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Maurya S, Arya CK, Parmar N, Sathyanarayanan N, Joshi CG, Ramanathan G. Genomic profiling and characteristics of a C1 degrading heterotrophic fresh-water bacterium Paracoccus sp. strain DMF. Arch Microbiol 2023; 206:6. [PMID: 38015256 DOI: 10.1007/s00203-023-03729-z] [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: 03/31/2023] [Revised: 10/27/2023] [Accepted: 10/30/2023] [Indexed: 11/29/2023]
Abstract
Paracoccus species are metabolically versatile gram-negative, aerobic facultative methylotrophic bacteria showing enormous promise for environmental and bioremediation studies. Here we report, the complete genome analysis of Paracoccus sp. strain DMF (P. DMF) that was isolated from a domestic wastewater treatment plant in Kanpur, India (26.4287 °N, 80.3891 °E) based on its ability to degrade a recalcitrant organic solvent N, N-dimethylformamide (DMF). The results reveal a genome size of 4,202,269 base pairs (bp) with a G + C content of 67.9%. The assembled genome comprises 4141 coding sequences (CDS), 46 RNA sequences, and 2 CRISPRs. Interestingly, catabolic operons related to the conventional marine-based methylated amines (MAs) degradation pathway were functionally annotated within the genome of an obligated aerobic heterotroph that is P. DMF. The genomic data-based characterization presented here for the novel heterotroph P. DMF aims to improve the understanding of the phenotypic gene products, enzymes, and pathways involved with greater emphasis on facultative methylotrophic motility-based latent pathogenicity.
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Affiliation(s)
- Shiwangi Maurya
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Chetan Kumar Arya
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Nidhi Parmar
- Gujarat Biotechnology Research Centre (GBRC), Gandhinagar, Gujarat, 382 011, India
| | - Nitish Sathyanarayanan
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bangalore, 560065, India
| | - Chaitanya G Joshi
- Gujarat Biotechnology Research Centre (GBRC), Gandhinagar, Gujarat, 382 011, India
| | - Gurunath Ramanathan
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India.
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Sane M, Diwan GD, Bhat BA, Wahl LM, Agashe D. Shifts in mutation spectra enhance access to beneficial mutations. Proc Natl Acad Sci U S A 2023; 120:e2207355120. [PMID: 37216547 PMCID: PMC10235995 DOI: 10.1073/pnas.2207355120] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 03/27/2023] [Indexed: 05/24/2023] Open
Abstract
Biased mutation spectra are pervasive, with wide variation in the magnitude of mutational biases that influence genome evolution and adaptation. How do such diverse biases evolve? Our experiments show that changing the mutation spectrum allows populations to sample previously undersampled mutational space, including beneficial mutations. The resulting shift in the distribution of fitness effects is advantageous: Beneficial mutation supply and beneficial pleiotropy both increase, while deleterious load reduces. More broadly, simulations indicate that reducing or reversing the direction of a long-term bias is always selectively favored. Such changes in mutation bias can occur easily via altered function of DNA repair genes. A phylogenetic analysis shows that these genes are repeatedly gained and lost in bacterial lineages, leading to frequent bias shifts in opposite directions. Thus, shifts in mutation spectra may evolve under selection and can directly alter the outcome of adaptive evolution by facilitating access to beneficial mutations.
