1
|
Zajkowski T, Lee MD, Sharma S, Vallota-Eastman A, Kuska M, Malczewska M, Rothschild LJ. Conserved functions of prion candidates suggest a primeval role of protein self-templating. Proteins 2023; 91:1298-1315. [PMID: 37519023 DOI: 10.1002/prot.26558] [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: 01/16/2023] [Revised: 06/14/2023] [Accepted: 07/07/2023] [Indexed: 08/01/2023]
Abstract
Amyloid-based prions have simple structures, a wide phylogenetic distribution, and a plethora of functions in contemporary organisms, suggesting they may be an ancient phenomenon. However, this hypothesis has yet to be addressed with a systematic, computational, and experimental approach. Here we present a framework to help guide future experimental verification of candidate prions with conserved functions to understand their role in the early stages of evolution and potentially in the origins of life. We identified candidate prions in all high-quality proteomes available in UniProt computationally, assessed their phylogenomic distributions, and analyzed candidate-prion functional annotations. Of the 27 980 560 proteins scanned, 228 561 were identified as candidate prions (~0.82%). Among these candidates, there were 84 Gene Ontology (GO) terms conserved across the three domains of life. We found that candidate prions with a possible role in adaptation were particularly well-represented within this group. We discuss unifying features of candidate prions to elucidate the primeval roles of prions and their associated functions. Candidate prions annotated as transcription factors, DNA binding, and kinases are particularly well suited to generating diverse responses to changes in their environment and could allow for adaptation and population expansion into more diverse environments. We hypothesized that a relationship between these functions and candidate prions could be evolutionarily ancient, even if individual prion domains themselves are not evolutionarily conserved. Candidate prions annotated with these universally occurring functions potentially represent the oldest extant prions on Earth and are therefore excellent experimental targets.
Collapse
Affiliation(s)
- Tomasz Zajkowski
- Universities Space Research Association at NASA Ames Research Center, Mountain View, California, USA
- Polish Astrobiology Society, Warsaw, Poland
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California, USA
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
| | - Michael D Lee
- Blue Marble Space Institute of Science, Seattle, Washington, USA
- KBR, NASA Ames Research Center, Mountain View, California, USA
| | - Siddhant Sharma
- Blue Marble Space Institute of Science, Seattle, Washington, USA
- School of Chemistry, University of New South Wales, Sydney, Australia
| | - Alec Vallota-Eastman
- Department of Earth Science, University of California, Santa Barbara, California, USA
| | - Mikołaj Kuska
- Polish Astrobiology Society, Warsaw, Poland
- Department of Biophysics, Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - Małgorzata Malczewska
- Polish Astrobiology Society, Warsaw, Poland
- Department of Biophysics, Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - Lynn J Rothschild
- Space Science and Astrobiology Division, NASA Ames Research Center, Mountain View, California, USA
| |
Collapse
|
2
|
Harrison PM. fLPS 2.0: rapid annotation of compositionally-biased regions in biological sequences. PeerJ 2021; 9:e12363. [PMID: 34760378 PMCID: PMC8557692 DOI: 10.7717/peerj.12363] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 09/30/2021] [Indexed: 12/12/2022] Open
Abstract
Compositionally-biased (CB) regions in biological sequences are enriched for a subset of sequence residue types. These can be shorter regions with a concentrated bias (i.e., those termed ‘low-complexity’), or longer regions that have a compositional skew. These regions comprise a prominent class of the uncharacterized ‘dark matter’ of the protein universe. Here, I report the latest version of the fLPS package for the annotation of CB regions, which includes added consideration of DNA sequences, to label the eight possible biased regions of DNA. In this version, the user is now able to restrict analysis to a specified subset of residue types, and also to filter for previously annotated domains to enable detection of discontinuous CB regions. A ‘thorough’ option has been added which enables the labelling of subtler biases, typically made from a skew for several residue types. In the output, protein CB regions are now labelled with bias classes reflecting the physico-chemical character of the biasing residues. The fLPS 2.0 package is available from: https://github.com/pmharrison/flps2 or in a Supplemental File of this paper.
Collapse
Affiliation(s)
- Paul M Harrison
- Department of Biology, McGill University, Montreal, QC, Canada
| |
Collapse
|
3
|
Moran KL, Shlyakhtina Y, Portal MM. The role of non-genetic information in evolutionary frameworks. Crit Rev Biochem Mol Biol 2021; 56:255-283. [PMID: 33970731 DOI: 10.1080/10409238.2021.1908949] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The evolution of organisms has been a subject of paramount debate for hundreds of years and though major advances in the field have been made, the precise mechanisms underlying evolutionary processes remain fragmentary. Strikingly, the majority of the core principles accepted across the many fields of biology only consider genetic information as the major - if not exclusive - biological information carrier and thus consider it as the main evolutionary avatar. However, the real picture appears far more complex than originally anticipated, as compelling data suggest that nongenetic information steps up when highly dynamic evolutionary frameworks are explored. In light of recent evidence, we discuss herein the dynamic nature and complexity of nongenetic information carriers, and their emerging relevance in the evolutionary process. We argue that it is possible to overcome the historical arguments which dismissed these carriers, and instead consider that they are indeed core to life itself as they support a sustainable, continuous source of rapid adaptation in ever-changing environments. Ultimately, we will address the intricacies of genetic and non-genetic networks underlying evolutionary models to build a framework where both core biological information concepts are considered non-negligible and equally fundamental.
Collapse
Affiliation(s)
- Katherine L Moran
- Cell Plasticity & Epigenetics Lab, Cancer Research UK - Manchester Institute, The University of Manchester, Manchester, UK
| | - Yelyzaveta Shlyakhtina
- Cell Plasticity & Epigenetics Lab, Cancer Research UK - Manchester Institute, The University of Manchester, Manchester, UK
| | - Maximiliano M Portal
- Cell Plasticity & Epigenetics Lab, Cancer Research UK - Manchester Institute, The University of Manchester, Manchester, UK
| |
Collapse
|
4
|
Harrison PM. Variable absorption of mutational trends by prion-forming domains during Saccharomycetes evolution. PeerJ 2020; 8:e9669. [PMID: 32844065 PMCID: PMC7415223 DOI: 10.7717/peerj.9669] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 07/16/2020] [Indexed: 12/13/2022] Open
Abstract
Prions are self-propagating alternative states of protein domains. They are linked to both diseases and functional protein roles in eukaryotes. Prion-forming domains in Saccharomyces cerevisiae are typically domains with high intrinsic protein disorder (i.e., that remain unfolded in the cell during at least some part of their functioning), that are converted to self-replicating amyloid forms. S. cerevisiae is a member of the fungal class Saccharomycetes, during the evolution of which a large population of prion-like domains has appeared. It is still unclear what principles might govern the molecular evolution of prion-forming domains, and intrinsically disordered domains generally. Here, it is discovered that in a set of such prion-forming domains some evolve in the fungal class Saccharomycetes in such a way as to absorb general mutation biases across millions of years, whereas others do not, indicating a spectrum of selection pressures on composition and sequence. Thus, if the bias-absorbing prion formers are conserving a prion-forming capability, then this capability is not interfered with by the absorption of bias changes over the duration of evolutionary epochs. Evidence is discovered for selective constraint against the occurrence of lysine residues (which likely disrupt prion formation) in S. cerevisiae prion-forming domains as they evolve across Saccharomycetes. These results provide a case study of the absorption of mutational trends by compositionally biased domains, and suggest methodology for assessing selection pressures on the composition of intrinsically disordered regions.
Collapse
Affiliation(s)
- Paul M Harrison
- Department of Biology, McGill University, Monteal, Quebec, Canada
| |
Collapse
|
5
|
Kasari V, Pochopien AA, Margus T, Murina V, Turnbull K, Zhou Y, Nissan T, Graf M, Nováček J, Atkinson GC, Johansson MJO, Wilson DN, Hauryliuk V. A role for the Saccharomyces cerevisiae ABCF protein New1 in translation termination/recycling. Nucleic Acids Res 2019; 47:8807-8820. [PMID: 31299085 PMCID: PMC7145556 DOI: 10.1093/nar/gkz600] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/14/2019] [Accepted: 07/11/2019] [Indexed: 11/12/2022] Open
Abstract
Translation is controlled by numerous accessory proteins and translation factors. In the yeast Saccharomyces cerevisiae, translation elongation requires an essential elongation factor, the ABCF ATPase eEF3. A closely related protein, New1, is encoded by a non-essential gene with cold sensitivity and ribosome assembly defect knock-out phenotypes. Since the exact molecular function of New1 is unknown, it is unclear if the ribosome assembly defect is direct, i.e. New1 is a bona fide assembly factor, or indirect, for instance due to a defect in protein synthesis. To investigate this, we employed yeast genetics, cryo-electron microscopy (cryo-EM) and ribosome profiling (Ribo-Seq) to interrogate the molecular function of New1. Overexpression of New1 rescues the inviability of a yeast strain lacking the otherwise strictly essential translation factor eEF3. The structure of the ATPase-deficient (EQ2) New1 mutant locked on the 80S ribosome reveals that New1 binds analogously to the ribosome as eEF3. Finally, Ribo-Seq analysis revealed that loss of New1 leads to ribosome queuing upstream of 3′-terminal lysine and arginine codons, including those genes encoding proteins of the cytoplasmic translational machinery. Our results suggest that New1 is a translation factor that fine-tunes the efficiency of translation termination or ribosome recycling.
