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Espada‐Hinojosa S, Karthäuser C, Srivastava A, Schuster L, Winter T, de Oliveira AL, Schulz F, Horn M, Sievert S, Bright M. Comparative genomics of a vertically transmitted thiotrophic bacterial ectosymbiont and its close free-living relative. Mol Ecol Resour 2024; 24:e13889. [PMID: 38010882 PMCID: PMC10952691 DOI: 10.1111/1755-0998.13889] [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: 01/09/2023] [Revised: 08/31/2023] [Accepted: 10/20/2023] [Indexed: 11/29/2023]
Abstract
Thiotrophic symbioses between sulphur-oxidizing bacteria and various unicellular and metazoan eukaryotes are widespread in reducing marine environments. The giant colonial ciliate Zoothamnium niveum, however, is the only host of thioautotrophic symbionts that has been cultivated along with its symbiont, the vertically transmitted ectosymbiont Candidatus Thiobius zoothamnicola (short Thiobius). Because theoretical predictions posit a smaller genome in vertically transmitted endosymbionts compared to free-living relatives, we investigated whether this is true also for an ectosymbiont. We used metagenomics to recover the high-quality draft genome of this bacterial symbiont. For comparison we have also sequenced a closely related free-living cultured but not formally described strain Milos ODIII6 (short ODIII6). We then performed comparative genomics to assess the functional capabilities at gene, metabolic pathway and trait level. 16S rRNA gene trees and average amino acid identity confirmed the close phylogenetic relationship of both bacteria. Indeed, Thiobius has about a third smaller genome than its free-living relative ODIII6, with reduced metabolic capabilities and fewer functional traits. The functional capabilities of Thiobius were a subset of those of the more versatile ODIII6, which possessed additional genes for oxygen, sulphur and hydrogen utilization and for the acquisition of phosphorus illustrating features that may be adaptive for the unstable environmental conditions at hydrothermal vents. In contrast, Thiobius possesses genes potentially enabling it to utilize lactate and acetate heterotrophically, compounds that may be provided as byproducts by the host. The present study illustrates the effect of strict host-dependence of a bacterial ectosymbiont on genome evolution and host adaptation.
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Affiliation(s)
| | - Clarissa Karthäuser
- Biology DepartmentWoods Hole Oceanographic InstitutionWoods HoleMassachusettsUSA
| | - Abhishek Srivastava
- Department of Functional and Evolutionary EcologyUniversity of ViennaViennaAustria
| | - Lukas Schuster
- Department of Functional and Evolutionary EcologyUniversity of ViennaViennaAustria
- Present address:
Deakin UniversityBurwoodAustralia
| | - Teresa Winter
- Department of Functional and Evolutionary EcologyUniversity of ViennaViennaAustria
| | - André Luiz de Oliveira
- Department of Functional and Evolutionary EcologyUniversity of ViennaViennaAustria
- Present address:
Max Planck Institute for Marine MicrobiologyBremenGermany
| | - Frederik Schulz
- Center for Microbiology and Environmental Systems ScienceUniversity of ViennaViennaAustria
- Present address:
DOE Joint Genome InstituteBerkeleyCaliforniaUSA
| | - Matthias Horn
- Center for Microbiology and Environmental Systems ScienceUniversity of ViennaViennaAustria
| | - Stefan Sievert
- Biology DepartmentWoods Hole Oceanographic InstitutionWoods HoleMassachusettsUSA
| | - Monika Bright
- Department of Functional and Evolutionary EcologyUniversity of ViennaViennaAustria
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Tapia SM, Pérez‐Torrado R, Adam AC, Macías LG, Barrio E, Querol A. Functional divergence in the proteins encoded by ARO80 from S. uvarum, S. kudriavzevii and S. cerevisiae explain differences in the aroma production during wine fermentation. Microb Biotechnol 2022; 15:2281-2291. [PMID: 35536034 PMCID: PMC9328738 DOI: 10.1111/1751-7915.14071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 04/19/2022] [Accepted: 04/24/2022] [Indexed: 11/27/2022] Open
Abstract
Phenylethanol (PE) and phenylethyl acetate (PEA) are commonly desired compounds in wine because of their rose-like aroma. The yeast S. cerevisiae produces the PE either through de novo biosynthesis by shikimate pathway followed by the Ehrlich pathway or the direct phenylalanine catabolism via Ehrlich pathway, and then converted into PEA. Previous work demonstrated that, compared to S. cerevisiae, other Saccharomyces species, such as S. kudriavzevii and S. uvarum, produce higher concentrations of PE and PEA from the precursor phenylalanine, which indicates differential activities of the biosynthetic-involved enzymes. A previous in-silico analysis suggested that the transcriptional activator Aro80p is one of the best candidates to explain these differences. An improved functional analysis identified significant radical amino acid changes in the S. uvarum and S. kudriavzevii Aro80p that could impact the expression of the catabolic genes ARO9 and ARO10, and hence, the production of PE from phenylalanine. Indeed, wine S. cerevisiae strains carrying the S. uvarum and S. kudriavzevii ARO80 alleles increased the production of both compounds in the presence of phenylalanine by increasing the expression of ARO9 and ARO10. This study provides novel insights of the unidentified Aro80p regulatory region and the potential usage of alternatives ARO80 alleles to enhance the PE and PEA concentration in wine.
