1
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Eckardt NA, Avin-Wittenberg T, Bassham DC, Chen P, Chen Q, Fang J, Genschik P, Ghifari AS, Guercio AM, Gibbs DJ, Heese M, Jarvis RP, Michaeli S, Murcha MW, Mursalimov S, Noir S, Palayam M, Peixoto B, Rodriguez PL, Schaller A, Schnittger A, Serino G, Shabek N, Stintzi A, Theodoulou FL, Üstün S, van Wijk KJ, Wei N, Xie Q, Yu F, Zhang H. The lowdown on breakdown: Open questions in plant proteolysis. THE PLANT CELL 2024; 36:2931-2975. [PMID: 38980154 PMCID: PMC11371169 DOI: 10.1093/plcell/koae193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 05/16/2024] [Accepted: 06/19/2024] [Indexed: 07/10/2024]
Abstract
Proteolysis, including post-translational proteolytic processing as well as protein degradation and amino acid recycling, is an essential component of the growth and development of living organisms. In this article, experts in plant proteolysis pose and discuss compelling open questions in their areas of research. Topics covered include the role of proteolysis in the cell cycle, DNA damage response, mitochondrial function, the generation of N-terminal signals (degrons) that mark many proteins for degradation (N-terminal acetylation, the Arg/N-degron pathway, and the chloroplast N-degron pathway), developmental and metabolic signaling (photomorphogenesis, abscisic acid and strigolactone signaling, sugar metabolism, and postharvest regulation), plant responses to environmental signals (endoplasmic-reticulum-associated degradation, chloroplast-associated degradation, drought tolerance, and the growth-defense trade-off), and the functional diversification of peptidases. We hope these thought-provoking discussions help to stimulate further research.
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Affiliation(s)
| | - Tamar Avin-Wittenberg
- Department of Plant and Environmental Sciences, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Diane C Bassham
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Poyu Chen
- School of Biological Science and Technology, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | - Qian Chen
- Ministry of Agriculture and Rural Affairs Key Laboratory for Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Jun Fang
- Section of Molecular Plant Biology, Department of Biology, University of Oxford, Oxford OX1 3RB, UK
| | - Pascal Genschik
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, 12, rue du Général Zimmer, Strasbourg 67084, France
| | - Abi S Ghifari
- School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Angelica M Guercio
- Department of Plant Biology, College of Biological Sciences, University of California-Davis, Davis, CA 95616, USA
| | - Daniel J Gibbs
- School of Biosciences, University of Birmingham, Edgbaston B1 2RU, UK
| | - Maren Heese
- Department of Developmental Biology, University of Hamburg, Ohnhorststr. 18, Hamburg 22609, Germany
| | - R Paul Jarvis
- Section of Molecular Plant Biology, Department of Biology, University of Oxford, Oxford OX1 3RB, UK
| | - Simon Michaeli
- Department of Postharvest Sciences, Agricultural Research Organization (ARO), Volcani Institute, Rishon LeZion 7505101, Israel
| | - Monika W Murcha
- School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Sergey Mursalimov
- Department of Postharvest Sciences, Agricultural Research Organization (ARO), Volcani Institute, Rishon LeZion 7505101, Israel
| | - Sandra Noir
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, 12, rue du Général Zimmer, Strasbourg 67084, France
| | - Malathy Palayam
- Department of Plant Biology, College of Biological Sciences, University of California-Davis, Davis, CA 95616, USA
| | - Bruno Peixoto
- Section of Molecular Plant Biology, Department of Biology, University of Oxford, Oxford OX1 3RB, UK
| | - Pedro L Rodriguez
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Cientificas-Universidad Politecnica de Valencia, Valencia ES-46022, Spain
| | - Andreas Schaller
- Department of Plant Physiology and Biochemistry, Institute of Biology, University of Hohenheim, Stuttgart 70599, Germany
| | - Arp Schnittger
- Department of Developmental Biology, University of Hamburg, Ohnhorststr. 18, Hamburg 22609, Germany
| | - Giovanna Serino
- Department of Biology and Biotechnology, Sapienza Universita’ di Roma, p.le A. Moro 5, Rome 00185, Italy
| | - Nitzan Shabek
- Department of Plant Biology, College of Biological Sciences, University of California-Davis, Davis, CA 95616, USA
| | - Annick Stintzi
- Department of Plant Physiology and Biochemistry, Institute of Biology, University of Hohenheim, Stuttgart 70599, Germany
| | | | - Suayib Üstün
- Faculty of Biology and Biotechnology, Ruhr-University of Bochum, Bochum 44780, Germany
| | - Klaas J van Wijk
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, NY 14853, USA
| | - Ning Wei