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Affiliation(s)
- Mrudula Sane
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru560065, India
| | - Gaurav D. Diwan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru560065, India
- Bioquant, University of Heidelberg,69120Heidelberg, Germany
- Heidelberg University Biochemistry Center (BZH), 69120Heidelberg, Germany
| | - Bhoomika A. Bhat
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru560065, India
- Undergraduate Programme, Indian Institute of Science, Bengaluru 560012, India
| | - Lindi M. Wahl
- Mathematics, Western University, London, ON, N6A 5B7, Canada
| | - Deepa Agashe
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru560065, India
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3
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Bohlin J. A simple stochastic model describing the evolution of genomic GC content in asexually reproducing organisms. Sci Rep 2022; 12:18569. [PMID: 36329129 PMCID: PMC9631610 DOI: 10.1038/s41598-022-21709-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 09/30/2022] [Indexed: 11/06/2022] Open
Abstract
A genome's nucleotide composition can usually be summarized with (G)uanine + (C)ytosine (GC) or (A)denine + (T)hymine (AT) frequencies as GC% = 100% - AT%. Genomic AT/GC content has been linked to environment and selective processes in asexually reproducing organisms. A model is presented relating the evolution of genomic GC content over time to AT [Formula: see text] GC and GC [Formula: see text] AT mutation rates. By employing Itô calculus it is shown that if mutation rates are subject to random perturbations, that can vary over time, several implications follow. In particular, an extra Brownian motion term appears influencing genomic nucleotide variability; the greater the random perturbations the more genomic nucleotide variability. This can have several interpretations depending on the context. For instance, reducing the influence of the random perturbations on the AT/GC mutation rates and thus genomic nucleotide variability, to limit fitness decreasing and deleterious mutations, will likely suggest channeling of resources. On the other hand, increased genomic nucleotide diversity may be beneficial in variable environments. In asexually reproducing organisms, the Brownian motion term can be considered to be inversely reflective of the selective pressures an organism is subjected to at the molecular level. The presented model is a generalization of a previous model, limited to microbial symbionts, to all asexually reproducing, non-recombining organisms. Last, a connection between the presented model and the classical Luria-Delbrück mutation model is presented in an Itô calculus setting.
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Affiliation(s)
- Jon Bohlin
- grid.418193.60000 0001 1541 4204Division of Infection Control, Department of Methods Development and Analysis, Norwegian Institute of Public Health, Oslo, Norway ,grid.418193.60000 0001 1541 4204Centre for Fertility and Health, Norwegian Institute of Public Health, P.O. Box 4404, Lovisenberggata 8, 0403 Oslo, Norway
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4
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Mahajan S, Agashe D. Evolutionary jumps in bacterial GC content. G3 GENES|GENOMES|GENETICS 2022; 12:6586800. [PMID: 35579351 PMCID: PMC9339322 DOI: 10.1093/g3journal/jkac108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 04/20/2022] [Indexed: 11/29/2022]
Abstract
Genomic GC (Guanine-Cytosine) content is a fundamental molecular trait linked with many key genomic features such as codon and amino acid use. Across bacteria, GC content is surprisingly diverse and has been studied for many decades; yet its evolution remains incompletely understood. Since it is difficult to observe GC content evolve on laboratory time scales, phylogenetic comparative approaches are instrumental; but this dimension is rarely studied systematically in the case of bacterial GC content. We applied phylogenetic comparative models to analyze GC content evolution in multiple bacterial groups across 2 major bacterial phyla. We find that GC content diversifies via a combination of gradual evolution and evolutionary “jumps.” Surprisingly, unlike prior reports that solely focused on reductions in GC, we found a comparable number of jumps with both increased and decreased GC content. Overall, many of the identified jumps occur in lineages beyond the well-studied peculiar examples of endosymbiotic and AT-rich marine bacteria and do not support the predicted role of oxygen dependence. Our analysis of rapid and large shifts in GC content thus identifies new clades and novel contexts to further understand the ecological and evolutionary drivers of this important genomic trait.
