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Wickner RB, Edskes HK, Son M, Wu S. Anti-Prion Systems Block Prion Transmission, Attenuate Prion Generation, Cure Most Prions as They Arise and Limit Prion-Induced Pathology in Saccharomyces cerevisiae. BIOLOGY 2022; 11:biology11091266. [PMID: 36138748 PMCID: PMC9495834 DOI: 10.3390/biology11091266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/08/2022] [Accepted: 08/16/2022] [Indexed: 11/16/2022]
Abstract
Simple Summary Virus and bacterial infections are opposed by their hosts at many levels. Similarly, we find that infectious proteins (prions) are severely restricted by an array of host systems, acting independently to prevent infection, generation, propagation and the ill effects of yeast prions. These ‘anti-prion systems’ work in normal cells without the overproduction or deficiency of any components. DNA repair systems reverse the effects of DNA damage, with only a rare lesion propagated as a mutation. Similarly, the combined effects of several anti-prion systems cure and block the generation of all but 1 in about 5000 prions arising. We expect that application of our approach to mammalian cells will detect analogous or even homologous systems that will be useful in devising therapy for human amyloidoses, most of which are prions. Abstract All variants of the yeast prions [PSI+] and [URE3] are detrimental to their hosts, as shown by the dramatic slowing of growth (or even lethality) of a majority, by the rare occurrence in wild isolates of even the mildest variants and by the absence of reproducible benefits of these prions. To deal with the prion problem, the host has evolved an array of anti-prion systems, acting in normal cells (without overproduction or deficiency of any component) to block prion transmission from other cells, to lower the rates of spontaneous prion generation, to cure most prions as they arise and to limit the damage caused by those variants that manage to elude these (necessarily) imperfect defenses. Here we review the properties of prion protein sequence polymorphisms Btn2, Cur1, Hsp104, Upf1,2,3, ribosome-associated chaperones, inositol polyphosphates, Sis1 and Lug1, which are responsible for these anti-prion effects. We recently showed that the combined action of ribosome-associated chaperones, nonsense-mediated decay factors and the Hsp104 disaggregase lower the frequency of [PSI+] appearance as much as 5000-fold. Moreover, while Btn2 and Cur1 are anti-prion factors against [URE3] and an unrelated artificial prion, they promote [PSI+] prion generation and propagation.
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Mozzachiodi S, Bai FY, Baldrian P, Bell G, Boundy-Mills K, Buzzini P, Čadež N, Riffo FC, Dashko S, Dimitrov R, Fisher KJ, Gibson BR, Gouliamova D, Greig D, Heistinger L, Hittinger CT, Jecmenica M, Koufopanou V, Landry CR, Mašínová T, Naumova ES, Opulente D, Peña JJ, Petrovič U, Tsai IJ, Turchetti B, Villarreal P, Yurkov A, Liti G, Boynton P. Yeasts from temperate forests. Yeast 2022; 39:4-24. [PMID: 35146791 DOI: 10.1002/yea.3699] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Yeasts are ubiquitous in temperate forests. While this broad habitat is well-defined, the yeasts inhabiting it and their life cycles, niches, and contributions to ecosystem functioning are less understood. Yeasts are present on nearly all sampled substrates in temperate forests worldwide. They associate with soils, macroorganisms, and other habitats, and no doubt contribute to broader ecosystem-wide processes. Researchers have gathered information leading to hypotheses about yeasts' niches and their life cycles based on physiological observations in the laboratory as well as genomic analyses, but the challenge remains to test these hypotheses in the forests themselves. Here we summarize the habitat and global patterns of yeast diversity, give some information on a handful of well-studied temperate forest yeast genera, discuss the various strategies to isolate forest yeasts, and explain temperate forest yeasts' contributions to biotechnology. We close with a summary of the many future directions and outstanding questions facing researchers in temperate forest yeast ecology. Yeasts present an exciting opportunity to better understand the hidden world of microbial ecology in this threatened and global habitat.
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Affiliation(s)
| | - Feng-Yan Bai
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Petr Baldrian
- Laboratory of Environmental Microbiology, Institute of Microbiology of the Czech Academy of Sciences, Praha 4, Czech Republic
| | - Graham Bell
- Biology Department and Redpath Museum, McGill University, Québec, Canada
| | - Kyria Boundy-Mills
- Department of Food Science and Technology, University of California Davis, Davis, CA, USA
| | - Pietro Buzzini
- Department of Agriculture, Food and Environmental Sciences & Industrial Yeasts Collection DBVPG, University of Perugia, Italy
| | - Neža Čadež
- Biotechnical Faculty, Food Science and Technology Department, University of Ljubljana, Ljubljana, Slovenia
| | - Francisco Cubillos Riffo
- Universidad de Santiago de Chile, Facultad de Química y Biología, Departamento de Biología, Santiago, Chile.,Millennium Institute for Integrative Biology (iBio), Santiago, Chile
| | - Sofia Dashko
- DSM Food Specialties, Center for Food Innovation, AX, Delft, The Netherlands
| | - Roumen Dimitrov
- Institute of Microbiology, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Kaitlin J Fisher
- Laboratory of Genetics, Wisconsin Energy Institute, DOE Great Lakes Bioenergy Research Center, Center for Genomic Science Innovation, J. F. Crow Institute for the Study of Evolution, University of Wisconsin-Madison, Madison, WI, USA
| | - Brian R Gibson
- Technische Universität Berlin, Institute of Food Technology and Food Chemistry, Chair of Brewing and Beverage Technology, Berlin, Germany
| | - Dilnora Gouliamova
- Institute of Microbiology, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Duncan Greig
- Centre for Life's Origins and Evolution, University College London, London, UK
| | - Lina Heistinger
- ETH Zurich, Department of Biology, Institute of Biochemistry, Switzerland
| | - Chris Todd Hittinger
- Laboratory of Genetics, Wisconsin Energy Institute, DOE Great Lakes Bioenergy Research Center, Center for Genomic Science Innovation, J. F. Crow Institute for the Study of Evolution, University of Wisconsin-Madison, Madison, WI, USA
| | | | | | - Christian R Landry
- Département de Biochimie, de Microbiologie et de Bio-informatique, Faculté des Sciences et de Génie, Université Laval, Canada.,Institut de Biologie Intégrative et des Systèmes, Université Laval, Canada.,PROTEO, Le regroupement québécois de recherche sur la fonction, l'ingénierie et les applications des protéines, Université Laval, Canada.,Centre de Recherche sur les Données Massives, Université Laval, Canada.,Département de Biologie, Faculté des Sciences et de Génie, Université Laval, Canada
| | - Tereza Mašínová
- Laboratory of Environmental Microbiology, Institute of Microbiology of the Czech Academy of Sciences, Praha 4, Czech Republic
| | - Elena S Naumova
- State Research Institute of Genetics and Selection of Industrial Microorganisms of National Research Centre "Kurchatov Institute", Moscow, Russia
| | - Dana Opulente
- Department of Biology, Villanova University, Villanova, Pennsylvania, USA
| | | | - Uroš Petrovič
- Biotechnical Faculty, Department of Biology, University of Ljubljana, Ljubljana, Slovenia.,Jožef Stefan Institute, Department of Molecular and Biomedical Sciences, Ljubljana, Slovenia
| | | | - Benedetta Turchetti
- Department of Agriculture, Food and Environmental Sciences & Industrial Yeasts Collection DBVPG, University of Perugia, Italy
| | - Pablo Villarreal
- Universidad de Santiago de Chile, Facultad de Química y Biología, Departamento de Biología, Santiago, Chile.,Millennium Institute for Integrative Biology (iBio), Santiago, Chile
| | - Andrey Yurkov
- Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Gianni Liti
- Université Côte d'Azur, CNRS, INSERM, IRCAN, Nice, France
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3
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Bai FY, Han DY, Duan SF, Wang QM. The Ecology and Evolution of the Baker’s Yeast Saccharomyces cerevisiae. Genes (Basel) 2022; 13:genes13020230. [PMID: 35205274 PMCID: PMC8871604 DOI: 10.3390/genes13020230] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 01/24/2022] [Accepted: 01/25/2022] [Indexed: 01/01/2023] Open
Abstract
The baker’s yeast Saccharomyces cerevisiae has become a powerful model in ecology and evolutionary biology. A global effort on field survey and population genetics and genomics of S. cerevisiae in past decades has shown that the yeast distributes ubiquitously in nature with clearly structured populations. The global genetic diversity of S. cerevisiae is mainly contributed by strains from Far East Asia, and the ancient basal lineages of the species have been found only in China, supporting an ‘out-of-China’ origin hypothesis. The wild and domesticated populations are clearly separated in phylogeny and exhibit hallmark differences in sexuality, heterozygosity, gene copy number variation (CNV), horizontal gene transfer (HGT) and introgression events, and maltose utilization ability. The domesticated strains from different niches generally form distinct lineages and harbor lineage-specific CNVs, HGTs and introgressions, which contribute to their adaptations to specific fermentation environments. However, whether the domesticated lineages originated from a single, or multiple domestication events is still hotly debated and the mechanism causing the diversification of the wild lineages remains to be illuminated. Further worldwide investigations on both wild and domesticated S. cerevisiae, especially in Africa and West Asia, will be helpful for a better understanding of the natural and domestication histories and evolution of S. cerevisiae.
