1
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Kandola T, Venkatesan S, Zhang J, Lerbakken BT, Von Schulze A, Blanck JF, Wu J, Unruh JR, Berry P, Lange JJ, Box AC, Cook M, Sagui C, Halfmann R. Pathologic polyglutamine aggregation begins with a self-poisoning polymer crystal. eLife 2023; 12:RP86939. [PMID: 37921648 PMCID: PMC10624427 DOI: 10.7554/elife.86939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2023] Open
Abstract
A long-standing goal of amyloid research has been to characterize the structural basis of the rate-determining nucleating event. However, the ephemeral nature of nucleation has made this goal unachievable with existing biochemistry, structural biology, and computational approaches. Here, we addressed that limitation for polyglutamine (polyQ), a polypeptide sequence that causes Huntington's and other amyloid-associated neurodegenerative diseases when its length exceeds a characteristic threshold. To identify essential features of the polyQ amyloid nucleus, we used a direct intracellular reporter of self-association to quantify frequencies of amyloid appearance as a function of concentration, conformational templates, and rational polyQ sequence permutations. We found that nucleation of pathologically expanded polyQ involves segments of three glutamine (Q) residues at every other position. We demonstrate using molecular simulations that this pattern encodes a four-stranded steric zipper with interdigitated Q side chains. Once formed, the zipper poisoned its own growth by engaging naive polypeptides on orthogonal faces, in a fashion characteristic of polymer crystals with intramolecular nuclei. We further show that self-poisoning can be exploited to block amyloid formation, by genetically oligomerizing polyQ prior to nucleation. By uncovering the physical nature of the rate-limiting event for polyQ aggregation in cells, our findings elucidate the molecular etiology of polyQ diseases.
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Affiliation(s)
- Tej Kandola
- Stowers Institute for Medical ResearchKansas CityUnited States
- The Open UniversityMilton KeynesUnited Kingdom
| | | | - Jiahui Zhang
- Department of Physics, North Carolina State UniversityRaleighUnited States
| | | | | | | | - Jianzheng Wu
- Stowers Institute for Medical ResearchKansas CityUnited States
- Department of Biochemistry and Molecular Biology, University of Kansas Medical CenterKansas CityUnited States
| | - Jay R Unruh
- Stowers Institute for Medical ResearchKansas CityUnited States
| | - Paula Berry
- Stowers Institute for Medical ResearchKansas CityUnited States
| | - Jeffrey J Lange
- Stowers Institute for Medical ResearchKansas CityUnited States
| | - Andrew C Box
- Stowers Institute for Medical ResearchKansas CityUnited States
| | - Malcolm Cook
- Stowers Institute for Medical ResearchKansas CityUnited States
| | - Celeste Sagui
- Department of Physics, North Carolina State UniversityRaleighUnited States
| | - Randal Halfmann
- Stowers Institute for Medical ResearchKansas CityUnited States
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2
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Kandola T, Venkatesan S, Zhang J, Lerbakken B, Schulze AV, Blanck JF, Wu J, Unruh J, Berry P, Lange JJ, Box A, Cook M, Sagui C, Halfmann R. Pathologic polyglutamine aggregation begins with a self-poisoning polymer crystal. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.20.533418. [PMID: 36993401 PMCID: PMC10055281 DOI: 10.1101/2023.03.20.533418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
A long-standing goal of amyloid research has been to characterize the structural basis of the rate-determining nucleating event. However, the ephemeral nature of nucleation has made this goal unachievable with existing biochemistry, structural biology, and computational approaches. Here, we addressed that limitation for polyglutamine (polyQ), a polypeptide sequence that causes Huntington's and other amyloid-associated neurodegenerative diseases when its length exceeds a characteristic threshold. To identify essential features of the polyQ amyloid nucleus, we used a direct intracellular reporter of self-association to quantify frequencies of amyloid appearance as a function of concentration, conformational templates, and rational polyQ sequence permutations. We found that nucleation of pathologically expanded polyQ involves segments of three glutamine (Q) residues at every other position. We demonstrate using molecular simulations that this pattern encodes a four-stranded steric zipper with interdigitated Q side chains. Once formed, the zipper poisoned its own growth by engaging naive polypeptides on orthogonal faces, in a fashion characteristic of polymer crystals with intramolecular nuclei. We further show that self-poisoning can be exploited to block amyloid formation, by genetically oligomerizing polyQ prior to nucleation. By uncovering the physical nature of the rate-limiting event for polyQ aggregation in cells, our findings elucidate the molecular etiology of polyQ diseases.
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Affiliation(s)
- Tej Kandola
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
- The Open University, Milton Keyes, MK7 6AA, UK
| | | | - Jiahui Zhang
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | | | - Alex Von Schulze
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Jillian F Blanck
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Jianzheng Wu
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Jay Unruh
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Paula Berry
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Jeffrey J Lange
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Andrew Box
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Malcolm Cook
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Celeste Sagui
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Randal Halfmann
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
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3
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Zhouravleva GA, Bondarev SA, Trubitsina NP. How Big Is the Yeast Prion Universe? Int J Mol Sci 2023; 24:11651. [PMID: 37511408 PMCID: PMC10380529 DOI: 10.3390/ijms241411651] [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: 06/29/2023] [Revised: 07/14/2023] [Accepted: 07/17/2023] [Indexed: 07/30/2023] Open
Abstract
The number of yeast prions and prion-like proteins described since 1994 has grown from two to nearly twenty. If in the early years most scientists working with the classic mammalian prion, PrPSc, were skeptical about the possibility of using the term prion to refer to yeast cytoplasmic elements with unusual properties, it is now clear that prion-like phenomena are widespread and that yeast can serve as a convenient model for studying them. Here we give a brief overview of the yeast prions discovered so far and focus our attention to the various approaches used to identify them. The prospects for the discovery of new yeast prions are also discussed.