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Affiliation(s)
- Saurabh Mahajan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research , Bengaluru 560065, India
- Atria University , Bengaluru 560024, India
| | - Deepa Agashe
- National Centre for Biological Sciences, Tata Institute of Fundamental Research , Bengaluru 560065, India
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Halter T, Köstlbacher S, Collingro A, Sixt BS, Tönshoff ER, Hendrickx F, Kostanjšek R, Horn M. Ecology and evolution of chlamydial symbionts of arthropods. ISME COMMUNICATIONS 2022; 2:45. [PMID: 37938728 PMCID: PMC9723776 DOI: 10.1038/s43705-022-00124-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 03/31/2022] [Accepted: 04/08/2022] [Indexed: 05/08/2023]
Abstract
The phylum Chlamydiae consists of obligate intracellular bacteria including major human pathogens and diverse environmental representatives. Here we investigated the Rhabdochlamydiaceae, which is predicted to be the largest and most diverse chlamydial family, with the few described members known to infect arthropod hosts. Using published 16 S rRNA gene sequence data we identified at least 388 genus-level lineages containing about 14 051 putative species within this family. We show that rhabdochlamydiae are mainly found in freshwater and soil environments, suggesting the existence of diverse, yet unknown hosts. Next, we used a comprehensive genome dataset including metagenome assembled genomes classified as members of the family Rhabdochlamydiaceae, and we added novel complete genome sequences of Rhabdochlamydia porcellionis infecting the woodlouse Porcellio scaber, and of 'Candidatus R. oedothoracis' associated with the linyphiid dwarf spider Oedothorax gibbosus. Comparative analysis of basic genome features and gene content with reference genomes of well-studied chlamydial families with known host ranges, namely Parachlamydiaceae (protist hosts) and Chlamydiaceae (human and other vertebrate hosts) suggested distinct niches for members of the Rhabdochlamydiaceae. We propose that members of the family represent intermediate stages of adaptation of chlamydiae from protists to vertebrate hosts. Within the genus Rhabdochlamydia, pronounced genome size reduction could be observed (1.49-1.93 Mb). The abundance and genomic distribution of transposases suggests transposable element expansion and subsequent gene inactivation as a mechanism of genome streamlining during adaptation to new hosts. This type of genome reduction has never been described before for any member of the phylum Chlamydiae. This study provides new insights into the molecular ecology, genomic diversity, and evolution of representatives of one of the most divergent chlamydial families.
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Affiliation(s)
- Tamara Halter
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
- Doctoral School in Microbiology and Environmental Science, University of Vienna, Vienna, Austria
| | - Stephan Köstlbacher
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
- Doctoral School in Microbiology and Environmental Science, University of Vienna, Vienna, Austria
| | - Astrid Collingro
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Barbara S Sixt
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Elena R Tönshoff
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich (ETH), Zurich, Switzerland
| | | | - Rok Kostanjšek
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Matthias Horn
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria.
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6
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Hu EZ, Lan XR, Liu ZL, Gao J, Niu DK. A positive correlation between GC content and growth temperature in prokaryotes. BMC Genomics 2022; 23:110. [PMID: 35139824 PMCID: PMC8827189 DOI: 10.1186/s12864-022-08353-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 01/31/2022] [Indexed: 01/27/2023] Open
Abstract
Background GC pairs are generally more stable than AT pairs; GC-rich genomes were proposed to be more adapted to high temperatures than AT-rich genomes. Previous studies consistently showed positive correlations between growth temperature and the GC contents of structural RNA genes. However, for the whole genome sequences and the silent sites of the codons in protein-coding genes, the relationship between GC content and growth temperature is in a long-lasting debate. Results With a dataset much larger than previous studies (681 bacteria and 155 archaea with completely assembled genomes), our phylogenetic comparative analyses showed positive correlations between optimal growth temperature (Topt) and GC content both in bacterial and archaeal structural RNA genes and in bacterial whole genome sequences, chromosomal sequences, plasmid sequences, core genes, and accessory genes. However, in the 155 archaea, we did not observe a significant positive correlation of Topt with whole-genome GC content (GCw) or GC content at four-fold degenerate sites. We randomly drew 155 samples from the 681 bacteria for 1000 rounds. In most cases (> 95%), the positive correlations between Topt and genomic GC contents became statistically nonsignificant (P > 0.05). This result suggested that the small sample sizes might account for the lack of positive correlations between growth temperature and genomic GC content in the 155 archaea and the bacterial samples of previous studies. Comparing the GC content among four categories (psychrophiles/psychrotrophiles, mesophiles, thermophiles, and hyperthermophiles) also revealed a positive correlation between GCw and growth temperature in bacteria. By including the GCw of incompletely assembled genomes, we expanded the sample size of archaea to 303. Positive correlations between GCw and Topt appear especially after excluding the halophilic archaea whose GC contents might be strongly shaped by intense UV radiation. Conclusions This study explains the previous contradictory observations and ends a long debate. Prokaryotes growing in high temperatures have higher GC contents. Thermal adaptation is one possible explanation for the positive association. Meanwhile, we propose that the elevated efficiency of DNA repair in response to heat mutagenesis might have the by-product of increasing GC content like that happens in intracellular symbionts and marine bacterioplankton. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-022-08353-7.
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Affiliation(s)
- En-Ze Hu
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Xin-Ran Lan
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Zhi-Ling Liu
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Jie Gao
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Deng-Ke Niu
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China.
