1
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Smoak RA, Snyder LF, Fassler JS, He BZ. Parallel expansion and divergence of an adhesin family in pathogenic yeasts. Genetics 2023; 223:iyad024. [PMID: 36794645 PMCID: PMC10319987 DOI: 10.1093/genetics/iyad024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 02/08/2023] [Accepted: 02/09/2023] [Indexed: 02/17/2023] Open
Abstract
Opportunistic yeast pathogens arose multiple times in the Saccharomycetes class, including the recently emerged, multidrug-resistant (MDR) Candida auris. We show that homologs of a known yeast adhesin family in Candida albicans, the Hyr/Iff-like (Hil) family, are enriched in distinct clades of Candida species as a result of multiple, independent expansions. Following gene duplication, the tandem repeat-rich region in these proteins diverged extremely rapidly and generated large variations in length and β-aggregation potential, both of which are known to directly affect adhesion. The conserved N-terminal effector domain was predicted to adopt a β-helical fold followed by an α-crystallin domain, making it structurally similar to a group of unrelated bacterial adhesins. Evolutionary analyses of the effector domain in C. auris revealed relaxed selective constraint combined with signatures of positive selection, suggesting functional diversification after gene duplication. Lastly, we found the Hil family genes to be enriched at chromosomal ends, which likely contributed to their expansion via ectopic recombination and break-induced replication. Combined, these results suggest that the expansion and diversification of adhesin families generate variation in adhesion and virulence within and between species and are a key step toward the emergence of fungal pathogens.
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Affiliation(s)
- Rachel A Smoak
- Civil and Environmental Engineering, The University of Iowa, Iowa City, IA 52242, USA
| | - Lindsey F Snyder
- Interdisciplinary Graduate Program in Genetics, The University of Iowa, Iowa City, IA 52242, USA
| | - Jan S Fassler
- Interdisciplinary Graduate Program in Genetics, The University of Iowa, Iowa City, IA 52242, USA
- Department of Biology, The University of Iowa, Iowa City, IA 52242, USA
| | - Bin Z He
- Interdisciplinary Graduate Program in Genetics, The University of Iowa, Iowa City, IA 52242, USA
- Department of Biology, The University of Iowa, Iowa City, IA 52242, USA
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2
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Lipke PN, Ragonis-Bachar P. Sticking to the Subject: Multifunctionality in Microbial Adhesins. J Fungi (Basel) 2023; 9:jof9040419. [PMID: 37108873 PMCID: PMC10144551 DOI: 10.3390/jof9040419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/25/2023] [Accepted: 03/27/2023] [Indexed: 03/31/2023] Open
Abstract
Bacterial and fungal adhesins mediate microbial aggregation, biofilm formation, and adhesion to host. We divide these proteins into two major classes: professional adhesins and moonlighting adhesins that have a non-adhesive activity that is evolutionarily conserved. A fundamental difference between the two classes is the dissociation rate. Whereas moonlighters, including cytoplasmic enzymes and chaperones, can bind with high affinity, they usually dissociate quickly. Professional adhesins often have unusually long dissociation rates: minutes or hours. Each adhesin has at least three activities: cell surface association, binding to a ligand or adhesive partner protein, and as a microbial surface pattern for host recognition. We briefly discuss Bacillus subtilis TasA, pilin adhesins, gram positive MSCRAMMs, and yeast mating adhesins, lectins and flocculins, and Candida Awp and Als families. For these professional adhesins, multiple activities include binding to diverse ligands and binding partners, assembly into molecular complexes, maintenance of cell wall integrity, signaling for cellular differentiation in biofilms and in mating, surface amyloid formation, and anchorage of moonlighting adhesins. We summarize the structural features that lead to these diverse activities. We conclude that adhesins resemble other proteins with multiple activities, but they have unique structural features to facilitate multifunctionality.
