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Kim J, Chang N, Kim Y, Lee J, Oh D, Choi J, Kim O, Kim S, Choi M, Lee J, Lee J, Kim J, Cho M, Kim M, Lee K, Hwang D, Sa JK, Park S, Baek S, Im D. The Novel Tetra-Specific Drug C-192, Conjugated Using UniStac, Alleviates Non-Alcoholic Steatohepatitis in an MCD Diet-Induced Mouse Model. Pharmaceuticals (Basel) 2023; 16:1601. [PMID: 38004466 PMCID: PMC10674394 DOI: 10.3390/ph16111601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 11/08/2023] [Accepted: 11/10/2023] [Indexed: 11/26/2023] Open
Abstract
Non-alcoholic steatohepatitis (NASH) is a complex disease resulting from chronic liver injury associated with obesity, type 2 diabetes, and inflammation. Recently, the importance of developing multi-target drugs as a strategy to address complex diseases such as NASH has been growing; however, their manufacturing processes remain time- and cost-intensive and inefficient. To overcome these limitations, we developed UniStac, a novel enzyme-mediated conjugation platform for multi-specific drug development. UniStac demonstrated high conjugation yields, optimal thermal stabilities, and robust biological activities. We designed a tetra-specific compound, C-192, targeting glucagon-like peptide 1 (GLP-1), glucagon (GCG), fibroblast growth factor 21 (FGF21), and interleukin-1 receptor antagonist (IL-1RA) simultaneously for the treatment of NASH using UniStac. The biological activity and treatment efficacy of C-192 were confirmed both in vitro and in vivo using a methionine-choline-deficient (MCD) diet-induced mouse model. C-192 exhibited profound therapeutic efficacies compared to conventional drugs, including liraglutide and dulaglutide. C-192 significantly improved alanine transaminase levels, triglyceride accumulation, and the non-alcoholic fatty liver disease activity score. In this study, we demonstrated the feasibility of UniStac in creating multi-specific drugs and confirmed the therapeutic potential of C-192, a drug that integrates multiple mechanisms into a single molecule for the treatment of NASH.
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Affiliation(s)
- Jihye Kim
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Nakho Chang
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Yunki Kim
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Jaehyun Lee
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Daeseok Oh
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Jaeyoung Choi
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Onyou Kim
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Sujin Kim
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Myongho Choi
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Junyeob Lee
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Junghwa Lee
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Jungyul Kim
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Minji Cho
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Minsu Kim
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Kwanghwan Lee
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Dukhyun Hwang
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Jason K. Sa
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul 02841, Republic of Korea
| | - Sungjin Park
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
| | - Seungjae Baek
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Daeseong Im
- Onegene Biotechnology, Inc., 205 Ace Gwanggyo Tower 2, 91 Changnyong-daero 256 beon-gil, Yeongtong-gu, Suwon-si 16229, Republic of Korea; (J.K.); (J.C.); (J.K.); (K.L.)
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Regulation of BRCA1 stability through the tandem UBX domains of isoleucyl-tRNA synthetase 1. Nat Commun 2022; 13:6732. [PMID: 36347866 PMCID: PMC9643514 DOI: 10.1038/s41467-022-34612-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 10/27/2022] [Indexed: 11/11/2022] Open
Abstract
Aminoacyl-tRNA synthetases (ARSs) have evolved to acquire various additional domains. These domains allow ARSs to communicate with other cellular proteins in order to promote non-translational functions. Vertebrate cytoplasmic isoleucyl-tRNA synthetases (IARS1s) have an uncharacterized unique domain, UNE-I. Here, we present the crystal structure of the chicken IARS1 UNE-I complexed with glutamyl-tRNA synthetase 1 (EARS1). UNE-I consists of tandem ubiquitin regulatory X (UBX) domains that interact with a distinct hairpin loop on EARS1 and protect its neighboring proteins in the multi-synthetase complex from degradation. Phosphomimetic mutation of the two serine residues in the hairpin loop releases IARS1 from the complex. IARS1 interacts with BRCA1 in the nucleus, regulates its stability by inhibiting ubiquitylation via the UBX domains, and controls DNA repair function.
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Osei-Amponsa V, Walters KJ. Proteasome substrate receptors and their therapeutic potential. Trends Biochem Sci 2022; 47:950-964. [PMID: 35817651 PMCID: PMC9588529 DOI: 10.1016/j.tibs.2022.06.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 06/02/2022] [Accepted: 06/14/2022] [Indexed: 11/22/2022]
Abstract
The ubiquitin-proteasome system (UPS) is critical for protein quality control and regulating protein lifespans. Following ubiquitination, UPS substrates bind multidomain receptors that, in addition to ubiquitin-binding sites, contain functional domains that bind to deubiquitinating enzymes (DUBs) or the E3 ligase E6AP/UBE3A. We provide an overview of the proteasome, focusing on its receptors and DUBs. We highlight the key role of dynamics and importance of the substrate receptors having domains for both binding and processing ubiquitin chains. The UPS is rich with therapeutic opportunities, with proteasome inhibitors used clinically and ongoing development of small molecule proteolysis targeting chimeras (PROTACs) for the degradation of disease-associated proteins. We discuss the therapeutic potential of proteasome receptors, including hRpn13, for which PROTACs have been developed.
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Affiliation(s)
- Vasty Osei-Amponsa
- Protein Processing Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA
| | - Kylie J Walters
- Protein Processing Section, Center for Structural Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA.
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Hu X, Tang L, Zheng M, Liu J, Zhang Z, Li Z, Yang Q, Xiang S, Fang L, Ren Q, Liu X, Huang CZ, Mao C, Zuo H. Structure-Guided Designing Pre-Organization in Bivalent Aptamers. J Am Chem Soc 2022; 144:4507-4514. [PMID: 35245025 DOI: 10.1021/jacs.1c12593] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Multivalent interaction is often used in molecular design and leads to engineered multivalent ligands with increased binding avidities toward target molecules. The resulting binding avidity relies critically on the rigid scaffold that joins multiple ligands as the scaffold controls the relative spatial positions and orientations toward target molecules. Currently, no general design rules exist to construct a simple and rigid DNA scaffold for properly joining multiple ligands. Herein, we report a crystal structure-guided strategy for the rational design of a rigid bivalent aptamer with precise control over spatial separation and orientation. Such a pre-organization allows the two aptamer moieties simultaneously to bind to the target protein at their native conformations. The bivalent aptamer binding has been extensively characterized, and an enhanced binding has been clearly observed. This strategy, we believe, could potentially be generally applicable to design multivalent aptamers.
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Affiliation(s)
- Xiaoli Hu
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Linlin Tang
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Mengxi Zheng
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jian Liu
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Zhe Zhang
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Zhe Li
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Quan Yang
- Department of Cardiology, The Fourth People's Hospital of Sichuan Province, Chengdu 610016, China
| | - Shoubo Xiang
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Liang Fang
- Department of Oncology, The Ninth People's Hospital of Chongqing, Chongqing 400700, China
| | - Qiao Ren
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Xuemei Liu
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Cheng Zhi Huang
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Chengde Mao
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China.,Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Hua Zuo
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
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Fungal Secondary Metabolites as Inhibitors of the Ubiquitin-Proteasome System. Int J Mol Sci 2021; 22:ijms222413309. [PMID: 34948102 PMCID: PMC8707610 DOI: 10.3390/ijms222413309] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/04/2021] [Accepted: 12/07/2021] [Indexed: 12/19/2022] Open
Abstract
The ubiquitin–proteasome system (UPS) is the major non-lysosomal pathway responsible for regulated degradation of intracellular proteins in eukaryotes. As the principal proteolytic pathway in the cytosol and the nucleus, the UPS serves two main functions: the quality control function (i.e., removal of damaged, misfolded, and functionally incompetent proteins) and a major regulatory function (i.e., targeted degradation of a variety of short-lived regulatory proteins involved in cell cycle control, signal transduction cascades, and regulation of gene expression and metabolic pathways). Aberrations in the UPS are implicated in numerous human pathologies such as cancer, neurodegenerative disorders, autoimmunity, inflammation, or infectious diseases. Therefore, the UPS has become an attractive target for drug discovery and development. For the past two decades, much research has been focused on identifying and developing compounds that target specific components of the UPS. Considerable effort has been devoted to the development of both second-generation proteasome inhibitors and inhibitors of ubiquitinating/deubiquitinating enzymes. With the feature of unique structure and bioactivity, secondary metabolites (natural products) serve as the lead compounds in the development of new therapeutic drugs. This review, for the first time, summarizes fungal secondary metabolites found to act as inhibitors of the UPS components.
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Chen X, Htet ZM, López-Alfonzo E, Martin A, Walters KJ. Proteasome interaction with ubiquitinated substrates: from mechanisms to therapies. FEBS J 2021; 288:5231-5251. [PMID: 33211406 PMCID: PMC8131406 DOI: 10.1111/febs.15638] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 11/10/2020] [Accepted: 11/17/2020] [Indexed: 12/11/2022]
Abstract
The 26S proteasome is responsible for regulated proteolysis in eukaryotic cells. Its substrates are diverse in structure, function, sequence length, and amino acid composition, and are targeted to the proteasome by post-translational modification with ubiquitin. Ubiquitination occurs through a complex enzymatic cascade and can also signal for other cellular events, unrelated to proteasome-catalyzed degradation. Like other post-translational protein modifications, ubiquitination is reversible, with ubiquitin chain hydrolysis catalyzed by the action of deubiquitinating enzymes (DUBs), ~ 90 of which exist in humans and allow for temporal events and dynamic ubiquitin-chain remodeling. DUBs have been known for decades to be an integral part of the proteasome, as deubiquitination is coupled to substrate unfolding and translocation into the internal degradation chamber. Moreover, the proteasome also binds several ubiquitinating enzymes and shuttle factors that recruit ubiquitinated substrates. The role of this intricate machinery and how ubiquitinated substrates interact with proteasomes remains an area of active investigation. Here, we review what has been learned about the mechanisms used by the proteasome to bind ubiquitinated substrates, substrate shuttle factors, ubiquitination machinery, and DUBs. We also discuss many open questions that require further study or the development of innovative approaches to be answered. Finally, we address the promise of expanded therapeutic targeting that could benefit from such new discoveries.
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Affiliation(s)
- Xiang Chen
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Zaw Min Htet
- Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California at Berkeley, CA, USA
| | - Erika López-Alfonzo
- Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California at Berkeley, CA, USA
| | - Andreas Martin
- Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California at Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California at Berkeley, CA, USA
| | - Kylie J Walters
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
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Xu Y, Song X, Wang D, Wang Y, Li P, Li J. Proteomic insights into synaptic signaling in the brain: the past, present and future. Mol Brain 2021; 14:37. [PMID: 33596935 PMCID: PMC7888154 DOI: 10.1186/s13041-021-00750-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 02/09/2021] [Indexed: 12/29/2022] Open
Abstract
Chemical synapses in the brain connect neurons to form neural circuits, providing the structural and functional bases for neural communication. Disrupted synaptic signaling is closely related to a variety of neurological and psychiatric disorders. In the past two decades, proteomics has blossomed as a versatile tool in biological and biomedical research, rendering a wealth of information toward decoding the molecular machinery of life. There is enormous interest in employing proteomic approaches for the study of synapses, and substantial progress has been made. Here, we review the findings of proteomic studies of chemical synapses in the brain, with special attention paid to the key players in synaptic signaling, i.e., the synaptic protein complexes and their post-translational modifications. Looking toward the future, we discuss the technological advances in proteomics such as data-independent acquisition mass spectrometry (DIA-MS), cross-linking in combination with mass spectrometry (CXMS), and proximity proteomics, along with their potential to untangle the mystery of how the brain functions at the molecular level. Last but not least, we introduce the newly developed synaptomic methods. These methods and their successful applications marked the beginnings of the synaptomics era.