Collapse
Affiliation(s)
- Villu Kasari
- Department of Molecular Biology, Umeå University, Building 6K, 6L University Hospital Area, 90187 Umeå, Sweden.,Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Building 6K and 6L, University Hospital Area, 90187 Umeå, Sweden
| | - Agnieszka A Pochopien
- Institute for Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Tõnu Margus
- Department of Molecular Biology, Umeå University, Building 6K, 6L University Hospital Area, 90187 Umeå, Sweden.,Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Building 6K and 6L, University Hospital Area, 90187 Umeå, Sweden
| | - Victoriia Murina
- Department of Molecular Biology, Umeå University, Building 6K, 6L University Hospital Area, 90187 Umeå, Sweden.,Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Building 6K and 6L, University Hospital Area, 90187 Umeå, Sweden
| | - Kathryn Turnbull
- Department of Molecular Biology, Umeå University, Building 6K, 6L University Hospital Area, 90187 Umeå, Sweden.,Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Building 6K and 6L, University Hospital Area, 90187 Umeå, Sweden
| | - Yang Zhou
- Department of Molecular Biology, Umeå University, Building 6K, 6L University Hospital Area, 90187 Umeå, Sweden
| | - Tracy Nissan
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, 10691, Sweden.,School of Life Science, University of Sussex, Brighton, BN19RH, UK
| | - Michael Graf
- Institute for Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Jiří Nováček
- Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 62500 Brno, Czech Republic
| | - Gemma C Atkinson
- Department of Molecular Biology, Umeå University, Building 6K, 6L University Hospital Area, 90187 Umeå, Sweden
| | - Marcus J O Johansson
- Department of Molecular Biology, Umeå University, Building 6K, 6L University Hospital Area, 90187 Umeå, Sweden
| | - Daniel N Wilson
- Institute for Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Vasili Hauryliuk
- Department of Molecular Biology, Umeå University, Building 6K, 6L University Hospital Area, 90187 Umeå, Sweden.,Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Building 6K and 6L, University Hospital Area, 90187 Umeå, Sweden.,University of Tartu, Institute of Technology, 50411 Tartu, Estonia
| |
Collapse
|
6
|
Su TY, Harrison PM. Conservation of Prion-Like Composition and Sequence in Prion-Formers and Prion-Like Proteins of Saccharomyces cerevisiae. Front Mol Biosci 2019; 6:54. [PMID: 31355208 PMCID: PMC6639077 DOI: 10.3389/fmolb.2019.00054] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 06/26/2019] [Indexed: 01/15/2023] Open
Abstract
Prions in eukaryotes have been linked to diseases, evolutionary capacitance, large-scale genetic control, and long-term memory formation. Prion formation and propagation have been studied extensively in the budding yeast Saccharomyces cerevisiae. Here, we have analysed the conservation of sequence and of prion-like composition for prion-forming proteins and for other prion-like proteins from S. cerevisiae, across three evolutionary levels. We discover that prion-like status is well-conserved for about half the set of prion-formers at the Saccharomycetes level, and that prion-forming domains evolve more quickly as sequences than other prion-like domains do. Such increased mutation rates may be linked to the acquisition of functional roles for prion-forming domains during the evolutionary epoch of Saccharomycetes. Domain scores for prion-like composition in S. cerevisiae are strongly correlated with scores for such composition weighted evolutionarily over the dozens of fungal species examined, indicating conservation of such prion-like status. Examples of notable prion-like proteins that are highly conserved both in sequence and prion-like composition are discussed.
Collapse
Affiliation(s)
- Ting-Yi Su
- Department of Biology, McGill University, Montreal, QC, Canada
| | - Paul M Harrison
- Department of Biology, McGill University, Montreal, QC, Canada
| |
Collapse
|
7
|
Abstract
Prions in eukaryotes have been linked to diseases, evolutionary capacitance, large-scale genetic control and long-term memory formation. In bacteria, constructed prion-forming proteins have been described, such as the prion-forming protein recently described for Clostridium botulinum transcription terminator Rho. Here, I analyzed the evolution of the Rho prion-forming domain across bacteria, and discovered that its conservation is sporadic both in the Clostridium genus and in bacteria generally. Nonetheless, it has an apparent evolutionary reach into eight or more different bacterial phyla. Motivated by these results, I investigated whether this pattern of wide-ranging evolutionary sporadicity is typical of bacterial prion-like domains. A measure of coverage of a domain (C) within its evolutionary range was derived, which is effectively a weighted fraction of the number of species in which the domain is found. I observe that occurrence across multiple phyla is not uncommon for bacterial prion-like protein domain families, but that they tend to sample of a low fraction of species within their evolutionary range, like Rho. The Rho prion-like domain family is one of the top three most widely distributed prion-like protein domain families in terms of number of phyla. There are >60 prion-like protein domain families that have at least the evolutionary coverage of Rho, and are found in multiple phyla. The implications of these findings for evolution and for experimental investigations into prion-forming proteins are discussed.
Collapse
Affiliation(s)
- Paul M. Harrison
- Department of Biology, McGill University, Montreal, QC, Canada
- * E-mail:
| |
Collapse
|
8
|
Allwein B, Kelly C, Kammoonah S, Mayor T, Cameron DM. Prion-dependent proteome remodeling in response to environmental stress is modulated by prion variant and genetic background. Prion 2019; 13:53-64. [PMID: 30773982 PMCID: PMC6422386 DOI: 10.1080/19336896.2019.1583041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
A number of fungal proteins are capable of adopting multiple alternative, self-perpetuating prion conformations. These prion variants are associated with functional alterations of the prion-forming protein and thus the generation of new, heritable traits that can be detrimental or beneficial. Here we sought to determine the extent to which the previously-reported ZnCl2-sensitivity trait of yeast harboring the [PSI+] prion is modulated by genetic background and prion variant, and whether this trait is accompanied by prion-dependent proteomic changes that could illuminate its physiological basis. We also examined the degree to which prion variant and genetic background influence other prion-dependent phenotypes. We found that ZnCl2 exposure not only reduces colony growth but also limits chronological lifespan of [PSI+] relative to [psi−] cells. This reduction in viability was observed for multiple prion variants in both the S288C and W303 genetic backgrounds. Quantitative proteomic analysis revealed that under exposure to ZnCl2 the expression of stress response proteins was elevated and the expression of proteins involved in energy metabolism was reduced in [PSI+] relative to [psi−] cells. These results suggest that cellular stress and slowed growth underlie the phenotypes we observed. More broadly, we found that prion variant and genetic background modulate prion-dependent changes in protein abundance and can profoundly impact viability in diverse environments. Thus, access to a constellation of prion variants combined with the accumulation of genetic variation together have the potential to substantially increase phenotypic diversity within a yeast population, and therefore to enhance its adaptation potential in changing environmental conditions.
Collapse
Affiliation(s)
- Ben Allwein
- a Department of Biology , Ursinus College , Collegeville , PA , USA
| | - Christina Kelly
- a Department of Biology , Ursinus College , Collegeville , PA , USA
| | - Shaima Kammoonah
- b Department of Biochemistry and Molecular Biology, Michael Smith Laboratories , University of British Columbia , Vancouver , British Columbia , Canada
| | - Thibault Mayor
- b Department of Biochemistry and Molecular Biology, Michael Smith Laboratories , University of British Columbia , Vancouver , British Columbia , Canada
| | - Dale M Cameron
- a Department of Biology , Ursinus College , Collegeville , PA , USA
| |
Collapse
|
9
|
Harrison PM. Compositionally Biased Dark Matter in the Protein Universe. Proteomics 2018; 18:e1800069. [PMID: 30260558 DOI: 10.1002/pmic.201800069] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 08/29/2018] [Indexed: 01/01/2023]
Abstract
Compositionally biased regions (BRs) occur when a few amino-acid types are enriched in a protein segment. There are possibly BR types in the known protein universe that have not been characterized experimentally. The UniProt protein database has been surveyed for evidence of such compositionally ''dark matter''. A ''dark biased region'' (DBR) is defined as a biased region with low probability of being an individual structural domain or intrinsically disordered region. The bias annotation program fLPS is used to generate a list of >13 million BRs, which is then thoroughly filtered for structure and intrinsic disorder. About a third of BRs (31%) has both substantial intrinsic disorder and structure. After filtering, there are ≈0.9 million DBRs (≈7% of the original BRs in ≈1.4% of proteins). These DBRs are hugely enriched in eukaryotes and hugely depleted in bacteria. They tend to be more hydrophobic than other protein regions, but are made of less extreme combinations of hydrophobic/hydrophilic residues. Given varying assumptions, It has been estimated that how many DBRs there might be for the high bias levels examined (with p-values < 1 × 10-06 ), deriving a reasonable range of 0.7-7.2% of proteins having such DBRs. Hypotheses are examined about what such DBRs might be, that is, that they are from un- or undersampled domain/region categories or are unappreciated categories somewhat like existing ones.