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Affiliation(s)
- Galina A Zhouravleva
- Department of Genetics and Biotechnology, St. Petersburg State University, 199034 St. Petersburg, Russia
- Laboratory of Amyloid Biology, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Stanislav A Bondarev
- Department of Genetics and Biotechnology, St. Petersburg State University, 199034 St. Petersburg, Russia
- Laboratory of Amyloid Biology, St. Petersburg State University, 199034 St. Petersburg, Russia
| | - Nina P Trubitsina
- Department of Genetics and Biotechnology, St. Petersburg State University, 199034 St. Petersburg, Russia
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4
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Miller SC, Wegrzynowicz AK, Cole SJ, Hayward RE, Ganser SJ, Hines JK. Hsp40/JDP Requirements for the Propagation of Synthetic Yeast Prions. Viruses 2022; 14:v14102160. [PMID: 36298715 PMCID: PMC9611480 DOI: 10.3390/v14102160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 09/22/2022] [Accepted: 09/27/2022] [Indexed: 11/05/2022] Open
Abstract
Yeast prions are protein-based transmissible elements, most of which are amyloids. The chaperone protein network in yeast is inexorably linked to the spreading of prions during cell division by fragmentation of amyloid prion aggregates. Specifically, the core “prion fragmentation machinery” includes the proteins Hsp104, Hsp70 and the Hsp40/J-domain protein (JDP) Sis1. Numerous novel amyloid-forming proteins have been created and examined in the yeast system and occasionally these amyloids are also capable of continuous Hsp104-dependent propagation in cell populations, forming synthetic prions. However, additional chaperone requirements, if any, have not been determined. Here, we report the first instances of a JDP-Hsp70 system requirement for the propagation of synthetic prions. We utilized constructs from a system of engineered prions with prion-forming domains (PrDs) consisting of a polyQ stretch interrupted by a single heterologous amino acid interspersed every fifth residue. These “polyQX” PrDs are fused to the MC domains of Sup35, creating chimeric proteins of which a subset forms synthetic prions in yeast. For four of these prions, we show that SIS1 repression causes prion loss in a manner consistent with Sis1′s known role in prion fragmentation. PolyQX prions were sensitive to Sis1 expression levels to differing degrees, congruent with the variability observed among native prions. Our results expand the scope known Sis1 functionality, demonstrating that Sis1 acts on amyloids broadly, rather than through specific protein–protein interactions with individual yeast prion-forming proteins.
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5
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Kushnirov VV, Dergalev AA, Alieva MK, Alexandrov AI. Structural Bases of Prion Variation in Yeast. Int J Mol Sci 2022; 23:ijms23105738. [PMID: 35628548 PMCID: PMC9147965 DOI: 10.3390/ijms23105738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Revised: 05/13/2022] [Accepted: 05/18/2022] [Indexed: 12/04/2022] Open
Abstract
Amyloids are protein aggregates with a specific filamentous structure that are related to a number of human diseases, and also to some important physiological processes in animals and other kingdoms of life. Amyloids in yeast can stably propagate as heritable units, prions. Yeast prions are of interest both on their own and as a model for amyloids and prions in general. In this review, we consider the structure of yeast prions and its variation, how such structures determine the balance of aggregated and soluble prion protein through interaction with chaperones and how the aggregated state affects the non-prion functions of these proteins.
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6
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Amyloid Fragmentation and Disaggregation in Yeast and Animals. Biomolecules 2021; 11:biom11121884. [PMID: 34944528 PMCID: PMC8699242 DOI: 10.3390/biom11121884] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/10/2021] [Accepted: 12/12/2021] [Indexed: 12/29/2022] Open
Abstract
Amyloids are filamentous protein aggregates that are associated with a number of incurable diseases, termed amyloidoses. Amyloids can also manifest as infectious or heritable particles, known as prions. While just one prion is known in humans and animals, more than ten prion amyloids have been discovered in fungi. The propagation of fungal prion amyloids requires the chaperone Hsp104, though in excess it can eliminate some prions. Even though Hsp104 acts to disassemble prion fibrils, at normal levels it fragments them into multiple smaller pieces, which ensures prion propagation and accelerates prion conversion. Animals lack Hsp104, but disaggregation is performed by the same complement of chaperones that assist Hsp104 in yeast—Hsp40, Hsp70, and Hsp110. Exogenous Hsp104 can efficiently cooperate with these chaperones in animals and promotes disaggregation, especially of large amyloid aggregates, which indicates its potential as a treatment for amyloid diseases. However, despite the significant effects, Hsp104 and its potentiated variants may be insufficient to fully dissolve amyloid. In this review, we consider chaperone mechanisms acting to disassemble heritable protein aggregates in yeast and animals, and their potential use in the therapy of human amyloid diseases.
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7
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Fomicheva A, Ross ED. From Prions to Stress Granules: Defining the Compositional Features of Prion-Like Domains That Promote Different Types of Assemblies. Int J Mol Sci 2021; 22:ijms22031251. [PMID: 33513942 PMCID: PMC7865556 DOI: 10.3390/ijms22031251] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/21/2021] [Accepted: 01/22/2021] [Indexed: 12/12/2022] Open
Abstract
Stress granules are ribonucleoprotein assemblies that form in response to cellular stress. Many of the RNA-binding proteins found in stress granule proteomes contain prion-like domains (PrLDs), which are low-complexity sequences that compositionally resemble yeast prion domains. Mutations in some of these PrLDs have been implicated in neurodegenerative diseases, including amyotrophic lateral sclerosis and frontotemporal dementia, and are associated with persistent stress granule accumulation. While both stress granules and prions are macromolecular assemblies, they differ in both their physical properties and complexity. Prion aggregates are highly stable homopolymeric solids, while stress granules are complex dynamic biomolecular condensates driven by multivalent homotypic and heterotypic interactions. Here, we use stress granules and yeast prions as a paradigm to examine how distinct sequence and compositional features of PrLDs contribute to different types of PrLD-containing assemblies.