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Affiliation(s)
- Feng-Yan Bai
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Chaoyang District, Beijing 100101, China; (D.-Y.H.); (S.-F.D.)
- College of Life Sciences, University of Chinese Academy of Sciences, Shijingshan District, Beijing 100049, China
- Correspondence: ; Tel.: +86-10-6480-7406
| | - Da-Yong Han
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Chaoyang District, Beijing 100101, China; (D.-Y.H.); (S.-F.D.)
| | - Shou-Fu Duan
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Chaoyang District, Beijing 100101, China; (D.-Y.H.); (S.-F.D.)
| | - Qi-Ming Wang
- School of Life Sciences, Institute of Life Sciences and Green Development, Hebei University, Baoding 071002, China;
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Chakravarty AK, Jarosz DF. More than Just a Phase: Prions at the Crossroads of Epigenetic Inheritance and Evolutionary Change. J Mol Biol 2018; 430:4607-4618. [PMID: 30031007 DOI: 10.1016/j.jmb.2018.07.017] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 07/08/2018] [Accepted: 07/16/2018] [Indexed: 12/11/2022]
Abstract
A central tenet of molecular biology is that heritable information is stored in nucleic acids. However, this paradigm has been overturned by a group of proteins called "prions." Prion proteins, many of which are intrinsically disordered, can adopt multiple conformations, at least one of which has the capacity to self-template. This unusual folding landscape drives a form of extreme epigenetic inheritance that can be stable through both mitotic and meiotic cell divisions. Although the first prion discovered-mammalian PrP-is the causative agent of debilitating neuropathies, many additional prions have now been identified that are not obviously detrimental and can even be adaptive. Intrinsically disordered regions, which endow proteins with the bulk property of "phase-separation," can also be drivers of prion formation. Indeed, many protein domains that promote phase separation have been described as prion-like. In this review, we describe how prions lie at the crossroads of phase separation, epigenetic inheritance, and evolutionary adaptation.
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Affiliation(s)
- Anupam K Chakravarty
- Department of Chemical and Systems Biology, Stanford University, 269 Campus Drive, Stanford, CA 94305, United States
| | - Daniel F Jarosz
- Department of Chemical and Systems Biology, Stanford University, 269 Campus Drive, Stanford, CA 94305, United States; Department of Developmental Biology, Stanford University, 269 Campus Drive, Stanford, CA 94305, United States.
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Cascarina SM, Paul KR, Machihara S, Ross ED. Sequence features governing aggregation or degradation of prion-like proteins. PLoS Genet 2018; 14:e1007517. [PMID: 30005071 PMCID: PMC6059496 DOI: 10.1371/journal.pgen.1007517] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 07/25/2018] [Accepted: 06/26/2018] [Indexed: 01/12/2023] Open
Abstract
Enhanced protein aggregation and/or impaired clearance of aggregates can lead to neurodegenerative disorders such as Alzheimer's Disease, Huntington's Disease, and prion diseases. Therefore, many protein quality control factors specialize in recognizing and degrading aggregation-prone proteins. Prions, which generally result from self-propagating protein aggregates, must therefore evade or outcompete these quality control systems in order to form and propagate in a cellular context. We developed a genetic screen in yeast that allowed us to explore the sequence features that promote degradation versus aggregation of a model glutamine/asparagine (Q/N)-rich prion domain from the yeast prion protein, Sup35, and two model glycine (G)-rich prion-like domains from the human proteins hnRNPA1 and hnRNPA2. Unexpectedly, we found that aggregation propensity and degradation propensity could be uncoupled in multiple ways. First, only a subset of classically aggregation-promoting amino acids elicited a strong degradation response in the G-rich prion-like domains. Specifically, large aliphatic residues enhanced degradation of the prion-like domains, whereas aromatic residues promoted prion aggregation without enhancing degradation. Second, the degradation-promoting effect of aliphatic residues was suppressed in the context of the Q/N-rich prion domain, and instead led to a dose-dependent increase in the frequency of spontaneous prion formation. Degradation suppression correlated with Q/N content of the surrounding prion domain, potentially indicating an underappreciated activity for these residues in yeast prion domains. Collectively, these results provide key insights into how certain aggregation-prone proteins may evade protein quality control degradation systems.
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Affiliation(s)
- Sean M. Cascarina
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Kacy R. Paul
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Satoshi Machihara
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Eric D. Ross
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States of America
- * E-mail:
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6
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Upadhyay A, Mishra A. Amyloids of multiple species: are they helpful in survival? Biol Rev Camb Philos Soc 2018; 93:1363-1386. [DOI: 10.1111/brv.12399] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 01/13/2018] [Accepted: 01/18/2018] [Indexed: 12/12/2022]
Affiliation(s)
- Arun Upadhyay
- Cellular and Molecular Neurobiology Unit; Indian Institute of Technology Jodhpur; Rajasthan 342011 India
| | - Amit Mishra
- Cellular and Molecular Neurobiology Unit; Indian Institute of Technology Jodhpur; Rajasthan 342011 India
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7
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Knowles TPJ, Mezzenga R. Amyloid Fibrils as Building Blocks for Natural and Artificial Functional Materials. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:6546-61. [PMID: 27165397 DOI: 10.1002/adma.201505961] [Citation(s) in RCA: 339] [Impact Index Per Article: 42.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 03/15/2016] [Indexed: 05/20/2023]
Abstract
Proteinaceous materials based on the amyloid core structure have recently been discovered at the origin of biological functionality in a remarkably diverse set of roles, and attention is increasingly turning towards such structures as the basis of artificial self-assembling materials. These roles contrast markedly with the original picture of amyloid fibrils as inherently pathological structures. Here we outline the salient features of this class of functional materials, both in the context of the functional roles that have been revealed for amyloid fibrils in nature, as well as in relation to their potential as artificial materials. We discuss how amyloid materials exemplify the emergence of function from protein self-assembly at multiple length scales. We focus on the connections between mesoscale structure and material function, and demonstrate how the natural examples of functional amyloids illuminate the potential applications for future artificial protein based materials.