Collapse
Affiliation(s)
- Paul M Harrison
- Department of Biology, McGill University, Montreal, QC, H3A 1B1, Canada
| |
Collapse
|
10
|
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.
Collapse
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:
| |
Collapse
|
11
|
Harrison PM. fLPS: Fast discovery of compositional biases for the protein universe. BMC Bioinformatics 2017; 18:476. [PMID: 29132292 PMCID: PMC5684748 DOI: 10.1186/s12859-017-1906-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 11/01/2017] [Indexed: 12/03/2022] Open
Abstract
Background Proteins often contain regions that are compositionally biased (CB), i.e., they are made from a small subset of amino-acid residue types. These CB regions can be functionally important, e.g., the prion-forming and prion-like regions that are rich in asparagine and glutamine residues. Results Here I report a new program fLPS that can rapidly annotate CB regions. It discovers both single-residue and multiple-residue biases. It works through a process of probability minimization. First, contigs are constructed for each amino-acid type out of sequence windows with a low degree of bias; second, these contigs are searched exhaustively for low-probability subsequences (LPSs); third, such LPSs are iteratively assessed for merger into possible multiple-residue biases. At each of these stages, efficiency measures are taken to avoid or delay probability calculations unless/until they are necessary. On a current desktop workstation, the fLPS algorithm can annotate the biased regions of the yeast proteome (>5700 sequences) in <1 s, and of the whole current TrEMBL database (>65 million sequences) in as little as ~1 h, which is >2 times faster than the commonly used program SEG, using default parameters. fLPS discovers both shorter CB regions (of the sort that are often termed ‘low-complexity sequence’), and milder biases that may only be detectable over long tracts of sequence. Conclusions fLPS can readily handle very large protein data sets, such as might come from metagenomics projects. It is useful in searching for proteins with similar CB regions, and for making functional inferences about CB regions for a protein of interest. The fLPS package is available from: http://biology.mcgill.ca/faculty/harrison/flps.html, or https://github.com/pmharrison/flps, or is a supplement to this article. Electronic supplementary material The online version of this article (10.1186/s12859-017-1906-3) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Paul M Harrison
- Department of Biology, McGill University, Montreal, QC, Canada.
| |
Collapse
|
12
|
Wang K, Melki R, Kabani M. A prolonged chronological lifespan is an unexpected benefit of the [PSI+] prion in yeast. PLoS One 2017; 12:e0184905. [PMID: 28910422 PMCID: PMC5599042 DOI: 10.1371/journal.pone.0184905] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 09/01/2017] [Indexed: 11/19/2022] Open
Abstract
Self-replicating ‘proteinaceous infectious particles’ or prions are responsible for complex heritable traits in the yeast Saccharomyces cerevisiae. Our current understanding of the biology of yeast prions stems from studies mostly done in the context of actively dividing cells in optimal laboratory growth conditions. Evidence suggest that fungal prions exist in the wild where most cells are in a non-dividing quiescent state, because of imperfect growth conditions, scarcity of nutrients and competition. We know little about the faithful transmission of yeast prions in such conditions and their physiological consequences throughout the lifespan of yeast cells. We addressed this issue for the [PSI+] prion that results from the self-assembly of the translation release factor Sup35p into insoluble fibrillar aggregates. [PSI+] leads to increased nonsense suppression and confers phenotypic plasticity in response to environmental fluctuations. Here, we report that while [PSI+] had little to no effect on growth per se, it dramatically improved the survival of yeast cells in stationary phase. Remarkably, prolonged chronological lifespan persisted even after [PSI+] was cured from the cells, suggesting that prions may facilitate the acquisition of complex new traits. Such an important selective advantage may contribute to the evolutionary conservation of the prion-forming ability of Sup35p orthologues in distantly related yeast species.
Collapse
Affiliation(s)
- Kai Wang
- Paris-Saclay Institute of Neuroscience, Centre National de la Recherche Scientifique, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Ronald Melki
- Paris-Saclay Institute of Neuroscience, Centre National de la Recherche Scientifique, Université Paris-Saclay, Gif-sur-Yvette, France
- * E-mail: (MK); (RM)
| | - Mehdi Kabani
- Paris-Saclay Institute of Neuroscience, Centre National de la Recherche Scientifique, Université Paris-Saclay, Gif-sur-Yvette, France
- * E-mail: (MK); (RM)
| |
Collapse
|
13
|
Abstract
Prions are infectious protein polymers that have been found to cause fatal diseases in mammals. Prions have also been identified in fungi (yeast and filamentous fungi), where they behave as cytoplasmic non-Mendelian genetic elements. Fungal prions correspond in most cases to fibrillary β-sheet-rich protein aggregates termed amyloids. Fungal prion models and, in particular, yeast prions were instrumental in the description of fundamental aspects of prion structure and propagation. These models established the "protein-only" nature of prions, the physical basis of strain variation, and the role of a variety of chaperones in prion propagation and amyloid aggregate handling. Yeast and fungal prions do not necessarily correspond to harmful entities but can have adaptive roles in these organisms.
Collapse
|
14
|
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.
Collapse
|
15
|
An L, Harrison PM. The evolutionary scope and neurological disease linkage of yeast-prion-like proteins in humans. Biol Direct 2016; 11:32. [PMID: 27457357 PMCID: PMC4960796 DOI: 10.1186/s13062-016-0134-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 07/14/2016] [Indexed: 11/12/2022] Open
Abstract
Background Prions are proteinaceous particles that propagate alternative protein conformations/states to further copies of the same proteins, and are transmitted from cell-to-cell, and organism-to-organism. Prions are usually made of the beta-sheet rich assemblies termed amyloid. The original prion protein PrP causes devastating neurodegenerative disorders in humans and other mammals. In the yeast Saccharomyces cerevisiae, many prion-forming proteins have been observed; a prominent feature of these proteins is an intrinsically disordered domain rich in glutamine (Q) and asparagine (N) residues. Several human proteins that are yeast-prion-like, in particular those with poly-glutamine (poly-Q) expansions, have been experimentally implicated in human neurodegenerative diseases. Results Here, we have constructed a comprehensive list of human yeast-prion-like proteins that are linked to human neurological disease. Surprisingly, different methods to annotate yeast-prion-like proteins in humans have limited intersection. However, independent of annotation method, we find that human yeast-prion-like proteins as a group have a statistically significant genetic linkage to neurological disease, that is caused specifically by linkage to neurodegenerative diseases. This is despite: (i) no especially high expression of yeast-prion-like proteins in the central nervous system, or (ii) no general enrichment of intrinsically disordered proteins in neurological/neurodegenerative diseases. Cytoskeletal proteins are significantly overrepresented in the set of human yeast-prion-like neurological proteins. Whether involved in neurological pathomechanisms or not, yeast-prion-like proteins in humans have very limited conservation outside of Deuterostomia (< ~10 %) with only a handful having prion-like character in both human and S. cerevisiae. The only such protein with a disease linkage is PUB1/TIA1, which functions as a stress granule component. Thus, the yeast-prion-like character of proteins linked to neurodegenerative diseases has not been conserved over the deep evolutionary time since the last common ancestor of yeasts and humans. Conclusion Our results provide a comprehensive picture of yeast-prion-like proteins in humans and contribute to the strategic basis for experimental investigation of the link between yeast-prion-like protein character and neurological disease. Reviewers Reviewed by Istvan Simon and Alexander Schleiffer. For the full reviews, please go to the Reviewers’ comments section. Electronic supplementary material The online version of this article (doi:10.1186/s13062-016-0134-5) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Lu An
- Department of Biology, McGill University, Montreal, QC, Canada
| | - Paul M Harrison
- Department of Biology, McGill University, Montreal, QC, Canada.
| |
Collapse
|
16
|
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.