- School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Qi Xie
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, the Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Feifei Yu
- College of Grassland Science and Technology, China Agricultural University, Beijing 100083, China
| | - Hongtao Zhang
- Plant Sciences and the Bioeconomy, Rothamsted Research, Harpenden AL5 2JQ, UK
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2
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van Wijk KJ. Intra-chloroplast proteases: A holistic network view of chloroplast proteolysis. THE PLANT CELL 2024; 36:3116-3130. [PMID: 38884601 PMCID: PMC11371162 DOI: 10.1093/plcell/koae178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Revised: 06/12/2024] [Accepted: 06/12/2024] [Indexed: 06/18/2024]
Abstract
Different proteases and peptidases are present within chloroplasts and nonphotosynthetic plastids to process precursor proteins and to degrade cleaved chloroplast transit peptides and damaged, misfolded, or otherwise unwanted proteins. Collectively, these proteases and peptidases form a proteolysis network, with complementary activities and hierarchies, and build-in redundancies. Furthermore, this network is distributed across the different intra-chloroplast compartments (lumen, thylakoid, stroma, envelope). The challenge is to determine the contributions of each peptidase (system) to this network in chloroplasts and nonphotosynthetic plastids. This will require an understanding of substrate recognition mechanisms, degrons, substrate, and product size limitations, as well as the capacity and degradation kinetics of each protease. Multiple extra-plastidial degradation pathways complement these intra-chloroplast proteases. This review summarizes our current understanding of these intra-chloroplast proteases in Arabidopsis and crop plants with an emphasis on considerations for building a qualitative and quantitative network view.
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Affiliation(s)
- Klaas J van Wijk
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, NY 14853, USA
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3
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Wang N, Gao JG, Wu MW. Molecular docking and molecular simulation studies for N-degron selectivity of chloroplastic ClpS from Chlamydomonas reinhardtii. Comput Biol Chem 2023; 103:107825. [PMID: 36773520 DOI: 10.1016/j.compbiolchem.2023.107825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 01/31/2023] [Accepted: 02/02/2023] [Indexed: 02/11/2023]
Abstract
Regarding the importance of N-degron pathway in protein degradation network, the adaptor protein ClpS recognizes the substrates bearing classical N-degrons, and delivers them to caseinolytic protease complex ClpAP for degradation. Interestingly, the majority of N-degrons located near the N-terminus of protein substrate are belonged to the hydrophobic type amino acids. Chloroplast, an important organelle for plant photosynthesis, contain a diversified Clp degradation system. Despite several studies have confirmed that chloroplastic ClpS is able to interact with classical N-degrons derived from prokaryotes, whereas, the molecular mechanism underlying how the chloroplastic ClpS protein could recognize the substrate tagged by N-degrons is still unclear until now. Chlamydomonas reinhardtii is a kind of unicellular model organism for photosynthesis researches, which possesses a large cup-shaped chloroplast, and the corresponding genome data indicates that it owns bacterial homologous adaptor protein, named CrClpS1. However, the relevant biochemical knowledges, and protein structure researches for CrClpS1 adaptor aren't reported up to date. The molecular interactions between CrClpS1 and possible N-degrons are undefined as well. Here, we build a reliable homology model of CrClpS1 and find a hydrophobic pocket for N-degron binding. We combine molecular docking, molecular dynamic simulations, and MM/PBSA, MM/GBSA binding free energy estimations to elucidate the molecular properties of CrClpS1-N-degron interactions. Besides, we investigate the conformational changes for CrClpS1-apo in water-solvent environment and analyze its possible biological significances through a long time molecular dynamic simulation. Specifically, the adaptor CrClpS1 displays the stronger interactions with Phe, Trp, Tyr, His and Ile with respect to other amino acids. Using the residue decomposition analysis, the interactions between CrClpS1 and N-degrons are heavily depended on several conservative residues, which are located around the hydrophobic pocket, implying that chloroplast isolated from Chlamydomonas reinhadtii adopts a relatively conservative N-degron recognition mode. Besides, the opening-closure of hydrophobic pocket of CrClpS1 might be beneficial for the N-degron selectivity.