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8
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Tobiasson V, Amunts A. Ciliate mitoribosome illuminates evolutionary steps of mitochondrial translation. eLife 2020; 9:59264. [PMID: 32553108 PMCID: PMC7326499 DOI: 10.7554/elife.59264] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 06/08/2020] [Indexed: 12/23/2022] Open
Abstract
To understand the steps involved in the evolution of translation, we used Tetrahymena thermophila, a ciliate with high coding capacity of the mitochondrial genome, as the model organism and characterized its mitochondrial ribosome (mitoribosome) using cryo-EM. The structure of the mitoribosome reveals an assembly of 94-ribosomal proteins and four-rRNAs with an additional protein mass of ~700 kDa on the small subunit, while the large subunit lacks 5S rRNA. The structure also shows that the small subunit head is constrained, tRNA binding sites are formed by mitochondria-specific protein elements, conserved protein bS1 is excluded, and bacterial RNA polymerase binding site is blocked. We provide evidence for anintrinsic protein targeting system through visualization of mitochondria-specific mL105 by the exit tunnel that would facilitate the recruitment of a nascent polypeptide. Functional protein uS3m is encoded by three complementary genes from the nucleus and mitochondrion, establishing a link between genetic drift and mitochondrial translation. Finally, we reannotated nine open reading frames in the mitochondrial genome that code for mitoribosomal proteins.
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Affiliation(s)
- Victor Tobiasson
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden.,Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Solna, Sweden
| | - Alexey Amunts
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden.,Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Solna, Sweden
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9
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Drozdova PB, Barbitoff YA, Belousov MV, Skitchenko RK, Rogoza TM, Leclercq JY, Kajava AV, Matveenko AG, Zhouravleva GA, Bondarev SA. Estimation of amyloid aggregate sizes with semi-denaturing detergent agarose gel electrophoresis and its limitations. Prion 2020; 14:118-128. [PMID: 32306832 PMCID: PMC7199750 DOI: 10.1080/19336896.2020.1751574] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Semi-denaturing detergent agarose gel electrophoresis (SDD-AGE) was proposed by Vitaly V. Kushnirov in the Michael D. Ter-Avanesyan’s laboratory as a method to compare sizes of amyloid aggregates. Currently, this method is widely used for amyloid investigation, but mostly as a qualitative approach. In this work, we assessed the possibilities and limitations of the quantitative analysis of amyloid aggregate size distribution using SDD-AGE results. For this purpose, we used aggregates of two well-characterized yeast amyloid-forming proteins, Sup35 and Rnq1, and developed a protocol to standardize image analysis and process the result. A detailed investigation of factors that may affect the results of SDD-AGE revealed that both the cell lysis method and electrophoresis conditions can substantially affect the estimation of aggregate size. Despite this, quantitative analysis of SDD-AGE results is possible when one needs to estimate and compare the size of aggregates on the same gel, or even in different experiments, if the experimental conditions are tightly controlled and additional standards are used.
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Affiliation(s)
- Polina B Drozdova
- Department of Genetics and Biotechnology, St. Petersburg State University, St. Petersburg, Russia.,Institute of Biology, Irkutsk State University, Irkutsk, Russia
| | - Yury A Barbitoff
- Department of Genetics and Biotechnology, St. Petersburg State University, St. Petersburg, Russia
| | - Mikhail V Belousov
- Department of Genetics and Biotechnology, St. Petersburg State University, St. Petersburg, Russia.,Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology, St. Petersburg, Russia
| | - Rostislav K Skitchenko
- International Research Institute of Bioengineering, ITMO University, St. Petersburg, Russia
| | - Tatyana M Rogoza
- Department of Genetics and Biotechnology, St. Petersburg State University, St. Petersburg, Russia.,Vavilov Institute of General Genetics Russian Academy of Sciences, St. Petersburg Branch, St. Petersburg, Russia
| | - Jeremy Y Leclercq
- Centre de Recherche En Biologie Cellulaire De Montpellier, UMR 5237 CNRS, Montpellier, France
| | - Andrey V Kajava
- International Research Institute of Bioengineering, ITMO University, St. Petersburg, Russia.,Centre de Recherche En Biologie Cellulaire De Montpellier, UMR 5237 CNRS, Montpellier, France
| | - Andrew G Matveenko
- Department of Genetics and Biotechnology, St. Petersburg State University, St. Petersburg, Russia
| | - Galina A Zhouravleva
- Department of Genetics and Biotechnology, St. Petersburg State University, St. Petersburg, Russia.,Laboratory of Amyloid Biology, St. Petersburg State University, St. Petersburg, Russia
| | - Stanislav A Bondarev
- Department of Genetics and Biotechnology, St. Petersburg State University, St. Petersburg, Russia.,Laboratory of Amyloid Biology, St. Petersburg State University, St. Petersburg, Russia
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10
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Yeast Sup35 Prion Structure: Two Types, Four Parts, Many Variants. Int J Mol Sci 2019; 20:ijms20112633. [PMID: 31146333 PMCID: PMC6600473 DOI: 10.3390/ijms20112633] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 05/22/2019] [Accepted: 05/27/2019] [Indexed: 12/14/2022] Open
Abstract
The yeast [PSI+] prion, formed by the Sup35 (eRF3) protein, has multiple structural variants differing in the strength of nonsense suppressor phenotype. Structure of [PSI+] and its variation are characterized poorly. Here, we mapped Sup35 amyloid cores of 26 [PSI+] ex vivo prions of different origin using proteinase K digestion and mass spectrometric identification of resistant peptides. In all [PSI+] variants the Sup35 amino acid residues 2-32 were fully resistant and the region up to residue 72 was partially resistant. Proteinase K-resistant structures were also found within regions 73-124, 125-153, and 154-221, but their presence differed between [PSI+] isolates. Two distinct digestion patterns were observed for region 2-72, which always correlated with the "strong" and "weak" [PSI+] nonsense suppressor phenotypes. Also, all [PSI+] with a weak pattern were eliminated by multicopy HSP104 gene and were not toxic when combined with multicopy SUP35. [PSI+] with a strong pattern showed opposite properties, being resistant to multicopy HSP104 and lethal with multicopy SUP35. Thus, Sup35 prion cores can be composed of up to four elements. [PSI+] variants can be divided into two classes reliably distinguishable basing on structure of the first element and the described assays.