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Affiliation(s)
- Peter N. Lipke
- Biology Department, Brooklyn College of the City University of New York, Brooklyn, NY 11215, USA
- Correspondence:
| | - Peleg Ragonis-Bachar
- Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel
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3
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Novelty Search Promotes Antigenic Diversity in Microbial Pathogens. Pathogens 2023; 12:pathogens12030388. [PMID: 36986310 PMCID: PMC10053453 DOI: 10.3390/pathogens12030388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 02/12/2023] [Accepted: 02/21/2023] [Indexed: 03/05/2023] Open
Abstract
Driven by host–pathogen coevolution, cell surface antigens are often the fastest evolving parts of a microbial pathogen. The persistent evolutionary impetus for novel antigen variants suggests the utility of novelty-seeking algorithms in predicting antigen diversification in microbial pathogens. In contrast to traditional genetic algorithms maximizing variant fitness, novelty-seeking algorithms optimize variant novelty. Here, we designed and implemented three evolutionary algorithms (fitness-seeking, novelty-seeking, and hybrid) and evaluated their performances in 10 simulated and 2 empirically derived antigen fitness landscapes. The hybrid walks combining fitness- and novelty-seeking strategies overcame the limitations of each algorithm alone, and consistently reached global fitness peaks. Thus, hybrid walks provide a model for microbial pathogens escaping host immunity without compromising variant fitness. Biological processes facilitating novelty-seeking evolution in natural pathogen populations include hypermutability, recombination, wide dispersal, and immune-compromised hosts. The high efficiency of the hybrid algorithm improves the evolutionary predictability of novel antigen variants. We propose the design of escape-proof vaccines based on high-fitness variants covering a majority of the basins of attraction on the fitness landscape representing all potential variants of a microbial antigen.
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Abstract
The genus Saccharomyces is an evolutionary paradox. On the one hand, it is composed of at least eight clearly phylogenetically delineated species; these species are reproductively isolated from each other, and hybrids usually cannot complete their sexual life cycles. On the other hand, Saccharomyces species have a long evolutionary history of hybridization, which has phenotypic consequences for adaptation and domestication. A variety of cellular, ecological, and evolutionary mechanisms are responsible for this partial reproductive isolation among Saccharomyces species. These mechanisms have caused the evolution of diverse Saccharomyces species and hybrids, which occupy a variety of wild and domesticated habitats. In this article, we introduce readers to the mechanisms isolating Saccharomyces species, the circumstances in which reproductive isolation mechanisms are effective and ineffective, and the evolutionary consequences of partial reproductive isolation. We discuss both the evolutionary history of the genus Saccharomyces and the human history of taxonomists and biologists struggling with species concepts in this fascinating genus.
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Affiliation(s)
- Jasmine Ono
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6AA, UK; ,
| | - Duncan Greig
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6AA, UK; ,
| | - Primrose J Boynton
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6AA, UK; ,
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5
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Rahi ML, Mather PB, Ezaz T, Hurwood DA. The Molecular Basis of Freshwater Adaptation in Prawns: Insights from Comparative Transcriptomics of Three Macrobrachium Species. Genome Biol Evol 2019; 11:1002-1018. [PMID: 30840062 PMCID: PMC6450038 DOI: 10.1093/gbe/evz045] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/12/2019] [Indexed: 12/17/2022] Open
Abstract
Elucidating the molecular basis of adaptation to different environmental conditions is important because adaptive ability of a species can shape its distribution, influence speciation, and also drive a variety of evolutionary processes. For crustaceans, colonization of freshwater habitats has significantly impacted diversity, but the molecular basis of this process is poorly understood. In the current study, we examined three prawn species from the genus Macrobrachium (M. australiense, M. tolmerum, and M. novaehollandiae) to better understand the molecular basis of freshwater adaptation using a comparative transcriptomics approach. Each of these species naturally inhabit environments with different salinity levels; here, we exposed them to the same experimental salinity conditions (0‰ and 15‰), to compare expression patterns of candidate genes that previously have been shown to influence phenotypic traits associated with freshwater adaptation (e.g., genes associated with osmoregulation). Differential gene expression analysis revealed 876, 861, and 925 differentially expressed transcripts under the two salinities for M. australiense, M. tolmerum, and M. novaehollandiae, respectively. Of these, 16 were found to be unannotated novel transcripts and may be taxonomically restricted or orphan genes. Functional enrichment and molecular pathway mapping revealed 13 functionally enriched categories and 11 enriched molecular pathways that were common to the three Macrobrachium species. Pattern of selection analysis revealed 26 genes with signatures of positive selection among pairwise species comparisons. Overall, our results indicate that the same key genes and similar molecular pathways are likely to be involved with freshwater adaptation widely across this decapod group; with nonoverlapping sets of genes showing differential expression (mainly osmoregulatory genes) and signatures of positive selection (genes involved with different life history traits).