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Affiliation(s)
- Yalan Xu
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Medical College, Qingdao University, Qingdao, 266021, China
| | - Xiuyue Song
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Medical College, Qingdao University, Qingdao, 266021, China
| | - Dong Wang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Medical College, Qingdao University, Qingdao, 266021, China
| | - Yin Wang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Medical College, Qingdao University, Qingdao, 266021, China
| | - Peifeng Li
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Medical College, Qingdao University, Qingdao, 266021, China
| | - Jing Li
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Medical College, Qingdao University, Qingdao, 266021, China.
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Impact of Losing hRpn13 Pru or UCHL5 on Proteasome Clearance of Ubiquitinated Proteins and RA190 Cytotoxicity. Mol Cell Biol 2020; 40:MCB.00122-20. [PMID: 32631902 DOI: 10.1128/mcb.00122-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 06/26/2020] [Indexed: 01/18/2023] Open
Abstract
hRpn13/ADRM1 links substrate recruitment with deubiquitination at the proteasome through its proteasome- and ubiquitin-binding Pru domain and DEUBAD domain, which binds and activates deubiquitinating enzyme (DUB) UCHL5/Uch37. Here, we edit the HCT116 colorectal cancer cell line to delete part of the hRpn13 Pru, producing cells that express truncated hRpn13 (trRpn13), which is competent for UCHL5 binding but defective for proteasome interaction. trRpn13 cells demonstrate reduced levels of proteasome-bound ubiquitinated proteins, indicating that the loss of hRpn13 function at proteasomes cannot be fully compensated for by the two other dedicated substrate receptors (hRpn1 and hRpn10). Previous studies indicated that the loss of full-length hRpn13 causes a corresponding reduction of UCHL5. We find UCHL5 levels unaltered in trRpn13 cells, but hRpn11 is elevated in ΔhRpn13 and trRpn13 cells, perhaps from cell stress. Despite the ∼90 DUBs in human cells, including two others in addition to UCHL5 at the proteasome, we found deletion of UCHL5 from HCT116 cells to cause increased levels of ubiquitinated proteins in whole-cell extract and at proteasomes, suggesting that UCHL5 activity cannot be fully assumed by other DUBs. We also report anticancer molecule RA190, which binds covalently to hRpn13 and UCHL5, to require hRpn13 Pru and not UCHL5 for cytotoxicity.
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Lu X, Ebelle DL, Matsuo H, Walters KJ. An Extended Conformation for K48 Ubiquitin Chains Revealed by the hRpn2:Rpn13:K48-Diubiquitin Structure. Structure 2020; 28:495-506.e3. [PMID: 32160516 DOI: 10.1016/j.str.2020.02.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 02/06/2020] [Accepted: 02/26/2020] [Indexed: 12/24/2022]
Abstract
Rpn13/Adrm1 is recruited to the proteasome by PSMD1/Rpn2, where it serves as a substrate receptor that binds preferentially to K48-linked ubiquitin chains, an established signal for protein proteolysis. Here, we use NMR to solve the structure of hRpn13 Pru:hRpn2 (940-953):K48-diubiquitin. Surprisingly, hRpn2-bound hRpn13 selects a dynamic, extended conformation of K48-diubiquitin that is unique from previously determined structures. NMR experiments on free K48-diubiquitin demonstrate the presence of the reported "closed" conformation observed by crystallography, but also this more extended state, in which the hRpn13-binding surface is exposed. This extended K48-diubiquitin conformation is defined by interactions between L73 from G76-linked (distal) ubiquitin and a Y59-centered surface of K48-linked (proximal) ubiquitin. Furthermore, hRpn13 exchanges between the two ubiquitins within 100 ms, although prefers the proximal ubiquitin due to interactions with the K48 linker region. Altogether, these data lead to a revised model of how ubiquitinated substrates interact with the proteasome.
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Affiliation(s)
- Xiuxiu Lu
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Danielle L Ebelle
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Hiroshi Matsuo
- Basic Research Laboratory, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Kylie J Walters
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA.
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Mechanisms of noncanonical binding dynamics in multivalent protein-protein interactions. Proc Natl Acad Sci U S A 2019; 116:25659-25667. [PMID: 31776263 DOI: 10.1073/pnas.1902909116] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein multivalency can provide increased affinity and specificity relative to monovalent counterparts, but these emergent biochemical properties and their mechanistic underpinnings are difficult to predict as a function of the biophysical properties of the multivalent binding partners. Here, we present a mathematical model that accurately simulates binding kinetics and equilibria of multivalent protein-protein interactions as a function of the kinetics of monomer-monomer binding, the structure and topology of the multidomain interacting partners, and the valency of each partner. These properties are all experimentally or computationally estimated a priori, including approximating topology with a worm-like chain model applicable to a variety of structurally disparate systems, thus making the model predictive without parameter fitting. We conceptualize multivalent binding as a protein-protein interaction network: ligand and receptor valencies determine the number of interacting species in the network, with monomer kinetics and structural properties dictating the dynamics of each species. As predicted by the model and validated by surface plasmon resonance experiments, multivalent interactions can generate several noncanonical macroscopic binding dynamics, including a transient burst of high-energy configurations during association, biphasic equilibria resulting from interligand competition at high concentrations, and multiexponential dissociation arising from differential lifetimes of distinct network species. The transient burst was only uncovered when extending our analysis to trivalent interactions due to the significantly larger network, and we were able to predictably tune burst magnitude by altering linker rigidity. This study elucidates mechanisms of multivalent binding and establishes a framework for model-guided analysis and engineering of such interactions.
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Ubiquitin in disguise unveils a cryptic binding site in 1.2-MDa anaphase-promoting complex/cyclosome. Proc Natl Acad Sci U S A 2019; 116:17142-17144. [PMID: 31371495 DOI: 10.1073/pnas.1911388116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Protein engineering of a ubiquitin-variant inhibitor of APC/C identifies a cryptic K48 ubiquitin chain binding site. Proc Natl Acad Sci U S A 2019; 116:17280-17289. [PMID: 31350353 DOI: 10.1073/pnas.1902889116] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ubiquitin (Ub)-mediated proteolysis is a fundamental mechanism used by eukaryotic cells to maintain homeostasis and protein quality, and to control timing in biological processes. Two essential aspects of Ub regulation are conjugation through E1-E2-E3 enzymatic cascades and recognition by Ub-binding domains. An emerging theme in the Ub field is that these 2 properties are often amalgamated in conjugation enzymes. In addition to covalent thioester linkage to Ub's C terminus for Ub transfer reactions, conjugation enzymes often bind noncovalently and weakly to Ub at "exosites." However, identification of such sites is typically empirical and particularly challenging in large molecular machines. Here, studying the 1.2-MDa E3 ligase anaphase-promoting complex/cyclosome (APC/C), which controls cell division and many aspects of neurobiology, we discover a method for identifying unexpected Ub-binding sites. Using a panel of Ub variants (UbVs), we identify a protein-based inhibitor that blocks Ub ligation to APC/C substrates in vitro and ex vivo. Biochemistry, NMR, and cryo-electron microscopy (cryo-EM) structurally define the UbV interaction, explain its inhibitory activity through binding the surface on the APC2 subunit that recruits the E2 enzyme UBE2C, and ultimately reveal that this APC2 surface is also a Ub-binding exosite with preference for K48-linked chains. The results provide a tool for probing APC/C activity, have implications for the coordination of K48-linked Ub chain binding by APC/C with the multistep process of substrate polyubiquitylation, and demonstrate the power of UbV technology for identifying cryptic Ub-binding sites within large multiprotein complexes.
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McDowell MA, Byrne AM, Mylona E, Johnson R, Sagfors A, Crepin VF, Lea S, Frankel G. The S. Typhi effector StoD is an E3/E4 ubiquitin ligase which binds K48- and K63-linked diubiquitin. Life Sci Alliance 2019; 2:2/3/e201800272. [PMID: 31142637 PMCID: PMC6545606 DOI: 10.26508/lsa.201800272] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 05/03/2019] [Accepted: 05/07/2019] [Indexed: 11/24/2022] Open
Abstract
Salmonella Typhi is estimated to cause 100,000–200,000 deaths annually, yet its infection strategy remains elusive. This article reports of the first Typhi-specific effector, which has an E3/E4 ubiquitin ligase activity and can uniquely bind K48- and K63-linked diubiquitin. Salmonella enterica (e.g., serovars Typhi and Typhimurium) relies on translocation of effectors via type III secretion systems (T3SS). Specialization of typhoidal serovars is thought to be mediated via pseudogenesis. Here, we show that the Salmonella Typhi STY1076/t1865 protein, named StoD, a homologue of the enteropathogenic Escherichia coli/enterohemorrhagic E. coli/Citrobacter rodentium NleG, is a T3SS effector. The StoD C terminus (StoD-C) is a U-box E3 ubiquitin ligase, capable of autoubiquitination in the presence of multiple E2s. The crystal structure of the StoD N terminus (StoD-N) at 2.5 Å resolution revealed a ubiquitin-like fold. In HeLa cells expressing StoD, ubiquitin is redistributed into puncta that colocalize with StoD. Binding assays showed that StoD-N and StoD-C bind the same exposed surface of the β-sheet of ubiquitin, suggesting that StoD could simultaneously interact with two ubiquitin molecules. Consistently, StoD interacted with both K63- (KD = 5.6 ± 1 μM) and K48-linked diubiquitin (KD = 15 ± 4 μM). Accordingly, we report the first S. Typhi–specific T3SS effector. We suggest that StoD recognizes and ubiquitinates pre-ubiquitinated targets, thus subverting intracellular signaling by functioning as an E4 enzyme.