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Affiliation(s)
- Tuomas P J Knowles
- Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW, Cambridge, United Kingdom
| | - Raffaele Mezzenga
- Department of Health Sciences and Technology, ETH Zurich, Switzerland
- Department of Materials Science, ETH Zurich, Switzerland
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8
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Abstract
Although prions were first discovered through their link to severe brain degenerative diseases in animals, the emergence of prions as regulators of the phenotype of the yeast Saccharomyces cerevisiae and the filamentous fungus Podospora anserina has revealed a new facet of prion biology. In most cases, fungal prions are carried without apparent detriment to the host cell, representing a novel form of epigenetic inheritance. This raises the question of whether or not yeast prions are beneficial survival factors or actually gives rise to a "disease state" that is selected against in nature. To date, most studies on the impact of fungal prions have focused on laboratory-cultivated "domesticated" strains of S. cerevisiae. At least eight prions have now been described in this species, each with the potential to impact on a wide range of cellular processes. The discovery of prions in nondomesticated strains of S. cerevisiae and P. anserina has confirmed that prions are not simply an artifact of "domestication" of this species. In this review, I describe what we currently know about the phenotypic impact of fungal prions. I then describe how the interplay between host genotype and the prion-mediated changes can generate a wide array of phenotypic diversity. How such prion-generated diversity may be of benefit to the host in survival in a fluctuating, often hazardous environment is then outlined. Prion research has now entered a new phase in which we must now consider their biological function and evolutionary significance in the natural world.
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Affiliation(s)
- Mick F Tuite
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, United Kingdom.
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9
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Abstract
The unusual genetic properties of the non-chromosomal genetic elements [URE3] and [PSI+] led to them being identified as prions (infectious proteins) of Ure2p and Sup35p respectively. Ure2p and Sup35p, and now several other proteins, can form amyloid, a linear ordered polymer of protein monomers, with a part of each molecule, the prion domain, forming the core of this β-sheet structure. Amyloid filaments passed to a new cell seed the conversion of the normal form of the protein into the same amyloid form. The cell's phenotype is affected, usually from the deficiency of the normal form of the protein. Solid-state NMR studies indicate that the yeast prion amyloids are in-register parallel β-sheet structures, in which each residue (e.g. Asn35) forms a row along the filament long axis. The favourable interactions possible for aligned identical hydrophilic and hydrophobic residues are believed to be the mechanism for propagation of amyloid conformation. Thus, just as DNA mediates inheritance by templating its own sequence, these proteins act as genes by templating their conformation. Distinct isolates of a given prion have different biological properties, presumably determined by differences between the amyloid structures. Many lines of evidence indicate that the Saccharomyces cerevisiae prions are pathological disease agents, although the example of the [Het-s] prion of Podospora anserina shows that a prion can have beneficial aspects.
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10
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Abstract
Sup35p of Saccharomyces cerevisiae can form the [PSI+] prion, an infectious amyloid in which the protein is largely inactive. The part of Sup35p that forms the amyloid is the region normally involved in control of mRNA turnover. The formation of [PSI+] by Sup35p's from other yeasts has been interpreted to imply that the prion-forming ability of Sup35p is conserved in evolution, and thus of survival/fitness/evolutionary value to these organisms. We surveyed a larger number of yeast and fungal species by the same criteria as used previously and find that the Sup35p from many species cannot form prions. [PSI+] could be formed by the Sup35p from Candida albicans, Candida maltosa, Debaromyces hansenii, and Kluyveromyces lactis, but orders of magnitude less often than the S. cerevisiae Sup35p converts to the prion form. The Sup35s from Schizosaccharomyces pombe and Ashbya gossypii clearly do not form [PSI+]. We were also unable to detect [PSI+] formation by the Sup35ps from Aspergillus nidulans, Aspergillus fumigatus, Magnaporthe grisea, Ustilago maydis, or Cryptococcus neoformans. Each of two C. albicans SUP35 alleles can form [PSI+], but transmission from one to the other is partially blocked. These results suggest that the prion-forming ability of Sup35p is not a conserved trait, but is an occasional deleterious side effect of a protein domain conserved for another function.
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Abstract
The conformational diseases, linked to protein aggregation into amyloid conformations, range from non-infectious neurodegenerative disorders, such as Alzheimer disease (AD), to highly infectious ones, such as human transmissible spongiform encephalopathies (TSEs). They are commonly known as prion diseases. However, since all amyloids could be considered prions (from those involved in cell-to-cell transmission to those responsible for real neuronal invasion), it is necessary to find an underlying cause of the different capacity to infect that each of the proteins prone to form amyloids has. As proposed here, both the intrinsic cytotoxicity and the number of nuclei of aggregation per cell could be key factors in this transmission capacity of each amyloid.
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Affiliation(s)
- Raimon Sabate
- Conformational Diseases Group; Department of Physical Chemistry; Faculty of Pharmacy; University of Barcelona (UB); Barcelona, Spain; Institut of Nanoscience and Nanotechnology of the University of Barcelona (IN2UB); Barcelona, Spain
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13
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Westergard L, True HL. Extracellular environment modulates the formation and propagation of particular amyloid structures. Mol Microbiol 2014; 92:698-715. [PMID: 24628771 DOI: 10.1111/mmi.12579] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/13/2014] [Indexed: 11/27/2022]
Abstract
Amyloidogenic proteins, including prions, assemble into multiple forms of structurally distinct fibres. The [PSI(+)] prion, endogenous to the yeast Saccharomyces cerevisiae, is a dominantly inherited, epigenetic modifier of phenotypes. [PSI(+)] formation relies on the coexistence of another prion, [RNQ(+)]. Here, in order to better define the role of amyloid diversity on cellular phenotypes, we investigated how physiological and environmental changes impact the generation and propagation of diverse protein conformations from a single polypeptide. Utilizing the yeast model system, we defined extracellular factors that influence the formation of a spectrum of alternative self-propagating amyloid structures of the Sup35 protein, called [PSI(+)] variants. Strikingly, exposure to specific stressful environments dramatically altered the variants of [PSI(+)] that formed de novo. Additionally, we found that stress also influenced the association between the [PSI(+)] and [RNQ(+)] prions in a way that it superceded their typical relationship. Furthermore, changing the growth environment modified both the biochemical properties and [PSI(+)]-inducing capabilities of the [RNQ(+)] template. These data suggest that the cellular environment contributes to both the generation and the selective propagation of specific amyloid structures, providing insight into a key feature that impacts phenotypic diversity in yeast and the cross-species transmission barriers characteristic of prion diseases.
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Affiliation(s)
- Laura Westergard
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
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14
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Abstract
Yeast prions are infectious proteins that spread exclusively by mating. The frequency of prions in the wild therefore largely reflects the rate of spread by mating counterbalanced by prion growth slowing effects in the host. We recently showed that the frequency of outcross mating is about 1% of mitotic doublings with 23–46% of total matings being outcrosses. These findings imply that even the mildest forms of the [PSI+], [URE3] and [PIN+] prions impart > 1% growth/survival detriment on their hosts. Our estimate of outcrossing suggests that Saccharomyces cerevisiae is far more sexual than previously thought and would therefore be more responsive to the adaptive effects of natural selection compared with a strictly asexual yeast. Further, given its large effective population size, a growth/survival detriment of > 1% for yeast prions should strongly select against prion-infected strains in wild populations of Saccharomyces cerevisiae.
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Affiliation(s)
- Amy C Kelly
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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15
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Abstract
The concept of a prion as an infectious self-propagating protein isoform was initially proposed to explain certain mammalian diseases. It is now clear that yeast also has heritable elements transmitted via protein. Indeed, the "protein only" model of prion transmission was first proven using a yeast prion. Typically, known prions are ordered cross-β aggregates (amyloids). Recently, there has been an explosion in the number of recognized prions in yeast. Yeast continues to lead the way in understanding cellular control of prion propagation, prion structure, mechanisms of de novo prion formation, specificity of prion transmission, and the biological roles of prions. This review summarizes what has been learned from yeast prions.