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Affiliation(s)
- Md Lifat Rahi
- Science and Engineering Faculty, School of Earth Environment and Biological Sciences (EEBS), Queensland University of Technology (QUT), Brisbane, Queensland, Australia
| | - Peter B Mather
- Science and Engineering Faculty, School of Earth Environment and Biological Sciences (EEBS), Queensland University of Technology (QUT), Brisbane, Queensland, Australia
| | - Tariq Ezaz
- Wildlife Genetics Laboratory, Institute for Applied Ecology, University of Canberra, Australian Capital Territory, Australia
| | - David A Hurwood
- Science and Engineering Faculty, School of Earth Environment and Biological Sciences (EEBS), Queensland University of Technology (QUT), Brisbane, Queensland, Australia
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6
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Nath A. Prediction and molecular insights into fungal adhesins and adhesin like proteins. Comput Biol Chem 2019; 80:333-340. [PMID: 31078912 DOI: 10.1016/j.compbiolchem.2019.05.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 04/02/2019] [Accepted: 05/02/2019] [Indexed: 10/26/2022]
Abstract
Adhesion is the foremost step in pathogenesis and biofilm formation and is facilitated by a special class of cell wall proteins known as adhesins. Formation of biofilms in catheters and other medical devices subsequently leads to infections. As compared to bacterial adhesins, there is relatively less work for the characterization and identification of fungal adhesins. Understanding the sequence characterization of fungal adhesins may facilitate a better understanding of its role in pathogenesis. Experimental methods for investigation and characterization of fungal adhesins are labor intensive and expensive. Therefore, there is a need for fast and efficient computational methods for the identification and characterization of fungal adhesins. The aim of the current study is twofold: (i) to develop an accurate predictor for fungal adhesins, (ii) to sieve out the prominent molecular signatures present in fungal adhesins. Of the many supervised learning algorithms implemented in the current study, voting ensembles resulted in enhanced prediction accuracy. The best voting-ensemble consisting of three support vector machines with three different kernels (PolyK, RBF, PuK) achieved an accuracy of 94.9% on leave one out cross validation and 98.0% accuracy on blind testing set. A preference/avoidance list of molecular features as well as human interpretable rules are also extracted giving insights into the general sequence features of fungal adhesins. Fungal adhesins are characterized by high Threonine and Cysteine and avoidance for Phenylalanine and Methionine. They also have avoidance for average hydrophilicity. The current analysis possibly will facilitate the understanding of the mechanism of fungal adhesin function which may further help in designing methods for restricting adhesin mediated pathogenesis.
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Affiliation(s)
- Abhigyan Nath
- Department of Biochemistry, Pt. Jawahar Lal Nehru Memorial Medical College, Raipur, 492001, India.
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7
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The therapeutic and nutraceutical potential of agmatine, and its enhanced production using Aspergillus oryzae. Amino Acids 2019; 52:181-197. [DOI: 10.1007/s00726-019-02720-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Accepted: 03/05/2019] [Indexed: 12/30/2022]
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8
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Lipke PN. What We Do Not Know about Fungal Cell Adhesion Molecules. J Fungi (Basel) 2018; 4:jof4020059. [PMID: 29772751 PMCID: PMC6023273 DOI: 10.3390/jof4020059] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 04/27/2018] [Accepted: 05/10/2018] [Indexed: 12/16/2022] Open
Abstract
There has been extensive research on structure and function of fungal cell adhesion molecules, but the most of the work has been about adhesins in Candida albicans and Saccharomyces cerevisiae. These yeasts are members of a single ascomycete order, and adhesion molecules from the six other fungal phyla are only sparsely described in the literature. In these other phyla, most of the research is at the cellular level, rather than at the molecular level, so there has been little characterization of the adhesion molecules themselves. A catalog of known adhesins shows some common features: high Ser/Thr content, tandem repeats, N- and O-glycosylations, GPI anchors, dibasic sequence motifs, and potential amyloid-forming sequences. However, none of these features is universal. Known ligands include proteins and glycans on homologous cells and host cells. Existing and novel tools can exploit the availability of genome sequences to identify and characterize new fungal adhesins. These include bioinformatics tools and well-established yeast surface display models, which could be coupled with an adhesion substrate array. Thus, new knowledge could be exploited to answer key questions in fungal ecology, animal and plant pathogenesis, and roles of biofilms in infection and biomass turnover.