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Affiliation(s)
| | - Alexander Mp Byrne
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Elli Mylona
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Rebecca Johnson
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Agnes Sagfors
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Valerie F Crepin
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Susan Lea
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Gad Frankel
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
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14
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Liu P, Verhaar AP, Peppelenbosch MP. Signaling Size: Ankyrin and SOCS Box-Containing ASB E3 Ligases in Action. Trends Biochem Sci 2018; 44:64-74. [PMID: 30446376 DOI: 10.1016/j.tibs.2018.10.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 10/09/2018] [Accepted: 10/15/2018] [Indexed: 12/14/2022]
Abstract
Ankyrin repeat and suppressor of cytokine signaling (SOCS) box (Asb) proteins are ubiquitin E3 ligases. The subfamily of six-ankyrin repeat domain-containing Asb proteins (Asb5, Asb9, Asb11, and Asb13) is of specific interest because they display unusual strong evolutionary conservation (e.g., urochordate and human ASB11 are >49% similar at the amino acid level) and mediate compartment size expansion, regulating, for instance, the size of the brain and muscle compartment. Thus, they may be involved in the explanation of the differences in brain size between humans and apes. Mechanistically, many questions remain, but it has become clear that regulation of canonical Notch signaling and also mitochondrial function are important effectors. Here, we review the action and function of six ankyrin repeat domain-containing Asb proteins in physiology and pathophysiology.
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Affiliation(s)
- Pengyu Liu
- Department of Gastroenterology and Hepatology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Auke P Verhaar
- Department of Gastroenterology and Hepatology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Maikel P Peppelenbosch
- Department of Gastroenterology and Hepatology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
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15
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Cancer Mutations of the Tumor Suppressor SPOP Disrupt the Formation of Active, Phase-Separated Compartments. Mol Cell 2018; 72:19-36.e8. [PMID: 30244836 DOI: 10.1016/j.molcel.2018.08.027] [Citation(s) in RCA: 227] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 05/29/2018] [Accepted: 08/03/2018] [Indexed: 12/30/2022]
Abstract
Mutations in the tumor suppressor SPOP (speckle-type POZ protein) cause prostate, breast, and other solid tumors. SPOP is a substrate adaptor of the cullin3-RING ubiquitin ligase and localizes to nuclear speckles. Although cancer-associated mutations in SPOP interfere with substrate recruitment to the ligase, mechanisms underlying assembly of SPOP with its substrates in liquid nuclear bodies and effects of SPOP mutations on assembly are poorly understood. Here, we show that substrates trigger phase separation of SPOP in vitro and co-localization in membraneless organelles in cells. Enzymatic activity correlates with cellular co-localization and in vitro mesoscale assembly formation. Disease-associated SPOP mutations that lead to the accumulation of proto-oncogenic proteins interfere with phase separation and co-localization in membraneless organelles, suggesting that substrate-directed phase separation of this E3 ligase underlies the regulation of ubiquitin-dependent proteostasis.
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16
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Wu Y, Kang J, Zhang L, Liang Z, Tang X, Yan Y, Qian H, Zhang X, Xu W, Mao F. Ubiquitination regulation of inflammatory responses through NF-κB pathway. Am J Transl Res 2018; 10:881-891. [PMID: 29636878 PMCID: PMC5883129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 02/01/2018] [Indexed: 06/08/2023]
Abstract
The development of inflammation is mutually affected with damaged DNA and the abnormal expression of protein modification. Ubiquitination, a way of protein modification, plays a key role in regulating various biological functions including inflammation responses. The ubiquitin enzymes and deubiquitinating enzymes (DUBs) jointly control the ubiquitination. The fact that various ubiquitin linkage chains control the fate of the substrate suggests that the regulatory mechanisms of ubiquitin enzymes are central for ubiquitination. In inflammation diseases, the pro-inflammatory transcription factor NF-κB regulates transcription of pro-labour mediators in response to inflammatory stimuli and expression of numerous genes that control inflammation which is associated with ubiquitination. The ubiquitination regulates NF-κB signaling pathway with many receptor families, including NOD-like receptors (NLR), Toll-like receptors (TLR) and RIG-I-like receptors (RLR), mainly by K63-linked polyubiquitin chains. In this review, we highlight the study of ubiquitination in the inflammatory signaling pathway including NF-κB signaling regulated by ubiquitin enzymes and DUBs. Furthermore, it is emphasized that the interaction of ubiquitin-mediated inflammatory signaling system accurately regulates the inflammatory responses.
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Affiliation(s)
- Yunbing Wu
- Key Laboratory of Medical Science and Laboratory Medicine of Jiangsu Province, School of Medicine, Jiangsu UniversityZhenjiang 212013, Jiangsu, China
| | - Jingjing Kang
- Key Laboratory of Medical Science and Laboratory Medicine of Jiangsu Province, School of Medicine, Jiangsu UniversityZhenjiang 212013, Jiangsu, China
| | - Lu Zhang
- Key Laboratory of Medical Science and Laboratory Medicine of Jiangsu Province, School of Medicine, Jiangsu UniversityZhenjiang 212013, Jiangsu, China
| | - Zhaofeng Liang
- Key Laboratory of Medical Science and Laboratory Medicine of Jiangsu Province, School of Medicine, Jiangsu UniversityZhenjiang 212013, Jiangsu, China
| | - Xudong Tang
- Jiangsu University of Science and TechnologyZhenjiang 212018, Jiangsu, China
| | - Yongmin Yan
- Key Laboratory of Medical Science and Laboratory Medicine of Jiangsu Province, School of Medicine, Jiangsu UniversityZhenjiang 212013, Jiangsu, China
| | - Hui Qian
- Key Laboratory of Medical Science and Laboratory Medicine of Jiangsu Province, School of Medicine, Jiangsu UniversityZhenjiang 212013, Jiangsu, China
| | - Xu Zhang
- Key Laboratory of Medical Science and Laboratory Medicine of Jiangsu Province, School of Medicine, Jiangsu UniversityZhenjiang 212013, Jiangsu, China
| | - Wenrong Xu
- Key Laboratory of Medical Science and Laboratory Medicine of Jiangsu Province, School of Medicine, Jiangsu UniversityZhenjiang 212013, Jiangsu, China
| | - Fei Mao
- Key Laboratory of Medical Science and Laboratory Medicine of Jiangsu Province, School of Medicine, Jiangsu UniversityZhenjiang 212013, Jiangsu, China
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17
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Gray KM, Kaifer KA, Baillat D, Wen Y, Bonacci TR, Ebert AD, Raimer AC, Spring AM, Have ST, Glascock JJ, Gupta K, Van Duyne GD, Emanuele MJ, Lamond AI, Wagner EJ, Lorson CL, Matera AG. Self-oligomerization regulates stability of survival motor neuron protein isoforms by sequestering an SCF Slmb degron. Mol Biol Cell 2018; 29:96-110. [PMID: 29167380 PMCID: PMC5909936 DOI: 10.1091/mbc.e17-11-0627] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 11/14/2017] [Indexed: 12/16/2022] Open
Abstract
Spinal muscular atrophy (SMA) is caused by homozygous mutations in human SMN1 Expression of a duplicate gene (SMN2) primarily results in skipping of exon 7 and production of an unstable protein isoform, SMNΔ7. Although SMN2 exon skipping is the principal contributor to SMA severity, mechanisms governing stability of survival motor neuron (SMN) isoforms are poorly understood. We used a Drosophila model system and label-free proteomics to identify the SCFSlmb ubiquitin E3 ligase complex as a novel SMN binding partner. SCFSlmb interacts with a phosphor degron embedded within the human and fruitfly SMN YG-box oligomerization domains. Substitution of a conserved serine (S270A) interferes with SCFSlmb binding and stabilizes SMNΔ7. SMA-causing missense mutations that block multimerization of full-length SMN are also stabilized in the degron mutant background. Overexpression of SMNΔ7S270A, but not wild-type (WT) SMNΔ7, provides a protective effect in SMA model mice and human motor neuron cell culture systems. Our findings support a model wherein the degron is exposed when SMN is monomeric and sequestered when SMN forms higher-order multimers.
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Affiliation(s)
- Kelsey M Gray
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
| | - Kevin A Kaifer
- Molecular Pathogenesis and Therapeutics Program, Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211
| | - David Baillat
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77550
| | - Ying Wen
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
| | - Thomas R Bonacci
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599
| | - Allison D Ebert
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Amanda C Raimer
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
| | - Ashlyn M Spring
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
| | - Sara Ten Have
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee DD15EH, UK
| | - Jacqueline J Glascock
- Molecular Pathogenesis and Therapeutics Program, Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211
| | - Kushol Gupta
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104
| | - Gregory D Van Duyne
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104
| | - Michael J Emanuele
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599
| | - Angus I Lamond
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee DD15EH, UK
| | - Eric J Wagner
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77550
| | - Christian L Lorson
- Molecular Pathogenesis and Therapeutics Program, Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211
| | - A Gregory Matera
- Curriculum in Genetics and Molecular Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599
- Integrative Program in Biological and Genome Sciences, Department of Biology and Department of Genetics, University of North Carolina, Chapel Hill, NC 27599
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18
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Structure of the Rpn13-Rpn2 complex provides insights for Rpn13 and Uch37 as anticancer targets. Nat Commun 2017; 8:15540. [PMID: 28598414 PMCID: PMC5494190 DOI: 10.1038/ncomms15540] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 04/07/2017] [Indexed: 12/16/2022] Open
Abstract
Proteasome-ubiquitin receptor hRpn13/Adrm1 binds and activates deubiquitinating enzyme Uch37/UCHL5 and is targeted by bis-benzylidine piperidone RA190, which restricts cancer growth in mice xenografts. Here, we solve the structure of hRpn13 with a segment of hRpn2 that serves as its proteasome docking site; a proline-rich C-terminal hRpn2 extension stretches across a narrow canyon of the ubiquitin-binding hRpn13 Pru domain blocking an RA190-binding surface. Biophysical analyses in combination with cell-based assays indicate that hRpn13 binds preferentially to hRpn2 and proteasomes over RA190. hRpn13 also exists outside of proteasomes where it may be RA190 sensitive. RA190 does not affect hRpn13 interaction with Uch37, but rather directly binds and inactivates Uch37. hRpn13 deletion from HCT116 cells abrogates RA190-induced accumulation of substrates at proteasomes. We propose that RA190 targets hRpn13 and Uch37 through parallel mechanisms and at proteasomes, RA190-inactivated Uch37 cannot disassemble hRpn13-bound ubiquitin chains.
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19
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Hänzelmann P, Schindelin H. The Interplay of Cofactor Interactions and Post-translational Modifications in the Regulation of the AAA+ ATPase p97. Front Mol Biosci 2017; 4:21. [PMID: 28451587 PMCID: PMC5389986 DOI: 10.3389/fmolb.2017.00021] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 03/24/2017] [Indexed: 12/18/2022] Open
Abstract
The hexameric type II AAA ATPase (ATPase associated with various activities) p97 (also referred to as VCP, Cdc48, and Ter94) is critically involved in a variety of cellular activities including pathways such as DNA replication and repair which both involve chromatin remodeling, and is a key player in various protein quality control pathways mediated by the ubiquitin proteasome system as well as autophagy. Correspondingly, p97 has been linked to various pathophysiological states including cancer, neurodegeneration, and premature aging. p97 encompasses an N-terminal domain, two highly conserved ATPase domains and an unstructured C-terminal tail. This enzyme hydrolyzes ATP and utilizes the resulting energy to extract or disassemble protein targets modified with ubiquitin from stable protein assemblies, chromatin and membranes. p97 participates in highly diverse cellular processes and hence its activity is tightly controlled. This is achieved by multiple regulatory cofactors, which either associate with the N-terminal domain or interact with the extreme C-terminus via distinct binding elements and target p97 to specific cellular pathways, sometimes requiring the simultaneous association with more than one cofactor. Most cofactors are recruited to p97 through conserved binding motifs/domains and assist in substrate recognition or processing by providing additional molecular properties. A tight control of p97 cofactor specificity and diversity as well as the assembly of higher-order p97-cofactor complexes is accomplished by various regulatory mechanisms, which include bipartite binding, binding site competition, changes in oligomeric assemblies, and nucleotide-induced conformational changes. Furthermore, post-translational modifications (PTMs) like acetylation, palmitoylation, phosphorylation, SUMOylation, and ubiquitylation of p97 have been reported which further modulate its diverse molecular activities. In this review, we will describe the molecular basis of p97-cofactor specificity/diversity and will discuss how PTMs can modulate p97-cofactor interactions and affect the physiological and patho-physiological functions of p97.