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Affiliation(s)
- Sebastián M. Tapia
- Departamento de Biotecnología de los AlimentosGrupo de Biología de Sistemas en Levaduras de Interés BiotecnológicoInstituto de Agroquímica y Tecnología de Los Alimentos (IATA)‐CSIC46980ValenciaSpain
| | - Roberto Pérez‐Torrado
- Departamento de Biotecnología de los AlimentosGrupo de Biología de Sistemas en Levaduras de Interés BiotecnológicoInstituto de Agroquímica y Tecnología de Los Alimentos (IATA)‐CSIC46980ValenciaSpain
| | - Ana Cristina Adam
- Departamento de Biotecnología de los AlimentosGrupo de Biología de Sistemas en Levaduras de Interés BiotecnológicoInstituto de Agroquímica y Tecnología de Los Alimentos (IATA)‐CSIC46980ValenciaSpain
| | - Laura G. Macías
- Departamento de Biotecnología de los AlimentosGrupo de Biología de Sistemas en Levaduras de Interés BiotecnológicoInstituto de Agroquímica y Tecnología de Los Alimentos (IATA)‐CSIC46980ValenciaSpain
- Departament de GenèticaUniversitat de ValènciaValenciaSpain
| | - Eladio Barrio
- Departamento de Biotecnología de los AlimentosGrupo de Biología de Sistemas en Levaduras de Interés BiotecnológicoInstituto de Agroquímica y Tecnología de Los Alimentos (IATA)‐CSIC46980ValenciaSpain
- Departament de GenèticaUniversitat de ValènciaValenciaSpain
| | - Amparo Querol
- Departamento de Biotecnología de los AlimentosGrupo de Biología de Sistemas en Levaduras de Interés BiotecnológicoInstituto de Agroquímica y Tecnología de Los Alimentos (IATA)‐CSIC46980ValenciaSpain
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Waldern J, Schiraldi NJ, Belfort M, Novikova O. Bacterial Group II Intron Genomic Neighborhoods Reflect Survival Strategies: Hiding and Hijacking. Mol Biol Evol 2021; 37:1942-1948. [PMID: 32134458 PMCID: PMC7306698 DOI: 10.1093/molbev/msaa055] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Group II (gII) introns are mobile retroelements that can spread to new DNA sites through retrotransposition, which can be influenced by a variety of host factors. To determine if these host factors bear any relationship to the genomic location of gII introns, we developed a bioinformatic pipeline wherein we focused on the genomic neighborhoods of bacterial gII introns within their native contexts and sought to determine global relationships between introns and their surrounding genes. We found that, although gII introns inhabit diverse regions, these neighborhoods are often functionally enriched for genes that could promote gII intron retention or proliferation. On one hand, we observe that gII introns are frequently found hiding in mobile elements or after transcription terminators. On the other hand, gII introns are enriched in locations in which they could hijack host functions for their movement, potentially timing expression of the intron with genes that produce favorable conditions for retrotransposition. Thus, we propose that gII intron distributions have been shaped by relationships with their surrounding genomic neighbors.