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7
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Hall JPJ, Wright RCT, Harrison E, Muddiman KJ, Wood AJ, Paterson S, Brockhurst MA. Plasmid fitness costs are caused by specific genetic conflicts enabling resolution by compensatory mutation. PLoS Biol 2021; 19:e3001225. [PMID: 34644303 PMCID: PMC8544851 DOI: 10.1371/journal.pbio.3001225] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 10/25/2021] [Accepted: 09/20/2021] [Indexed: 12/13/2022] Open
Abstract
Plasmids play an important role in bacterial genome evolution by transferring genes between lineages. Fitness costs associated with plasmid carriage are expected to be a barrier to gene exchange, but the causes of plasmid fitness costs are poorly understood. Single compensatory mutations are often sufficient to completely ameliorate plasmid fitness costs, suggesting that such costs are caused by specific genetic conflicts rather than generic properties of plasmids, such as their size, metabolic burden, or gene expression level. By combining the results of experimental evolution with genetics and transcriptomics, we show here that fitness costs of 2 divergent large plasmids in Pseudomonas fluorescens are caused by inducing maladaptive expression of a chromosomal tailocin toxin operon. Mutations in single genes unrelated to the toxin operon, and located on either the chromosome or the plasmid, ameliorated the disruption associated with plasmid carriage. We identify one of these compensatory loci, the chromosomal gene PFLU4242, as the key mediator of the fitness costs of both plasmids, with the other compensatory loci either reducing expression of this gene or mitigating its deleterious effects by up-regulating a putative plasmid-borne ParAB operon. The chromosomal mobile genetic element Tn6291, which uses plasmids for transmission, remained up-regulated even in compensated strains, suggesting that mobile genetic elements communicate through pathways independent of general physiological disruption. Plasmid fitness costs caused by specific genetic conflicts are unlikely to act as a long-term barrier to horizontal gene transfer (HGT) due to their propensity for amelioration by single compensatory mutations, helping to explain why plasmids are so common in bacterial genomes.
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Affiliation(s)
- James P. J. Hall
- Department of Evolution, Ecology and Behaviour, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom
| | - Rosanna C. T. Wright
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom
- Division of Evolution and Genomic Sciences, University of Manchester, Manchester, United Kingdom
| | - Ellie Harrison
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom
| | - Katie J. Muddiman
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom
| | - A. Jamie Wood
- Department of Biology, University of York, York, United Kingdom
- Department of Mathematics, University of York, York, United Kingdom
| | - Steve Paterson
- Department of Evolution, Ecology and Behaviour, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Michael A. Brockhurst
- Division of Evolution and Genomic Sciences, University of Manchester, Manchester, United Kingdom
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8
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Yi K, Kim SY, Bleazard T, Kim T, Youk J, Ju YS. Mutational spectrum of SARS-CoV-2 during the global pandemic. Exp Mol Med 2021; 53:1229-1237. [PMID: 34453107 PMCID: PMC8393781 DOI: 10.1038/s12276-021-00658-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 04/29/2021] [Accepted: 05/11/2021] [Indexed: 02/07/2023] Open
Abstract
Viruses accumulate mutations under the influence of natural selection and host-virus interactions. Through a systematic comparison of 351,525 full viral genome sequences collected during the recent COVID-19 pandemic, we reveal the spectrum of SARS-CoV-2 mutations. Unlike those of other viruses, the mutational spectrum of SARS-CoV-2 exhibits extreme asymmetry, with a much higher rate of C>U than U>C substitutions, as well as a higher rate of G>U than U>G substitutions. This suggests directional genome sequence evolution during transmission. The substantial asymmetry and directionality of the mutational spectrum enable pseudotemporal tracing of SARS-CoV-2 without prior information about the root sequence, collection time, and sampling region. This shows that the viral genome sequences collected in Asia are similar to the original genome sequence. Adjusted estimation of the dN/dS ratio accounting for the asymmetrical mutational spectrum also shows evidence of negative selection on viral genes, consistent with previous reports. Our findings provide deep insights into the mutational processes in SARS-CoV-2 viral infection and advance the understanding of the history and future evolution of the virus.