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Affiliation(s)
- Ning Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100101, China.
| | - Jian-Guo Gao
- Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang University, Urumqi, China
| | - Ming-Wei Wu
- University of Chinese Academy of Sciences, Beijing 100101, China; Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
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4
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Winckler LI, Dissmeyer N. Molecular determinants of protein half-life in chloroplasts with focus on the Clp protease system. Biol Chem 2023; 404:499-511. [PMID: 36972025 DOI: 10.1515/hsz-2022-0320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 03/09/2023] [Indexed: 03/29/2023]
Abstract
Abstract
Proteolysis is an essential process to maintain cellular homeostasis. One pathway that mediates selective protein degradation and which is in principle conserved throughout the kingdoms of life is the N-degron pathway, formerly called the ‘N-end rule’. In the cytosol of eukaryotes and prokaryotes, N-terminal residues can be major determinants of protein stability. While the eukaryotic N-degron pathway depends on the ubiquitin proteasome system, the prokaryotic counterpart is driven by the Clp protease system. Plant chloroplasts also contain such a protease network, which suggests that they might harbor an organelle specific N-degron pathway similar to the prokaryotic one. Recent discoveries indicate that the N-terminal region of proteins affects their stability in chloroplasts and provides support for a Clp-mediated entry point in an N-degron pathway in plastids. This review discusses structure, function and specificity of the chloroplast Clp system, outlines experimental approaches to test for an N-degron pathway in chloroplasts, relates these aspects into general plastid proteostasis and highlights the importance of an understanding of plastid protein turnover.
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Affiliation(s)
- Lioba Inken Winckler
- Department of Plant Physiology and Protein Metabolism Laboratory, University of Osnabruck, Barbarastrasse 11, D-49076 Osnabruck, Germany
- Center of Cellular Nanoanalytics (CellNanOs), Barbarastrasse 11, D-49076 Osnabruck, Germany
- Faculty of Biology, University of Osnabruck, Barbarastrasse 11, D-49076 Osnabruck, Germany
| | - Nico Dissmeyer
- Department of Plant Physiology and Protein Metabolism Laboratory, University of Osnabruck, Barbarastrasse 11, D-49076 Osnabruck, Germany
- Center of Cellular Nanoanalytics (CellNanOs), Barbarastrasse 11, D-49076 Osnabruck, Germany
- Faculty of Biology, University of Osnabruck, Barbarastrasse 11, D-49076 Osnabruck, Germany
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5
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In vitro production of N-degron fused proteins and its application. Methods Enzymol 2023. [PMID: 37532410 DOI: 10.1016/bs.mie.2023.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
The N-degron pathway, first discovered several decades ago by Varshavsky's laboratory, controls the half-life of target proteins depending on their N-terminal residues. In vivo cell biology studies have established the physiological role of the N-degron pathway. However, in vitro studies such as biochemical assays and structural biology studies are relatively limited. The N-degron substrates cannot be obtained via simple protein expression. The N-degron residues are exposed via the proteolytic process from the translated nascent polypeptide chains. Thus, methods for the fusion expression with several cleavable tags and subsequent treatment with specific proteases to design the exposed N-degron signals have been introduced. Recently, we developed a unique fusion technique using microtubule-associated protein 1A/1B light chain 3B (LC3B), a key marker protein of autophagy, to obtain a high yield of the purified target proteins with variable N-terminal residues for various biochemical studies including enzymatic and binding assays, and crystallization of N-degron complex. This chapter describes the protocols that include the vector map designed for producing LC3B fused target proteins, methods for expression and purification of an example protein, p62/SQSMT1, using different N-terminal residues, and methods to obtain the purified ATG4B protease, which is used for processing LC3B tag and exposing the required N-terminal residues of the target protein.