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Affiliation(s)
- Peter N Lipke
- Biology Department, Brooklyn College, City University of New York, Brooklyn, NY 11210, USA.
- The Graduate Center, City University of New York, New York, NY 10016, USA.
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9
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Rowley PA, Patterson K, Sandmeyer SB, Sawyer SL. Control of yeast retrotransposons mediated through nucleoporin evolution. PLoS Genet 2018; 14:e1007325. [PMID: 29694349 PMCID: PMC5918913 DOI: 10.1371/journal.pgen.1007325] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 03/21/2018] [Indexed: 02/07/2023] Open
Abstract
Yeasts serve as hosts to several types of genetic parasites. Few studies have addressed the evolutionary trajectory of yeast genes that control the stable co-existence of these parasites with their host cell. In Saccharomyces yeasts, the retrovirus-like Ty retrotransposons must access the nucleus. We show that several genes encoding components of the yeast nuclear pore complex have experienced natural selection for substitutions that change the encoded protein sequence. By replacing these S. cerevisiae genes with orthologs from other Saccharomyces species, we discovered that natural sequence changes have affected the mobility of Ty retrotransposons. Specifically, changing the genetic sequence of NUP84 or NUP82 to match that of other Saccharomyces species alters the mobility of S. cerevisiae Ty1 and Ty3. Importantly, all tested housekeeping functions of NUP84 and NUP82 remained equivalent across species. Signatures of natural selection, resulting in altered interactions with viruses and parasitic genetic elements, are common in host defense proteins. Yet, few instances have been documented in essential housekeeping proteins. The nuclear pore complex is the gatekeeper of the nucleus. This study shows how the evolution of this large, ubiquitous eukaryotic complex can alter the replication of a molecular parasite, but concurrently maintain essential host functionalities regarding nucleocytoplasmic trafficking.
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Affiliation(s)
- Paul A. Rowley
- BioFrontiers Institute, Department of Molecular Cellular and Developmental Biology, University of Colorado Boulder, Boulder, CO, United States of America
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States of America
| | - Kurt Patterson
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, Irvine, CA, United States of America
| | - Suzanne B. Sandmeyer
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, Irvine, CA, United States of America
| | - Sara L. Sawyer
- BioFrontiers Institute, Department of Molecular Cellular and Developmental Biology, University of Colorado Boulder, Boulder, CO, United States of America
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10
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Amyloid-Like β-Aggregates as Force-Sensitive Switches in Fungal Biofilms and Infections. Microbiol Mol Biol Rev 2017; 82:82/1/e00035-17. [PMID: 29187516 DOI: 10.1128/mmbr.00035-17] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Cellular aggregation is an essential step in the formation of biofilms, which promote fungal survival and persistence in hosts. In many of the known yeast cell adhesion proteins, there are amino acid sequences predicted to form amyloid-like β-aggregates. These sequences mediate amyloid formation in vitro. In vivo, these sequences mediate a phase transition from a disordered state to a partially ordered state to create patches of adhesins on the cell surface. These β-aggregated protein patches are called adhesin nanodomains, and their presence greatly increases and strengthens cell-cell interactions in fungal cell aggregation. Nanodomain formation is slow (with molecular response in minutes and the consequences being evident for hours), and strong interactions lead to enhanced biofilm formation. Unique among functional amyloids, fungal adhesin β-aggregation can be triggered by the application of physical shear force, leading to cellular responses to flow-induced stress and the formation of robust biofilms that persist under flow. Bioinformatics analysis suggests that this phenomenon may be widespread. Analysis of fungal abscesses shows the presence of surface amyloids in situ, a finding which supports the idea that phase changes to an amyloid-like state occur in vivo. The amyloid-coated fungi bind the damage-associated molecular pattern receptor serum amyloid P component, and there may be a consequential modulation of innate immune responses to the fungi. Structural data now suggest mechanisms for the force-mediated induction of the phase change. We summarize and discuss evidence that the sequences function as triggers for protein aggregation and subsequent cellular aggregation, both in vitro and in vivo.