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Affiliation(s)
- Kijong Yi
- grid.37172.300000 0001 2292 0500Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141 Korea
| | - Su Yeon Kim
- grid.37172.300000 0001 2292 0500Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141 Korea
| | - Thomas Bleazard
- grid.70909.370000 0001 2199 6511National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Hertfordshire, EN6 3QG UK
| | - Taewoo Kim
- grid.37172.300000 0001 2292 0500Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141 Korea
| | - Jeonghwan Youk
- grid.37172.300000 0001 2292 0500Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141 Korea ,grid.511166.4GENOME INSIGHT Inc, Daejeon, 34051 Korea
| | - Young Seok Ju
- grid.37172.300000 0001 2292 0500Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141 Korea ,grid.511166.4GENOME INSIGHT Inc, Daejeon, 34051 Korea
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Analyses of publicly available Hungatella hathewayi genomes revealed genetic distances indicating they belong to more than one species. Virulence 2021; 12:1950-1964. [PMID: 34304696 PMCID: PMC8312603 DOI: 10.1080/21505594.2021.1950955] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Hungatella hathewayi has been observed to be a member of the gut microbiome. Unfortunately, little is known about this organism in spite of being associated with human fatalities; it is important to understand virulence mechanisms and epidemiological prospective to cause disease. In this study, a patient with chronic neurologic symptoms presented to the clinic with subsequent isolation of a strain with phenotypic characteristics suggestive of Clostridium difficile. However, whole-genome sequence found the organism to be H. hathewayi. Analysis including publicly available Hungatella genomes found substantial genomic differences as compared to the type strain, indicating this isolate was not C. difficile. We examined the whole-genome of Hungatella species and related genera, using comparative genomics to fully examine species identification and toxin production. Orthogonal phylogenetic using the 16S rRNA gene and entire genome analyses that included genome distance analyses using Genome-to-Genome Distance (GGDC), Average Nucleotide Identity (ANI), and a pan-genome analysis with inclusion of available public genomes determined the speciation to be Hungatella. Two clearly differentiated groups were identified, one including a reference H. hathewayi genome (strain DSM-13,479) and a second group that was determined to be H. effluvii, which included our clinical isolate. Also, some genomes reported as H. hathewayi were found to belong to other genera, including Clostridium and Faecalicatena. We show that the Hungatella species have an open pan-genome reflecting high genomic diversity. This study highlights the importance of correctly assigning taxonomic identification, particularly in disease-associated strains, to better understand virulence and therapeutic options.
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Simón D, Cristina J, Musto H. Nucleotide Composition and Codon Usage Across Viruses and Their Respective Hosts. Front Microbiol 2021; 12:646300. [PMID: 34262534 PMCID: PMC8274242 DOI: 10.3389/fmicb.2021.646300] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Accepted: 06/04/2021] [Indexed: 11/13/2022] Open
Abstract
The genetic material of the three domains of life (Bacteria, Archaea, and Eukaryota) is always double-stranded DNA, and their GC content (molar content of guanine plus cytosine) varies between ≈ 13% and ≈ 75%. Nucleotide composition is the simplest way of characterizing genomes. Despite this simplicity, it has several implications. Indeed, it is the main factor that determines, among other features, dinucleotide frequencies, repeated short DNA sequences, and codon and amino acid usage. Which forces drive this strong variation is still a matter of controversy. For rather obvious reasons, most of the studies concerning this huge variation and its consequences, have been done in free-living organisms. However, no recent comprehensive study of all known viruses has been done (that is, concerning all available sequences). Viruses, by far the most abundant biological entities on Earth, are the causative agents of many diseases. An overview of these entities is important also because their genetic material is not always double-stranded DNA: indeed, certain viruses have as genetic material single-stranded DNA, double-stranded RNA, single-stranded RNA, and/or retro-transcribing. Therefore, one may wonder if what we have learned about the evolution of GC content and its implications in prokaryotes and eukaryotes also applies to viruses. In this contribution, we attempt to describe compositional properties of ∼ 10,000 viral species: base composition (globally and according to Baltimore classification), correlations among non-coding regions and the three codon positions, and the relationship of the nucleotide frequencies and codon usage of viruses with the same feature of their hosts. This allowed us to determine how the base composition of phages strongly correlate with the value of their respective hosts, while eukaryotic viruses do not (with fungi and protists as exceptions). Finally, we discuss some of these results concerning codon usage: reinforcing previous results, we found that phages and hosts exhibit moderate to high correlations, while for eukaryotes and their viruses the correlations are weak or do not exist.
