitously present and required for correct protein folding in all proteomes. The determinants underlying helix formation in the confined space of the ribosome exit tunnel are relatively unknown. We chose the second transmembrane segment, S2, of a voltage-gated potassium channel, Kv1.3, as a model to probe this issue. Since the N terminus of S2 is initially in an extended conformation in the folding vestibule of the ribosome yet ultimately emerges at the exit port as a helix, S2 is ideally suited for delineating sequential events and folding determinants of helix formation inside the ribosome. We show that S2's extended N terminus inside the tunnel is converted into a helix by a single, distant mutation in the nascent peptide. This transition depends on nascent peptide sequence at specific tunnel locations. Co-translational secondary folding of nascent chains inside the ribosome has profound physiological consequences that bear on correct membrane insertion, tertiary folding, oligomerization, and biochemical modification of the newborn protein during biogenesis.
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Affiliation(s)
- LiWei Tu
- Department of Physiology, University of Pennsylvania, PA 19104-6085, Philadelphia, USA
| | - Carol Deutsch
- Department of Physiology, University of Pennsylvania, PA 19104-6085, Philadelphia, USA.
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