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Affiliation(s)
- Susan W Liebman
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada 89557, USA.
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Ramazzotti M, Berná L, Stefanini I, Cavalieri D. A computational pipeline to discover highly phylogenetically informative genes in sequenced genomes: application to Saccharomyces cerevisiae natural strains. Nucleic Acids Res 2012; 40:3834-48. [PMID: 22266652 PMCID: PMC3351171 DOI: 10.1093/nar/gks005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The quest for genes representing genetic relationships of strains or individuals within populations and their evolutionary history is acquiring a novel dimension of complexity with the advancement of next-generation sequencing (NGS) technologies. In fact, sequencing an entire genome uncovers genetic variation in coding and non-coding regions and offers the possibility of studying Saccharomyces cerevisiae populations at the strain level. Nevertheless, the disadvantageous cost-benefit ratio (the amount of details disclosed by NGS against the time-expensive and expertise-demanding data assembly process) still precludes the application of these techniques to the routinely assignment of yeast strains, making the selection of the most reliable molecular markers greatly desirable. In this work we propose an original computational approach to discover genes that can be used as a descriptor of the population structure. We found 13 genes whose variability can be used to recapitulate the phylogeny obtained from genome-wide sequences. The same approach that we prove to be successful in yeasts can be generalized to any other population of individuals given the availability of high-quality genomic sequences and of a clear population structure to be targeted.
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Affiliation(s)
- Matteo Ramazzotti
- Department of Preclinical and Clinical Pharmacology, University of Florence, Viale G. Pieraccini 6, 50139 Firenze, Italy
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[PSI+] Prion transmission barriers protect Saccharomyces cerevisiae from infection: intraspecies 'species barriers'. Genetics 2011; 190:569-79. [PMID: 22095075 DOI: 10.1534/genetics.111.136655] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
[PSI+] is a prion of Sup35p, an essential translation termination and mRNA turnover factor. The existence of lethal [PSI+] variants, the absence of [PSI+] in wild strains, the mRNA turnover function of the Sup35p prion domain, and the stress reaction to prion infection suggest that [PSI+] is a disease. Nonetheless, others have proposed that [PSI+] and other yeast prions benefit their hosts. We find that wild Saccharomyces cerevisiae strains are polymorphic for the sequence of the prion domain and particularly in the adjacent M domain. Here we establish that these variations within the species produce barriers to prion transmission. The barriers are partially asymmetric in some cases, and evidence for variant specificity in barriers is presented. We propose that, as the PrP 129M/V polymorphism protects people from Creutzfeldt-Jakob disease, the Sup35p polymorphisms were selected to protect yeast cells from prion infection. In one prion incompatibility group, the barrier is due to N109S in the Sup35 prion domain and several changes in the middle (M) domain, with either the single N109S mutation or the group of M changes (without the N109S) producing a barrier. In another, the barrier is due to a large deletion in the repeat domain. All are outside the region previously believed to determine transmission compatibility. [SWI+], a prion of the chromatin remodeling factor Swi1p, was also proposed to benefit its host. We find that none of 70 wild strains carry this prion, suggesting that it is not beneficial.
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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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Baudin-Baillieu A, Fabret C, Namy O. Are prions part of the dark matter of the cell? Prion 2011; 5:299-304. [PMID: 22052346 DOI: 10.4161/pri.18316] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The [PSI+] determinant in Saccharomyces cerevisiae is the prion protein corresponding to the eRF3 translation termination factor. Numerous infectious proteins have been described in yeast, in comparison of the unique PrP protein in higher eukaryotes. The presence of the PrP prion is associated with mammalian diseases. Whether fungal prions are beneficial or deleterious are still under discussions. The review focuses on [PSI+]-induced phenotypes and the resulting physiological consequences to shed light on the cellular changes occurring in a [PSI+] cell and its possible role in nature. To date, only two genes directly regulated at the translational level by [PSI+] have been identified. Yet, through all the published works, obtaining a consensus for the described [PSI+] phenotypes appeared a tricky task. They are highly dependent on the prion variant and the genetic background of the strain. The [PSI+] prion might generate diverse modifications not only at the translational, but also at the transcriptional levels, and the phenotypic heterogeneity is the result of these complex combinations of the genotypic expression.
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20
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Baudin-Baillieu A, Fabret C, Namy O. Are prions part of the dark matter of the cell? Prion 2011; 5. [PMID: 22052346 PMCID: PMC4012406 DOI: 10.4161/pri.5.4.18316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The [PSI+] determinant in Saccharomyces cerevisiae is the prion protein corresponding to the eRF3 translation termination factor. Numerous infectious proteins have been described in yeast, in comparison of the unique PrP protein in higher eukaryotes. The presence of the PrP prion is associated with mammalian diseases. Whether fungal prions are beneficial or deleterious are still under discussions. The review focuses on [PSI+]-induced phenotypes and the resulting physiological consequences to shed light on the cellular changes occurring in a [PSI+] cell and its possible role in nature. To date, only two genes directly regulated at the translational level by [PSI+] have been identified. Yet, through all the published works, obtaining a consensus for the described [PSI+] phenotypes appeared a tricky task. They are highly dependent on the prion variant and the genetic background of the strain. The [PSI+] prion might generate diverse modifications not only at the translational, but also at the transcriptional levels, and the phenotypic heterogeneity is the result of these complex combinations of the genotypic expression.
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21
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Chen B, Bruce KL, Newnam GP, Gyoneva S, Romanyuk AV, Chernoff YO. Genetic and epigenetic control of the efficiency and fidelity of cross-species prion transmission. Mol Microbiol 2010; 76:1483-99. [PMID: 20444092 DOI: 10.1111/j.1365-2958.2010.07177.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Self-perpetuating amyloid-based protein isoforms (prions) transmit neurodegenerative diseases in mammals and phenotypic traits in yeast. Although mechanisms that control species specificity of prion transmission are poorly understood, studies of closely related orthologues of yeast prion protein Sup35 demonstrate that cross-species prion transmission is modulated by both genetic (specific sequence elements) and epigenetic (prion variants, or 'strains') factors. Depending on the prion variant, the species barrier could be controlled at the level of either heterologous co-aggregation or conversion of the aggregate-associated heterologous protein into a prion polymer. Sequence divergence influences cross-species transmission of different prion variants in opposing ways. The ability of a heterologous prion domain to either faithfully reproduce or irreversibly switch the variant-specific prion patterns depends on both sequence divergence and the prion variant. Sequence variations within different modules of prion domains contribute to transmission barriers in different cross-species combinations. Individual amino acid substitutions within short amyloidogenic stretches drastically alter patterns of cross-species prion conversion, implicating these stretches as major determinants of species specificity.
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Affiliation(s)
- Buxin Chen
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA 30332-0230, USA
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22
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Drummond DA, Wilke CO. The evolutionary consequences of erroneous protein synthesis. Nat Rev Genet 2009; 10:715-24. [PMID: 19763154 DOI: 10.1038/nrg2662] [Citation(s) in RCA: 357] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Errors in protein synthesis disrupt cellular fitness, cause disease phenotypes and shape gene and genome evolution. Experimental and theoretical results on this topic have accumulated rapidly in disparate fields, such as neurobiology, protein biosynthesis and degradation and molecular evolution, but with limited communication among disciplines. Here, we review studies of error frequencies, the cellular and organismal consequences of errors and the attendant long-range evolutionary responses to errors. We emphasize major areas in which little is known, such as the failure rates of protein folding, in addition to areas in which technological innovations may enable imminent gains, such as the elucidation of translational missense error frequencies. Evolutionary responses to errors fall into two broad categories: adaptations that minimize errors and their attendant costs and adaptations that exploit errors for the organism's benefit.