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Affiliation(s)
- Justin Waldern
- Department of Biological Sciences and RNA Institute, University at Albany, Albany, NY
| | - Nicholas J Schiraldi
- Academic and Research Computing Center, Information Technology Services, University at Albany, Albany, NY
| | - Marlene Belfort
- Department of Biological Sciences and RNA Institute, University at Albany, Albany, NY
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY
| | - Olga Novikova
- Department of Biological Sciences and RNA Institute, University at Albany, Albany, NY
- Corresponding author: E-mail:
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Waldern JM, Smith D, Piazza CL, Bailey EJ, Schiraldi NJ, Nemati R, Fabris D, Belfort M, Novikova O. Methylation of rRNA as a host defense against rampant group II intron retrotransposition. Mob DNA 2021; 12:9. [PMID: 33678171 PMCID: PMC7938551 DOI: 10.1186/s13100-021-00237-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 02/22/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Group II introns are mobile retroelements, capable of invading new sites in DNA. They are self-splicing ribozymes that complex with an intron-encoded protein to form a ribonucleoprotein that targets DNA after splicing. These molecules can invade DNA site-specifically, through a process known as retrohoming, or can invade ectopic sites through retrotransposition. Retrotransposition, in particular, can be strongly influenced by both environmental and cellular factors. RESULTS To investigate host factors that influence retrotransposition, we performed random insertional mutagenesis using the ISS1 transposon to generate a library of over 1000 mutants in Lactococcus lactis, the native host of the Ll.LtrB group II intron. By screening this library, we identified 92 mutants with increased retrotransposition frequencies (RTP-ups). We found that mutations in amino acid transport and metabolism tended to have increased retrotransposition frequencies. We further explored a subset of these RTP-up mutants, the most striking of which is a mutant in the ribosomal RNA methyltransferase rlmH, which exhibited a reproducible 20-fold increase in retrotransposition frequency. In vitro and in vivo experiments revealed that ribosomes in the rlmH mutant were defective in the m3Ψ modification and exhibited reduced binding to the intron RNA. CONCLUSIONS Taken together, our results reinforce the importance of the native host organism in regulating group II intron retrotransposition. In particular, the evidence from the rlmH mutant suggests a role for ribosome modification in limiting rampant retrotransposition.
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Affiliation(s)
- Justin M. Waldern
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
- Current address: Department of Biology, University of North Carolina, 270 Bell Tower Drive, Chapel Hill, NC 27599 USA
| | - Dorie Smith
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
| | - Carol Lyn Piazza
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
| | - E. Jake Bailey
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
| | - Nicholas J. Schiraldi
- Academic and Research Computing Center, Information Technology Services, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
| | - Reza Nemati
- Department of Chemistry, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
- Current address: Biogen, 125 Broadway, Cambridge, MA 02142 USA
| | - Dan Fabris
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
- Department of Chemistry, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
- Current address: Department of Chemistry, University of Connecticut, 55 N. Eagleville Road, Storrs, CT 06268 USA
| | - Marlene Belfort
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
- Department of Biomedical Sciences, School of Public Health, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
| | - Olga Novikova
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
- Current address: Biology Department, SUNY Buffalo State College, 1300 Elmwood Avenue, Buffalo, NY 14222 USA
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Macías LG, Morard M, Toft C, Barrio E. Comparative Genomics Between Saccharomyces kudriavzevii and S. cerevisiae Applied to Identify Mechanisms Involved in Adaptation. Front Genet 2019; 10:187. [PMID: 30930934 PMCID: PMC6425871 DOI: 10.3389/fgene.2019.00187] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 02/21/2019] [Indexed: 12/02/2022] Open
Abstract
Yeasts belonging to the Saccharomyces genus play an important role in human-driven fermentations. The species S. cerevisiae has been widely studied because it is the dominant yeast in most fermentations and it has been widely used as a model eukaryotic organism. Recently, other species of the Saccharomyces genus are gaining interest to solve the new challenges that the fermentation industry are facing. One of these species is S. kudriavzevii, which exhibits interesting physiological properties compared to S. cerevisiae, such as a better adaptation to grow at low temperatures, a higher glycerol synthesis and lower ethanol production. The aim of this study is to understand the molecular basis behind these phenotypic differences of biotechnological interest by using a species-based comparative genomics approach. In this work, we sequenced, assembled and annotated two new genomes of S. kudriavzevii. We used a combination of different statistical methods to identify functional divergence, signatures of positive selection and acceleration of substitution rates at specific amino acid sites of proteins in S. kudriavzevii when compared to S. cerevisiae, and vice versa. We provide a list of candidate genes in which positive selection could be acting during the evolution of both S. cerevisiae and S. kudriavzevii clades. Some of them could be related to certain important differences in metabolism previously reported by other authors such us DAL3 and ARO4, involved in nitrogen assimilation and amino acid biosynthesis. In addition, three of those genes (FBA1, ZIP1, and RQC2) showed accelerated evolutionary rates in Sk branch. Finally, genes of the riboflavin biosynthesis were also among those genes with a significant higher rate of nucleotide substitution and those proteins have amino acid positions contributing to functional divergence.