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11
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Abstract
This commentary describes scientific path and accomplishments of our late colleague, Prof. Michael D. Ter-Avanesyan, who made several seminal contributions into prion research.
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Affiliation(s)
- Vitaly V Kushnirov
- a Research Center of Biotechnology of Russian Academy of Sciences , A.N. Bach Institute of Biochemistry , Moscow , Russia
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12
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Affiliation(s)
- Andrea N. Killian
- Department of Chemistry, Lafayette College, Easton, Pennsylvania, United States of America
| | - Justin K. Hines
- Department of Chemistry, Lafayette College, Easton, Pennsylvania, United States of America
- * E-mail:
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13
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Reid KM, Sunanda P, Raghothama S, Krishnan V. Ensemble characterization of an intrinsically disordered FG-Nup peptide and its F>A mutant in DMSO-d6. Biopolymers 2017; 108. [DOI: 10.1002/bip.23036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 06/13/2017] [Accepted: 06/26/2017] [Indexed: 11/06/2022]
Affiliation(s)
- Korey M. Reid
- Department of Chemistry; California State University; Fresno California 93740
| | - Punnepalli Sunanda
- NMR Research Centre, Indian Institute of Science; Bangalore 560012 India
| | - S. Raghothama
- NMR Research Centre, Indian Institute of Science; Bangalore 560012 India
| | - V.V. Krishnan
- Department of Chemistry; California State University; Fresno California 93740
- Department of Pathology and Laboratory Medicine, University of California School of Medicine; Davis California 95616
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14
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Shattuck JE, Waechter AC, Ross ED. The effects of glutamine/asparagine content on aggregation and heterologous prion induction by yeast prion-like domains. Prion 2017; 11:249-264. [PMID: 28665753 DOI: 10.1080/19336896.2017.1344806] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Prion-like domains are low complexity, intrinsically disordered domains that compositionally resemble yeast prion domains. Many prion-like domains are involved in the formation of either functional or pathogenic protein aggregates. These aggregates range from highly dynamic liquid droplets to highly ordered detergent-insoluble amyloid-like aggregates. To better understand the amino acid sequence features that promote conversion to stable, detergent-insoluble aggregates, we used the prediction algorithm PAPA to identify predicted aggregation-prone prion-like domains with a range of compositions. While almost all of the predicted aggregation-prone domains formed foci when expressed in cells, the ability to form the detergent-insoluble aggregates was highly correlated with glutamine/asparagine (Q/N) content, suggesting that high Q/N content may specifically promote conversion to the amyloid state in vivo. We then used this data set to examine cross-seeding between prion-like proteins. The prion protein Sup35 requires the presence of a second prion, [PIN+], to efficiently form prions, but this requirement can be circumvented by the expression of various Q/N-rich protein fragments. Interestingly, almost all of the Q/N-rich domains that formed SDS-insoluble aggregates were able to promote prion formation by Sup35, highlighting the highly promiscuous nature of these interactions.
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Affiliation(s)
- Jenifer E Shattuck
- a Department of Biochemistry and Molecular Biology , Colorado State University , Fort Collins , CO , USA
| | - Aubrey C Waechter
- a Department of Biochemistry and Molecular Biology , Colorado State University , Fort Collins , CO , USA
| | - Eric D Ross
- a Department of Biochemistry and Molecular Biology , Colorado State University , Fort Collins , CO , USA
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15
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Melanosomal formation of PMEL core amyloid is driven by aromatic residues. Sci Rep 2017; 7:44064. [PMID: 28272432 PMCID: PMC5341037 DOI: 10.1038/srep44064] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 02/01/2017] [Indexed: 12/05/2022] Open
Abstract
PMEL is a pigment cell protein that forms physiological amyloid in melanosomes. Many amyloids and/or their oligomeric precursors are toxic, causing or contributing to severe, incurable diseases including Alzheimer’s and prion diseases. Striking similarities in intracellular formation pathways between PMEL and various pathological amyloids including Aβ and PrPSc suggest PMEL is an excellent model system to study endocytic amyloid. Learning how PMEL fibrils assemble without apparent toxicity may help developing novel therapies for amyloid diseases. Here we identify the critical PMEL domain that forms the melanosomal amyloid core (CAF). An unbiased alanine-scanning screen covering the entire region combined with quantitative electron microscopy analysis of the full set of mutants uncovers numerous essential residues. Many of these rely on aromaticity for function suggesting a role for π-stacking in melanosomal amyloid assembly. Various mutants are defective in amyloid nucleation. This extensive data set informs the first structural model of the CAF and provides insights into how the melanosomal amyloid core forms.