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Affiliation(s)
- D Allan Drummond
- FAS Center for Systems Biology, Harvard University, 52 Oxford Street, Cambridge, MA 02138, USA
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23
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Mironova LN, Goginashvili AI, Ter-Avanesyan MD. Biological functions of amyloids: Facts and hypotheses. Mol Biol 2008. [DOI: 10.1134/s0026893308050087] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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24
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Tsai IJ, Bensasson D, Burt A, Koufopanou V. Population genomics of the wild yeast Saccharomyces paradoxus: Quantifying the life cycle. Proc Natl Acad Sci U S A 2008; 105:4957-62. [PMID: 18344325 PMCID: PMC2290798 DOI: 10.1073/pnas.0707314105] [Citation(s) in RCA: 255] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Indexed: 01/12/2023] Open
Abstract
Most microbes have complex life cycles with multiple modes of reproduction that differ in their effects on DNA sequence variation. Population genomic analyses can therefore be used to estimate the relative frequencies of these different modes in nature. The life cycle of the wild yeast Saccharomyces paradoxus is complex, including clonal reproduction, outcrossing, and two different modes of inbreeding. To quantify these different aspects we analyzed DNA sequence variation in the third chromosome among 20 isolates from two populations. Measures of mutational and recombinational diversity were used to make two independent estimates of the population size. In an obligately sexual population these values should be approximately equal. Instead there is a discrepancy of about three orders of magnitude between our two estimates of population size, indicating that S. paradoxus goes through a sexual cycle approximately once in every 1,000 asexual generations. Chromosome III also contains the mating type locus (MAT), which is the most outbred part in the entire genome, and by comparing recombinational diversity as a function of distance from MAT we estimate the frequency of matings to be approximately 94% from within the same tetrad, 5% with a clonemate after switching the mating type, and 1% outcrossed. Our study illustrates the utility of population genomic data in quantifying life cycles.
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Affiliation(s)
- Isheng J. Tsai
- Division of Biology, Imperial College London, Silwood Park, Ascot, Berks SL5 7PY, United Kingdom
| | - Douda Bensasson
- Division of Biology, Imperial College London, Silwood Park, Ascot, Berks SL5 7PY, United Kingdom
| | - Austin Burt
- Division of Biology, Imperial College London, Silwood Park, Ascot, Berks SL5 7PY, United Kingdom
| | - Vassiliki Koufopanou
- Division of Biology, Imperial College London, Silwood Park, Ascot, Berks SL5 7PY, United Kingdom
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25
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Inge-Vechtomov SG, Zhouravleva GA, Chernoff YO. Biological roles of prion domains. Prion 2007; 1:228-35. [PMID: 19172114 PMCID: PMC2634536 DOI: 10.4161/pri.1.4.5059] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Accepted: 08/06/2007] [Indexed: 11/19/2022] Open
Abstract
In vivo amyloid formation is a widespread phenomenon in eukaryotes. Self-perpetuating amyloids provide a basis for the infectious or heritable protein isoforms (prions). At least for some proteins, amyloid-forming potential is conserved in evolution despite divergence of the amino acid (aa) sequences. In some cases, prion formation certainly represents a pathological process leading to a disease. However, there are several scenarios in which prions and other amyloids or amyloid-like aggregates are either shown or suspected to perform positive biological functions. Proven examples include self/nonself recognition, stress defense and scaffolding of other (functional) polymers. The role of prion-like phenomena in memory has been hypothesized. As an additional mechanism of heritable change, prion formation may in principle contribute to heritable variability at the population level. Moreover, it is possible that amyloid-based prions represent by-products of the transient feedback regulatory circuits, as normal cellular function of at least some prion proteins is decreased in the prion state.
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26
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Fowler DM, Koulov AV, Balch WE, Kelly JW. Functional amyloid--from bacteria to humans. Trends Biochem Sci 2007; 32:217-24. [PMID: 17412596 DOI: 10.1016/j.tibs.2007.03.003] [Citation(s) in RCA: 802] [Impact Index Per Article: 47.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 02/08/2007] [Accepted: 03/21/2007] [Indexed: 01/22/2023]
Abstract
Amyloid--a fibrillar, cross beta-sheet quaternary structure--was first discovered in the context of human disease and tissue damage, and was thought to always be detrimental to the host. Recent studies have identified amyloid fibers in bacteria, fungi, insects, invertebrates and humans that are functional. For example, human Pmel17 has important roles in the biosynthesis of the pigment melanin, and the factor XII protein of the hemostatic system is activated by amyloid. Functional amyloidogenesis in these systems requires tight regulation to avoid toxicity. A greater understanding of the diverse physiological applications of this fold has the potential to provide a fresh perspective for the treatment of amyloid diseases.
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Affiliation(s)
- Douglas M Fowler
- Department of Chemistry and The Skaggs Institute of Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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27
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Harrison LB, Yu Z, Stajich JE, Dietrich FS, Harrison PM. Evolution of Budding Yeast Prion-determinant Sequences Across Diverse Fungi. J Mol Biol 2007; 368:273-82. [PMID: 17320905 DOI: 10.1016/j.jmb.2007.01.070] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 01/01/2007] [Accepted: 01/25/2007] [Indexed: 11/21/2022]
Abstract
Prions are transmissible self-replicating alternative states of proteins. Four prions ([PSI+], [URE3], [RNQ+] and [NU+]) can be inherited cytoplasmically in Saccharomyces cerevisiae laboratory strains. In the case of [PSI+], there is increasing evidence that prion formation may engender mechanisms to uncover hidden genetic variation. Here, we have analysed the evolution of the prion-determinant (PD) domains across 21 fungi, focusing on compositional biases, repeats and substitution rates. We find evidence for constraint on all four PD domains, but each domain has its own evolutionary dynamics. For [PSI+], the Q/N bias is maintained in fungal clades that diverged one billion years ago, with purifying selection observed within the Saccharomyces species. The degree of Q/N bias is correlated with the degree of local homology to prion-associated repeats, which occur rarely in other proteins (<1% of sequences for the proteomes studied). The evolutionary conservation of Q/N bias in Sup35p is unusual, with only eight other S. cerevisiae proteins showing similar, phylogenetically deep patterns of bias conservation. The [URE3] PD domain is unique to Hemiascomycota; part of the PD domain shows purifying selection, whereas another part engenders bias changes between clades. Also, like for Sup35p, the [RNQ+] and [NU+] PD domains show purifying selection in Saccharomyces species. Additionally, in each proteome, we observe on average several hundred yeast-prion-like domains, with fewest in fission yeast. Our findings on yeast prion evolution provide further support for the functional significance of these molecules.
