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Zhang H, Wang X. The Role of Protein Quantity Control in Polyglutamine Spinocerebellar Ataxias. CEREBELLUM (LONDON, ENGLAND) 2024:10.1007/s12311-024-01722-w. [PMID: 39052145 DOI: 10.1007/s12311-024-01722-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/15/2024] [Indexed: 07/27/2024]
Abstract
Polyglutamine spinocerebellar ataxias (polyQ SCAs) represent the most prevalent subtype of SCAs. The primary pathogenic mechanism is believed to be the gain-of-function neurotoxicity of polyQ proteins. Strategies such as enhancing the degradation or inhibiting the accumulation of these mutant proteins are pivotal for reducing their toxicity and slowing disease progression. The protein quality control (PQC) system, comprising primarily molecular chaperones and the ubiquitin‒proteasome system (UPS), is essential for maintaining protein homeostasis by regulating protein folding, trafficking, and degradation. Notably, polyQ proteins can disrupt the PQC system by sequestering its critical components and impairing its proteasomal functions. Therefore, restoring the PQC system through genetic or pharmacological interventions could potentially offer beneficial effects and alleviate the symptoms of the disease. Here, we will provide a review on the distribution, expression, and genetic or pharmacological intervention of protein quality control system in cellular or animal models of PolyQ SCAs.
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Affiliation(s)
- Hongfeng Zhang
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Department of Neurology, School of Medicine, The First Affiliated Hospital of Xiamen University, Xiamen University, Xiamen, 361005, Fujian, China.
- Shenzhen Research Institute of Xiamen University, Shenzhen, 518057, Guangdong, China.
| | - Xin Wang
- State Key Laboratory of Cellular Stress Biology, Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, Department of Neurology, School of Medicine, The First Affiliated Hospital of Xiamen University, Xiamen University, Xiamen, 361005, Fujian, China.
- Shenzhen Research Institute of Xiamen University, Shenzhen, 518057, Guangdong, China.
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2
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Fassler JS, Skuodas S, Weeks DL, Phillips BT. Protein Aggregation and Disaggregation in Cells and Development. J Mol Biol 2021; 433:167215. [PMID: 34450138 PMCID: PMC8530975 DOI: 10.1016/j.jmb.2021.167215] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 08/01/2021] [Accepted: 08/18/2021] [Indexed: 12/12/2022]
Abstract
Protein aggregation is a feature of numerous neurodegenerative diseases. However, regulated, often reversible, formation of protein aggregates, also known as condensates, helps control a wide range of cellular activities including stress response, gene expression, memory, cell development and differentiation. This review presents examples of aggregates found in biological systems, how they are used, and cellular strategies that control aggregation and disaggregation. We include features of the aggregating proteins themselves, environmental factors, co-aggregates, post-translational modifications and well-known aggregation-directed activities that influence their formation, material state, stability and dissolution. We highlight the emerging roles of biomolecular condensates in early animal development, and disaggregation processing proteins that have recently been shown to play key roles in gametogenesis and embryogenesis.
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Affiliation(s)
- Jan S Fassler
- Department of Biology, University of Iowa, Iowa City, IA 52242, United States.
| | - Sydney Skuodas
- Department of Biology, University of Iowa, Iowa City, IA 52242, United States. https://twitter.com/@sskuodas
| | - Daniel L Weeks
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, United States
| | - Bryan T Phillips
- Department of Biology, University of Iowa, Iowa City, IA 52242, United States. https://twitter.com/@bt4phillips
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3
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Burns GD, Hilal OE, Sun Z, Reutter KR, Preston GM, Augustine AA, Brodsky JL, Guerriero CJ. Distinct classes of misfolded proteins differentially affect the growth of yeast compromised for proteasome function. FEBS Lett 2021; 595:2383-2394. [PMID: 34358326 DOI: 10.1002/1873-3468.14172] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 07/24/2021] [Accepted: 07/29/2021] [Indexed: 11/09/2022]
Abstract
Maintenance of the proteome (proteostasis) is essential for cellular homeostasis and prevents cytotoxic stress responses that arise from protein misfolding. However, little is known about how different types of misfolded proteins impact homeostasis, especially when protein degradation pathways are compromised. We examined the effects of misfolded protein expression on yeast growth by characterizing a suite of substrates possessing the same aggregation-prone domain but engaging different quality control pathways. We discovered that treatment with a proteasome inhibitor was more toxic in yeast expressing misfolded membrane proteins, and this growth defect was mirrored in yeast lacking a proteasome-specific transcription factor, Rpn4p. These results highlight weaknesses in the proteostasis network's ability to handle the stress arising from an accumulation of misfolded membrane proteins.