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16
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Serpionov GV, Alexandrov AI, Ter-Avanesyan MD. Distinct mechanisms of mutant huntingtin toxicity in different yeast strains. FEMS Yeast Res 2016; 17:fow102. [PMID: 27915242 DOI: 10.1093/femsyr/fow102] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 10/17/2016] [Accepted: 12/01/2016] [Indexed: 11/12/2022] Open
Abstract
Expansion of polyglutamine stretches in several proteins causes neurodegenerative amyloidoses, including Huntington disease. In yeast, mutant huntingtin (mHtt) with a stretch of 103 glutamine residues (HttQ103) forms toxic aggregates. A range of yeast strains have been used to elucidate the mechanisms of mHtt toxicity, and have revealed perturbations of various unrelated processes. HttQ103 aggregates can induce aggregation of cellular proteins, many of which contain glutamine/asparagine-rich regions, including Sup35 and Def1. In the strain 74-D694 HttQ103, toxicity is related to aggregation-mediated depletion of soluble Sup35 and its interacting partner Sup45. Def1 was also implicated in mHtt toxicity, since its lack detoxified HttQ103 in another yeast strain, BY4741. Here we show that in BY4742, deletion of DEF1 lowers HttQ103 toxicity and decreases the amount of its polymers, but does not affect copolymerization of Sup35. Furthermore, in contrast to 74-D694, increasing the levels of soluble Sup35 and Sup45 does not alleviate toxicity of HttQ103 in BY4742. These data demonstrate a difference in the mechanisms underlying mHtt toxicity in different yeast strains and suggest that in humans with Huntington disease, neurons of different brain compartments and cells in other tissues can also be damaged by different mechanisms.
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Affiliation(s)
- Genrikh V Serpionov
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow 119071, Russia
| | - Alexander I Alexandrov
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow 119071, Russia
| | - Michael D Ter-Avanesyan
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow 119071, Russia
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17
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Distinct Prion Domain Sequences Ensure Efficient Amyloid Propagation by Promoting Chaperone Binding or Processing In Vivo. PLoS Genet 2016; 12:e1006417. [PMID: 27814358 PMCID: PMC5096688 DOI: 10.1371/journal.pgen.1006417] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 10/10/2016] [Indexed: 11/19/2022] Open
Abstract
Prions are a group of proteins that can adopt a spectrum of metastable conformations in vivo. These alternative states change protein function and are self-replicating and transmissible, creating protein-based elements of inheritance and infectivity. Prion conformational flexibility is encoded in the amino acid composition and sequence of the protein, which dictate its ability not only to form an ordered aggregate known as amyloid but also to maintain and transmit this structure in vivo. But, while we can effectively predict amyloid propensity in vitro, the mechanism by which sequence elements promote prion propagation in vivo remains unclear. In yeast, propagation of the [PSI+] prion, the amyloid form of the Sup35 protein, has been linked to an oligopeptide repeat region of the protein. Here, we demonstrate that this region is composed of separable functional elements, the repeats themselves and a repeat proximal region, which are both required for efficient prion propagation. Changes in the numbers of these elements do not alter the physical properties of Sup35 amyloid, but their presence promotes amyloid fragmentation, and therefore maintenance, by molecular chaperones. Rather than acting redundantly, our observations suggest that these sequence elements make complementary contributions to prion propagation, with the repeat proximal region promoting chaperone binding to and the repeats promoting chaperone processing of Sup35 amyloid. Protein misfolding and assembly into ordered aggregates known as amyloid has emerged as a novel mechanism for regulation of protein function. In the case of prion proteins, the resulting amyloid is transmissible, creating protein-based elements of infectivity and inheritance. These unusual properties are linked to the amino acid composition and sequence of the protein, which confer both conformational flexibility and persistence in vivo, the latter of which occurs through mechanisms that are currently poorly understood. Here, we address this open question by studying a region of the yeast prion Sup35 that has been genetically linked to persistence. We find that this region is composed of two separable elements that are both required for efficient persistence of the amyloid. These elements do not contribute to amyloid stability. Rather, they promote distinct aspects of its functional interactions with molecular chaperones, which are required for efficient conformational self-replication and transmission.
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A simple enrichment procedure improves detection of membrane proteins by immunoblotting. Biotechniques 2016; 61:260-261. [PMID: 27839511 DOI: 10.2144/000114474] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 08/03/2016] [Indexed: 11/23/2022] Open
Abstract
We developed a novel approach to improve detection of membrane-associated proteins in yeast cell lysates by immunoblotting. Our method consists of a simple enrichment procedure using sedimentation to remove soluble proteins and the use of an alternative electrophoresis sample buffer, which allows for protein solubilization without heating. The efficacy of this approach was demonstrated for membrane proteins in Hansenula polymorpha (Pho87, Gas1, and Pmr1) and Saccharomyces cerevisiae (Gas1). Immunoblot analysis of proteins that are not membrane-associated showed that the precipitate fraction was depleted of Sup45, carboxypeptidase Y, and Hog1; however, tubulin and, to some extent, Sup35 and Tpd3 were precipitated together with the membrane proteins. The presence of tubulin in the same fraction as the membrane proteins allows its use as a reference protein.
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Abstract
The yeast Saccharomyces cerevisiae can harbor a number of distinct prions. Most of the yeast prion proteins contain a glutamine/asparagine (Q/N) rich region that drives prion formation. Prion-like domains, defined as regions with high compositional similarity to yeast prion domains, are common in eukaryotic proteomes, and mutations in various human proteins containing prion-like domains have been linked to degenerative diseases, including amyotrophic lateral sclerosis. Here, we discuss a recent study in which we utilized two strategies to generate prion activity in non-prion Q/N-rich domains. First, we made targeted mutations in four non-prion Q/N-rich domains, replacing predicted prion-inhibiting amino acids with prion-promoting amino acids. All four mutants formed foci when expressed in yeast, and two acquired bona fide prion activity. Prion activity could be generated with as few as two mutations, suggesting that many non-prion Q/N-rich proteins may be just a small number of mutations from acquiring aggregation or prion activity. Second, we created tandem repeats of short prion-prone segments, and observed length-dependent prion activity. These studies demonstrate the considerable progress that has been made in understanding the sequence basis for aggregation of prion and prion-like domains, and suggest possible mechanisms by which new prion domains could evolve.