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Affiliation(s)
- Luke B Harrison
- Department of Biology, McGill University, Stewart Biology Building, 1205 Docteur Penfield Ave, Montreal, QC, Canada H3A 1B1
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28
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Chen B, Newnam GP, Chernoff YO. Prion species barrier between the closely related yeast proteins is detected despite coaggregation. Proc Natl Acad Sci U S A 2007; 104:2791-6. [PMID: 17296932 PMCID: PMC1815260 DOI: 10.1073/pnas.0611158104] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Prions are self-perpetuating and, in most cases, aggregation-prone protein isoforms that transmit neurodegenerative diseases in mammals and control heritable traits in yeast. Prion conversion requires a very high level of identity of the interacting protein sequences. Decreased transmission of the prion state between divergent proteins is termed "species barrier" and was thought to occur because of the inability of divergent prion proteins to coaggregate. Species barrier can be overcome in cross-species infections, e.g., from "mad cows" to humans. We studied the counterparts of yeast prion protein Sup35, originated from three different species of the Saccharomyces sensu stricto group and exhibiting the range of prion domain divergence that overlaps with the range of divergence observed among distant mammalian species. All three proteins were capable of forming a prion in Saccharomyces cerevisiae, although prions formed by heterologous proteins were usually less stable than the endogenous S. cerevisiae prion. Heterologous Sup35 proteins coaggregated in the S. cerevisiae cells. However, in vivo cross-species prion conversion was decreased and in vitro polymerization was cross-inhibited in at least some heterologous combinations, thus demonstrating the existence of prion species barrier. Moreover, the barrier between the S. cerevisiae protein and its Saccharomyces paradoxus and Saccharomyces bayanus counterparts was asymmetric both in vivo and in vitro. Our data show that a decreased cross-species prion transmission does not necessarily correlate with a lack of cross-species coaggregation, suggesting that species-specificity of prion transmission is controlled at the level of conformational transition rather than coaggregation.
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Affiliation(s)
- Buxin Chen
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA 30332-0230
| | - Gary P. Newnam
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA 30332-0230
| | - Yury O. Chernoff
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA 30332-0230
- *To whom correspondence should be addressed. E-mail:
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29
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Landry CR, Townsend JP, Hartl DL, Cavalieri D. Ecological and evolutionary genomics of Saccharomyces cerevisiae. Mol Ecol 2006; 15:575-91. [PMID: 16499686 DOI: 10.1111/j.1365-294x.2006.02778.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Saccharomyces cerevisiae, the budding yeast, is the most thoroughly studied eukaryote at the cellular, molecular, and genetic levels. Yet, until recently, we knew very little about its ecology or population and evolutionary genetics. In recent years, it has been recognized that S. cerevisiae occupies numerous habitats and that populations harbour important genetic variation. There is therefore an increasing interest in understanding the evolutionary forces acting on the yeast genome. Several researchers have used the tools of functional genomics to study natural isolates of this unicellular fungus. Here, we review some of these studies, and show not only that budding yeast is a prime model system to address fundamental molecular and cellular biology questions, but also that it is becoming a powerful model species for ecological and evolutionary genomics studies as well.
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Affiliation(s)
- Christian R Landry
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
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30
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Nakayashiki T, Kurtzman CP, Edskes HK, Wickner RB. Yeast prions [URE3] and [PSI+] are diseases. Proc Natl Acad Sci U S A 2005; 102:10575-80. [PMID: 16024723 PMCID: PMC1180808 DOI: 10.1073/pnas.0504882102] [Citation(s) in RCA: 205] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Viruses, plasmids, and prions can spread in nature despite being a burden to their hosts. Because a prion arises de novo in more than one in 10(6) yeast cells and spreads to all offspring in meiosis, its absence in wild strains would imply that it has a net deleterious effect on its host. Among 70 wild Saccharomyces strains, we found the [PIN+] prion in 11 strains, but the [URE3] and [PSI+] prions were uniformly absent. In contrast, the "selfish" 2mu DNA was in 38 wild strains and the selfish RNA replicons L-BC, 20S, and 23S were found in 8, 14, and 1 strains, respectively. The absence of [URE3] and [PSI+] in wild strains indicates that each prion has a net deleterious effect on its host.
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Affiliation(s)
- Toru Nakayashiki
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 8, Room 225, Bethesda, MD 20892-0830, USA
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31
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Qin H, Wu WB, Comeron JM, Kreitman M, Li WH. Intragenic spatial patterns of codon usage bias in prokaryotic and eukaryotic genomes. Genetics 2005; 168:2245-60. [PMID: 15611189 PMCID: PMC1448744 DOI: 10.1534/genetics.104.030866] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To study the roles of translational accuracy, translational efficiency, and the Hill-Robertson effect in codon usage bias, we studied the intragenic spatial distribution of synonymous codon usage bias in four prokaryotic (Escherichia coli, Bacillus subtilis, Sulfolobus tokodaii, and Thermotoga maritima) and two eukaryotic (Saccharomyces cerevisiae and Drosophila melanogaster) genomes. We generated supersequences at each codon position across genes in a genome and computed the overall bias at each codon position. By quantitatively evaluating the trend of spatial patterns using isotonic regression, we show that in yeast and prokaryotic genomes, codon usage bias increases along translational direction, which is consistent with purifying selection against nonsense errors. Fruit fly genes show a nearly symmetric M-shaped spatial pattern of codon usage bias, with less bias in the middle and both ends. The low codon usage bias in the middle region is best explained by interference (the Hill-Robertson effect) between selections at different codon positions. In both yeast and fruit fly, spatial patterns of codon usage bias are characteristically different from patterns of GC-content variations. Effect of expression level on the strength of codon usage bias is more conspicuous than its effect on the shape of the spatial distribution.
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Affiliation(s)
- Hong Qin
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637, USA
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32
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Krishnan R, Lindquist SL. Structural insights into a yeast prion illuminate nucleation and strain diversity. Nature 2005; 435:765-72. [PMID: 15944694 PMCID: PMC1405905 DOI: 10.1038/nature03679] [Citation(s) in RCA: 412] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2004] [Accepted: 04/26/2005] [Indexed: 11/10/2022]
Abstract
Self-perpetuating changes in the conformations of amyloidogenic proteins play vital roles in normal biology and disease. Despite intense research, the architecture and conformational conversion of amyloids remain poorly understood. Amyloid conformers of Sup35 are the molecular embodiment of the yeast prion known as [PSI], which produces heritable changes in phenotype through self-perpetuating changes in protein folding. Here we determine the nature of Sup35's cooperatively folded amyloid core, and use this information to investigate central questions in prion biology. Specific segments of the amyloid core form intermolecular contacts in a 'Head-to-Head', 'Tail-to-Tail' fashion, but the 'Central Core' is sequestered through intramolecular contacts. The Head acquires productive interactions first, and these nucleate assembly. Variations in the length of the amyloid core and the nature of intermolecular interfaces form the structural basis of distinct prion 'strains', which produce variant phenotypes in vivo. These findings resolve several problems in yeast prion biology and have broad implications for other amyloids.
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Affiliation(s)
| | - Susan L. Lindquist
- *Corresponding author, Whitehead Institute for Biomedical Research, Phone: 617-258-5184, Fax: 617-258-7226,
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33
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Abstract
Compared to protein-coding sequences, the evolution of noncoding sequences and the selective constraints placed on these sequences is not well characterized. To compare the evolution of coding and noncoding sequences, we have conducted a survey for DNA polymorphism at five randomly chosen loci among a diverse collection of 81 strains of Saccharomyces cerevisiae. Average rates of both polymorphism and divergence are 40% lower at noncoding sites and 90% lower at nonsynonymous sites in comparison to synonymous sites. Although noncoding and coding sequences show substantial variability in ratios of polymorphism to divergence, two of the loci, MLS1 and PDR10, show a higher rate of polymorphism at noncoding compared to synonymous sites. The high rate of polymorphism is not accompanied by a high rate of divergence and is limited to a few small regions. These hypervariable regions include sites with three segregating bases at a single site and adjacent polymorphic sites. We show that this clustering of polymorphic sites is significantly greater than one would expect on the basis of the spacing between polymorphic fourfold degenerate sites. Although hypervariable noncoding sequences could result from selection on regulatory mutations, they could also result from transient mutational hotspots.
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Affiliation(s)
- Justin C Fay
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63108, USA.