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Affiliation(s)
- Grace D Burns
- Department of Biological Sciences, University of Pittsburgh, PA, USA
| | - Olivia E Hilal
- Department of Biological Sciences, University of Pittsburgh, PA, USA
| | - Zhihao Sun
- Department of Biological Sciences, University of Pittsburgh, PA, USA
| | | | - G Michael Preston
- Department of Biological Sciences, University of Pittsburgh, PA, USA
| | | | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, PA, USA
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4
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Creekmore BC, Chang YW, Lee EB. The Cryo-EM Effect: Structural Biology of Neurodegenerative Disease Proteostasis Factors. J Neuropathol Exp Neurol 2021; 80:494-513. [PMID: 33860329 PMCID: PMC8177850 DOI: 10.1093/jnen/nlab029] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Neurodegenerative diseases are characterized by the accumulation of misfolded proteins. This protein aggregation suggests that abnormal proteostasis contributes to aging-related neurodegeneration. A better fundamental understanding of proteins that regulate proteostasis may provide insight into the pathophysiology of neurodegenerative disease and may perhaps reveal novel therapeutic opportunities. The 26S proteasome is the key effector of the ubiquitin-proteasome system responsible for degrading polyubiquitinated proteins. However, additional factors, such as valosin-containing protein (VCP/p97/Cdc48) and C9orf72, play a role in regulation and trafficking of substrates through the normal proteostasis systems of a cell. Nonhuman AAA+ ATPases, such as the disaggregase Hsp104, also provide insights into the biochemical processes that regulate protein aggregation. X-ray crystallography and cryo-electron microscopy (cryo-EM) structures not bound to substrate have provided meaningful information about the 26S proteasome, VCP, and Hsp104. However, recent cryo-EM structures bound to substrate have provided new information about the function and mechanism of these proteostasis factors. Cryo-EM and cryo-electron tomography data combined with biochemical data have also increased the understanding of C9orf72 and its role in maintaining proteostasis. These structural insights provide a foundation for understanding proteostasis mechanisms with near-atomic resolution upon which insights can be gleaned regarding the pathophysiology of neurodegenerative diseases.
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Affiliation(s)
- Benjamin C Creekmore
- From the Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Graduate Program in Biochemistry and Molecular Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yi-Wei Chang
- From the Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Edward B Lee
- Translational Neuropathology Research Laboratory, Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
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5
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Shorter J, Southworth DR. Spiraling in Control: Structures and Mechanisms of the Hsp104 Disaggregase. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a034033. [PMID: 30745294 DOI: 10.1101/cshperspect.a034033] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Hsp104 is a hexameric AAA+ ATPase and protein disaggregase found in yeast, which couples ATP hydrolysis to the dissolution of diverse polypeptides trapped in toxic preamyloid oligomers, phase-transitioned gels, disordered aggregates, amyloids, and prions. Hsp104 shows plasticity in disaggregating diverse substrates, but how its hexameric architecture operates as a molecular machine has remained unclear. Here, we highlight structural advances made via cryoelectron microscopy (cryo-EM) that enhance our mechanistic understanding of Hsp104 and other related AAA+ translocases. Hsp104 hexamers are dynamic and adopt open "lock-washer" spiral states and closed ring structures that envelope polypeptide substrate inside the axial channel. ATP hydrolysis-driven conformational changes at the spiral seam ratchet substrate deeper into the channel. Remarkably, this mode of polypeptide translocation is reminiscent of models for how hexameric helicases unwind DNA and RNA duplexes. Thus, Hsp104 likely adapts elements of a deeply rooted, ring-translocase mechanism to the specialized task of protein disaggregation.