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Affiliation(s)
- Kacy R Paul
- a Department of Biochemistry and Molecular Biology ; Colorado State University ; Fort Collins , CO USA
| | - Eric D Ross
- a Department of Biochemistry and Molecular Biology ; Colorado State University ; Fort Collins , CO USA
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20
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Halfmann R. A glass menagerie of low complexity sequences. Curr Opin Struct Biol 2016; 38:18-25. [PMID: 27258703 DOI: 10.1016/j.sbi.2016.05.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 05/06/2016] [Accepted: 05/11/2016] [Indexed: 10/24/2022]
Abstract
Remarkably simple proteins play outsize roles in the execution of developmental complexity within biological systems. Sequence information determines structure and hence function, so how do low complexity sequences fulfill their functions? Recent discoveries are raising the curtain on a new dimension of the sequence-structure paradigm. In it, function derives not from the structures of individual proteins, but instead, from dynamic material properties of entire ensembles of the proteins acting in unison through phase changes. These phases include liquids, one-dimensional crystals, and - as elaborated herein - even glasses. The peculiar thermodynamics of glass-like protein assemblies, in particular, illuminate new principles of information flow through and, at times, orthogonal to the central dogma of molecular biology.
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Affiliation(s)
- Randal Halfmann
- Stowers Institute for Medical Research, 1000 E. 50th St., Kansas City, MO 64110, USA; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA.
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21
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Serpionov GV, Alexandrov AI, Antonenko YN, Ter-Avanesyan MD. A protein polymerization cascade mediates toxicity of non-pathological human huntingtin in yeast. Sci Rep 2015; 5:18407. [PMID: 26673834 PMCID: PMC4682096 DOI: 10.1038/srep18407] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 11/18/2015] [Indexed: 12/21/2022] Open
Abstract
Several neurodegenerative amyloidoses, including Huntington disease, are caused by expansion of polyglutamine (polyQ) stretches in otherwise unrelated proteins. In a yeast model, an N-terminal fragment of mutant huntingtin with a stretch of 103 glutamine residues aggregates and causes toxicity, while its non-toxic wild type variant with a sequence of 25 glutamines (Htt25Q) does not aggregate. Here, we observed that non-toxic polymers of various proteins with glutamine-rich domains could seed polymerization of Htt25Q, which caused toxicity by seeding polymerization of the glutamine/asparagine-rich Sup35 protein thus depleting the soluble pools of this protein and its interacting partner, Sup45. Importantly, only polymers of Htt25Q, but not of the initial benign polymers, induced Sup35 polymerization, indicating an intermediary role of Htt25Q in cross-seeding Sup35 polymerization. These data provide a novel insight into interactions between amyloidogenic proteins and suggest a possible role for these interactions in the pathogenesis of Huntington and other polyQ diseases.
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Affiliation(s)
- Genrikh V Serpionov
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences. 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Alexander I Alexandrov
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences. 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Yuri N Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie gori, 1, bldg. 40, Moscow 119991, Russia
| | - Michael D Ter-Avanesyan
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences. 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
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22
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Gasset-Rosa F, Giraldo R. Engineered bacterial hydrophobic oligopeptide repeats in a synthetic yeast prion, [REP-PSI (+)]. Front Microbiol 2015; 6:311. [PMID: 25954252 PMCID: PMC4404881 DOI: 10.3389/fmicb.2015.00311] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 03/29/2015] [Indexed: 11/25/2022] Open
Abstract
The yeast translation termination factor Sup35p, by aggregating as the [PSI (+)] prion, enables ribosomes to read-through stop codons, thus expanding the diversity of the Saccharomyces cerevisiae proteome. Yeast prions are functional amyloids that replicate by templating their conformation on native protein molecules, then assembling as large aggregates and fibers. Prions propagate epigenetically from mother to daughter cells by fragmentation of such assemblies. In the N-terminal prion-forming domain, Sup35p has glutamine/asparagine-rich oligopeptide repeats (OPRs), which enable propagation through chaperone-elicited shearing. We have engineered chimeras by replacing the polar OPRs in Sup35p by up to five repeats of a hydrophobic amyloidogenic sequence from the synthetic bacterial prionoid RepA-WH1. The resulting hybrid, [REP-PSI (+)], (i) was functional in a stop codon read-through assay in S. cerevisiae; (ii) generates weak phenotypic variants upon both its expression or transformation into [psi (-)] cells; (iii) these variants correlated with high molecular weight aggregates resistant to SDS during electrophoresis; and (iv) according to fluorescence microscopy, the fusion of the prion domains from the engineered chimeras to the reporter protein mCherry generated perivacuolar aggregate foci in yeast cells. All these are signatures of bona fide yeast prions. As assessed through biophysical approaches, the chimeras assembled as oligomers rather than as the fibers characteristic of [PSI (+)]. These results suggest that it is the balance between polar and hydrophobic residues in OPRs what determines prion conformational dynamics. In addition, our findings illustrate the feasibility of enabling new propagation traits in yeast prions by engineering OPRs with heterologous amyloidogenic sequence repeats.
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Affiliation(s)
| | - Rafael Giraldo
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas – Consejo Superior de Investigaciones CientíficasMadrid, Spain
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23
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Bondarev SA, Zhouravleva GA, Belousov MV, Kajava AV. Structure-based view on [PSI(+)] prion properties. Prion 2015; 9:190-9. [PMID: 26030475 PMCID: PMC4601339 DOI: 10.1080/19336896.2015.1044186] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 04/17/2015] [Accepted: 04/17/2015] [Indexed: 10/23/2022] Open
Abstract
Yeast [PSI(+)] prion is one of the most suitable and well characterized system for the investigation of the prion phenomenon. However, until recently, the lack of data on the 3D arrangement of Sup35p prion fibrils hindered progress in this area. The recent arrival in this field of new experimental techniques led to the parallel and in-register superpleated β-structure as a consensus model for Sup35p fibrils. Here, we analyzed the effect of amino acid substitutions of the Sup35 protein through the prism of this structural model. Application of a newly developed computational approach, called ArchCandy, gives us a better understanding of the effect caused by mutations on the fibril forming potential of Sup35 protein. This bioinformatics tool can be used for the design of new mutations with desired modification of prion properties. Thus, we provide examples of how today, having progress toward elucidation of the structural arrangement of Sup35p fibrils, researchers can advance more efficiently to a better understanding of prion [PSI(+)] stability and propagation.