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11
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High-throughput characterization of protein-protein interactions by reprogramming yeast mating. Proc Natl Acad Sci U S A 2017; 114:12166-12171. [PMID: 29087945 DOI: 10.1073/pnas.1705867114] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
High-throughput methods for screening protein-protein interactions enable the rapid characterization of engineered binding proteins and interaction networks. While existing approaches are powerful, none allow quantitative library-on-library characterization of protein interactions in a modifiable extracellular environment. Here, we show that sexual agglutination of Saccharomyces cerevisiae can be reprogrammed to link interaction strength with mating efficiency using synthetic agglutination (SynAg). Validation of SynAg with 89 previously characterized interactions shows a log-linear relationship between mating efficiency and protein binding strength for interactions with Kds ranging from below 500 pM to above 300 μM. Using induced chromosomal translocation to pair barcodes representing binding proteins, thousands of distinct interactions can be screened in a single pot. We demonstrate the ability to characterize protein interaction networks in a modifiable environment by introducing a soluble peptide that selectively disrupts a subset of interactions in a representative network by up to 800-fold. SynAg enables the high-throughput, quantitative characterization of protein-protein interaction networks in a fully defined extracellular environment at a library-on-library scale.
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12
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Rowley PA. The frenemies within: viruses, retrotransposons and plasmids that naturally infect Saccharomyces yeasts. Yeast 2017; 34:279-292. [PMID: 28387035 DOI: 10.1002/yea.3234] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 03/28/2017] [Accepted: 03/29/2017] [Indexed: 11/07/2022] Open
Abstract
Viruses are a major focus of current research efforts because of their detrimental impact on humanity and their ubiquity within the environment. Bacteriophages have long been used to study host-virus interactions within microbes, but it is often forgotten that the single-celled eukaryote Saccharomyces cerevisiae and related species are infected with double-stranded RNA viruses, single-stranded RNA viruses, LTR-retrotransposons and double-stranded DNA plasmids. These intracellular nucleic acid elements have some similarities to higher eukaryotic viruses, i.e. yeast retrotransposons have an analogous lifecycle to retroviruses, the particle structure of yeast totiviruses resembles the capsid of reoviruses and segregation of yeast plasmids is analogous to segregation strategies used by viral episomes. The powerful experimental tools available to study the genetics, cell biology and evolution of S. cerevisiae are well suited to further our understanding of how cellular processes are hijacked by eukaryotic viruses, retrotransposons and plasmids. This article has been written to briefly introduce viruses, retrotransposons and plasmids that infect Saccharomyces yeasts, emphasize some important cellular proteins and machineries with which they interact, and suggest the evolutionary consequences of these interactions. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- Paul A Rowley
- Department of Biological Sciences, The University of Idaho, Moscow, Idaho, USA
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13
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Banderas A, Koltai M, Anders A, Sourjik V. Sensory input attenuation allows predictive sexual response in yeast. Nat Commun 2016; 7:12590. [PMID: 27557894 PMCID: PMC5007329 DOI: 10.1038/ncomms12590] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 07/14/2016] [Indexed: 12/22/2022] Open
Abstract
Animals are known to adjust their sexual behaviour depending on mate competition. Here we report similar regulation for mating behaviour in a sexual unicellular eukaryote, the budding yeast Saccharomyces cerevisiae. We demonstrate that pheromone-based communication between the two mating types, coupled to input attenuation by recipient cells, enables yeast to robustly monitor relative mate abundance (sex ratio) within a mixed population and to adjust their commitment to sexual reproduction in proportion to their estimated chances of successful mating. The mechanism of sex-ratio sensing relies on the diffusible peptidase Bar1, which is known to degrade the pheromone signal produced by mating partners. We further show that such a response to sexual competition within a population can optimize the fitness trade-off between the costs and benefits of mating response induction. Our study thus provides an adaptive explanation for the known molecular mechanism of pheromone degradation in yeast. Cells of the yeast Saccharomyces cerevisiae can mate with other cells of opposite mating type. Here, the authors show that the combination of a pheromone and a pheromone-degrading enzyme allows yeast cells to monitor relative mate abundance within a population and adjust their commitment to sexual reproduction.