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6
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Dougan DA, Truscott KN. Affinity isolation and biochemical characterization of N-degron ligands using the N-recognin, ClpS. Methods Enzymol 2023. [PMID: 37532398 DOI: 10.1016/bs.mie.2023.02.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2023]
Abstract
The N-degron pathways are a set of proteolytic systems that relate the half-life of a protein to its N-terminal (Nt) residue. In Escherichia coli the principal N-degron pathway is known as the Leu/N-degron pathway. Proteins degraded by this pathway contain an Nt degradation signal (N-degron) composed of an Nt primary destabilizing (Nd1) residue (Leu, Phe, Trp or Tyr). All Leu/N-degron substrates are recognized by the adaptor protein, ClpS and delivered to the ClpAP protease for degradation. Although many components of the pathway are well defined, the physiological role of this pathway remains poorly understood. To address this gap in knowledge we developed a biospecific affinity chromatography technique to isolate physiological substrates of the Leu/N-degron pathway. In this chapter we describe the use of peptide arrays to determine the binding specificity of ClpS. We demonstrate how the information obtained from the peptide array, when coupled with ClpS affinity chromatography, can be used to specifically elute physiological Leu/N-degron ligands from a bacterial lysate. These techniques are illustrated using E. coli ClpS (EcClpS), but both are broadly suitable for application to related N-recognins and systems, not only for the determination of N-recognin specificity, but also for the identification of natural Leu/N-degron ligands from various bacterial and plant species that contain ClpS homologs.
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7
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Rowland E, Kim J, Friso G, Poliakov A, Ponnala L, Sun Q, van Wijk KJ. The CLP and PREP protease systems coordinate maturation and degradation of the chloroplast proteome in Arabidopsis thaliana. THE NEW PHYTOLOGIST 2022; 236:1339-1357. [PMID: 35946374 DOI: 10.1111/nph.18426] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 07/29/2022] [Indexed: 06/15/2023]
Abstract
A network of peptidases governs proteostasis in plant chloroplasts and mitochondria. This study reveals strong genetic and functional interactions in Arabidopsis between the chloroplast stromal CLP chaperone-protease system and the PREP1,2 peptidases, which are dually localized to chloroplast stroma and the mitochondrial matrix. Higher order mutants defective in CLP or PREP proteins were generated and analyzed by quantitative proteomics and N-terminal proteomics (terminal amine isotopic labeling of substrates (TAILS)). Strong synergistic interactions were observed between the CLP protease system (clpr1-2, clpr2-1, clpc1-1, clpt1, clpt2) and both PREP homologs (prep1, prep2) resulting in embryo lethality or growth and developmental phenotypes. Synergistic interactions were observed even when only one of the PREP proteins was lacking, suggesting that PREP1 and PREP2 have divergent substrates. Proteome phenotypes were driven by the loss of CLP protease capacity, with little impact from the PREP peptidases. Chloroplast N-terminal proteomes showed that many nuclear encoded chloroplast proteins have alternatively processed N-termini in prep1prep2, clpt1clpt2 and prep1prep2clpt1clpt2. Loss of chloroplast protease capacity interferes with stromal processing peptidase (SPP) activity due to folding stress and low levels of accumulated cleaved cTP fragments. PREP1,2 proteolysis of cleaved cTPs is complemented by unknown proteases. A model for CLP and PREP activity within a hierarchical chloroplast proteolysis network is proposed.