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34
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Talarek N, Maillet L, Cullin C, Aigle M. The [URE3] prion is not conserved among Saccharomyces species. Genetics 2005; 171:23-34. [PMID: 15956663 PMCID: PMC1456514 DOI: 10.1534/genetics.105.043489] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The [URE3] prion of Saccharomyces cerevisiae is a self-propagating inactive form of the nitrogen catabolism regulator Ure2p. To determine whether the [URE3] prion is conserved in S. cerevisiae-related yeast species, we have developed genetic tools allowing the detection of [URE3] in Saccharomyces paradoxus and Saccharomyces uvarum. We found that [URE3] is conserved in S. uvarum. In contrast, [URE3] was not detected in S. paradoxus. The inability of S. paradoxus Ure2p to switch to a prion isoform results from the primary sequence of the protein and not from the lack of cellular cofactors as heterologous Ure2p can propagate [URE3] in this species. Our data therefore demonstrate that [URE3] is conserved only in a subset of Saccharomyces species. Implications of our finding on the physiological and evolutionary meaning of the yeast [URE3] prion are discussed.
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Affiliation(s)
- Nicolas Talarek
- IBGC-CNRS/Université Victor Segalen Bordeaux2, UMR 5095, 33077 Bordeaux, France.
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35
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Abstract
Changes in protein conformation drive most biological processes, but none have seized the imagination of scientists and the public alike as have the self-replicating conformations of prions. Prions transmit lethal neurodegenerative diseases by means of the food chain. However, self-replicating protein conformations can also constitute molecular memories that transmit genetic information. Here, we showcase definitive evidence for the prion hypothesis and discuss examples in which prion-encoded heritable information has been harnessed during evolution to confer selective advantages. We then describe situations in which prion-enciphered events might have essential roles in long-term memory formation, transcriptional memory and genome-wide expression patterns.
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Affiliation(s)
- James Shorter
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA.
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36
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Chernoff YO. Amyloidogenic domains, prions and structural inheritance: rudiments of early life or recent acquisition? Curr Opin Chem Biol 2004; 8:665-71. [PMID: 15556413 DOI: 10.1016/j.cbpa.2004.09.002] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Amyloids are self-assembled fibre-like beta-rich protein aggregates. Amyloidogenic prion proteins propagate amyloid state in vivo and transmit it via infection or in cell divisions. While amyloid aggregation may occur in the absence of any other proteins, in vivo propagation of the amyloid state requires chaperone helpers. Yeast prion proteins contain prion domains which include distinct aggregation and propagation elements, responsible for these functions. Known aggregation and propagation elements are short in length and composed of relatively simple sequences, indicating possible ancient origin. Prion-like self-assembled structures could be involved in the initial steps of biological compartmentalization in early life.
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Affiliation(s)
- Yury O Chernoff
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 315 Ferst Drive, Atlanta, Georgia 30332-0363, USA.
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37
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Marais G, Charlesworth B, Wright SI. Recombination and base composition: the case of the highly self-fertilizing plant Arabidopsis thaliana. Genome Biol 2004; 5:R45. [PMID: 15239830 PMCID: PMC463295 DOI: 10.1186/gb-2004-5-7-r45] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2004] [Revised: 04/26/2004] [Accepted: 04/30/2004] [Indexed: 11/24/2022] Open
Abstract
The effects of recombination and self-fertilization on base composition were investigated both theoretically and experimentally in the Arabidopsis genome. Levels of inbreeding modulate the effect of recombination on base composition. Background Rates of recombination can vary among genomic regions in eukaryotes, and this is believed to have major effects on their genome organization in terms of base composition, DNA repeat density, intron size, evolutionary rates and gene order. In highly self-fertilizing species such as Arabidopsis thaliana, however, heterozygosity is expected to be strongly reduced and recombination will be much less effective, so that its influence on genome organization should be greatly reduced. Results Here we investigated theoretically the joint effects of recombination and self-fertilization on base composition, and tested the predictions with genomic data from the complete A. thaliana genome. We show that, in this species, both codon-usage bias and GC content do not correlate with the local rates of crossing over, in agreement with our theoretical results. Conclusions We conclude that levels of inbreeding modulate the effect of recombination on base composition, and possibly other genomic features (for example, transposable element dynamics). We argue that inbreeding should be considered when interpreting patterns of molecular evolution.
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Affiliation(s)
- G Marais
- Institute of Cell, Animal and Population Biology, University of Edinburgh, EH9 3JT Edinburgh, UK
| | - B Charlesworth
- Institute of Cell, Animal and Population Biology, University of Edinburgh, EH9 3JT Edinburgh, UK
| | - S I Wright
- Institute of Cell, Animal and Population Biology, University of Edinburgh, EH9 3JT Edinburgh, UK
- Current address: Department of Biology, York University, 4700 Keele St, Toronto, Ontario M3J 1P3, Canada
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38
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Abstract
An accurate view of adaptive mutations is essential to evolutionary genetics, but their rarity makes them difficult to study. This can be partially overcome using the many tools of yeast genetics and the ability to study very large populations over many generations. Adaptation to laboratory environments has occurred primarily by chromosomal rearrangements, often involving retrotransposons and apparently selected for their effects on gene regulation. Estimated rates of adaptive mutation are on the order of 1 in 10(11) cell divisions. There remains great potential for the genomic study of variation within yeast species to contribute to our understanding of adaptive mutation.
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Affiliation(s)
- Clifford Zeyl
- Department of Biology, Wake Forest University, P.O. Box 7325, Winston-Salem, NC 27109, USA.
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39
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Abstract
Morphological plasticity is a hallmark of eumycetes. In addition to genes and environment, epigenetic factors control cell, colony and thallus forms in many species, by creating reversible switches. Current knowledge indicates that the different shapes are due to structural or regulatory heritable states of cytoplasmic components. Cellular physiology differs in the various forms, permitting adaptation to fluctuation in the environment. These switches are part of the adaptation repertoire that fungi exhibit to colonize most niches.
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Affiliation(s)
- Fabienne Malagnac
- Institut de Génétique et Microbiologie, UMR CNRS 8621 Université de Paris Sud, 91405 Orsay cedex, France.
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40
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Resende CG, Outeiro TF, Sands L, Lindquist S, Tuite MF. Prion protein gene polymorphisms in Saccharomyces cerevisiae. Mol Microbiol 2003; 49:1005-17. [PMID: 12890024 DOI: 10.1046/j.1365-2958.2003.03608.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The yeast Saccharomyces cerevisiae genome encodes several proteins that, in laboratory strains, can take up a stable, transmissible prion form. In each case, this requires the Asn/Gln-rich prion-forming domain (PrD) of the protein to be intact. In order to further understand the evolutionary significance of this unusual property, we have examined four different prion genes and their corresponding PrDs, from a number of naturally occurring strains of S. cerevisiae. In 4 of the 16 strains studied we identified a new allele of the SUP35 gene (SUP35delta19) that contains a 19-amino-acid deletion within the N-terminal PrD, a deletion that eliminates the prion property of Sup35p. In these strains a second prion gene, RNQ1, was found to be highly polymorphic, with eight different RNQ1 alleles detected in the six diploid strains studied. In contrast, for one other prion gene (URE2) and the sequence of the NEW1 gene encoding a PrD, no significant degree of DNA polymorphism was detected. Analysis of the naturally occurring alleles of RNQ1 and SUP35 indicated that the various polymorphisms identified were associated with DNA tandem repeats (6, 12, 33, 42 or 57 bp) within the coding sequences. The expansion and contraction of DNA repeats within the RNQ1 gene may provide an evolutionary mechanism that can ensure rapid change between the [PRION+] and [prion-] states.