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Key Words
- Asu mutations, antisupressor mutations
- EM, electron microscopy
- NMR, nuclear magnetic resonance
- PNM, [PSI+] no more
- STEM, scanning transmission electron microscopy
- amyloid, prion, protein misfolding, protein structure, Saccharomyces cerevisiae, superpleated β-structure, [PSI+]
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Affiliation(s)
- Stanislav A Bondarev
- Department of Genetics and Biotechnology; St. Petersburg State University; St. Petersburg, Russia
| | - Galina A Zhouravleva
- Department of Genetics and Biotechnology; St. Petersburg State University; St. Petersburg, Russia
| | - Mikhail V Belousov
- Department of Genetics and Biotechnology; St. Petersburg State University; St. Petersburg, Russia
| | - Andrey V Kajava
- Centre de Recherches de Biochimie Macromoléculaire; CNRS; Université Montpellier; Montpellier, Cedex 5, France
- University ITMO; St. Petersburg, Russia
- Institut de Biologie Computationnelle; Montpellier, Cedex 5, France
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Distinct amino acid compositional requirements for formation and maintenance of the [PSI⁺] prion in yeast. Mol Cell Biol 2014; 35:899-911. [PMID: 25547291 DOI: 10.1128/mcb.01020-14] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Multiple yeast prions have been identified that result from the structural conversion of proteins into a self-propagating amyloid form. Amyloid-based prion activity in yeast requires a series of discrete steps. First, the prion protein must form an amyloid nucleus that can recruit and structurally convert additional soluble proteins. Subsequently, maintenance of the prion during cell division requires fragmentation of these aggregates to create new heritable propagons. For the Saccharomyces cerevisiae prion protein Sup35, these different activities are encoded by different regions of the Sup35 prion domain. An N-terminal glutamine/asparagine-rich nucleation domain is required for nucleation and fiber growth, while an adjacent oligopeptide repeat domain is largely dispensable for prion nucleation and fiber growth but is required for chaperone-dependent prion maintenance. Although prion activity of glutamine/asparagine-rich proteins is predominantly determined by amino acid composition, the nucleation and oligopeptide repeat domains of Sup35 have distinct compositional requirements. Here, we quantitatively define these compositional requirements in vivo. We show that aromatic residues strongly promote both prion formation and chaperone-dependent prion maintenance. In contrast, nonaromatic hydrophobic residues strongly promote prion formation but inhibit prion propagation. These results provide insight into why some aggregation-prone proteins are unable to propagate as prions.
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Odani W, Urata K, Okuda M, Okuma S, Koyama H, Pack CG, Fujiwara K, Nojima T, Kinjo M, Kawai-Noma S, Taguchi H. Peptide sequences converting polyglutamine into a prion in yeast. FEBS J 2014; 282:477-90. [PMID: 25406629 DOI: 10.1111/febs.13152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Revised: 11/09/2014] [Accepted: 11/17/2014] [Indexed: 11/29/2022]
Abstract
Amyloids are ordered protein aggregates composed of cross-β sheet structures. Amyloids include prions, defined as infectious proteins, which are responsible for mammalian transmissible spongiform encephalopathies, and fungal prions. Although the conventional view is that typical amyloids are associated with nontransmissible mammalian neurodegenerative diseases such as Alzheimer's disease, increasing evidence suggests that the boundary between transmissible and nontransmissible amyloids is ambiguous. To clarify the mechanism underlying the difference in transmissibility, we investigated the dynamics and the properties of polyglutamine (polyQ) amyloids in yeast cells, in which the polyQ aggregates are not transmissible but can be converted into transmissible amyloids. We found that polyQ had an increased tendency to form aggregates compared to the yeast prion Sup35. In addition, we screened dozens of peptides that converted the nontransmissible polyQ to transmissible aggregates when they flanked the polyQ stretch, and also investigated their cellular dynamics aiming to understand the mechanism of transmission.
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Affiliation(s)
- Wataru Odani
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
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Agaphonov M, Alexandrov A. Self-excising integrative yeast plasmid vectors containing an intronated recombinase gene. FEMS Yeast Res 2014; 14:1048-54. [PMID: 25124534 DOI: 10.1111/1567-1364.12197] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Revised: 08/06/2014] [Accepted: 08/06/2014] [Indexed: 11/28/2022] Open
Abstract
Site-specific recombinases are widely used for selectable marker recycling in molecular-genetic manipulations with eukaryotic cells. This usually involves the use of two genetic constructs, one of which possesses a selectable marker flanked by the recombinase recognition sequences, while the other one bears the recombinase gene. Combining the recombinase gene with its recognition sequences in one plasmid is usually avoided, as it may lead to undesirable recombination due to promoter leakage, while the plasmid is maintained in Escherichia coli cells. Here, we describe yeast vectors possessing Cre recombinase genes under control of regulatable yeast promoters and loxP sequences for the in vivo vector backbone excision. The plasmid stability in E. coli is ensured by the presence of an intron in the recombinase gene. Applicability of these vectors was validated by disruptions of the Hansenula polymorpha PMC1 and Saccharomyces cerevisiae HSP104 and PRB1 genes.