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Affiliation(s)
- Elden Rowland
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, NY, 14853, USA
| | - Jitae Kim
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, NY, 14853, USA
- S-Korea Bioenergy Research Center, Chonnam National University, Gwangju, 61186, South Korea
| | - Giulia Friso
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, NY, 14853, USA
| | - Anton Poliakov
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, NY, 14853, USA
| | | | - Qi Sun
- Computational Biology Service Unit, Cornell University, Ithaca, NY, 14853, USA
| | - Klaas J van Wijk
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, NY, 14853, USA
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8
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Crystal structure of the Ate1 arginyl-tRNA-protein transferase and arginylation of N-degron substrates. Proc Natl Acad Sci U S A 2022; 119:e2209597119. [PMID: 35878037 PMCID: PMC9351520 DOI: 10.1073/pnas.2209597119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
N-degron pathways are proteolytic systems that target proteins bearing N-terminal (Nt) degradation signals (degrons) called N-degrons. Nt-Arg of a protein is among Nt-residues that can be recognized as destabilizing ones by the Arg/N-degron pathway. A proteolytic cleavage of a protein can generate Arg at the N terminus of a resulting C-terminal (Ct) fragment either directly or after Nt-arginylation of that Ct-fragment by the Ate1 arginyl-tRNA-protein transferase (R-transferase), which uses Arg-tRNAArg as a cosubstrate. Ate1 can Nt-arginylate Nt-Asp, Nt-Glu, and oxidized Nt-Cys* (Cys-sulfinate or Cys-sulfonate) of proteins or short peptides. Ate1 genes of fungi, animals, and plants have been cloned decades ago, but a three-dimensional structure of Ate1 remained unknown. A detailed mechanism of arginylation is unknown as well. We describe here the crystal structure of the Ate1 R-transferase from the budding yeast Kluyveromyces lactis. The 58-kDa R-transferase comprises two domains that recognize, together, an acidic Nt-residue of an acceptor substrate, the Arg residue of Arg-tRNAArg, and a 3'-proximal segment of the tRNAArg moiety. The enzyme's active site is located, at least in part, between the two domains. In vitro and in vivo arginylation assays with site-directed Ate1 mutants that were suggested by structural results yielded inferences about specific binding sites of Ate1. We also analyzed the inhibition of Nt-arginylation activity of Ate1 by hemin (Fe3+-heme), and found that hemin induced the previously undescribed disulfide-mediated oligomerization of Ate1. Together, these results advance the understanding of R-transferase and the Arg/N-degron pathway.
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Sherpa D, Chrustowicz J, Schulman BA. How the ends signal the end: Regulation by E3 ubiquitin ligases recognizing protein termini. Mol Cell 2022; 82:1424-1438. [PMID: 35247307 PMCID: PMC9098119 DOI: 10.1016/j.molcel.2022.02.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/18/2022] [Accepted: 02/01/2022] [Indexed: 12/31/2022]
Abstract
Specificity of eukaryotic protein degradation is determined by E3 ubiquitin ligases and their selective binding to protein motifs, termed "degrons," in substrates for ubiquitin-mediated proteolysis. From the discovery of the first substrate degron and the corresponding E3 to a flurry of recent studies enabled by modern systems and structural methods, it is clear that many regulatory pathways depend on E3s recognizing protein termini. Here, we review the structural basis for recognition of protein termini by E3s and how this recognition underlies biological regulation. Diverse E3s evolved to harness a substrate's N and/or C terminus (and often adjacent residues as well) in a sequence-specific manner. Regulation is achieved through selective activation of E3s and also through generation of degrons at ribosomes or by posttranslational means. Collectively, many E3 interactions with protein N and C termini enable intricate control of protein quality and responses to cellular signals.
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Affiliation(s)
- Dawafuti Sherpa
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried, Bavaria, Germany
| | - Jakub Chrustowicz
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried, Bavaria, Germany
| | - Brenda A Schulman
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried, Bavaria, Germany.
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10
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Structural insights into Ubr1-mediated N-degron polyubiquitination. Nature 2021; 600:334-338. [PMID: 34789879 DOI: 10.1038/s41586-021-04097-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 10/06/2021] [Indexed: 11/09/2022]
Abstract
The N-degron pathway targets proteins that bear a destabilizing residue at the N terminus for proteasome-dependent degradation1. In yeast, Ubr1-a single-subunit E3 ligase-is responsible for the Arg/N-degron pathway2. How Ubr1 mediates the initiation of ubiquitination and the elongation of the ubiquitin chain in a linkage-specific manner through a single E2 ubiquitin-conjugating enzyme (Ubc2) remains unknown. Here we developed chemical strategies to mimic the reaction intermediates of the first and second ubiquitin transfer steps, and determined the cryo-electron microscopy structures of Ubr1 in complex with Ubc2, ubiquitin and two N-degron peptides, representing the initiation and elongation steps of ubiquitination. Key structural elements, including a Ubc2-binding region and an acceptor ubiquitin-binding loop on Ubr1, were identified and characterized. These structures provide mechanistic insights into the initiation and elongation of ubiquitination catalysed by Ubr1.