Collapse
Affiliation(s)
- Mick F Tuite
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, United Kingdom.
| |
Collapse
|
17
|
An L, Fitzpatrick D, Harrison PM. Emergence and evolution of yeast prion and prion-like proteins. BMC Evol Biol 2016; 16:24. [PMID: 26809710 PMCID: PMC4727409 DOI: 10.1186/s12862-016-0594-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 01/13/2016] [Indexed: 11/10/2022] Open
Abstract
Background Prions are transmissible, propagating alternative states of proteins, and are usually made from the fibrillar, beta-sheet-rich assemblies termed amyloid. Prions in the budding yeast Saccharomyces cerevisiae propagate heritable phenotypes, uncover hidden genetic variation, function in large-scale gene regulation, and can act like diseases. Almost all these amyloid prions have asparagine/glutamine-rich (N/Q–rich) domains. Other proteins, that we term here ‘prionogenic amyloid formers’ (PAFs), have been shown to form amyloid in vivo, and to have N/Q-rich domains that can propagate heritable states in yeast cells. Also, there are >200 other S.cerevisiae proteins with prion-like N/Q-rich sequence composition. Furthermore, human proteins with such N/Q-rich composition have been linked to the pathomechanisms of neurodegenerative amyloid diseases. Results Here, we exploit the increasing abundance of complete fungal genomes to examine the ancestry of prions/PAFs and other N/Q-rich proteins across the fungal kingdom. We find distinct evolutionary behavior for Q-rich and N-rich prions/PAFs; those of ancient ancestry (outside the budding yeasts, Saccharomycetes) are Q-rich, whereas N-rich cases arose early in Saccharomycetes evolution. This emergence of N-rich prion/PAFs is linked to a large-scale emergence of N-rich proteins during Saccharomycetes evolution, with Saccharomycetes showing a distinctive trend for population sizes of prion-like proteins that sets them apart from all the other fungi. Conversely, some clades, e.g. Eurotiales, have much fewer N/Q-rich proteins, and in some cases likely lose them en masse, perhaps due to greater amyloid intolerance, although they contain relatively more non-N/Q-rich predicted prions. We find that recent mutational tendencies arising during Saccharomycetes evolution (i.e., increased numbers of N residues and a tendency to form more poly-N tracts), contributed to the expansion/development of the prion phenomenon. Variation in these mutational tendencies in Saccharomycetes is correlated with the population sizes of prion-like proteins, thus implying that selection pressures on N/Q-rich protein sequences against amyloidogenesis are not generally maintained in budding yeasts. Conclusions These results help to delineate further the limits and origins of N/Q-rich prions, and provide insight as a case study of the evolution of compositionally-defined protein domains. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0594-3) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Lu An
- Department of Biology, McGill University, Montreal, QC, Canada
| | - David Fitzpatrick
- Bioinformatics and Molecular Evolution Unit, NUI Maynooth, Maynooth, Ireland
| | - Paul M Harrison
- Department of Biology, McGill University, Montreal, QC, Canada.
| |
Collapse
|
18
|
Abstract
A prion is an infectious protein horizontally transmitting a disease or trait without a required nucleic acid. Yeast and fungal prions are nonchromosomal genes composed of protein, generally an altered form of a protein that catalyzes the same alteration of the protein. Yeast prions are thus transmitted both vertically (as genes composed of protein) and horizontally (as infectious proteins, or prions). Formation of amyloids (linear ordered β-sheet-rich protein aggregates with β-strands perpendicular to the long axis of the filament) underlies most yeast and fungal prions, and a single prion protein can have any of several distinct self-propagating amyloid forms with different biological properties (prion variants). Here we review the mechanism of faithful templating of protein conformation, the biological roles of these prions, and their interactions with cellular chaperones, the Btn2 and Cur1 aggregate-handling systems, and other cellular factors governing prion generation and propagation. Human amyloidoses include the PrP-based prion conditions and many other, more common amyloid-based diseases, several of which show prion-like features. Yeast prions increasingly are serving as models for the understanding and treatment of many mammalian amyloidoses. Patients with different clinical pictures of the same amyloidosis may be the equivalent of yeasts with different prion variants.
Collapse
|
19
|
Abstract
A prion is an infectious protein horizontally transmitting a disease or trait without a required nucleic acid. Yeast and fungal prions are nonchromosomal genes composed of protein, generally an altered form of a protein that catalyzes the same alteration of the protein. Yeast prions are thus transmitted both vertically (as genes composed of protein) and horizontally (as infectious proteins, or prions). Formation of amyloids (linear ordered β-sheet-rich protein aggregates with β-strands perpendicular to the long axis of the filament) underlies most yeast and fungal prions, and a single prion protein can have any of several distinct self-propagating amyloid forms with different biological properties (prion variants). Here we review the mechanism of faithful templating of protein conformation, the biological roles of these prions, and their interactions with cellular chaperones, the Btn2 and Cur1 aggregate-handling systems, and other cellular factors governing prion generation and propagation. Human amyloidoses include the PrP-based prion conditions and many other, more common amyloid-based diseases, several of which show prion-like features. Yeast prions increasingly are serving as models for the understanding and treatment of many mammalian amyloidoses. Patients with different clinical pictures of the same amyloidosis may be the equivalent of yeasts with different prion variants.
Collapse
|
20
|
Dicer and Hsp104 function in a negative feedback loop to confer robustness to environmental stress. Cell Rep 2014; 10:47-61. [PMID: 25543137 DOI: 10.1016/j.celrep.2014.12.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 11/06/2014] [Accepted: 12/02/2014] [Indexed: 11/22/2022] Open
Abstract
Epigenetic mechanisms can be influenced by environmental cues and thus evoke phenotypic variation. This plasticity can be advantageous for adaptation but also detrimental if not tightly controlled. Although having attracted considerable interest, it remains largely unknown if and how environmental cues such as temperature trigger epigenetic alterations. Using fission yeast, we demonstrate that environmentally induced discontinuous phenotypic variation is buffered by a negative feedback loop that involves the RNase Dicer and the protein disaggregase Hsp104. In the absence of Hsp104, Dicer accumulates in cytoplasmic inclusions and heterochromatin becomes unstable at elevated temperatures, an epigenetic state inherited for many cell divisions after the heat stress. Loss of Dicer leads to toxic aggregation of an exogenous prionogenic protein. Our results highlight the importance of feedback regulation in building epigenetic memory and uncover Hsp104 and Dicer as homeostatic controllers that buffer environmentally induced stochastic epigenetic variation and toxic aggregation of prionogenic proteins.
Collapse
|
21
|
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.
Collapse
|
22
|
Harbi D, Harrison PM. Interaction networks of prion, prionogenic and prion-like proteins in budding yeast, and their role in gene regulation. PLoS One 2014; 9:e100615. [PMID: 24972093 PMCID: PMC4074094 DOI: 10.1371/journal.pone.0100615] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 05/09/2014] [Indexed: 12/12/2022] Open
Abstract
Prions are transmissible, propagating alternative states of proteins. Prions in budding yeast propagate heritable phenotypes and can function in large-scale gene regulation, or in some cases occur as diseases of yeast. Other ‘prionogenic’ proteins are likely prions that have been determined experimentally to form amyloid in vivo, and to have prion-like domains that are able to propagate heritable states. Furthermore, there are over 300 additional ‘prion-like’ yeast proteins that have similar amino-acid composition to prions (primarily a bias for asparagines and glutamines). Here, we examine the protein functional and interaction networks that involve prion, prionogenic and prion-like proteins. Set against a marked overall preference for N/Q-rich prion-like proteins not to interact with each other, we observe a significant tendency of prion/prionogenic proteins to interact with other, N/Q-rich prion-like proteins. This tendency is mostly due to a small number of networks involving the proteins NUP100p, LSM4p and PUB1p. In general, different data analyses of functional and interaction networks converge to indicate a strong linkage of prionogenic and prion-like proteins, to stress-granule assembly and related biological processes. These results further elucidate how prions may impact gene regulation, and reveal a broader horizon for the functional relevance of N/Q-rich prion-like domains.
Collapse
Affiliation(s)
- Djamel Harbi
- Department of Biology, McGill University, Montreal, Quebec, Canada
| | - Paul M. Harrison
- Department of Biology, McGill University, Montreal, Quebec, Canada
- * E-mail:
| |
Collapse
|
23
|
Abstract
The universe of prion and prion-like phenomena has expanded significantly in the past several years. Here, we overview the challenges in classifying this data informatically, given that terms such as “prion-like”, “prion-related” or “prion-forming” do not have a stable meaning in the scientific literature. We examine the spectrum of proteins that have been described in the literature as forming prions, and discuss how “prion” can have a range of meaning, with a strict definition being for demonstration of infection with in vitro-derived recombinant prions. We suggest that although prion/prion-like phenomena can largely be apportioned into a small number of broad groups dependent on the type of transmissibility evidence for them, as new phenomena are discovered in the coming years, a detailed ontological approach might be necessary that allows for subtle definition of different “flavors” of prion / prion-like phenomena.