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Affiliation(s)
- Petra Hänzelmann
- Rudolf Virchow Center for Experimental Biomedicine, University of WürzburgWürzburg, Germany
| | - Hermann Schindelin
- Rudolf Virchow Center for Experimental Biomedicine, University of WürzburgWürzburg, Germany
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20
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Kung YA, Hung CT, Chien KY, Shih SR. Control of the negative IRES trans-acting factor KHSRP by ubiquitination. Nucleic Acids Res 2017; 45:271-287. [PMID: 27899653 PMCID: PMC5224474 DOI: 10.1093/nar/gkw1042] [Citation(s) in RCA: 126] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 10/14/2016] [Accepted: 11/01/2016] [Indexed: 01/25/2023] Open
Abstract
Cells and viruses can utilize internal ribosome entry sites (IRES) to drive translation when cap-dependent translation is inhibited by stress or viral factors. IRES trans-acting factors (ITAFs) are known to participate in such cap-independent translation, but there are gaps in the understanding as to how ITAFs, particularly negative ITAFs, regulate IRES-driven translation. This study found that Lys109, Lys121 and Lys122 represent critical ubiquitination sites for far upstream element-binding protein 2 (KHSRP, also known as KH-type splicing regulatory protein or FBP2), a negative ITAF. Mutations at these sites subsequently reduced KHSRP ubiquitination and abolished its inhibitory effect on IRES-driven translation. We further found that interaction between the Kelch domain of Kelch-like protein 12 (KLHL12) and the C-terminal domain of KHSRP contributed to KHSRP ubiquitination, leading to downregulation of enterovirus IRES-mediated translation in infected cells and increased competition against other positive ITAFs. Together, these results show that ubiquitination can exert control over IRES-driven translation via modification of ITAFs, and to the best of our knowledge, this is the first description of such a regulatory mechanism for IRES-dependent translation.
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Affiliation(s)
- Yu-An Kung
- Research Center for Emerging Viral Infections, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
| | - Chuan-Tien Hung
- Research Center for Emerging Viral Infections, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
| | - Kun-Yi Chien
- Department of Biochemistry and Molecular Biology, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
- Clinical Proteomics Core Laboratory, Linkou Chang Gung Memorial Hospital, Taoyuan City 33305, Taiwan
| | - Shin-Ru Shih
- Research Center for Emerging Viral Infections, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan City 33302, Taiwan
- Clinical Virology Laboratory, Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan City 33305, Taiwan
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21
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Chen X, Randles L, Shi K, Tarasov SG, Aihara H, Walters KJ. Structures of Rpn1 T1:Rad23 and hRpn13:hPLIC2 Reveal Distinct Binding Mechanisms between Substrate Receptors and Shuttle Factors of the Proteasome. Structure 2016; 24:1257-1270. [PMID: 27396824 DOI: 10.1016/j.str.2016.05.018] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 05/10/2016] [Accepted: 05/25/2016] [Indexed: 12/14/2022]
Abstract
Three receptors (Rpn1/S2/PSMD2, Rpn10/S5a, Rpn13/Adrm1) in the proteasome bind substrates by interacting with conjugated ubiquitin chains and/or shuttle factors (Rad23/HR23, Dsk2/PLIC/ubiquilin, Ddi1) that carry ubiquitinated substrates to proteasomes. We solved the structure of two such receptors with their preferred shuttle factor, namely hRpn13(Pru):hPLIC2(UBL) and scRpn1 T1:scRad23(UBL). We find that ubiquitin folds in Rad23 and Dsk2 are fine-tuned by residue substitutions to achieve high affinity for Rpn1 and Rpn13, respectively. A single substitution in hPLIC2 yields enhanced interactions with the Rpn13 ubiquitin contact surface and sterically blocks hRpn13 binding to its preferred ubiquitin chain type, K48-linked chains. Rpn1 T1 binds two ubiquitins in tandem and we find that Rad23 binds exclusively to the higher-affinity Helix28/Helix30 site. Rad23 contacts at Helix28/Helix30 are optimized compared to ubiquitin by multiple conservative amino acid substitutions. Thus, shuttle factors deliver substrates to proteasomes through fine-tuned ubiquitin-like surfaces.
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Affiliation(s)
- Xiang Chen
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Leah Randles
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Ke Shi
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Sergey G Tarasov
- Biophysics Resource, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Hideki Aihara
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Kylie J Walters
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA.
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22
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Khan M, Syed GH, Kim SJ, Siddiqui A. Hepatitis B Virus-Induced Parkin-Dependent Recruitment of Linear Ubiquitin Assembly Complex (LUBAC) to Mitochondria and Attenuation of Innate Immunity. PLoS Pathog 2016; 12:e1005693. [PMID: 27348524 PMCID: PMC4922663 DOI: 10.1371/journal.ppat.1005693] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 05/19/2016] [Indexed: 12/18/2022] Open
Abstract
Hepatitis B virus (HBV) suppresses innate immune signaling to establish persistent infection. Although HBV is a DNA virus, its pre-genomic RNA (pgRNA) can be sensed by RIG-I and activates MAVS to mediate interferon (IFN) λ synthesis. Despite of the activation of RIG-I-MAVS axis by pgRNA, the underlying mechanism explaining how HBV infection fails to induce interferon-αβ (IFN) synthesis remained uncharacterized. We demonstrate that HBV induced parkin is able to recruit the linear ubiquitin assembly complex (LUBAC) to mitochondria and abrogates IFN β synthesis. Parkin interacts with MAVS, accumulates unanchored linear polyubiquitin chains on MAVS via LUBAC, to disrupt MAVS signalosome and attenuate IRF3 activation. This study highlights the novel role of parkin in antiviral signaling which involves LUBAC being recruited to the mitochondria. These results provide avenues of investigations on the role of mitochondrial dynamics in innate immunity. Hepatitis B virus (HBV) chronic infection is one of the major causes of hepatocellular carcinoma. HBV infection is associated with mitochondrial dysfunction. We previously showed that persistent infection of HBV requires rapid clearance of impaired mitochondria by mitophagy, a cellular quality control process that insures survival of HBV infected cells. During the process, Parkin, an RBR E3 ligase, is recruited to mitochondria to induce mitophagy. In this study, we show that the Parkin, plays a critical role in the modulation of innate immune signaling. Using HBV expressing cells, we show that the Parkin recruits linear ubiquitin assembly complex (LUBAC) to the mitochondria and subsequently inhibits downstream signaling of mitochondrial antiviral signaling protein (MAVS). Mitochondrial LUBAC then catalyzes linear ubiquitin chains on MAVS, which abrogates its downstream events such as MAVS-TRAFs interaction and abolishes IRF3 phosphorylation. The results of this study highlight the molecular details explaining how HBV can suppress interferon synthesis implicating a mitophagy-independent role of Parkin. HBV-induced mitochondrial damage serves as the platform for recruitment of Parkin and LUBAC, which together modify MAVS by ubiquitination and cripples its downstream signaling.
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Affiliation(s)
- Mohsin Khan
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, La Jolla, California, United States of America
| | - Gulam Hussain Syed
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, La Jolla, California, United States of America
| | - Seong-Jun Kim
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, La Jolla, California, United States of America
| | - Aleem Siddiqui
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, La Jolla, California, United States of America
- * E-mail:
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23
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He F, Wollscheid HP, Nowicka U, Biancospino M, Valentini E, Ehlinger A, Acconcia F, Magistrati E, Polo S, Walters KJ. Myosin VI Contains a Compact Structural Motif that Binds to Ubiquitin Chains. Cell Rep 2016; 14:2683-94. [PMID: 26971995 DOI: 10.1016/j.celrep.2016.01.079] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 11/24/2015] [Accepted: 01/27/2016] [Indexed: 12/13/2022] Open
Abstract
Myosin VI is critical for cargo trafficking and sorting during early endocytosis and autophagosome maturation, and abnormalities in these processes are linked to cancers, neurodegeneration, deafness, and hypertropic cardiomyopathy. We identify a structured domain in myosin VI, myosin VI ubiquitin-binding domain (MyUb), that binds to ubiquitin chains, especially those linked via K63, K11, and K29. Herein, we solve the solution structure of MyUb and MyUb:K63-linked diubiquitin. MyUb folds as a compact helix-turn-helix-like motif and nestles between the ubiquitins of K63-linked diubiquitin, interacting with distinct surfaces of each. A nine-amino-acid extension at the C-terminal helix (Helix2) of MyUb is required for myosin VI interaction with endocytic and autophagic adaptors. Structure-guided mutations revealed that a functional MyUb is necessary for optineurin interaction. In addition, we found that an isoform-specific helix restricts MyUb binding to ubiquitin chains. This work provides fundamental insights into myosin VI interaction with ubiquitinated cargo and functional adaptors.
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Affiliation(s)
- Fahu He
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Hans-Peter Wollscheid
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy
| | - Urszula Nowicka
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Matteo Biancospino
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy
| | - Eleonora Valentini
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy
| | - Aaron Ehlinger
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Filippo Acconcia
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy
| | - Elisa Magistrati
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy
| | - Simona Polo
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, 20139 Milano, Italy; DIPO, Dipartimento di Oncologia ed Emato-oncologia, Università degli Studi di Milano, Via di Rudinì 8, 20122 Milan, Italy.
| | - Kylie J Walters
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA.
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24
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Shi Y, Chen X, Elsasser S, Stocks BB, Tian G, Lee BH, Shi Y, Zhang N, de Poot SAH, Tuebing F, Sun S, Vannoy J, Tarasov SG, Engen JR, Finley D, Walters KJ. Rpn1 provides adjacent receptor sites for substrate binding and deubiquitination by the proteasome. Science 2016; 351:351/6275/aad9421. [PMID: 26912900 DOI: 10.1126/science.aad9421] [Citation(s) in RCA: 191] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Hundreds of pathways for degradation converge at ubiquitin recognition by a proteasome. Here, we found that the five known proteasomal ubiquitin receptors in yeast are collectively nonessential for ubiquitin recognition and identified a sixth receptor, Rpn1. A site ( T1: ) in the Rpn1 toroid recognized ubiquitin and ubiquitin-like ( UBL: ) domains of substrate shuttling factors. T1 structures with monoubiquitin or lysine 48 diubiquitin show three neighboring outer helices engaging two ubiquitins. T1 contributes a distinct substrate-binding pathway with preference for lysine 48-linked chains. Proximal to T1 within the Rpn1 toroid is a second UBL-binding site ( T2: ) that assists in ubiquitin chain disassembly, by binding the UBL of deubiquitinating enzyme Ubp6. Thus, a two-site recognition domain intrinsic to the proteasome uses distinct ubiquitin-fold ligands to assemble substrates, shuttling factors, and a deubiquitinating enzyme.