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11
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Chrustowicz J, Sherpa D, Teyra J, Loke MS, Popowicz GM, Basquin J, Sattler M, Prabu JR, Sidhu SS, Schulman BA. Multifaceted N-Degron Recognition and Ubiquitylation by GID/CTLH E3 Ligases. J Mol Biol 2021; 434:167347. [PMID: 34767800 DOI: 10.1016/j.jmb.2021.167347] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 11/02/2021] [Accepted: 11/02/2021] [Indexed: 12/22/2022]
Abstract
N-degron E3 ubiquitin ligases recognize specific residues at the N-termini of substrates. Although molecular details of N-degron recognition are known for several E3 ligases, the range of N-terminal motifs that can bind a given E3 substrate binding domain remains unclear. Here, we discovered capacity of Gid4 and Gid10 substrate receptor subunits of yeast "GID"/human "CTLH" multiprotein E3 ligases to tightly bind a wide range of N-terminal residues whose recognition is determined in part by the downstream sequence context. Screening of phage displaying peptide libraries with exposed N-termini identified novel consensus motifs with non-Pro N-terminal residues binding Gid4 or Gid10 with high affinity. Structural data reveal that conformations of flexible loops in Gid4 and Gid10 complement sequences and folds of interacting peptides. Together with analysis of endogenous substrate degrons, the data show that degron identity, substrate domains harboring targeted lysines, and varying E3 ligase higher-order assemblies combinatorially determine efficiency of ubiquitylation and degradation.
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Affiliation(s)
- Jakub Chrustowicz
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany. https://twitter.com/chrustowicz_j
| | - Dawafuti Sherpa
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany. https://twitter.com/dawafutisherpa
| | - Joan Teyra
- The Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Mun Siong Loke
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Grzegorz M Popowicz
- Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany; Bavarian NMR Center, Department of Chemistry, Technical University of Munich, Germany
| | - Jerome Basquin
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Michael Sattler
- Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany; Bavarian NMR Center, Department of Chemistry, Technical University of Munich, Germany
| | - J Rajan Prabu
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany. https://twitter.com/rajanprabu
| | - Sachdev S Sidhu
- The Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Brenda A Schulman
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
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12
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Aminopeptidases trim Xaa-Pro proteins, initiating their degradation by the Pro/N-degron pathway. Proc Natl Acad Sci U S A 2021; 118:2115430118. [PMID: 34663735 DOI: 10.1073/pnas.2115430118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/12/2021] [Indexed: 12/26/2022] Open
Abstract
N-degron pathways are proteolytic systems that recognize proteins bearing N-terminal (Nt) degradation signals (degrons) called N-degrons. Our previous work identified Gid4 as a recognition component (N-recognin) of the Saccharomyces cerevisiae proteolytic system termed the proline (Pro)/N-degron pathway. Gid4 is a subunit of the oligomeric glucose-induced degradation (GID) ubiquitin ligase. Gid4 targets proteins through the binding to their Nt-Pro residue. Gid4 is also required for degradation of Nt-Xaa-Pro (Xaa is any amino acid residue) proteins such as Nt-[Ala-Pro]-Aro10 and Nt-[Ser-Pro]-Pck1, with Pro at position 2. Here, we show that specific aminopeptidases function as components of the Pro/N-degron pathway by removing Nt-Ala or Nt-Ser and yielding Nt-Pro, which can be recognized by Gid4-GID. Nt-Ala is removed by the previously uncharacterized aminopeptidase Fra1. The enzymatic activity of Fra1 is shown to be essential for the GID-dependent degradation of Nt-[Ala-Pro]-Aro10. Fra1 can also trim Nt-[Ala-Pro-Pro-Pro] (stopping immediately before the last Pro) and thereby can target for degradation a protein bearing this Nt sequence. Nt-Ser is removed largely by the mitochondrial/cytosolic/nuclear aminopeptidase Icp55. These advances are relevant to eukaryotes from fungi to animals and plants, as Fra1, Icp55, and the GID ubiquitin ligase are conserved in evolution. In addition to discovering the mechanism of targeting of Xaa-Pro proteins, these insights have also expanded the diversity of substrates of the Pro/N-degron pathway.