Collapse
Affiliation(s)
- Djamel Harbi
- Department of Biology; McGill University; Montreal, QC Canada
| | - Paul M Harrison
- Department of Biology; McGill University; Montreal, QC Canada
| |
Collapse
|
24
|
Espinosa Angarica V, Angulo A, Giner A, Losilla G, Ventura S, Sancho J. PrionScan: an online database of predicted prion domains in complete proteomes. BMC Genomics 2014; 15:102. [PMID: 24498877 PMCID: PMC3922584 DOI: 10.1186/1471-2164-15-102] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 02/04/2014] [Indexed: 12/17/2022] Open
Abstract
Background Prions are a particular type of amyloids related to a large variety of important processes in cells, but also responsible for serious diseases in mammals and humans. The number of experimentally characterized prions is still low and corresponds to a handful of examples in microorganisms and mammals. Prion aggregation is mediated by specific protein domains with a remarkable compositional bias towards glutamine/asparagine and against charged residues and prolines. These compositional features have been used to predict new prion proteins in the genomes of different organisms. Despite these efforts, there are only a few available data sources containing prion predictions at a genomic scale. Description Here we present PrionScan, a new database of predicted prion-like domains in complete proteomes. We have previously developed a predictive methodology to identify and score prionogenic stretches in protein sequences. In the present work, we exploit this approach to scan all the protein sequences in public databases and compile a repository containing relevant information of proteins bearing prion-like domains. The database is updated regularly alongside UniprotKB and in its present version contains approximately 28000 predictions in proteins from different functional categories in more than 3200 organisms from all the taxonomic subdivisions. PrionScan can be used in two different ways: database query and analysis of protein sequences submitted by the users. In the first mode, simple queries allow to retrieve a detailed description of the properties of a defined protein. Queries can also be combined to generate more complex and specific searching patterns. In the second mode, users can submit and analyze their own sequences. Conclusions It is expected that this database would provide relevant insights on prion functions and regulation from a genome-wide perspective, allowing researches performing cross-species prion biology studies. Our database might also be useful for guiding experimentalists in the identification of new candidates for further experimental characterization.
Collapse
Affiliation(s)
- Vladimir Espinosa Angarica
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain.
| | | | | | | | | | | |
Collapse
|
25
|
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.
Collapse
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
| | | |
Collapse
|
26
|
Marchante R, Rowe M, Zenthon J, Howard MJ, Tuite MF. Structural definition is important for the propagation of the yeast [PSI+] prion. Mol Cell 2013; 50:675-85. [PMID: 23746351 PMCID: PMC3679450 DOI: 10.1016/j.molcel.2013.05.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Revised: 04/12/2013] [Accepted: 05/02/2013] [Indexed: 11/30/2022]
Abstract
Prions are propagated in Saccharomyces cerevisiae with remarkable efficiency, yet we know little about the structural basis of sequence variations in the prion protein that support or prohibit propagation of the prion conformation. We show that certain single-amino-acid substitutions in the prion protein Sup35 impact negatively on the maintenance of the associated prion-based [PSI(+)] trait by combining in vivo phenotypic analysis with solution NMR structural studies. A clear correlation is observed between mutationally induced conformational differences in one of the oligopeptide repeats (R2) in the N terminus of Sup35 and the relative ability to propagate [PSI(+)]. Strikingly, substitution of one of a Gly-Gly pair with highly charged residues that significantly increase structural definition of R2 lead to a severe [PSI(+)] propagation defect. These findings offer a molecular explanation for the dominant-negative effects of such psi-no-more (PNM) mutations and demonstrate directly the importance of localized structural definition in prion propagation.
Collapse
Affiliation(s)
- Ricardo Marchante
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
| | | | | | | | | |
Collapse
|
27
|
Antonets KS, Nizhnikov AA. SARP: A Novel Algorithm to Assess Compositional Biases in Protein Sequences. Evol Bioinform Online 2013; 9:263-73. [PMID: 23919085 PMCID: PMC3728207 DOI: 10.4137/ebo.s12299] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The composition of a defined set of subunits (nucleotides, amino acids) is one of the key features of biological sequences. Compositional biases are local shifts in amino acid or nucleotide frequencies that can occur as an adaptation of an organism to an extreme ecological niche, or as the signature of a specific function or localization of the corresponding protein. The calculation of probability is a method for annotating compositional bias and providing accurate detection of biased subsequences. Here, we present a Sequence Analysis based on the Ranking of Probabilities (SARP), a novel algorithm for the annotation of compositional biases based on ranking subsequences by their probabilities. SARP provides the same accuracy as the previously published Lower Probability Subsequences (LPS) algorithm but performs at an approximately 230-fold faster rate. It can be recommended for use when working with large datasets to reduce the time and resources required.
Collapse
Affiliation(s)
- Kirill S Antonets
- Department of Genetics and Biotechnology, St. Petersburg State University, St. Petersburg, Russia
| | | |
Collapse
|
28
|
Abstract
Ure2p, normally a regulator of nitrogen catabolism in Saccharomyces cerevisiae, can be a prion (infectious protein) by forming a folded in-register parallel amyloid called [URE3]. Using S. cerevisiae as a test bed, we previously showed that Ure2p of Candida albicans (CaUre2p) can also form a prion, but that Ure2p of C. glabrata (CgUre2p) cannot. Here, we constructed C. glabrata strains to test whether CgUre2p can form a prion in its native environment. We find that while CaUre2p can form a [URE3] in C. glabrata, CgUre2p cannot, although the latter has a prion domain sequence more similar to that of ScUre2p than that of CaUre2p. This supports the notion that prion formation is not a conserved property of Ure2p but is a pathology arising sporadically. We find that some [URE3albicans] variants are restricted in their transmissibility to certain recipient strains. In addition, we show that the C. glabrata HO can induce switching of the C. glabrata mating type locus.
Collapse
|
29
|
Saibil HR, Seybert A, Habermann A, Winkler J, Eltsov M, Perkovic M, Castaño-Diez D, Scheffer MP, Haselmann U, Chlanda P, Lindquist S, Tyedmers J, Frangakis AS. Heritable yeast prions have a highly organized three-dimensional architecture with interfiber structures. Proc Natl Acad Sci U S A 2012; 109:14906-14911. [PMID: 22927413 PMCID: PMC3443181 DOI: 10.1073/pnas.1211976109] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024] Open
Abstract
Yeast prions constitute a "protein-only" mechanism of inheritance that is widely deployed by wild yeast to create diverse phenotypes. One of the best-characterized prions, [PSI(+)], is governed by a conformational change in the prion domain of Sup35, a translation-termination factor. When this domain switches from its normal soluble form to an insoluble amyloid, the ensuing change in protein synthesis creates new traits. Two factors make these traits heritable: (i) the amyloid conformation is self-templating; and (ii) the protein-remodeling factor heat-shock protein (Hsp)104 (acting together with Hsp70 chaperones) partitions the template to daughter cells with high fidelity. Prions formed by several other yeast proteins create their own phenotypes but share the same mechanistic basis of inheritance. Except for the amyloid fibril itself, the cellular architecture underlying these protein-based elements of inheritance is unknown. To study the 3D arrangement of prion assemblies in their cellular context, we examined yeast [PSI(+)] prions in the native, hydrated state in situ, taking advantage of recently developed methods for cryosectioning of vitrified cells. Cryo-electron tomography of the vitrified sections revealed the prion assemblies as aligned bundles of regularly spaced fibrils in the cytoplasm with no bounding structures. Although the fibers were widely spaced, other cellular complexes, such as ribosomes, were excluded from the fibril arrays. Subtomogram image averaging, made possible by the organized nature of the assemblies, uncovered the presence of an additional array of densities between the fibers. We suggest these structures constitute a self-organizing mechanism that coordinates fiber deposition and the regulation of prion inheritance.