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Affiliation(s)
- James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Daniel R Southworth
- Department of Biochemistry and Biophysics; and the Institute for Neurodegenerative Diseases, University of California San Francisco, San Francisco, California 94158
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Doonan LM, Guerriero CJ, Preston GM, Buck TM, Khazanov N, Fisher EA, Senderowitz H, Brodsky JL. Hsp104 facilitates the endoplasmic-reticulum-associated degradation of disease-associated and aggregation-prone substrates. Protein Sci 2019; 28:1290-1306. [PMID: 31050848 DOI: 10.1002/pro.3636] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 04/29/2019] [Indexed: 12/20/2022]
Abstract
Misfolded proteins in the endoplasmic reticulum (ER) are selected for ER-associated degradation (ERAD). More than 60 disease-associated proteins are substrates for the ERAD pathway due to the presence of missense or nonsense mutations. In yeast, the Hsp104 molecular chaperone disaggregates detergent-insoluble ERAD substrates, but the spectrum of disease-associated ERAD substrates that may be aggregation prone is unknown. To determine if Hsp104 recognizes aggregation-prone ERAD substrates associated with human diseases, we developed yeast expression systems for a hydrophobic lipid-binding protein, apolipoprotein B (ApoB), along with a chimeric protein harboring a nucleotide-binding domain from the cystic fibrosis transmembrane conductance regulator (CFTR) into which disease-causing mutations were introduced. We discovered that Hsp104 facilitates the degradation of ER-associated ApoB as well as a truncated CFTR chimera in which a premature stop codon corresponds to a disease-causing mutation. Chimeras containing a wild-type version of the CFTR domain or a different mutation were stable and thus Hsp104 independent. We also discovered that the detergent solubility of the unstable chimera was lower than the stable chimeras, and Hsp104 helped retrotranslocate the unstable chimera from the ER, consistent with disaggregase activity. To determine why the truncated chimera was unstable, we next performed molecular dynamics simulations and noted significant unraveling of the CFTR nucleotide-binding domain. Because human cells lack Hsp104, these data indicate that an alternate disaggregase or mechanism facilitates the removal of aggregation-prone, disease-causing ERAD substrates in their native environments.
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Affiliation(s)
- Lynley M Doonan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260
| | - Christopher J Guerriero
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260
| | - G Michael Preston
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260
| | - Teresa M Buck
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260
| | - Netaly Khazanov
- Department of Chemistry, Bar Ilan University, Ramat Gan, 5290002, Israel
| | - Edward A Fisher
- Division of Cardiology, Department of Medicine and Cell Biology, New York University, New York, New York, 10016
| | - Hanoch Senderowitz
- Department of Chemistry, Bar Ilan University, Ramat Gan, 5290002, Israel
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260
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March ZM, Mack KL, Shorter J. AAA+ Protein-Based Technologies to Counter Neurodegenerative Disease. Biophys J 2019; 116:1380-1385. [PMID: 30952364 PMCID: PMC6486517 DOI: 10.1016/j.bpj.2019.03.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 02/21/2019] [Accepted: 03/13/2019] [Indexed: 01/25/2023] Open
Abstract
Protein misfolding and overloaded proteostasis networks underlie a range of neurodegenerative diseases. No cures exist for these diseases, but developing effective therapeutic agents targeting the toxic, misfolded protein species in disease is one promising strategy. AAA+ (ATPases associated with diverse cellular activities) protein translocases, which naturally unfold and translocate substrate proteins, could be potent therapeutic agents to disassemble toxic protein conformers in neurodegenerative disease. Here, we discuss repurposing AAA+ protein translocases Hsp104 and proteasome-activating nucleotidase (PAN) to alleviate the toxicity from protein misfolding in neurodegenerative disease. Hsp104 effectively protects various animal models from neurodegeneration underpinned by protein misfolding, and enhanced Hsp104 variants strongly counter neurodegenerative disease-associated protein misfolding toxicity in yeast, Caenorhabditis elegans, and mammalian cells. Similarly, a recently engineered PAN variant (PANet) mitigates photoreceptor degeneration instigated by protein misfolding in a mouse model of retinopathy. Further study and engineering of AAA+ translocases like Hsp104 and PAN will reveal promising agents to combat protein misfolding toxicity in neurodegenerative disease.