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Affiliation(s)
- Yuan Shi
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Xiang Chen
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Suzanne Elsasser
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Bradley B Stocks
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA
| | - Geng Tian
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Byung-Hoon Lee
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Yanhong Shi
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA. Department of Analytical Chemistry, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, P. R. China
| | - Naixia Zhang
- Department of Analytical Chemistry, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, P. R. China
| | - Stefanie A H de Poot
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Fabian Tuebing
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Shuangwu Sun
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Jacob Vannoy
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA. Linganore High School, Frederick, MD 21701, USA
| | - Sergey G Tarasov
- Biophysics Resource, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - John R Engen
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA.
| | - Daniel Finley
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
| | - Kylie J Walters
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA.
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25
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Kim D, Pushkarsky I, Tay A, Di Carlo D. Research highlights: aptamers on a chip. LAB ON A CHIP 2015; 15:1630-1633. [PMID: 25710698 DOI: 10.1039/c5lc90032h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Aptamers, oligonucleic acid or peptide molecules with binding affinity to a specific molecule, have gained broad scientific attention due to their stability, ease of production and modification, and durability, and therefore have been employed in a wide range of applications both in basic research and clinical science. Recent advances in high-throughput sequencing are poised to revolutionize the selection of aptamers, while microfluidic and microarray approaches have helped automate these processes of selection. Here we highlight work addressing several challenges in using aptamers more widely. We discuss array-based discovery of multivalent aptamers which is used to develop high affinity or paired aptamers by cleverly selecting new aptamers that bind to previously aptamer-bound proteins. Other highlighted work is addressing problems in analyzing local cell secretions, as well as refreshable sensors that detect signals over hundreds of cycles and can be refreshed with DI water scavenged from the air, leading to less reagent storage towards wearable sensors.
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Affiliation(s)
- Donghyuk Kim
- Department of Bioengineering, California NanoSystems Institute, Jonsson Comprehensive Cancer Center, University of California Los Angeles, 420 Westwood Plaza, 5121 Engineering V, Box 951600, Los Angeles, California 90095, USA.
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26
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Goren K, Karabline-Kuks J, Shiloni Y, Barak-Kulbak E, Miller SJ, Portnoy M. Multivalency as a key factor for high activity of selective supported organocatalysts for the Baylis-Hillman reaction. Chemistry 2015; 21:1191-7. [PMID: 25376519 DOI: 10.1002/chem.201404560] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Indexed: 11/05/2022]
Abstract
The polystyrene-supported N-alkylimidazole-based dendritic catalysts for the Baylis-Hillman reaction exhibit one of the strongest beneficial effects of multivalent architecture ever reported for an organocatalyst. The yields in the model reaction of methyl vinyl ketone with p-nitrobenzaldehyde are more than tripled when a non-dendritic catalyst is replaced by a second- or third-generation analogue. Moreover, the reaction of the less active substrates will not occur with the non-dendritic catalyst and will proceed to a significant extent only with the analogous catalysts of higher generations. A substantial additional enhancement of the reaction yield could be achieved by increasing the content of water in the reaction solvent. The plausible cause of the dendritic effect is the assistance of the second, nearby imidazole moiety in the presumably rate-determining proton transfer in the intermediate adduct, after the first imidazole unit induced the formation of the new carbon-carbon bond.
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Affiliation(s)
- Kerem Goren
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel-Aviv University, Tel-Aviv 69978 (Israel); Current Address: Teva Pharmaceutical Industries Ltd, P.O.B. 3190, 2 Denmark Street, Petah Tikva (Israel)
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27
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Sinha P, Pazhamala LT, Singh VK, Saxena RK, Krishnamurthy L, Azam S, Khan AW, Varshney RK. Identification and Validation of Selected Universal Stress Protein Domain Containing Drought-Responsive Genes in Pigeonpea (Cajanus cajan L.). FRONTIERS IN PLANT SCIENCE 2015; 6:1065. [PMID: 26779199 PMCID: PMC4701917 DOI: 10.3389/fpls.2015.01065] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 11/16/2015] [Indexed: 05/04/2023]
Abstract
Pigeonpea is a resilient crop, which is relatively more drought tolerant than many other legume crops. To understand the molecular mechanisms of this unique feature of pigeonpea, 51 genes were selected using the Hidden Markov Models (HMM) those codes for proteins having close similarity to universal stress protein domain. Validation of these genes was conducted on three pigeonpea genotypes (ICPL 151, ICPL 8755, and ICPL 227) having different levels of drought tolerance. Gene expression analysis using qRT-PCR revealed 6, 8, and 18 genes to be ≥2-fold differentially expressed in ICPL 151, ICPL 8755, and ICPL 227, respectively. A total of 10 differentially expressed genes showed ≥2-fold up-regulation in the more drought tolerant genotype, which encoded four different classes of proteins. These include plant U-box protein (four genes), universal stress protein A-like protein (four genes), cation/H(+) antiporter protein (one gene) and an uncharacterized protein (one gene). Genes C.cajan_29830 and C.cajan_33874 belonging to uspA, were found significantly expressed in all the three genotypes with ≥2-fold expression variations. Expression profiling of these two genes on the four other legume crops revealed their specific role in pigeonpea. Therefore, these genes seem to be promising candidates for conferring drought tolerance specifically to pigeonpea.
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Affiliation(s)
- Pallavi Sinha
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)Hyderabad, India
| | - Lekha T. Pazhamala
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)Hyderabad, India
| | - Vikas K. Singh
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)Hyderabad, India
| | - Rachit K. Saxena
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)Hyderabad, India
| | - L. Krishnamurthy
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)Hyderabad, India
| | - Sarwar Azam
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)Hyderabad, India
| | - Aamir W. Khan
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)Hyderabad, India
| | - Rajeev K. Varshney
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)Hyderabad, India
- School of Plant Biology and the Institute of Agriculture, The University of Western AustraliaPerth, WA, Australia
- *Correspondence: Rajeev K. Varshney
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28
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Sinha P, Pazhamala LT, Singh VK, Saxena RK, Krishnamurthy L, Azam S, Khan AW, Varshney RK. Identification and Validation of Selected Universal Stress Protein Domain Containing Drought-Responsive Genes in Pigeonpea (Cajanus cajan L.). FRONTIERS IN PLANT SCIENCE 2015. [PMID: 26779199 DOI: 10.3380/fpls.2015.01065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Pigeonpea is a resilient crop, which is relatively more drought tolerant than many other legume crops. To understand the molecular mechanisms of this unique feature of pigeonpea, 51 genes were selected using the Hidden Markov Models (HMM) those codes for proteins having close similarity to universal stress protein domain. Validation of these genes was conducted on three pigeonpea genotypes (ICPL 151, ICPL 8755, and ICPL 227) having different levels of drought tolerance. Gene expression analysis using qRT-PCR revealed 6, 8, and 18 genes to be ≥2-fold differentially expressed in ICPL 151, ICPL 8755, and ICPL 227, respectively. A total of 10 differentially expressed genes showed ≥2-fold up-regulation in the more drought tolerant genotype, which encoded four different classes of proteins. These include plant U-box protein (four genes), universal stress protein A-like protein (four genes), cation/H(+) antiporter protein (one gene) and an uncharacterized protein (one gene). Genes C.cajan_29830 and C.cajan_33874 belonging to uspA, were found significantly expressed in all the three genotypes with ≥2-fold expression variations. Expression profiling of these two genes on the four other legume crops revealed their specific role in pigeonpea. Therefore, these genes seem to be promising candidates for conferring drought tolerance specifically to pigeonpea.
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Affiliation(s)
- Pallavi Sinha
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) Hyderabad, India
| | - Lekha T Pazhamala
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) Hyderabad, India
| | - Vikas K Singh
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) Hyderabad, India
| | - Rachit K Saxena
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) Hyderabad, India
| | - L Krishnamurthy
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) Hyderabad, India
| | - Sarwar Azam
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) Hyderabad, India
| | - Aamir W Khan
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) Hyderabad, India
| | - Rajeev K Varshney
- Center of Excellence in Genomics (CEG), International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)Hyderabad, India; School of Plant Biology and the Institute of Agriculture, The University of Western AustraliaPerth, WA, Australia
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29
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Cho M, Oh SS, Nie J, Stewart R, Radeke MJ, Eisenstein M, Coffey PJ, Thomson JA, Soh HT. Array-based discovery of aptamer pairs. Anal Chem 2014; 87:821-8. [PMID: 25495696 PMCID: PMC4287840 DOI: 10.1021/ac504076k] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Affinity
reagent pairs that recognize distinct epitopes on a target
protein can greatly improve the sensitivity and specificity of molecular
detection. Importantly, such pairs can be conjugated to generate reagents
that achieve two-site “bidentate” target recognition,
with affinities greatly exceeding either monovalent component. DNA
aptamers are especially well-suited for such constructs, because they
can be linked via standard synthesis techniques without requiring
chemical conjugation. Unfortunately, aptamer pairs are difficult to
generate, primarily because conventional selection methods preferentially
yield aptamers that recognize a dominant “hot spot”
epitope. Our array-based discovery platform for multivalent aptamers
(AD-MAP) overcomes this problem to achieve efficient discovery of
aptamer pairs. We use microfluidic selection and high-throughput sequencing
to obtain an enriched pool of aptamer sequences. Next, we synthesize
a custom array based on these sequences, and perform parallel affinity
measurements to identify the highest-affinity aptamer for the target
protein. We use this aptamer to form complexes that block the primary
binding site on the target, and then screen the same array with these
complexes to identify aptamers that bind secondary epitopes. We used
AD-MAP to discover DNA aptamer pairs that bind distinct sites on human
angiopoietin-2 with high affinities, even in undiluted serum. To the
best of our knowledge, this is the first work to discover new aptamer
pairs using arrays. We subsequently conjugated these aptamers with
a flexible linker to construct ultra-high-affinity bidentate reagents,
with equilibrium dissociation constants as low as 97 pM: >200-fold
better than either component aptamer. Functional studies confirm that
both aptamers critically contribute to this ultrahigh affinity, highlighting
the promise of such reagents for research and clinical use.