Collapse
Affiliation(s)
- Helen R. Saibil
- Crystallography and Institute for Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, United Kingdom
| | - Anja Seybert
- Institut für Biophysik and Frankfurt Institute for Molecular Life Sciences (FMLS), Johann Wolfgang Goethe Universität, D-60438 Frankfurt, Germany
| | - Anja Habermann
- Institut für Biophysik and Frankfurt Institute for Molecular Life Sciences (FMLS), Johann Wolfgang Goethe Universität, D-60438 Frankfurt, Germany
| | - Juliane Winkler
- Center for Molecular Biology of the University of Heidelberg and German Cancer Research Center, DKFZ-ZMBH Alliance, Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Mikhail Eltsov
- Institut für Biophysik and Frankfurt Institute for Molecular Life Sciences (FMLS), Johann Wolfgang Goethe Universität, D-60438 Frankfurt, Germany
- European Molecular Biology Laboratory (EMBL), D-69117 Heidelberg, Germany; and
| | - Mario Perkovic
- Institut für Biophysik and Frankfurt Institute for Molecular Life Sciences (FMLS), Johann Wolfgang Goethe Universität, D-60438 Frankfurt, Germany
| | - Daniel Castaño-Diez
- European Molecular Biology Laboratory (EMBL), D-69117 Heidelberg, Germany; and
| | - Margot P. Scheffer
- Institut für Biophysik and Frankfurt Institute for Molecular Life Sciences (FMLS), Johann Wolfgang Goethe Universität, D-60438 Frankfurt, Germany
- European Molecular Biology Laboratory (EMBL), D-69117 Heidelberg, Germany; and
| | - Uta Haselmann
- European Molecular Biology Laboratory (EMBL), D-69117 Heidelberg, Germany; and
| | - Petr Chlanda
- European Molecular Biology Laboratory (EMBL), D-69117 Heidelberg, Germany; and
| | - Susan Lindquist
- Whitehead Institute and Howard Hughes Medical Institute (HHMI), Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Jens Tyedmers
- Center for Molecular Biology of the University of Heidelberg and German Cancer Research Center, DKFZ-ZMBH Alliance, Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Achilleas S. Frangakis
- Institut für Biophysik and Frankfurt Institute for Molecular Life Sciences (FMLS), Johann Wolfgang Goethe Universität, D-60438 Frankfurt, Germany
- European Molecular Biology Laboratory (EMBL), D-69117 Heidelberg, Germany; and
| |
Collapse
|
30
|
Tyedmers J. Patterns of [PSI (+) ] aggregation allow insights into cellular organization of yeast prion aggregates. Prion 2012; 6:191-200. [PMID: 22449721 DOI: 10.4161/pri.18986] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The yeast prion phenomenon is very widespread and mounting evidence suggests that it has an impact on cellular regulatory mechanisms related to phenotypic responses to changing environments. Studying the aggregation patterns of prion amyloids during different stages of the prion life cycle is a first key step to understand major principles of how and where cells generate, organize and turn-over prion aggregates. The induction of the [PSI (+) ] state involves the actin cytoskeleton and quality control compartments such as the Insoluble Protein Deposit (IPOD). An initially unstable transitional induction state can be visualized by overexpression of the prion determinant and displays characteristic large ring- and ribbon-shaped aggregates consisting of poorly fragmented bundles of very long prion fibrils. In the mature prion state, the aggregation pattern is characterized by highly fragmented, shorter prion fibrils that form aggregates, which can be visualized through tagging with fluorescent proteins. The number of aggregates formed varies, ranging from a single large aggregate at the IPOD to multiple smaller ones, depending on several parameters discussed. Aggregate units below the resolution of light microscopy that are detectable by fluorescence correlation spectroscopy are in equilibrium with larger aggregates in this stage and can mediate faithful inheritance of the prion state. Loss of the prion state is often characterized by reduced fragmentation of prion fibrils and fewer, larger aggregates.
Collapse
Affiliation(s)
- Jens Tyedmers
- Center for Molecular Biology of the University of Heidelberg (ZMBH, Heidelberg, Germany.
| |
Collapse
|
31
|
PrionHome: a database of prions and other sequences relevant to prion phenomena. PLoS One 2012; 7:e31785. [PMID: 22363733 PMCID: PMC3282748 DOI: 10.1371/journal.pone.0031785] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Accepted: 01/18/2012] [Indexed: 01/03/2023] Open
Abstract
Prions are units of propagation of an altered state of a protein or proteins; prions can propagate from organism to organism, through cooption of other protein copies. Prions contain no necessary nucleic acids, and are important both as both pathogenic agents, and as a potential force in epigenetic phenomena. The original prions were derived from a misfolded form of the mammalian Prion Protein PrP. Infection by these prions causes neurodegenerative diseases. Other prions cause non-Mendelian inheritance in budding yeast, and sometimes act as diseases of yeast. We report the bioinformatic construction of the PrionHome, a database of >2000 prion-related sequences. The data was collated from various public and private resources and filtered for redundancy. The data was then processed according to a transparent classification system of prionogenic sequences (i.e., sequences that can make prions), prionoids (i.e., proteins that propagate like prions between individual cells), and other prion-related phenomena. There are eight PrionHome classifications for sequences. The first four classifications are derived from experimental observations: prionogenic sequences, prionoids, other prion-related phenomena, and prion interactors. The second four classifications are derived from sequence analysis: orthologs, paralogs, pseudogenes, and candidate-prionogenic sequences. Database entries list: supporting information for PrionHome classifications, prion-determinant areas (where relevant), and disordered and compositionally-biased regions. Also included are literature references for the PrionHome classifications, transcripts and genomic coordinates, and structural data (including comparative models made for the PrionHome from manually curated alignments). We provide database usage examples for both vertebrate and fungal prion contexts. Using the database data, we have performed a detailed analysis of the compositional biases in known budding-yeast prionogenic sequences, showing that the only abundant bias pattern is for asparagine bias with subsidiary serine bias. We anticipate that this database will be a useful experimental aid and reference resource. It is freely available at: http://libaio.biol.mcgill.ca/prion.
Collapse
|
32
|
Staniforth GL, Tuite MF. Fungal prions. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 107:417-56. [PMID: 22482457 DOI: 10.1016/b978-0-12-385883-2.00007-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
For both mammalian and fungal prion proteins, conformational templating drives the phenomenon of protein-only infectivity. The conformational conversion of a protein to its transmissible prion state is associated with changes to host cellular physiology. In mammals, this change is synonymous with disease, whereas in fungi no notable detrimental effect on the host is typically observed. Instead, fungal prions can serve as epigenetic regulators of inheritance in the form of partial loss-of-function phenotypes. In the presence of environmental challenges, the prion state [PRION(+)], with its resource for phenotypic plasticity, can be associated with a growth advantage. The growing number of yeast proteins that can switch to a heritable [PRION(+)] form represents diverse and metabolically penetrating cellular functions, suggesting that the [PRION(+)] state in yeast is a functional one, albeit rarely found in nature. In this chapter, we introduce the biochemical and genetic properties of fungal prions, many of which are shared by the mammalian prion protein PrP, and then outline the major contributions that studies on fungal prions have made to prion biology.
Collapse
Affiliation(s)
- Gemma L Staniforth
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, Kent, United Kingdom
| | | |
Collapse
|
33
|
Assessment of inactivating stop codon mutations in forty Saccharomyces cerevisiae strains: implications for [PSI] prion- mediated phenotypes. PLoS One 2011; 6:e28684. [PMID: 22194885 PMCID: PMC3240633 DOI: 10.1371/journal.pone.0028684] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 11/13/2011] [Indexed: 11/19/2022] Open
Abstract
The yeast prion [PSI+] has been implicated in the generation of novel phenotypes by a mechanism involving a reduction in translation fidelity causing readthrough of naturally occurring stop codons. Some [PSI+] associated phenotypes may also be generated due to readthrough of inactivating stop codon mutations (ISCMs). Using next generation sequencing we have sequenced the genomes of two Saccharomyces cerevisiae strains that are commonly used for the study of the yeast [PSI+] prion. We have identified approximately 26,000 and 6,500 single nucleotide polymorphisms (SNPs) in strains 74-D694 and G600 respectively, compared to reference strain S288C. In addition to SNPs that produce non-synonymous amino acid changes we have also identified a number of SNPs that cause potential ISCMs in these strains, one of which we show is associated with a [PSI+]-dependent stress resistance phenotype in strain G600. We identified twenty-two potential ISCMs in strain 74-D694, present in genes involved in a variety of cellular processes including nitrogen metabolism, signal transduction and oxidative stress response. The presence of ISCMs in a subset of these genes provides possible explanations for previously identified [PSI+]-associated phenotypes in this strain. A comparison of ISCMs in strains G600 and 74-D694 with S. cerevisiae strains sequenced as part of the Saccharomyces Genome Resequencing Project (SGRP) shows much variation in the generation of strain-specific ISCMs and suggests this process is possible under complex genetic control. Additionally we have identified a major difference in the abilities of strains G600 and 74-D694 to grow at elevated temperatures. However, this difference appears unrelated to novel SNPs identified in strain 74-D694 present in proteins involved in the heat shock response, but may be attributed to other SNP differences in genes previously identified as playing a role in high temperature growth.
Collapse
|
34
|
Wickner RB, Edskes HK, Bateman D, Kelly AC, Gorkovskiy A. The yeast prions [PSI+] and [URE3] are molecular degenerative diseases. Prion 2011; 5:258-62. [PMID: 22052353 DOI: 10.4161/pri.17748] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The yeast prions [URE3] and [PSI] are not found in wild strains, suggesting they are not an advantage. Prion-forming ability is not conserved, even within Saccharomyces, suggesting it is a disease. Prion domains have non-prion functions, explaining some conservation of sequence. However, in spite of the sequence being constrained in evolution by these non-prion functions, the prion domains vary more rapidly than the remainder of the molecule, and these changes produce a transmission barrier, suggesting that these changes were selected to block prion infection. Yeast prions [PSI] and [URE3] induce a cellular stress response (Hsp104 and Hsp70 induction), suggesting the cells are not happy about being infected. Recently, we showed that the array of [PSI] and [URE3] prions includes a majority of lethal or very toxic variants, a result not expected if either prion were an adaptive cellular response to stress.