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Bouchnak I, van Wijk KJ. Structure, function, and substrates of Clp AAA+ protease systems in cyanobacteria, plastids, and apicoplasts: A comparative analysis. J Biol Chem 2021; 296:100338. [PMID: 33497624 PMCID: PMC7966870 DOI: 10.1016/j.jbc.2021.100338] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 01/22/2021] [Accepted: 01/22/2021] [Indexed: 02/08/2023] Open
Abstract
ATPases Associated with diverse cellular Activities (AAA+) are a superfamily of proteins that typically assemble into hexameric rings. These proteins contain AAA+ domains with two canonical motifs (Walker A and B) that bind and hydrolyze ATP, allowing them to perform a wide variety of different functions. For example, AAA+ proteins play a prominent role in cellular proteostasis by controlling biogenesis, folding, trafficking, and degradation of proteins present within the cell. Several central proteolytic systems (e.g., Clp, Deg, FtsH, Lon, 26S proteasome) use AAA+ domains or AAA+ proteins to unfold protein substrates (using energy from ATP hydrolysis) to make them accessible for degradation. This allows AAA+ protease systems to degrade aggregates and large proteins, as well as smaller proteins, and feed them as linearized molecules into a protease chamber. This review provides an up-to-date and a comparative overview of the essential Clp AAA+ protease systems in Cyanobacteria (e.g., Synechocystis spp), plastids of photosynthetic eukaryotes (e.g., Arabidopsis, Chlamydomonas), and apicoplasts in the nonphotosynthetic apicomplexan pathogen Plasmodium falciparum. Recent progress and breakthroughs in identifying Clp protease structures, substrates, substrate adaptors (e.g., NblA/B, ClpS, ClpF), and degrons are highlighted. We comment on the physiological importance of Clp activity, including plastid biogenesis, proteostasis, the chloroplast Protein Unfolding Response, and metabolism, across these diverse lineages. Outstanding questions as well as research opportunities and priorities to better understand the essential role of Clp systems in cellular proteostasis are discussed.
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Affiliation(s)
- Imen Bouchnak
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, New York, USA
| | - Klaas J van Wijk
- Section of Plant Biology, School of Integrative Plant Sciences (SIPS), Cornell University, Ithaca, New York, USA.
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Kim L, Heo J, Kwon DH, Shin JS, Jang SH, Park ZY, Song HK. Structural basis for the N-degron specificity of ClpS1 from Arabidopsis thaliana. Protein Sci 2020; 30:700-708. [PMID: 33368743 DOI: 10.1002/pro.4018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/11/2020] [Accepted: 12/22/2020] [Indexed: 12/25/2022]
Abstract
The N-degron pathway determines the half-life of proteins in both prokaryotes and eukaryotes by precisely recognizing the N-terminal residue (N-degron) of substrates. ClpS proteins from bacteria bind to substrates containing hydrophobic N-degrons (Leu, Phe, Tyr, and Trp) and deliver them to the caseinolytic protease system ClpAP. This mechanism is preserved in organelles such as mitochondria and chloroplasts. Bacterial ClpS adaptors bind preferentially to Leu and Phe N-degrons; however, ClpS1 from Arabidopsis thaliana (AtClpS1) shows a difference in that it binds strongly to Phe and Trp N-degrons and only weakly to Leu. This difference in behavior cannot be explained without structural information due to the high sequence homology between bacterial and plant ClpS proteins. Here, we report the structure of AtClpS1 at 2.0 Å resolution in the presence of a bound N-degron. The key determinants for α-amino group recognition are conserved among all ClpS proteins, but the α3-helix of eukaryotic AtClpS1 is significantly shortened, and consequently, a loop forming a pocket for the N-degron is moved slightly outward to enlarge the pocket. In addition, amino acid replacement from Val to Ala causes a reduction in hydrophobic interactions with Leu N-degron. A combination of the fine-tuned hydrophobic residues in the pocket and the basic gatekeeper at the entrance of the pocket controls the N-degron selectivity of the plant ClpS protein.