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Affiliation(s)
- Catarina G Resende
- Research School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
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41
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Abstract
Saccharomyces cerevisiae's ability to form the prion [PSI+] may increase the rate of evolvability, defined as the rate of appearance of heritable and potentially adaptive phenotypic variants. The increase in evolvability occurs when the appearance of the prion causes read-through translation and reveals hidden variation in untranslated regions. Eventually the portion of the phenotypic variation that is adaptive loses its dependence on the revealing mechanism. The mechanism is reversible, so the restoration of normal translation termination conceals the revealed deleterious variation, leaving the yeast without a permanent handicap. Given that the ability to form [PSI+] is known to be fixed and conserved in yeast, we construct a mathematical model to calculate whether this ability is more likely to have become fixed due to chance alone or due to its evolvability characteristics. We find that evolvability is a more likely explanation, as long as environmental change makes partial read-through of stop codons adaptive at a frequency of at least once every million years.
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Affiliation(s)
- Joanna Masel
- Center for Computational Genetics and Biological Modeling, Department of Biological Sciences, Stanford University, Stanford, California 94305, USA.
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42
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Baum J, Thomas AW, Conway DJ. Evidence for diversifying selection on erythrocyte-binding antigens of Plasmodium falciparum and P. vivax. Genetics 2003; 163:1327-36. [PMID: 12702678 PMCID: PMC1462517 DOI: 10.1093/genetics/163.4.1327] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Malaria parasite antigens involved in erythrocyte invasion are primary vaccine candidates. The erythrocyte-binding antigen 175K (EBA-175) of Plasmodium falciparum binds to glycophorin A on the human erythrocyte surface via an N-terminal cysteine-rich region (termed region II) and is a target of antibody responses. A survey of polymorphism in a malaria-endemic population shows that nucleotide alleles in eba-175 region II occur at more intermediate frequencies than expected under neutrality, but polymorphisms in the homologous domains of two closely related genes, eba-140 (encoding a second erythrocyte-binding protein) and psieba-165 (a putative pseudogene), show an opposite trend. McDonald-Kreitman tests employing interspecific comparison with the orthologous genes in P. reichenowi (a closely related parasite of chimpanzees) reveal a significant excess of nonsynonymous polymorphism in P. falciparum eba-175 but not in eba-140. An analysis of the Duffy-binding protein gene, encoding a major erythrocyte-binding antigen in the other common human malaria parasite P. vivax, also reveals a significant excess of nonsynonymous polymorphisms when compared with divergence from its ortholog in P. knowlesi (a closely related parasite of macaques). The results suggest that EBA-175 in P. falciparum and DBP in P. vivax are both under diversifying selection from acquired human immune responses.
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Affiliation(s)
- Jake Baum
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, United Kingdom.
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43
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Abstract
Fungal prions are fascinating protein-based genetic elements. They alter cellular phenotypes through self-perpetuating changes in protein conformation and are cytoplasmically partitioned from mother cell to daughter. The four prions of Saccharomyces cerevisiae and Podospora anserina affect diverse biological processes: translational termination, nitrogen regulation, inducibility of other prions, and heterokaryon incompatibility. They share many attributes, including unusual genetic behaviors, that establish criteria to identify new prions. Indeed, other fungal traits that baffled microbiologists meet some of these criteria and might be caused by prions. Recent research has provided notable insight about how prions are induced and propagated and their many biological roles. The ability to become a prion appears to be evolutionarily conserved in two cases. [PSI(+)] provides a mechanism for genetic variation and phenotypic diversity in response to changing environments. All available evidence suggests that prions epigenetically modulate a wide variety of fundamental biological processes, and many await discovery.
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Affiliation(s)
- Susan M Uptain
- Howard Hughes Medical Institute, Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637, USA.
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44
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Masel J, Bergman A. THE EVOLUTION OF THE EVOLVABILITY PROPERTIES OF THE YEAST PRION [PSI+]. Evolution 2003. [DOI: 10.1554/02-535] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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45
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Edskes HK, Wickner RB. Conservation of a portion of the S. cerevisiae Ure2p prion domain that interacts with the full-length protein. Proc Natl Acad Sci U S A 2002; 99 Suppl 4:16384-91. [PMID: 12177423 PMCID: PMC139898 DOI: 10.1073/pnas.162349599] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The [URE3] prion of Saccharomyces cerevisiae is a self-propagating inactive amyloid form of the Ure2 protein. Ure2p residues 1-65 constitute the prion domain, and the remaining C-terminal portion regulates nitrogen catabolism. We have examined the URE2 genes of wild-type isolates of S. cerevisiae and those of several pathogenic yeasts and a filamentous fungus. We find that the normal function of the S. cerevisiae Ure2p in nitrogen regulation is fully complemented by the Ure2p of Candida albicans, Candida glabrata, Candida kefyr, Candida maltosa, Saccharomyces bayanus, and Saccharomyces paradoxus, all of which have high homology in the C-terminal nitrogen regulation domain. However, there is considerable divergence of their N-terminal domains from that of Ure2p of S. cerevisiae. [URE3(Sc)] showed efficient transmission into S. cerevisiae ure2Delta cells if expressing a Ure2p of species within Saccharomyces. However, [URE3(Sc)] did not seed self-propagating inactivation of the Ure2p's from the other yeasts. When overexpressed as a fusion with green fluorescent protein, residues 5-47 of the S. cerevisiae prion domain are necessary for curing the [URE3] prion. Residues 11-39 are necessary for an inactivating interaction with the full-length Ure2p. A nearly identical region is highly conserved among many of the yeasts examined in this study, despite the wide divergence of sequences found in other parts of the N-terminal domains.
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Affiliation(s)
- Herman K Edskes
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA
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46
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Current awareness on yeast. Yeast 2002; 19:285-92. [PMID: 11816036 DOI: 10.1002/yea.821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In order to keep subscribers up-to-date with the latest developments in their field, this current awareness service is provided by John Wiley & Sons and contains newly-published material on yeasts. Each bibliography is divided into 10 sections. 1 Books, Reviews & Symposia; 2 General; 3 Biochemistry; 4 Biotechnology; 5 Cell Biology; 6 Gene Expression; 7 Genetics; 8 Physiology; 9 Medical Mycology; 10 Recombinant DNA Technology. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted. (3 weeks journals - search completed 5th. Dec. 2001)
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47
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Abstract
The experimental evidence accumulated for the last half of the century clearly suggests that inherited variation is not restricted to the changes in genomic sequences. The prion model, originally based on unusual transmission of certain neurodegenerative diseases in mammals, provides a molecular mechanism for the template-like reproduction of alternative protein conformations. Recent data extend this model to protein-based genetic elements in yeast and other fungi. Reproduction and transmission of yeast protein-based genetic elements is controlled by the "prion replication" machinery of the cell, composed of the protein helpers responsible for the processes of assembly and disassembly of protein structures and multiprotein complexes. Among these, the stress-related chaperones of Hsp100 and Hsp70 groups play an important role. Alterations of levels or activity of these proteins result in "mutator" or "antimutator" affects in regard to protein-based genetic elements. "Protein mutagens" have also been identified that affect formation and/or propagation of the alternative protein conformations. Prion-forming abilities appear to be conserved in evolution, despite the divergence of the corresponding amino acid sequences. Moreover, a wide variety of proteins of different origins appear to possess the ability to form amyloid-like aggregates, that in certain conditions might potentially result in prion-like switches. This suggests a possible mechanism for the inheritance of acquired traits, postulated in the Lamarckian theory of evolution. The prion model also puts in doubt the notion that cloned animals are genetically identical to their genome donors, and suggests that genome sequence would not provide a complete information about the genetic makeup of an organism.
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Affiliation(s)
- Y O Chernoff
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, M/C 0363, 315 Ferst Drive, Atlanta, GA 30332-0363, USA.
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