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Affiliation(s)
- Laura G Macías
- Departament de Genètica, Universitat de València, Valencia, Spain.,Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos IATA, CSIC, Valencia, Spain
| | - Miguel Morard
- Departament de Genètica, Universitat de València, Valencia, Spain.,Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos IATA, CSIC, Valencia, Spain
| | - Christina Toft
- Departament de Genètica, Universitat de València, Valencia, Spain.,Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos IATA, CSIC, Valencia, Spain
| | - Eladio Barrio
- Departament de Genètica, Universitat de València, Valencia, Spain.,Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos IATA, CSIC, Valencia, Spain
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6
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Allen AR. One bacillus to rule them all? - Investigating broad range host adaptation in Mycobacterium bovis. INFECTION GENETICS AND EVOLUTION 2017; 53:68-76. [PMID: 28434972 DOI: 10.1016/j.meegid.2017.04.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 04/11/2017] [Accepted: 04/19/2017] [Indexed: 12/12/2022]
Affiliation(s)
- Adrian R Allen
- Agri-Food and Biosciences Institute, AFBI Stormont, Department of Bacteriology, Lamont Building, Stoney Road, Belfast BT4 3SD, United Kingdom.
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Caffrey BE, Williams TA, Jiang X, Toft C, Hokamp K, Fares MA. Proteome-wide analysis of functional divergence in bacteria: exploring a host of ecological adaptations. PLoS One 2012; 7:e35659. [PMID: 22563391 PMCID: PMC3338524 DOI: 10.1371/journal.pone.0035659] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 03/21/2012] [Indexed: 12/31/2022] Open
Abstract
Functional divergence is the process by which new genes and functions originate through the modification of existing ones. Both genetic and environmental factors influence the evolution of new functions, including gene duplication or changes in the ecological requirements of an organism. Novel functions emerge at the expense of ancestral ones and are generally accompanied by changes in the selective forces at constrained protein regions. We present software capable of analyzing whole proteomes, identifying putative amino acid replacements leading to functional change in each protein and performing statistical tests on all tabulated data. We apply this method to 750 complete bacterial proteomes to identify high-level patterns of functional divergence and link these patterns to ecological adaptations. Proteome-wide analyses of functional divergence in bacteria with different ecologies reveal a separation between proteins involved in information processing (Ribosome biogenesis etc.) and those which are dependent on the environment (energy metabolism, defense etc.). We show that the evolution of pathogenic and symbiotic bacteria is constrained by their association with the host, and also identify unusual events of functional divergence even in well-studied bacteria such as Escherichia coli. We present a description of the roles of phylogeny and ecology in functional divergence at the level of entire proteomes in bacteria.