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Affiliation(s)
- Minseon Cho
- Department of Mechanical Engineering, University of California-Santa Barbara , Santa Barbara, California 93106, United States
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30
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Cereda M, Pozzoli U, Rot G, Juvan P, Schweitzer A, Clark T, Ule J. RNAmotifs: prediction of multivalent RNA motifs that control alternative splicing. Genome Biol 2014; 15:R20. [PMID: 24485098 PMCID: PMC4054596 DOI: 10.1186/gb-2014-15-1-r20] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Accepted: 01/31/2014] [Indexed: 12/16/2022] Open
Abstract
RNA-binding proteins (RBPs) regulate splicing according to position-dependent principles, which can be exploited for analysis of regulatory motifs. Here we present RNAmotifs, a method that evaluates the sequence around differentially regulated alternative exons to identify clusters of short and degenerate sequences, referred to as multivalent RNA motifs. We show that diverse RBPs share basic positional principles, but differ in their propensity to enhance or repress exon inclusion. We assess exons differentially spliced between brain and heart, identifying known and new regulatory motifs, and predict the expression pattern of RBPs that bind these motifs. RNAmotifs is available at https://bitbucket.org/rogrro/rna_motifs.
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31
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Krzeszinski JY, Choe V, Shao J, Bao X, Cheng H, Luo S, Huo K, Rao H. XPC promotes MDM2-mediated degradation of the p53 tumor suppressor. Mol Biol Cell 2013; 25:213-21. [PMID: 24258024 PMCID: PMC3890342 DOI: 10.1091/mbc.e13-05-0293] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
XPC binds MDM2 ubiquitin ligase and participates in the MDM2-mediated p53 degradation. Furthermore, XPC overexpression stimulates p53 degradation following UV irradiation. Combined, the results suggest a key role of XPC in p53 degradation. Although ubiquitin receptor Rad23 has been implicated in bringing ubiquitylated p53 to the proteasome, how Rad23 recognizes p53 remains unclear. We demonstrate that XPC, a Rad23-binding protein, regulates p53 turnover. p53 protein in XPC-deficient cells remains ubiquitylated, but its association with the proteasome is drastically reduced, indicating that XPC regulates a postubiquitylation event. Furthermore, we found that XPC participates in the MDM2-mediated p53 degradation pathway via direct interaction with MDM2. XPC W690S pathogenic mutant is specifically defective for MDM2 binding and p53 degradation. p53 is known to become stabilized following UV irradiation but can be rendered unstable by XPC overexpression, underscoring a critical role of XPC in p53 regulation. Elucidation of the proteolytic role of XPC in cancer cells will help to unravel the detailed mechanisms underlying the coordination of DNA repair and proteolysis.
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Affiliation(s)
- Jing Yan Krzeszinski
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200433, People's Republic of China Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229 First Affiliated Hospital, Nanchang University, Jiangxi 330006, People's Republic of China
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32
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Hopkins JF, Spencer DF, Laboissiere S, Neilson JAD, Eveleigh RJM, Durnford DG, Gray MW, Archibald JM. Proteomics reveals plastid- and periplastid-targeted proteins in the chlorarachniophyte alga Bigelowiella natans. Genome Biol Evol 2013; 4:1391-406. [PMID: 23221610 PMCID: PMC3542566 DOI: 10.1093/gbe/evs115] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Chlorarachniophytes are unicellular marine algae with plastids (chloroplasts) of secondary endosymbiotic origin. Chlorarachniophyte cells retain the remnant nucleus (nucleomorph) and cytoplasm (periplastidial compartment, PPC) of the green algal endosymbiont from which their plastid was derived. To characterize the diversity of nucleus-encoded proteins targeted to the chlorarachniophyte plastid, nucleomorph, and PPC, we isolated plastid–nucleomorph complexes from the model chlorarachniophyte Bigelowiella natans and subjected them to high-pressure liquid chromatography-tandem mass spectrometry. Our proteomic analysis, the first of its kind for a nucleomorph-bearing alga, resulted in the identification of 324 proteins with 95% confidence. Approximately 50% of these proteins have predicted bipartite leader sequences at their amino termini. Nucleus-encoded proteins make up >90% of the proteins identified. With respect to biological function, plastid-localized light-harvesting proteins were well represented, as were proteins involved in chlorophyll biosynthesis. Phylogenetic analyses revealed that many, but by no means all, of the proteins identified in our proteomic screen are of apparent green algal ancestry, consistent with the inferred evolutionary origin of the plastid and nucleomorph in chlorarachniophytes.
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Affiliation(s)
- Julia F Hopkins
- Department of Biochemistry and Molecular Biology, Dalhousie University, Nova Scotia, Canada
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33
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Ehlinger A, Walters KJ. Structural insights into proteasome activation by the 19S regulatory particle. Biochemistry 2013; 52:3618-28. [PMID: 23672618 DOI: 10.1021/bi400417a] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Since its discovery in the late 1970s, the ubiquitin-proteasome system (UPS) has become recognized as the major pathway for regulated cellular proteolysis. Processes such as cell cycle control, pathogen resistance, and protein quality control rely on selective protein degradation at the proteasome for homeostatic function. Perhaps as a consequence of the importance of this pathway, and the genesis of severe diseases upon its dysregulation, protein degradation by the UPS is highly controlled from the level of substrate recognition to proteolysis. Technological advances over the past decade have created an explosion of structural and mechanistic information that has underscored the complexity of the proteasome and its upstream regulatory factors. Significant insights have come from the study of the 19S proteasome regulatory particle (RP) responsible for recognition and processing of ubiquitinated substrates destined for proteolysis. Established as a highly dynamic proteasome activator, the RP has a large number of both permanent and transient components with specialized functional roles that are critical for proteasome function. In this review, we highlight recent mechanistic developments in the study of proteasome activation by the RP and how they provide context to our current understanding of the UPS.
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Affiliation(s)
- Aaron Ehlinger
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota , Minneapolis, Minnesota 55455, United States
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34
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Ahmad KM, Xiao Y, Soh HT. Selection is more intelligent than design: improving the affinity of a bivalent ligand through directed evolution. Nucleic Acids Res 2012; 40:11777-83. [PMID: 23042245 PMCID: PMC3526301 DOI: 10.1093/nar/gks899] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Multivalent molecular interactions can be exploited to dramatically enhance the performance of an affinity reagent. The enhancement in affinity and specificity achieved with a multivalent construct depends critically on the effectiveness of the scaffold that joins the ligands, as this determines their positions and orientations with respect to the target molecule. Currently, no generalizable design rules exist for construction of an optimal multivalent ligand for targets with known structures, and the design challenge remains an insurmountable obstacle for the large number of proteins whose structures are not known. As an alternative to such design-based strategies, we report here a directed evolution-based method for generating optimal bivalent aptamers. To demonstrate this approach, we fused two thrombin aptamers with a randomized DNA sequence and used a microfluidic in vitro selection strategy to isolate scaffolds with exceptionally high affinities. Within five rounds of selection, we generated a bivalent aptamer that binds thrombin with an apparent dissociation constant (Kd) <10 pM, representing a ∼200-fold improvement in binding affinity over the monomeric aptamers and a ∼15-fold improvement over the best designed bivalent construct. The process described here can be used to produce high-affinity multivalent aptamers and could potentially be adapted to other classes of biomolecules.
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Affiliation(s)
- Kareem M Ahmad
- Interdepartmental Program in Biomolecular Science and Engineering, University of California Santa Barbara, Santa Barbara, CA 91306, USA
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35
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Affiliation(s)
- Alexander Varshavsky
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.
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36
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Huang B, Ojogun N, Ragland SA, Carlyon JA. Monoubiquitinated proteins decorate the Anaplasma phagocytophilum-occupied vacuolar membrane. ACTA ACUST UNITED AC 2012; 64:32-41. [PMID: 22066989 DOI: 10.1111/j.1574-695x.2011.00873.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An emerging theme among vacuole-adapted bacterial pathogens is the ability to hijack ubiquitin machinery to modulate host cellular processes and secure pathogen survival. Mono- and polyubiquitination differentially dictate the subcellular localization, activity, and fate of protein substrates. Monoubiquitination directs membrane traffic from the plasma membrane to the endosome and has been shown to promote autophagy. Anaplasma phagocytophilum is an obligate intracellular bacterium that replicates within a host cell-derived vacuole that co-opts membrane traffic and numerous other host cell processes. Here, we show that monoubiquitinated proteins decorate the A. phagocytophilum-occupied vacuolar membrane (AVM) during infection of promyelocytic HL-60 cell, endothelial RF/6A cells, and to a lesser extent, embryonic tick ISE6 cells. Monoubiquitinated proteins are present on the AVM upon its formation and continue to accumulate throughout infection. Tetracycline-mediated inhibition of de novo bacterial protein synthesis promotes the loss of ubiquitinated proteins from the AVM. This effect is reversible, as removal of tetracycline restores AVM ubiquitination to pretreatment levels. These results demonstrate a novel mechanism by which A. phagocytophilum remodels the composition of its host cell-derived vacuolar membrane and present the first example of a Rickettsiales pathogen co-opting ubiquitin during intracellular residence.
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Affiliation(s)
- Bernice Huang
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA 23298-0678, USA.
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37
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Abstract
Many intracellular proteins are metabolically unstable or can become unstable during their lifetime in a cell. The in vivo half-lives of specific proteins range from less than a minute to many days. Among the functions of intracellular proteolysis are the elimination of misfolded or otherwise abnormal proteins; maintenance of amino acid pools in cells affected by stresses such as starvation; and generation of protein fragments that act as hormones, antigens, or other effectors. One major function of proteolytic pathways is the selective destruction of proteins whose concentrations must vary with time and alterations in the state of a cell. Short in vivo half-lives of such proteins provide a way to generate their spatial gradients and to rapidly adjust their concentration or subunit composition through changes in the rate of their degradation. The regulated (and processive) degradation of intracellular proteins is carried out largely by the ubiquitin-proteasome system (Ub system), in conjunction with autophagy-lysosome pathways. Other contributors to intracellular proteolysis include cytosolic and nuclear proteases, such as caspases, calpains, and separases. They often function as "upstream" components of the Ub system, which destroys protein fragments that had been produced by these (nonprocessive) proteases. Ub, a 76-residue protein, mediates selective proteolysis through its enzymatic conjugation to proteins that contain primary degradation signals (degrons (1)), thereby marking such proteins for degradation by the 26S proteasome, an ATP-dependent multisubunit protease. Ub conjugation involves the formation of a poly-Ub chain that is linked (in most cases) to the ε-amino group of an internal Lys residue in a substrate protein. Ub is a "secondary" degron, in that Ub is conjugated to proteins that contain primary degradation signals.
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38
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Abstract
Ubiquitin and ubiquitin chains are recognized by a large and growing family of receptor proteins. NMR spectroscopy provides a powerful means to evaluate whether and how a protein binds to ubiquitin. It can be used to measure binding affinities, to map interaction surfaces, and to solve the three-dimensional structure of ubiquitin:receptor complexes. Herein, we describe three NMR techniques of varying complexity that are valuable tools to characterize protein:protein complexes. These include heteronuclear correlation experiments, paramagnetic relaxation enhancement (PRE) experiments via spin labeling, and techniques designed to obtain intermolecular dipole-dipole interactions by nuclear Overhauser effects (NOEs).