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Affiliation(s)
- Zachary M March
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Korrie L Mack
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
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Durie CL, Lin J, Scull NW, Mack KL, Jackrel ME, Sweeny EA, Castellano LM, Shorter J, Lucius AL. Hsp104 and Potentiated Variants Can Operate as Distinct Nonprocessive Translocases. Biophys J 2019; 116:1856-1872. [PMID: 31027887 DOI: 10.1016/j.bpj.2019.03.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 03/14/2019] [Accepted: 03/25/2019] [Indexed: 01/09/2023] Open
Abstract
Heat shock protein (Hsp) 104 is a hexameric ATPases associated with diverse cellular activities motor protein that enables cells to survive extreme stress. Hsp104 couples the energy of ATP binding and hydrolysis to solubilize proteins trapped in aggregated structures. The mechanism by which Hsp104 disaggregates proteins is not completely understood but may require Hsp104 to partially or completely translocate polypeptides across its central channel. Here, we apply transient state, single turnover kinetics to investigate the ATP-dependent translocation of soluble polypeptides by Hsp104 and Hsp104A503S, a potentiated variant developed to resolve misfolded conformers implicated in neurodegenerative disease. We establish that Hsp104 and Hsp104A503S can operate as nonprocessive translocases for soluble substrates, indicating a "partial threading" model of translocation. Remarkably, Hsp104A503S exhibits altered coupling of ATP binding to translocation and decelerated dissociation from polypeptide substrate compared to Hsp104. This altered coupling and prolonged substrate interaction likely increases entropic pulling forces, thereby enabling more effective aggregate dissolution by Hsp104A503S.
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Affiliation(s)
- Clarissa L Durie
- University of Alabama at Birmingham, Chemistry Department, Birmingham, Alabama
| | - JiaBei Lin
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Nathaniel W Scull
- University of Alabama at Birmingham, Chemistry Department, Birmingham, Alabama
| | - Korrie L Mack
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Meredith E Jackrel
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Elizabeth A Sweeny
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Laura M Castellano
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Aaron L Lucius
- University of Alabama at Birmingham, Chemistry Department, Birmingham, Alabama.
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Hofer S, Kainz K, Zimmermann A, Bauer MA, Pendl T, Poglitsch M, Madeo F, Carmona-Gutierrez D. Studying Huntington's Disease in Yeast: From Mechanisms to Pharmacological Approaches. Front Mol Neurosci 2018; 11:318. [PMID: 30233317 PMCID: PMC6131589 DOI: 10.3389/fnmol.2018.00318] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 08/16/2018] [Indexed: 12/22/2022] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disorder that leads to progressive neuronal loss, provoking impaired motor control, cognitive decline, and dementia. So far, HD remains incurable, and available drugs are effective only for symptomatic management. HD is caused by a mutant form of the huntingtin protein, which harbors an elongated polyglutamine domain and is highly prone to aggregation. However, many aspects underlying the cytotoxicity of mutant huntingtin (mHTT) remain elusive, hindering the efficient development of applicable interventions to counteract HD. An important strategy to obtain molecular insights into human disorders in general is the use of eukaryotic model organisms, which are easy to genetically manipulate and display a high degree of conservation regarding disease-relevant cellular processes. The budding yeast Saccharomyces cerevisiae has a long-standing and successful history in modeling a plethora of human maladies and has recently emerged as an effective tool to study neurodegenerative disorders, including HD. Here, we summarize some of the most important contributions of yeast to HD research, specifically concerning the elucidation of mechanistic features of mHTT cytotoxicity and the potential of yeast as a platform to screen for pharmacological agents against HD.