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Affiliation(s)
- Brian E. Caffrey
- Department of Genetics, University of Dublin, Trinity College, Dublin, Ireland
| | - Tom A. Williams
- Department of Genetics, University of Dublin, Trinity College, Dublin, Ireland
| | - Xiaowei Jiang
- Department of Genetics, University of Dublin, Trinity College, Dublin, Ireland
| | - Christina Toft
- Department of Molecular Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Karsten Hokamp
- Department of Genetics, University of Dublin, Trinity College, Dublin, Ireland
| | - Mario A. Fares
- Department of Genetics, University of Dublin, Trinity College, Dublin, Ireland
- Integrative Systems Biology Group, Instituto de Biología Molecular y Celular de Plantas, CSIC-Universidad Politécnica de Valencia (UPV), Valencia, Spain
- * E-mail:
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Kjeldsen KU, Bataillon T, Pinel N, De Mita S, Lund MB, Panitz F, Bendixen C, Stahl DA, Schramm A. Purifying selection and molecular adaptation in the genome of Verminephrobacter, the heritable symbiotic bacteria of earthworms. Genome Biol Evol 2012; 4:307-15. [PMID: 22333491 PMCID: PMC3318438 DOI: 10.1093/gbe/evs014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
While genomic erosion is common among intracellular symbionts, patterns of genome evolution in heritable extracellular endosymbionts remain elusive. We study vertically transmitted extracellular endosymbionts (Verminephrobacter, Betaproteobacteria) that form a beneficial, species-specific, and evolutionarily old (60–130 Myr) association with earthworms. We assembled a draft genome of Verminephrobacter aporrectodeae and compared it with the genomes of Verminephrobacter eiseniae and two nonsymbiotic close relatives (Acidovorax). Similar to V. eiseniae, the V. aporrectodeae genome was not markedly reduced in size and showed no A–T bias. We characterized the strength of purifying selection (ω = dN/dS) and codon usage bias in 876 orthologous genes. Symbiont genomes exhibited strong purifying selection (ω = 0.09 ± 0.07), although transition to symbiosis entailed relaxation of purifying selection as evidenced by 50% higher ω values and less codon usage bias in symbiont compared with reference genomes. Relaxation was not evenly distributed among functional gene categories but was overrepresented in genes involved in signal transduction and cell envelope biogenesis. The same gene categories also harbored instances of positive selection in the Verminephrobacter clade. In total, positive selection was detected in 89 genes, including also genes involved in DNA metabolism, tRNA modification, and TonB-dependent iron uptake, potentially highlighting functions important in symbiosis. Our results suggest that the transition to symbiosis was accompanied by molecular adaptation, while purifying selection was only moderately relaxed, despite the evolutionary age and stability of the host association. We hypothesize that biparental transmission of symbionts and rare genetic mixing during transmission can prevent genome erosion in heritable symbionts.
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Jiang X, Fares MA. Functional Diversification of the Twin-Arginine Translocation Pathway Mediates the Emergence of Novel Ecological Adaptations. Mol Biol Evol 2011; 28:3183-93. [DOI: 10.1093/molbev/msr154] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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10
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Abstract
Host-adapted bacteria include mutualists and pathogens of animals, plants and insects. Their study is therefore important for biotechnology, biodiversity and human health. The recent rapid expansion in bacterial genome data has provided insights into the adaptive, diversifying and reductive evolutionary processes that occur during host adaptation. The results have challenged many pre-existing concepts built from studies of laboratory bacterial strains. Furthermore, recent studies have revealed genetic changes associated with transitions from parasitism to mutualism and opened new research avenues to understand the functional reshaping of bacteria as they adapt to growth in the cytoplasm of a eukaryotic host.
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11
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Sachs JL, Essenberg CJ, Turcotte MM. New paradigms for the evolution of beneficial infections. Trends Ecol Evol 2011; 26:202-9. [PMID: 21371775 DOI: 10.1016/j.tree.2011.01.010] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 01/24/2011] [Accepted: 01/25/2011] [Indexed: 10/18/2022]
Abstract
A longstanding paradigm predicts that microbial parasites and mutualists exhibit disparate evolutionary patterns. Parasites are predicted to promote arms races with hosts, rapid evolution and sexual recombination. By contrast, mutualists have been linked with beneficial coadaptation, evolutionary stasis and asexuality. In this review we discuss the recent surge of molecular data on microbes that are being used to test and reshape these ideas. New analyses reveal that beneficial microbes often share mechanisms of infection and defense with parasites, and can also exhibit rapid evolution and extensive genetic exchange. To explain these patterns, new paradigms must take into account the varied population biology of beneficial microbes, their potential conflicts with hosts, and the mosaic nature of genome evolution that requires locus-based tests to analyze the genetics of host adaptation.
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Affiliation(s)
- Joel L Sachs
- Department of Biology, University of California, Riverside, CA 92521, USA.