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39
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Wang YE, Pernet O, Lee B. Regulation of the nucleocytoplasmic trafficking of viral and cellular proteins by ubiquitin and small ubiquitin-related modifiers. Biol Cell 2011; 104:121-38. [PMID: 22188262 PMCID: PMC3625690 DOI: 10.1111/boc.201100105] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 11/22/2011] [Indexed: 12/29/2022]
Abstract
Nucleocytoplasmic trafficking of many cellular proteins is regulated by nuclear import/export signals as well as post-translational modifications such as covalent conjugation of ubiquitin and small ubiquitin-related modifiers (SUMOs). Ubiquitination and SUMOylation are rapid and reversible ways to modulate the intracellular localisation and function of substrate proteins. These pathways have been co-opted by some viruses, which depend on the host cell machinery to transport their proteins in and out of the nucleus. In this review, we will summarise our current knowledge on the ubiquitin/SUMO-regulated nuclear/subnuclear trafficking of cellular proteins and describe examples of viral exploitation of these pathways.
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Affiliation(s)
- Yao E Wang
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, CA 90095, USA
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Cho SK, Ryu MY, Seo DH, Kang BG, Kim WT. The Arabidopsis RING E3 ubiquitin ligase AtAIRP2 plays combinatory roles with AtAIRP1 in abscisic acid-mediated drought stress responses. PLANT PHYSIOLOGY 2011; 157:2240-57. [PMID: 21969385 PMCID: PMC3327188 DOI: 10.1104/pp.111.185595] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The ubiquitin (Ub)-26S proteasome pathway is implicated in various cellular processes in higher plants. AtAIRP1, a C3H2C3-type RING (for Really Interesting New Gene) E3 Ub ligase, is a positive regulator in the Arabidopsis (Arabidopsis thaliana) abscisic acid (ABA)-dependent drought response. Here, the AtAIRP2 (for Arabidopsis ABA-insensitive RING protein 2) gene was identified and characterized. AtAIRP2 encodes a cytosolic C3HC4-type RING E3 Ub ligase whose expression was markedly induced by ABA and dehydration stress. Thus, AtAIRP2 belongs to a different RING subclass than AtAIRP1 with a limited sequence identity. AtAIRP2-overexpressing transgenic (35S:AtAIRP2-sGFP) and atairp2 loss-of-function mutant plants exhibited hypersensitive and hyposensitive phenotypes, respectively, to ABA in terms of seed germination, root growth, and stomatal movement. 35S:AtAIRP2-sGFP plants were highly tolerant to severe drought stress, and atairp2 alleles were more susceptible to water stress than were wild-type plants. Higher levels of drought-induced hydrogen peroxide production were detected in 35S:AtAIRP2-sGFP as compared with atairp2 plants. ABA-inducible drought-related genes were up-regulated in 35S:AtAIRP2-sGFP and down-regulated in atairp2 progeny. The positive effects of AtAIRP2 on ABA-induced stress genes were dependent on SNF1-related protein kinases, key components of the ABA signaling pathway. Therefore, AtAIRP2 is involved in positive regulation of ABA-dependent drought stress responses. To address the functional relationship between AtAIRP1 and AtAIRP2, FLAG-AtAIRP1 and AtAIRP2-sGFP genes were ectopically expressed in atairp2-2 and atairp1 plants, respectively. Constitutive expression of FLAG-AtAIRP1 and AtAIRP2-sGFP in atairp2-2 and atairp1 plants, respectively, reciprocally rescued the loss-of-function ABA-insensitive phenotypes during germination. Additionally, atairp1/35S:AtAIRP2-sGFP and atairp2-2/35S:FLAG-AtAIRP1 complementation lines were more tolerant to dehydration stress relative to atairp1 and atairp2-2 single knockout plants. Overall, these results suggest that AtAIRP2 plays combinatory roles with AtAIRP1 in Arabidopsis ABA-mediated drought stress responses.
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The phosphatidylinositol transfer protein RdgBβ binds 14-3-3 via its unstructured C-terminus, whereas its lipid-binding domain interacts with the integral membrane protein ATRAP (angiotensin II type I receptor-associated protein). Biochem J 2011; 439:97-111. [DOI: 10.1042/bj20110649] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
PITPs [PI (phosphatidylinositol) transfer proteins] bind and transfer PI between intracellular membranes and participate in many cellular processes including signalling, lipid metabolism and membrane traffic. The largely uncharacterized PITP RdgBβ (PITPNC1; retinal degeneration type B β), contains a long C-terminal disordered region following its defining N-terminal PITP domain. In the present study we report that the C-terminus contains two tandem phosphorylated binding sites (Ser274 and Ser299) for 14-3-3. The C-terminus also contains PEST sequences which are shielded by 14-3-3 binding. Like many proteins containing PEST sequences, the levels of RdgBβ are regulated by proteolysis. RdgBβ is degraded with a half-life of 4 h following ubiquitination via the proteasome. A mutant RdgBβ which is unable to bind 14-3-3 is degraded even faster with a half-life of 2 h. In vitro, RdgBβ is 100-fold less active than PITPα for PI transfer, and RdgBβ proteins (wild-type and a mutant that cannot bind 14-3-3) expressed in COS-7 cells or endogenous proteins from heart cytosol do not exhibit transfer activity. When cells are treated with PMA, the PITP domain of RdgBβ interacts with the integral membrane protein ATRAP (angiotensin II type I receptor-associated protein; also known as AGTRAP) causing membrane recruitment. We suggest that RdgBβ executes its function following recruitment to membranes via its PITP domain and the C-terminal end of the protein could regulate entry to the hydrophobic cavity.
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The Cdc48 ATPase modulates the interaction between two proteolytic factors Ufd2 and Rad23. Proc Natl Acad Sci U S A 2011; 108:13558-63. [PMID: 21807993 DOI: 10.1073/pnas.1104051108] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Rad23 and cell division cycle protein 48 (Cdc48), two key regulators of postubiquitylation events, act on distinct and overlapping sets of substrates. The principle underlying their division of labor and cooperation in proteolysis remains elusive. Both Rad23 and Cdc48 bind a ubiquitin protein ligase ubiquitin fusion degradation-2 (Ufd2), and regulate the degradation of Ufd2 substrates. With its ability to bind ubiquitin chains directly and the proteasome via different domains, Rad23 serves as a bridge linking ubiquitylated substrates to the proteasome. The significance and specific role of the Ufd2-Cdc48 interaction are unclear. Here, we demonstrate that mutations in Ufd2 alter its interaction with Cdc48 and impair its function in substrate proteolysis but not in ubiquitylation. Furthermore, Cdc48 promotes the disassembly of the Ufd2-Rad23 complex in an manner that is dependent on ATP and Ufd2 binding, revealing a biochemical role for Cdc48. Rad23 was shown to bind separately to Ufd2 and to the proteasome subunit Rpn1, which define two distinct steps in proteolysis. The action of Cdc48 could free Rad23 from Ufd2 to allow its subsequent association with Rpn1, which in turn may facilitate the orderly transfer of the substrate from the ubiquitylation apparatus to the proteasome.
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Varshavsky A. The N-end rule pathway and regulation by proteolysis. Protein Sci 2011; 20:1298-345. [PMID: 21633985 PMCID: PMC3189519 DOI: 10.1002/pro.666] [Citation(s) in RCA: 509] [Impact Index Per Article: 39.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 05/16/2011] [Accepted: 05/18/2011] [Indexed: 01/12/2023]
Abstract
The N-end rule relates the regulation of the in vivo half-life of a protein to the identity of its N-terminal residue. Degradation signals (degrons) that are targeted by the N-end rule pathway include a set called N-degrons. The main determinant of an N-degron is a destabilizing N-terminal residue of a protein. In eukaryotes, the N-end rule pathway is a part of the ubiquitin system and consists of two branches, the Ac/N-end rule and the Arg/N-end rule pathways. The Ac/N-end rule pathway targets proteins containing N(α) -terminally acetylated (Nt-acetylated) residues. The Arg/N-end rule pathway recognizes unacetylated N-terminal residues and involves N-terminal arginylation. Together, these branches target for degradation a majority of cellular proteins. For example, more than 80% of human proteins are cotranslationally Nt-acetylated. Thus most proteins harbor a specific degradation signal, termed (Ac)N-degron, from the moment of their birth. Specific N-end rule pathways are also present in prokaryotes and in mitochondria. Enzymes that produce N-degrons include methionine-aminopeptidases, caspases, calpains, Nt-acetylases, Nt-amidases, arginyl-transferases and leucyl-transferases. Regulated degradation of specific proteins by the N-end rule pathway mediates a legion of physiological functions, including the sensing of heme, oxygen, and nitric oxide; selective elimination of misfolded proteins; the regulation of DNA repair, segregation and condensation; the signaling by G proteins; the regulation of peptide import, fat metabolism, viral and bacterial infections, apoptosis, meiosis, spermatogenesis, neurogenesis, and cardiovascular development; and the functioning of adult organs, including the pancreas and the brain. Discovered 25 years ago, this pathway continues to be a fount of biological insights.
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Affiliation(s)
- Alexander Varshavsky
- 1Division of Biology, California Institute of Technology, Pasadena, California 91125.
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Altered germination and subcellular localization patterns for PUB44/SAUL1 in response to stress and phytohormone treatments. PLoS One 2011; 6:e21321. [PMID: 21738636 PMCID: PMC3124495 DOI: 10.1371/journal.pone.0021321] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 05/24/2011] [Indexed: 11/25/2022] Open
Abstract
Background In plants, the ubiquitin-proteasome system is emerging as a significant regulatory system throughout the plant lifecycle. The ubiquitination of a target protein requires the sequential actions of the E1, E2 and E3 enzymes, with the latter E3 enzyme conferring target selection in this process. There are a large number of predicted E3 enzymes in plant genomes, and very little is known about the functions of many of these predicted genes. Here we report here an analysis of two closely-related members of the Arabidopsis Plant U-box (PUB) family of E3 ubiquitin ligases, PUB43 and PUB44. Principal Findings Homozygous pub44/pub44 mutant seedlings were found displayed a seedling lethal phenotype and this corresponded with widespread cell death lesions throughout the cotyledons and roots. Interestingly, heterozygous PUB44/pub44 seedlings were wild-type in appearance yet displayed intermediate levels of cell death lesions in comparison to pub44/pub44 seedlings. In contrast, homozygous pub43/pub43 mutants were viable and did not show any signs of cell death despite the PUB43 gene being more highly expressed than PUB44. The PUB44 mutants are not classical lesion mimic mutants as they did not have increased resistance to plant pathogens. We also observed increased germination rates in mutant seeds for both PUB44 and PUB43 under inhibitory concentrations of abscisic acid. Finally, the subcellular localization of PUB44 was investigated with transient expression assays in BY-2 cells. Under varying conditions, PUB44 was observed to be localized to the cytoplasm, plasma membrane, or nucleus. Conclusions Based on mutant plant analyses, the Arabidopsis PUB43 and PUB44 genes are proposed to function during seed germination and early seedling growth. Given PUB44's ability to shuttle from the nucleus to the plasma membrane, PUB44 may be active in different subcellular compartments as part of these biological functions.