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Affiliation(s)
- Sebastian Hofer
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Katharina Kainz
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Andreas Zimmermann
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
- Department of Internal Medicine, Medical University of Graz, Graz, Austria
| | - Maria A. Bauer
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Tobias Pendl
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Michael Poglitsch
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Frank Madeo
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
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Guerriero CJ, Weiberth KF, Brodsky JL. Hsp70 targets a cytoplasmic quality control substrate to the San1p ubiquitin ligase. J Biol Chem 2013; 288:18506-20. [PMID: 23653356 DOI: 10.1074/jbc.m113.475905] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Accumulation of misfolded proteins in cellular compartments can result in stress-induced cell death. In the endoplasmic reticulum (ER), ER-associated degradation clears aberrant proteins from the secretory pathway. In the cytoplasm and nucleus, this job is left to the cytoplasmic quality control (CytoQC) machinery. Both processes utilize chaperones and the ubiquitin-proteasome system to aid in protein elimination. Previous studies in yeast have drawn comparisons between these processes using data from structurally and topologically different substrates. We sought to draw a direct comparison between ERAD and CytoQC by studying the elimination of a single misfolded domain that, depending on its residence, is disposed by either of these pathways. The truncated, second nucleotide binding domain (NBD2*) from a yeast ERAD substrate, Ste6p*, resides at the cytoplasmic face of the ER. We show that a soluble form of NBD2* is cytoplasmic and unlike wild-type NBD2 is targeted for proteasome-mediated degradation. In contrast to Ste6p*, which employs the ER-localized Doa10p ubiquitin ligase, NBD2* is ubiquitinated by a nuclear E3 ligase San1p, a factor that is also required for its degradation. Although the yeast cytoplasmic Hsp70 chaperone, Ssa1p, has been thought to facilitate the nuclear import or to maintain the solubility of most CytoQC substrates, we discovered that Ssa1p facilitates the interaction between San1p and NBD2*, demonstrating that chaperones can aid in substrate recognition and San1p-dependent protein degradation. These results emphasize the diverse action of molecular chaperones during CytoQC.
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Affiliation(s)
- Christopher J Guerriero
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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Helsen CW, Glover JR. Insight into molecular basis of curing of [PSI+] prion by overexpression of 104-kDa heat shock protein (Hsp104). J Biol Chem 2011; 287:542-556. [PMID: 22081611 DOI: 10.1074/jbc.m111.302869] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Yeast prions are a powerful model for understanding the dynamics of protein aggregation associated with a number of human neurodegenerative disorders. The AAA+ protein disaggregase Hsp104 can sever the amyloid fibrils produced by yeast prions. This action results in the propagation of "seeds" that are transmitted to daughter cells during budding. Overexpression of Hsp104 eliminates the [PSI+] prion but not other prions. Using biochemical methods we identified Hsp104 binding sites in the highly charged middle domain of Sup35, the protein determinant of [PSI+]. Deletion of a short segment of the middle domain (amino acids 129-148) diminishes Hsp104 binding and strongly affects the ability of the middle domain to stimulate the ATPase activity of Hsp104. In yeast, [PSI+] maintained by Sup35 lacking this segment, like other prions, is propagated by Hsp104 but cannot be cured by Hsp104 overexpression. These results provide new insight into the enigmatic specificity of Hsp104-mediated curing of yeast prions and sheds light on the limitations of the ability of Hsp104 to eliminate aggregates produced by other aggregation-prone proteins.
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Affiliation(s)
- Christopher W Helsen
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - John R Glover
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
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Current awareness on yeast. Yeast 2010. [DOI: 10.1002/yea.1718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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