Collapse
Affiliation(s)
- Reed B Wickner
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD, USA.
| | | | | | | | | |
Collapse
|
35
|
Wickner RB, Edskes HK, Bateman D, Kelly AC, Gorkovskiy A. The yeast prions [PSI+] and [URE3] are molecular degenerative diseases. Prion 2011. [PMID: 22052353 DOI: 10.4161/pri.5.4.17748] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The yeast prions [URE3] and [PSI] are not found in wild strains, suggesting they are not an advantage. Prion-forming ability is not conserved, even within Saccharomyces, suggesting it is a disease. Prion domains have non-prion functions, explaining some conservation of sequence. However, in spite of the sequence being constrained in evolution by these non-prion functions, the prion domains vary more rapidly than the remainder of the molecule, and these changes produce a transmission barrier, suggesting that these changes were selected to block prion infection. Yeast prions [PSI] and [URE3] induce a cellular stress response (Hsp104 and Hsp70 induction), suggesting the cells are not happy about being infected. Recently, we showed that the array of [PSI] and [URE3] prions includes a majority of lethal or very toxic variants, a result not expected if either prion were an adaptive cellular response to stress.
Collapse
Affiliation(s)
- Reed B Wickner
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD, USA.
| | | | | | | | | |
Collapse
|
36
|
Kabani M, Melki R. Yeast prions assembly and propagation: contributions of the prion and non-prion moieties and the nature of assemblies. Prion 2011; 5:277-84. [PMID: 22052349 DOI: 10.4161/pri.18070] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Yeast prions are self-perpetuating protein aggregates that are at the origin of heritable and transmissible non-Mendelian phenotypic traits. Among these, [PSI+], [URE3] and [PIN+] are the most well documented prions and arise from the assembly of Sup35p, Ure2p and Rnq1p, respectively, into insoluble fibrillar assemblies. Fibril assembly depends on the presence of N- or C-terminal prion domains (PrDs) which are not homologous in sequence but share unusual amino-acid compositions, such as enrichment in polar residues (glutamines and asparagines) or the presence of oligopeptide repeats. Purified PrDs form amyloid fibrils that can convert prion-free cells to the prion state upon transformation. Nonetheless, isolated PrDs and full-length prion proteins have different aggregation, structural and infectious properties. In addition, mutations in the "non-prion" domains (non-PrDs) of Sup35p, Ure2p and Rnq1p were shown to affect their prion properties in vitro and in vivo. Despite these evidences, the implication of the functional non-PrDs in fibril assembly and prion propagation has been mostly overlooked. In this review, we discuss the contribution of non-PrDs to prion assemblies, and the structure-function relationship in prion infectivity in the light of recent findings on Sup35p and Ure2p assembly into infectious fibrils from our laboratory and others.
Collapse
Affiliation(s)
- Mehdi Kabani
- Laboratoire d'Enzymologie et Biochimie Structurales, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France.
| | | |
Collapse
|
37
|
Reconstructing the fungal tree of life using phylogenomics and a preliminary investigation of the distribution of yeast prion-like proteins in the fungal kingdom. J Mol Evol 2011; 73:116-33. [PMID: 21938499 DOI: 10.1007/s00239-011-9461-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 09/07/2011] [Indexed: 01/02/2023]
Abstract
We have used three independent phylogenomic approaches (concatenated alignments, single-, and multi-gene supertrees) to reconstruct the fungal tree of life (FTOL) using publicly available fungal genomes. This is the first time multi-gene families have been used in fungal supertree reconstruction and permits us to use up to 66% of the 1,001,217 genes in our fungal database. Our analyses show that different phylogenomic datasets derived from varying clustering criteria and alignment orientation do not have a major effect on phylogenomic supertree reconstruction. Overall the resultant phylogenomic trees are relatively congruent with one another and successfully recover the major fungal phyla, subphyla and classes. We find that where incongruences do occur, the inferences are usually poorly supported. Within the Ascomycota phylum, our phylogenies reconstruct monophyletic Saccharomycotina and Pezizomycotina subphyla clades and infer a sister group relationship between these to the exclusion of the Taphrinomycotina. Within the Pezizomycotina subphylum, all three phylogenies infer a sister group relationship between the Leotiomycetes and Sordariomycetes classes. However, there is conflict regarding the relationships with the Dothideomycetes and Eurotiomycetes classes. Within the Basidiomycota phylum, supertrees derived from single- and multi-gene families infer a sister group relationship between the Pucciniomycotina and Agaricomycotina subphyla while the concatenated phylogeny infers a poorly supported relationship between the Agaricomycotina and Ustilagomycotina. The reconstruction of a robust FTOL is important for future fungal comparative analyses. We illustrate this point by performing a preliminary investigation into the phyletic distribution of yeast prion-like proteins in the fungal kingdom.
Collapse
|
38
|
Engel A, Shewmaker F, Edskes HK, Dyda F, Wickner RB. Amyloid of the Candida albicans Ure2p prion domain is infectious and has an in-register parallel β-sheet structure. Biochemistry 2011; 50:5971-8. [PMID: 21634787 PMCID: PMC3144561 DOI: 10.1021/bi200142x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ure2p of Candida albicans (Ure2(albicans) or CaUre2p) can be a prion in Saccharomyces cerevisiae, but Ure2p of Candida glabrata (Ure2(glabrata)) cannot, even though the Ure2(glabrata) N-terminal domain is more similar to that of the S. cerevisiae Ure2p (Ure2(cerevisiae)) than Ure2(albicans) is. We show that the N-terminal N/Q-rich prion domain of Ure2(albicans) forms amyloid that is infectious, transmitting [URE3alb] to S. cerevisiae cells expressing only C. albicans Ure2p. Using solid-state nuclear magnetic resonance of selectively labeled C. albicans Ure2p(1-90), we show that this infectious amyloid has an in-register parallel β-sheet structure, like that of the S. cerevisiae Ure2p prion domain and other S. cerevisiae prion amyloids. In contrast, the N/Q-rich N-terminal domain of Ure2(glabrata) does not readily form amyloid, and that formed upon prolonged incubation is not infectious.
Collapse
Affiliation(s)
- Abbi Engel
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830
- Biochemistry and Molecular Biology Dept., Georgetown University Medical School, Washington, DC
| | - Frank Shewmaker
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830
| | - Herman K. Edskes
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830
| | - Fred Dyda
- Laboratory of Molecular Biology, National Institute of Diabetes Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830
| | - Reed B. Wickner
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830
| |
Collapse
|
39
|
Crow ET, Li L. Newly identified prions in budding yeast, and their possible functions. Semin Cell Dev Biol 2011; 22:452-9. [PMID: 21397710 DOI: 10.1016/j.semcdb.2011.03.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 03/01/2011] [Accepted: 03/02/2011] [Indexed: 11/25/2022]
Abstract
Yeast prions are atypical genetic elements that are transmitted as heritable protein conformations. [PSI+], [URE3], and [PIN+] are three well-studied prions in the budding yeast, Saccharomyces cerevisiae. In the last three years, several additional prions have been reported in yeast, including [SWI+], [OCT+], [MCA], [GAR+], [MOT3+], [ISP+], and [NSI+]. The growing number of yeast prions suggests that protein-based inheritance might be a widespread biological phenomenon. In this review, we summarize the characteristics of each prion element, and discuss their potential functional roles in yeast biology.
Collapse
Affiliation(s)
- Emily T Crow
- Department of Molecular Pharmacology and Biological Chemistry, The Feinberg School of Medicine, Northwestern University, 320 East Superior Street, Chicago, IL 60611, USA.
| | | |
Collapse
|
40
|
Abstract
[URE3] is a prion (infectious protein) of the Saccharomyces cerevisiae Ure2p, a regulator of nitrogen catabolism. We show that wild S. paradoxus can be infected with a [URE3] prion, supporting the use of S. cerevisiae as a prion test bed. We find that the Ure2p of Candida albicans and C. glabrata also regulate nitrogen catabolism. Conservation of amino acid sequence within the prion domain of Ure2p has been proposed as evidence that the [URE3] prion helps its host. We show that the C. albicans Ure2p, which does not conserve this sequence, can nonetheless form a [URE3] prion in S. cerevisiae, but the C. glabrata Ure2p, which does have the conserved sequence, cannot form [URE3] as judged by its performance in S. cerevisiae. These results suggest that the sequence is not conserved to preserve prion forming ability.
Collapse
|
41
|
Wickner RB, Edskes HK, Kryndushkin D, McGlinchey R, Bateman D, Kelly A. Prion diseases of yeast: amyloid structure and biology. Semin Cell Dev Biol 2011; 22:469-75. [PMID: 21345375 DOI: 10.1016/j.semcdb.2011.02.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2011] [Revised: 02/11/2011] [Accepted: 02/14/2011] [Indexed: 12/11/2022]
Abstract
Prion "variants" or "strains" are prions with the identical protein sequence, but different characteristics of the prion infection: e.g. different incubation periods for scrapie strains or different phenotype intensities for yeast prion variants. We have shown that infectious amyloids of the yeast prions [PSI+], [URE3] and [PIN+] each have an in-register parallel β-sheet architecture. Moreover, we have pointed out that this amyloid architecture can explain how one protein can faithfully transmit any of several conformations to new protein monomers. This explains how proteins can be genes.