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12
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Warnecke T, Rocha EPC. Function-specific accelerations in rates of sequence evolution suggest predictable epistatic responses to reduced effective population size. Mol Biol Evol 2011; 28:2339-49. [PMID: 21349981 DOI: 10.1093/molbev/msr054] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Changes in effective population size impinge on patterns of molecular evolution. Notably, slightly deleterious mutations are more likely to drift to fixation in smaller populations, which should typically also lead to an overall acceleration in the rates of evolution. This prediction has been validated empirically for several endosymbiont and island taxa. Here, we first show that rate accelerations are also evident in bacterial pathogens whose recent shifts in virulence make them prime candidates for reduced effective population size: Bacillus anthracis, Bordetella parapertussis, Mycobacterium leprae, Salmonella enterica typhi, Shigella spp., and Yersinia pestis. Using closely related genomes to analyze substitution rate dynamics across six phylogenetically independent bacterial clades, we demonstrate that relative rates of coding sequence evolution are biased according to gene functional category. Notably, genes that buffer against slightly deleterious mutations, such as chaperones, experience stronger rate accelerations than other functional classes at both nonsynonymous and synonymous sites. Although theory predicts altered evolutionary dynamics for buffer loci in the face of accumulating deleterious mutations, to observe even stronger rate accelerations is surprising. We suggest that buffer loci experience elevated substitution rates because the accumulation of deleterious mutations in the remainder of the genome favors compensatory substitutions in trans. Critically, the hyper-acceleration is evident across phylogenetically independent clades, supporting the hypothesis that reductions in effective population size predictably induce epistatic responses in genes that buffer against slightly deleterious mutations.
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Affiliation(s)
- Tobias Warnecke
- Department of Biology and Biochemistry, University of Bath, Bath, UK.
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Rytkönen KT, Williams TA, Renshaw GM, Primmer CR, Nikinmaa M. Molecular Evolution of the Metazoan PHD–HIF Oxygen-Sensing System. Mol Biol Evol 2011; 28:1913-26. [DOI: 10.1093/molbev/msr012] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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14
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Toft C, Fares MA. Structural calibration of the rates of amino acid evolution in a search for Darwin in drifting biological systems. Mol Biol Evol 2010; 27:2375-85. [PMID: 20466746 DOI: 10.1093/molbev/msq123] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
In the last two decades, many reports of proteins under positive selection have brought the neutral theory into question. However, the methods used to detect selection have ignored the evolvability of amino acids within proteins, which is fundamental to distinguishing positive selection from the relaxed constraints caused by genetic drift. Disentangling these two counterbalancing forces is essential to test the neutral theory. Here, we calibrate rates of amino acid divergence by using structural information from the full set of crystallized proteins in bacteria. In agreement with previous reports, we show that rates of amino acid evolution correlate negatively with the number of per-amino acid atomic interactions. Calibration of the rates of evolution allows identifying signatures of selection in biological systems that evolve under strong genetic drift, such as endosymbiotic bacteria. Application of this method identifies different rates and dynamics of evolution for highly connected amino acids in the structure compared with sparsely connected ones. We also unearth patterns of Darwinian selection in fundamental cellular proteins in endosymbiotic bacteria including the cochaperonin GroES, ribosomal proteins, proteins involved in cell cycle control, DNA-binding proteins, and proteins involved in DNA replication and repair. This is, to our knowledge, the first attempt to distinguish adaptive evolution from relaxed constraints in biological systems under genetic drift.
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Affiliation(s)
- Christina Toft
- Evolutionary Genetics and Bioinformatics Laboratory, Department of Genetics, University of Dublin, Trinity College, Dublin, Ireland
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Williams TA, Codoñer FM, Toft C, Fares MA. Two chaperonin systems in bacterial genomes with distinct ecological roles. Trends Genet 2009; 26:47-51. [PMID: 20036437 DOI: 10.1016/j.tig.2009.11.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 11/27/2009] [Accepted: 11/30/2009] [Indexed: 10/20/2022]
Abstract
Bacterial chaperonins are essential to cell viability and have a role in endosymbiosis, which leads to increased biological complexity. However, the extent to which chaperonins promote ecological innovation is unknown. We screened 622 bacterial genomes for genes encoding chaperonins, and found archaeal-like chaperonins in bacteria that inhabit archaeal ecological niches. We found that chaperonins encoded in pathogenic bacteria are the most functionally divergent. We identified the molecular basis of the dramatic structural changes in mitochondrial GROEL, a highly derived chaperonin gene. Our analysis suggests that chaperonins are important capacitors of evolutionary and ecological change.
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Affiliation(s)
- Tom A Williams
- Department of Genetics, University of Dublin, Trinity College, Dublin, Ireland
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Williams TA, Caffrey BE, Jiang X, Toft C, Fares MA. Phylogenomic inference of functional divergence. BMC Bioinformatics 2009. [PMCID: PMC2764135 DOI: 10.1186/1471-2105-10-s13-p4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
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