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Affiliation(s)
- Alvaro Banderas
- Max Planck Institute for Terrestrial Microbiology &LOEWE Research Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch-Str. 16, D-35037 Marburg, Germany.,Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
| | - Mihaly Koltai
- Max Planck Institute for Terrestrial Microbiology &LOEWE Research Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch-Str. 16, D-35037 Marburg, Germany
| | - Alexander Anders
- Max Planck Institute for Terrestrial Microbiology &LOEWE Research Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch-Str. 16, D-35037 Marburg, Germany
| | - Victor Sourjik
- Max Planck Institute for Terrestrial Microbiology &LOEWE Research Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch-Str. 16, D-35037 Marburg, Germany
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14
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Dunning LT, Hipperson H, Baker WJ, Butlin RK, Devaux C, Hutton I, Igea J, Papadopulos AST, Quan X, Smadja CM, Turnbull CGN, Savolainen V. Ecological speciation in sympatric palms: 1. Gene expression, selection and pleiotropy. J Evol Biol 2016; 29:1472-87. [PMID: 27177130 PMCID: PMC6680112 DOI: 10.1111/jeb.12895] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 05/04/2016] [Accepted: 05/11/2016] [Indexed: 02/02/2023]
Abstract
Ecological speciation requires divergent selection, reproductive isolation and a genetic mechanism to link the two. We examined the role of gene expression and coding sequence evolution in this process using two species of Howea palms that have diverged sympatrically on Lord Howe Island, Australia. These palms are associated with distinct soil types and have displaced flowering times, representing an ideal candidate for ecological speciation. We generated large amounts of RNA‐Seq data from multiple individuals and tissue types collected on the island from each of the two species. We found that differentially expressed loci as well as those with divergent coding sequences between Howea species were associated with known ecological and phenotypic differences, including response to salinity, drought, pH and flowering time. From these loci, we identified potential ‘ecological speciation genes’ and further validate their effect on flowering time by knocking out orthologous loci in a model plant species. Finally, we put forward six plausible ecological speciation loci, providing support for the hypothesis that pleiotropy could help to overcome the antagonism between selection and recombination during speciation with gene flow.
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Affiliation(s)
- L T Dunning
- Department of Life Sciences, Imperial College London, Ascot, UK
| | - H Hipperson
- Department of Life Sciences, Imperial College London, Ascot, UK
| | - W J Baker
- Royal Botanic Gardens, Kew, Richmond, UK
| | - R K Butlin
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK.,Sven Lovén Centre for Marine Sciences, Tjärnö, University of Gothenburg, Stromstäd, Sweden
| | - C Devaux
- Department of Life Sciences, Imperial College London, Ascot, UK
| | - I Hutton
- Lord Howe Island Museum, Lord Howe Island, NSW, Australia
| | - J Igea
- Department of Life Sciences, Imperial College London, Ascot, UK
| | - A S T Papadopulos
- Department of Life Sciences, Imperial College London, Ascot, UK.,Royal Botanic Gardens, Kew, Richmond, UK
| | - X Quan
- Department of Life Sciences, Imperial College London, Ascot, UK
| | - C M Smadja
- Department of Life Sciences, Imperial College London, Ascot, UK
| | - C G N Turnbull
- Department of Life Sciences, Imperial College London, London, UK
| | - V Savolainen
- Department of Life Sciences, Imperial College London, Ascot, UK.,Royal Botanic Gardens, Kew, Richmond, UK
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15
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Abstract
We tell of a journey that led to discovery of amyloids formed by yeast cell adhesins and their importance in biofilms and host immunity. We begin with the identification of the adhesin functional amyloid-forming sequences that mediate fiber formation in vitro. Atomic force microscopy and confocal microscopy show 2-dimensional amyloid "nanodomains" on the surface of cells that are activated for adhesion. These nanodomains are arrays of adhesin molecules that bind multivalent ligands with high avidity. Nanodomains form when adhesin molecules are stretched in the AFM or under laminar flow. Treatment with antiamyloid perturbants or mutation of the amyloid sequence prevents adhesion nanodomain formation and activation. We are now discovering biological consequences. Adhesin nanodomains promote formation and maintenance of biofilms, which are microbial communities. Also, in abscesses within candidiasis patients, we find adhesin amyloids on the surface of the fungi. In both human infection and a Caenorhabditis elegans infection model, the presence of fungal surface amyloids elicits anti-inflammatory responses. Thus, this is a story of how fungal adhesins respond to extension forces through formation of cell surface amyloid nanodomains, with key consequences for biofilm formation and host responses.
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