Collapse
Affiliation(s)
- Reed B Wickner
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, United States.
| | | | | | | | | | | |
Collapse
|
42
|
Harbi D, Kumar M, Harrison PM. LPS-annotate: complete annotation of compositionally biased regions in the protein knowledgebase. DATABASE-THE JOURNAL OF BIOLOGICAL DATABASES AND CURATION 2011; 2011:baq031. [PMID: 21216786 PMCID: PMC3017391 DOI: 10.1093/database/baq031] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Compositional bias (i.e. a skew in the composition of a biological sequence towards a subset of residue types) can occur at a wide variety of scales, from compositional biases of whole genomes, down to short regions in individual protein and gene–DNA sequences that are compositionally biased (CB regions). Such CB regions are made from a subset of residue types that are strewn along the length of the region in an irregular way. Here, we have developed the database server LPS-annotate, for the analysis of such CB regions, and protein disorder in protein sequences. The algorithm defines compositional bias through a thorough search for lowest-probability subsequences (LPSs) (i.e., the least likely sequence regions in terms of composition). Users can (i) initially annotate CB regions in input protein or nucleotide sequences of interest, and then (ii) query a database of greater than 1 500 000 pre-calculated protein-CB regions, for investigation of further functional hypotheses and inferences, about the specific CB regions that were discovered, and their protein disorder propensities. We demonstrate how a user can search for CB regions of similar compositional bias and protein disorder, with a worked example. We show that our annotations substantially augment the CB-region annotations that already exist in the UniProt database, with more comprehensive annotation of more complex CB regions. Our analysis indicates tens of thousands of CB regions that do not comprise globular domains or transmembrane domains, and that do not have a propensity to protein disorder, indicating a large cohort of protein-CB regions of biophysically uncharacterized types. This server and database is a conceptually novel addition to the workbench of tools now available to molecular biologists to generate hypotheses and inferences about the proteins that they are investigating. It can be accessed at http://libaio.biol.mcgill.ca/lps-annotate.html. Database URL:http://libaio.biol.mcgill.ca/lps-annotate.html
Collapse
Affiliation(s)
- Djamel Harbi
- Department of Biology, McGill University, Stewart Biology Building, 1205 Dr. Penfield Ave., Montreal, QC, H3A 1B1, Canada
| | | | | |
Collapse
|
43
|
Harrison PM, Khachane A, Kumar M. Genomic assessment of the evolution of the prion protein gene family in vertebrates. Genomics 2010; 95:268-77. [DOI: 10.1016/j.ygeno.2010.02.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2009] [Revised: 02/16/2010] [Accepted: 02/24/2010] [Indexed: 02/09/2023]
|
44
|
Nevzglyadova OV, Artemov AV, Mittenberg AG, Kostyleva EI, Mikhailova EV, Solovyov KV, Kuznetsova IM, Turoverov KK, Soidla TR. Comparison of crude lysate pellets from isogenic strains of yeast with different prion composition: Identification of prion-associated proteins. ACTA ACUST UNITED AC 2010. [DOI: 10.1134/s1990519x10010049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
45
|
Sindi SS, Serio TR. Prion dynamics and the quest for the genetic determinant in protein-only inheritance. Curr Opin Microbiol 2009; 12:623-30. [PMID: 19864176 DOI: 10.1016/j.mib.2009.09.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 09/12/2009] [Accepted: 09/14/2009] [Indexed: 01/24/2023]
Abstract
According to the prion hypothesis, proteins may act in atypical roles as genetic elements of infectivity and inheritance by undergoing self-replicating changes in physical state. While the preponderance of evidence strongly supports this concept particularly in fungi, the detailed mechanisms by which distinct protein forms specify unique phenotypes are emerging concepts. A particularly active area of investigation is the molecular nature of the heritable species, which has been probed through genetic, biochemical, and cell biological experimentation as well as by mathematical modeling. Here, we suggest that these studies are converging to implicate small aggregates composed of prion-state conformers as the transmissible genetic determinants of protein-based phenotypes.
Collapse
Affiliation(s)
- Suzanne S Sindi
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, 185 Meeting St., Box G-L2, Providence, RI 02912, USA
| | | |
Collapse
|
46
|
Masel J, Siegal ML. Robustness: mechanisms and consequences. Trends Genet 2009; 25:395-403. [PMID: 19717203 DOI: 10.1016/j.tig.2009.07.005] [Citation(s) in RCA: 240] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 07/11/2009] [Accepted: 07/13/2009] [Indexed: 01/09/2023]
Abstract
Biological systems are robust to perturbation by mutations and environmental fluctuations. New data are shedding light on the biochemical and network-level mechanisms responsible for robustness. Robustness to mutation might have evolved as an adaptation to reduce the effect of mutations, as a congruent byproduct of adaptive robustness to environmental variation, or as an intrinsic property of biological systems selected for their primary functions. Whatever its mechanism or origin, robustness to mutation results in the accumulation of phenotypically cryptic genetic variation. Partial robustness can lead to pre-adaptation, and thereby might contribute to evolvability. The identification and characterization of phenotypic capacitors - which act as switches of the degree of robustness - are critical to understanding the mechanisms and consequences of robustness.
Collapse
Affiliation(s)
- Joanna Masel
- Ecology & Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA.
| | | |
Collapse
|
47
|
Tyedmers J, Madariaga ML, Lindquist S. Prion switching in response to environmental stress. PLoS Biol 2009; 6:e294. [PMID: 19067491 PMCID: PMC2586387 DOI: 10.1371/journal.pbio.0060294] [Citation(s) in RCA: 207] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Accepted: 10/14/2008] [Indexed: 02/07/2023] Open
Abstract
Evolution depends on the manner in which genetic variation is translated into new phenotypes. There has been much debate about whether organisms might have specific mechanisms for "evolvability," which would generate heritable phenotypic variation with adaptive value and could act to enhance the rate of evolution. Capacitor systems, which allow the accumulation of cryptic genetic variation and release it under stressful conditions, might provide such a mechanism. In yeast, the prion [PSI(+)] exposes a large array of previously hidden genetic variation, and the phenotypes it thereby produces are advantageous roughly 25% of the time. The notion that [PSI(+)] is a mechanism for evolvability would be strengthened if the frequency of its appearance increased with stress. That is, a system that mediates even the haphazard appearance of new phenotypes, which have a reasonable chance of adaptive value would be beneficial if it were deployed at times when the organism is not well adapted to its environment. In an unbiased, high-throughput, genome-wide screen for factors that modify the frequency of [PSI(+)] induction, signal transducers and stress response genes were particularly prominent. Furthermore, prion induction increased by as much as 60-fold when cells were exposed to various stressful conditions, such as oxidative stress (H2O2) or high salt concentrations. The severity of stress and the frequency of [PSI(+)] induction were highly correlated. These findings support the hypothesis that [PSI(+)] is a mechanism to increase survival in fluctuating environments and might function as a capacitor to promote evolvability.
Collapse
Affiliation(s)
- Jens Tyedmers
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
| | - Maria Lucia Madariaga
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
- Harvard-MIT Division of Health Sciences and Technology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Susan Lindquist
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- * To whom correspondence should be addressed. E-mail:
| |
Collapse
|
48
|
Abstract
The [PSI(+)] prion causes widespread readthrough translation and is rare in natural populations of Saccharomyces, despite the fact that sex is expected to cause it to spread. Using the recently estimated rate of Saccharomyces outcrossing, we calculate the strength of selection necessary to maintain [PSI(+)] at levels low enough to be compatible with data. Using the best available parameter estimates, we find selection against [PSI(+)] to be significant. Inference regarding selection on modifiers of [PSI(+)] appearance depends on obtaining more precise and accurate estimates of the product of yeast effective population size N(e) and the spontaneous rate of [PSI(+)] appearance m. The ability to form [PSI(+)] has persisted in yeast over a long period of evolutionary time, despite a diversity of modifiers that could abolish it. If mN(e) < 1, this may be explained by insufficiently strong selection. If mN(e) > 1, then selection should favor the spread of [PSI(+)] resistance modifiers. In this case, rare conditions where [PSI(+)] is adaptive may permit its persistence in the face of negative selection.
Collapse
|
49
|
Wickner RB, Shewmaker F, Kryndushkin D, Edskes HK. Protein inheritance (prions) based on parallel in-register beta-sheet amyloid structures. Bioessays 2008; 30:955-64. [PMID: 18798523 DOI: 10.1002/bies.20821] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Most prions (infectious proteins) are self-propagating amyloids (filamentous protein multimers), and have been found in both mammals and fungal species. The prions [URE3] and [PSI+] of yeast are disease agents of Saccharomyces cerevisiae while [Het-s] of Podospora anserina may serve a normal cellular function. The parallel in-register beta-sheet structure shown by prion amyloids makes possible a templating action at the end of filaments which explains the faithful transmission of variant differences in these molecules. This property of self-reproduction, in turn, allows these proteins to act as de facto genes, encoding heritable information.
Collapse
Affiliation(s)
- Reed B Wickner
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA.
| | | | | | | |
Collapse
|
50
|
|