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Affiliation(s)
- Leehyeon Kim
- Department of Life Sciences, Korea University, Seoul, South Korea
| | - Jiwon Heo
- Department of Life Sciences, Korea University, Seoul, South Korea
| | - Do Hoon Kwon
- Department of Life Sciences, Korea University, Seoul, South Korea
| | - Jin Seok Shin
- Department of Life Sciences, Korea University, Seoul, South Korea
| | - Se Hwan Jang
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, South Korea
| | - Zee-Yong Park
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, South Korea
| | - Hyun Kyu Song
- Department of Life Sciences, Korea University, Seoul, South Korea
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Giri R, Bhardwaj T, Shegane M, Gehi BR, Kumar P, Gadhave K, Oldfield CJ, Uversky VN. Understanding COVID-19 via comparative analysis of dark proteomes of SARS-CoV-2, human SARS and bat SARS-like coronaviruses. Cell Mol Life Sci 2020; 78:1655-1688. [PMID: 32712910 PMCID: PMC7382329 DOI: 10.1007/s00018-020-03603-x] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 07/03/2020] [Accepted: 07/17/2020] [Indexed: 01/08/2023]
Abstract
The recently emerged coronavirus designated as SARS-CoV-2 (also known as 2019 novel coronavirus (2019-nCoV) or Wuhan coronavirus) is a causative agent of coronavirus disease 2019 (COVID-19), which is rapidly spreading throughout the world now. More than 1.21 million cases of SARS-CoV-2 infection and more than 67,000 COVID-19-associated mortalities have been reported worldwide till the writing of this article, and these numbers are increasing every passing hour. The World Health Organization (WHO) has declared the SARS-CoV-2 spread as a global public health emergency and admitted COVID-19 as a pandemic now. Multiple sequence alignment data correlated with the already published reports on SARS-CoV-2 evolution indicated that this virus is closely related to the bat severe acute respiratory syndrome-like coronavirus (bat SARS-like CoV) and the well-studied human SARS coronavirus (SARS-CoV). The disordered regions in viral proteins are associated with the viral infectivity and pathogenicity. Therefore, in this study, we have exploited a set of complementary computational approaches to examine the dark proteomes of SARS-CoV-2, bat SARS-like, and human SARS CoVs by analysing the prevalence of intrinsic disorder in their proteins. According to our findings, SARS-CoV-2 proteome contains very significant levels of structural order. In fact, except for nucleocapsid, Nsp8, and ORF6, the vast majority of SARS-CoV-2 proteins are mostly ordered proteins containing less intrinsically disordered protein regions (IDPRs). However, IDPRs found in SARS-CoV-2 proteins are functionally important. For example, cleavage sites in its replicase 1ab polyprotein are found to be highly disordered, and almost all SARS-CoV-2 proteins contains molecular recognition features (MoRFs), which are intrinsic disorder-based protein–protein interaction sites that are commonly utilized by proteins for interaction with specific partners. The results of our extensive investigation of the dark side of SARS-CoV-2 proteome will have important implications in understanding the structural and non-structural biology of SARS or SARS-like coronaviruses.
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Affiliation(s)
- Rajanish Giri
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India.
| | - Taniya Bhardwaj
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | - Meenakshi Shegane
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | - Bhuvaneshwari R Gehi
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | - Prateek Kumar
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | - Kundlik Gadhave
- School of Basic Sciences, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, 175005, India
| | | | - Vladimir N Uversky
- Department of Molecular Medicine, Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA.,Laboratory of New Methods in Biology, Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Moscow region, Pushchino, 142290, Russia
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