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Genini S, Badaoui B, Sclep G, Bishop SC, Waddington D, Pinard van der Laan MH, Klopp C, Cabau C, Seyfert HM, Petzl W, Jensen K, Glass EJ, de Greeff A, Smith HE, Smits MA, Olsaker I, Boman GM, Pisoni G, Moroni P, Castiglioni B, Cremonesi P, Del Corvo M, Foulon E, Foucras G, Rupp R, Giuffra E. Strengthening insights into host responses to mastitis infection in ruminants by combining heterogeneous microarray data sources. BMC Genomics 2011; 12:225. [PMID: 21569310 PMCID: PMC3118214 DOI: 10.1186/1471-2164-12-225] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 05/11/2011] [Indexed: 12/30/2022] Open
Abstract
Background Gene expression profiling studies of mastitis in ruminants have provided key but fragmented knowledge for the understanding of the disease. A systematic combination of different expression profiling studies via meta-analysis techniques has the potential to test the extensibility of conclusions based on single studies. Using the program Pointillist, we performed meta-analysis of transcription-profiling data from six independent studies of infections with mammary gland pathogens, including samples from cattle challenged in vivo with S. aureus, E. coli, and S. uberis, samples from goats challenged in vivo with S. aureus, as well as cattle macrophages and ovine dendritic cells infected in vitro with S. aureus. We combined different time points from those studies, testing different responses to mastitis infection: overall (common signature), early stage, late stage, and cattle-specific. Results Ingenuity Pathway Analysis of affected genes showed that the four meta-analysis combinations share biological functions and pathways (e.g. protein ubiquitination and polyamine regulation) which are intrinsic to the general disease response. In the overall response, pathways related to immune response and inflammation, as well as biological functions related to lipid metabolism were altered. This latter observation is consistent with the milk fat content depression commonly observed during mastitis infection. Complementarities between early and late stage responses were found, with a prominence of metabolic and stress signals in the early stage and of the immune response related to the lipid metabolism in the late stage; both mechanisms apparently modulated by few genes, including XBP1 and SREBF1. The cattle-specific response was characterized by alteration of the immune response and by modification of lipid metabolism. Comparison of E. coli and S. aureus infections in cattle in vivo revealed that affected genes showing opposite regulation had the same altered biological functions and provided evidence that E. coli caused a stronger host response. Conclusions This meta-analysis approach reinforces previous findings but also reveals several novel themes, including the involvement of genes, biological functions, and pathways that were not identified in individual studies. As such, it provides an interesting proof of principle for future studies combining information from diverse heterogeneous sources.
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Affiliation(s)
- Sem Genini
- Parco Tecnologico Padano - CERSA, Via Einstein, 26900 Lodi, Italy.
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Ahn J, Novince Z, Concel J, Byeon CH, Makhov AM, Byeon IJL, Zhang P, Gronenborn AM. The Cullin-RING E3 ubiquitin ligase CRL4-DCAF1 complex dimerizes via a short helical region in DCAF1. Biochemistry 2011; 50:1359-67. [PMID: 21226479 DOI: 10.1021/bi101749s] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The cullin4A-RING E3 ubiquitin ligase (CRL4) is a multisubunit protein complex, comprising cullin4A (CUL4), RING H2 finger protein (RBX1), and DNA damage-binding protein 1 (DDB1). Proteins that recruit specific targets to CRL4 for ubiquitination (ubiquitylation) bind the DDB1 adaptor protein via WD40 domains. Such CRL4 substrate recognition modules are DDB1- and CUL4-associated factors (DCAFs). Here we show that, for DCAF1, oligomerization of the protein and the CRL4 complex occurs via a short helical region (residues 845-873) N-terminal to DACF1's own WD40 domain. This sequence was previously designated as a LIS1 homology (LisH) motif. The oligomerization helix contains a stretch of four Leu residues, which appear to be essential for α-helical structure and oligomerization. In vitro reconstituted CRL4-DCAF1 complexes (CRL4(DCAF1)) form symmetric dimers as visualized by electron microscopy (EM), and dimeric CRL4(DCAF1) is a better E3 ligase for in vitro ubiquitination of the UNG2 substrate compared to a monomeric complex.
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Affiliation(s)
- Jinwoo Ahn
- University of Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
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Salt JN, Yoshioka K, Moeder W, Goring DR. Altered germination and subcellular localization patterns for PUB44/SAUL1 in response to stress and phytohormone treatments. PLoS One 2011. [PMID: 21738636 DOI: 10.1371/journal.pone.0021321pone-d-11-06319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/24/2023] Open
Abstract
BACKGROUND In plants, the ubiquitin-proteasome system is emerging as a significant regulatory system throughout the plant lifecycle. The ubiquitination of a target protein requires the sequential actions of the E1, E2 and E3 enzymes, with the latter E3 enzyme conferring target selection in this process. There are a large number of predicted E3 enzymes in plant genomes, and very little is known about the functions of many of these predicted genes. Here we report here an analysis of two closely-related members of the Arabidopsis Plant U-box (PUB) family of E3 ubiquitin ligases, PUB43 and PUB44. PRINCIPAL FINDINGS Homozygous pub44/pub44 mutant seedlings were found displayed a seedling lethal phenotype and this corresponded with widespread cell death lesions throughout the cotyledons and roots. Interestingly, heterozygous PUB44/pub44 seedlings were wild-type in appearance yet displayed intermediate levels of cell death lesions in comparison to pub44/pub44 seedlings. In contrast, homozygous pub43/pub43 mutants were viable and did not show any signs of cell death despite the PUB43 gene being more highly expressed than PUB44. The PUB44 mutants are not classical lesion mimic mutants as they did not have increased resistance to plant pathogens. We also observed increased germination rates in mutant seeds for both PUB44 and PUB43 under inhibitory concentrations of abscisic acid. Finally, the subcellular localization of PUB44 was investigated with transient expression assays in BY-2 cells. Under varying conditions, PUB44 was observed to be localized to the cytoplasm, plasma membrane, or nucleus. CONCLUSIONS Based on mutant plant analyses, the Arabidopsis PUB43 and PUB44 genes are proposed to function during seed germination and early seedling growth. Given PUB44's ability to shuttle from the nucleus to the plasma membrane, PUB44 may be active in different subcellular compartments as part of these biological functions.
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Affiliation(s)
- Jennifer N Salt
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
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Hwang CS, Shemorry A, Auerbach D, Varshavsky A. The N-end rule pathway is mediated by a complex of the RING-type Ubr1 and HECT-type Ufd4 ubiquitin ligases. Nat Cell Biol 2010; 12:1177-85. [PMID: 21076411 PMCID: PMC3003441 DOI: 10.1038/ncb2121] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 10/18/2010] [Indexed: 02/07/2023]
Abstract
Substrates of the N-end rule pathway are recognized by the Ubr1 E3 ubiquitin ligase through their destabilizing N-terminal residues. Our previous work showed that the Ubr1 E3 and the Ufd4 E3 co-target an internal degron of the Mgt1 DNA repair protein. Ufd4 is an E3 of the ubiquitin-fusion degradation (UFD) pathway that recognizes an N-terminal ubiquitin moiety. Here we report that the RING-type Ubr1 E3 and the HECT-type Ufd4 E3 interact, both physically and functionally. Although Ubr1 can recognize and polyubiquitylate an N-end rule substrate in the absence of Ufd4, the Ubr1-Ufd4 complex is more processive in that it produces a longer substrate-linked polyubiquitin chain. Conversely, Ubr1 can function as a polyubiquitylation-enhancing component of the Ubr1-Ufd4 complex in its targeting of UFD substrates. We also found that Ubr1 can recognize the N-terminal ubiquitin moiety. These and related advances unify two proteolytic systems that have been studied separately over two decades.
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Affiliation(s)
- Cheol-Sang Hwang
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA
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Scott DC, Monda JK, Grace CRR, Duda DM, Kriwacki RW, Kurz T, Schulman BA. A dual E3 mechanism for Rub1 ligation to Cdc53. Mol Cell 2010; 39:784-96. [PMID: 20832729 DOI: 10.1016/j.molcel.2010.08.030] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 07/29/2010] [Accepted: 08/13/2010] [Indexed: 10/19/2022]
Abstract
In ubiquitin-like protein (UBL) cascades, a thioester-linked E2∼UBL complex typically interacts with an E3 enzyme for UBL transfer to the target. Here we demonstrate a variant mechanism, whereby the E2 Ubc12 functions with two E3s, Hrt1 and Dcn1, for ligation of the UBL Rub1 to Cdc53's WHB subdomain. Hrt1 functions like a conventional RING E3, with its N terminus recruiting Cdc53 and C-terminal RING activating Ubc12∼Rub1. Dcn1's "potentiating neddylation" domain (Dcn1(P)) acts as an additional E3, reducing nonspecific Hrt1-mediated Ubc12∼Rub1 discharge and directing Ubc12's active site to Cdc53. Crystal structures of Dcn1(P)-Cdc53(WHB) and Ubc12 allow modeling of a catalytic complex, supported by mutational data. We propose that Dcn1's interactions with both Cdc53 and Ubc12 would restrict the otherwise flexible Hrt1 RING-bound Ubc12∼Rub1 to a catalytically competent orientation. Our data reveal mechanisms by which two E3s function synergistically to promote UBL transfer from one E2 to a target.
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Affiliation(s)
- Daniel C Scott
- Howard Hughes Medical Institute, St Jude Children's Research Hospital, Memphis, TN 38105, USA
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Gautheron J, Courtois G. "Without Ub I am nothing": NEMO as a multifunctional player in ubiquitin-mediated control of NF-kappaB activation. Cell Mol Life Sci 2010; 67:3101-13. [PMID: 20502939 PMCID: PMC11115954 DOI: 10.1007/s00018-010-0404-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 05/06/2010] [Accepted: 05/07/2010] [Indexed: 11/26/2022]
Abstract
Ubiquitination has emerged over the years as the most sophisticated way to modify proteins to affect their fate and function. In particular, it has been reported to be instrumental in regulating several steps of the NF-kappaB signalling pathway which controls inflammation, immunity, adhesion and cell survival. Integrating ubiquitination into NF-kappaB activation requires the regulatory subunit of IKK, NEMO, which not only displays affinity for polyubiquitin chains, but is also posttranslationally modified by a complex set of reactions involving ubiquitin. Here, we examine how studies of the NEMO/ubiquitin relationship have provided novel insights into the IKK activation process and have uncovered molecular mechanisms that should represent in the future attractive targets for specifically modulating NF-kappaB function.
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Affiliation(s)
- Jérémie Gautheron
- INSERM U781, Tour Lavoisier, Hôpital Necker-Enfants Malades and Université Paris-Descartes, 149, rue de Sèvres, 75015 Paris, France
| | - Gilles Courtois
- INSERM U781, Tour Lavoisier, Hôpital Necker-Enfants Malades and Université Paris-Descartes, 149, rue de Sèvres, 75015 Paris, France
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