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Affiliation(s)
- Michael Agaphonov
- A.N. Bach Institute of Biochemistry, Russian Academy of Science, Moscow, Russia
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27
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Stein KC, True HL. Extensive diversity of prion strains is defined by differential chaperone interactions and distinct amyloidogenic regions. PLoS Genet 2014; 10:e1004337. [PMID: 24811344 PMCID: PMC4014422 DOI: 10.1371/journal.pgen.1004337] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 03/13/2014] [Indexed: 11/27/2022] Open
Abstract
Amyloidogenic proteins associated with a variety of unrelated diseases are typically capable of forming several distinct self-templating conformers. In prion diseases, these different structures, called prion strains (or variants), confer dramatic variation in disease pathology and transmission. Aggregate stability has been found to be a key determinant of the diverse pathological consequences of different prion strains. Yet, it remains largely unclear what other factors might account for the widespread phenotypic variation seen with aggregation-prone proteins. Here, we examined a set of yeast prion variants of the [RNQ+] prion that differ in their ability to induce the formation of another yeast prion called [PSI+]. Remarkably, we found that the [RNQ+] variants require different, non-contiguous regions of the Rnq1 protein for both prion propagation and [PSI+] induction. This included regions outside of the canonical prion-forming domain of Rnq1. Remarkably, such differences did not result in variation in aggregate stability. Our analysis also revealed a striking difference in the ability of these [RNQ+] variants to interact with the chaperone Sis1. Thus, our work shows that the differential influence of various amyloidogenic regions and interactions with host cofactors are critical determinants of the phenotypic consequences of distinct aggregate structures. This helps reveal the complex interdependent factors that influence how a particular amyloid structure may dictate disease pathology and progression.
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Affiliation(s)
- Kevin C. Stein
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Heather L. True
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
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Bondarev SA, Shirokolobova ED, Trubitsina NP, Zhouravleva GA. Modification of [PSI +] prion properties by combining amino acid changes in N-terminal domain of Sup35 protein. Mol Biol 2014. [DOI: 10.1134/s0026893314020034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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29
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Abstract
Prion formation involves the conversion of proteins from a soluble form into an infectious amyloid form. Most yeast prion proteins contain glutamine/asparagine-rich regions that are responsible for prion aggregation. Prion formation by these domains is driven primarily by amino acid composition, not primary sequence, yet there is a surprising disconnect between the amino acids thought to have the highest aggregation propensity and those that are actually found in yeast prion domains. Specifically, a recent mutagenic screen suggested that both aromatic and non-aromatic hydrophobic residues strongly promote prion formation. However, while aromatic residues are common in yeast prion domains, non-aromatic hydrophobic residues are strongly under-represented. Here, we directly test the effects of hydrophobic and aromatic residues on prion formation. Remarkably, we found that insertion of as few as two hydrophobic residues resulted in a multiple orders-of-magnitude increase in prion formation, and significant acceleration of in vitro amyloid formation. Thus, insertion or deletion of hydrophobic residues provides a simple tool to control the prion activity of a protein. These data, combined with bioinformatics analysis, suggest a limit on the number of strongly prion-promoting residues tolerated in glutamine/asparagine-rich domains. This limit may explain the under-representation of non-aromatic hydrophobic residues in yeast prion domains. Prion activity requires not only that a protein be able to form prion fibers, but also that these fibers be cleaved to generate new independently-segregating aggregates to offset dilution by cell division. Recent studies suggest that aromatic residues, but not non-aromatic hydrophobic residues, support the fiber cleavage step. Therefore, we propose that while both aromatic and non-aromatic hydrophobic residues promote prion formation, aromatic residues are favored in yeast prion domains because they serve a dual function, promoting both prion formation and chaperone-dependent prion propagation.
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Abstract
A significant body of evidence shows that polyglutamine (polyQ) tracts are important for various biological functions. The characteristic polymorphism of polyQ length is thought to play an important role in the adaptation of organisms to their environment. However, proteins with expanded polyQ are prone to form amyloids, which cause diseases in humans and animals and toxicity in yeast. Saccharomyces cerevisiae contain at least 8 proteins which can form heritable amyloids, called prions, and most of them are proteins with glutamine- and asparagine-enriched domains. Yeast prion amyloids are susceptible to fragmentation by the protein disaggregase Hsp104, which allows them to propagate and be transmitted to daughter cells during cell divisions. We have previously shown that interspersion of polyQ domains with some non-glutamine residues stimulates fragmentation of polyQ amyloids in yeast and that yeast prion domains are often enriched in one of these residues. These findings indicate that yeast prion domains may have derived from polyQ tracts via accumulation and amplification of mutations. The same hypothesis may be applied to polyasparagine (polyN) tracts, since they display similar properties to polyQ, such as length polymorphism, amyloid formation and toxicity. We propose that mutations in polyQ/N may be favored by natural selection thus making prion domains likely by-products of the evolution of polyQ/N.
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Yeast prions and human prion-like proteins: sequence features and prediction methods. Cell Mol Life Sci 2014; 71:2047-63. [PMID: 24390581 DOI: 10.1007/s00018-013-1543-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/12/2013] [Accepted: 12/16/2013] [Indexed: 11/27/2022]
Abstract
Prions are self-propagating infectious protein isoforms. A growing number of prions have been identified in yeast, each resulting from the conversion of soluble proteins into an insoluble amyloid form. These yeast prions have served as a powerful model system for studying the causes and consequences of prion aggregation. Remarkably, a number of human proteins containing prion-like domains, defined as domains with compositional similarity to yeast prion domains, have recently been linked to various human degenerative diseases, including amyotrophic lateral sclerosis. This suggests that the lessons learned from yeast prions may help in understanding these human diseases. In this review, we examine what has been learned about the amino acid sequence basis for prion aggregation in yeast, and how this information has been used to develop methods to predict aggregation propensity. We then discuss how this information is being applied to understand human disease, and the challenges involved in applying yeast prediction methods to higher organisms.
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