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Affiliation(s)
- Diego Simón
- Laboratorio de Genómica Evolutiva, Departamento de Biología Celular y Molecular, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.,Laboratorio de Virología Molecular, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la Republica, Montevideo, Uruguay.,Laboratorio de Evolución Experimental de Virus, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Juan Cristina
- Laboratorio de Virología Molecular, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la Republica, Montevideo, Uruguay
| | - Héctor Musto
- Laboratorio de Genómica Evolutiva, Departamento de Biología Celular y Molecular, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
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11
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Duan B, Ding P, Navarre WW, Liu J, Xia B. Xenogeneic Silencing and Bacterial Genome Evolution: Mechanisms for DNA Recognition Imply Multifaceted Roles of Xenogeneic Silencers. Mol Biol Evol 2021; 38:4135-4148. [PMID: 34003286 PMCID: PMC8476142 DOI: 10.1093/molbev/msab136] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/08/2021] [Indexed: 12/14/2022] Open
Abstract
Horizontal gene transfer (HGT) is a major driving force for bacterial evolution. To avoid the deleterious effects due to the unregulated expression of newly acquired foreign genes, bacteria have evolved specific proteins named xenogeneic silencers to recognize foreign DNA sequences and suppress their transcription. As there is considerable diversity in genomic base compositions among bacteria, how xenogeneic silencers distinguish self- from nonself DNA in different bacteria remains poorly understood. This review summarizes the progress in studying the DNA binding preferences and the underlying molecular mechanisms of known xenogeneic silencer families, represented by H-NS of Escherichia coli, Lsr2 of Mycobacterium, MvaT of Pseudomonas, and Rok of Bacillus. Comparative analyses of the published data indicate that the differences in DNA recognition mechanisms enable these xenogeneic silencers to have clear characteristics in DNA sequence preferences, which are further correlated with different host genomic features. These correlations provide insights into the mechanisms of how these xenogeneic silencers selectively target foreign DNA in different genomic backgrounds. Furthermore, it is revealed that the genomic AT contents of bacterial species with the same xenogeneic silencer family proteins are distributed in a limited range and are generally lower than those species without any known xenogeneic silencers in the same phylum/class/genus, indicating that xenogeneic silencers have multifaceted roles on bacterial genome evolution. In addition to regulating horizontal gene transfer, xenogeneic silencers also act as a selective force against the GC to AT mutational bias found in bacterial genomes and help the host genomic AT contents maintained at relatively low levels.
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Affiliation(s)
- Bo Duan
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, and School of Life Sciences, Peking University, Beijing, 100871, China
| | - Pengfei Ding
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, and School of Life Sciences, Peking University, Beijing, 100871, China
| | - William Wiley Navarre
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, M5G 1M1, Canada
| | - Jun Liu
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, M5G 1M1, Canada
| | - Bin Xia
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, and School of Life Sciences, Peking University, Beijing, 100871, China
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12
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Nguyen DT, Wu B, Xiao S, Hao W. Evolution of a Record-Setting AT-Rich Genome: Indel Mutation, Recombination, and Substitution Bias. Genome Biol Evol 2020; 12:2344-2354. [PMID: 32986811 PMCID: PMC7846184 DOI: 10.1093/gbe/evaa202] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2020] [Indexed: 12/16/2022] Open
Abstract
Genome-wide nucleotide composition varies widely among species. Despite extensive research, the source of genome-wide nucleotide composition diversity remains elusive. Yeast mitochondrial genomes (mitogenomes) are highly A + T rich, and they provide a unique opportunity to study the evolution of AT-biased landscape. In this study, we sequenced ten complete mitogenomes of the Saccharomycodes ludwigii yeast with 8% G + C content, the lowest genome-wide %(G + C) in all published genomes to date. The S. ludwigii mitogenomes have high densities of short tandem repeats but severely underrepresented mononucleotide repeats. Comparative population genomics of these record-setting A + T-rich genomes shows dynamic indel mutations and strong mutation bias toward A/T. Indel mutations play a greater role in genomic variation among very closely related strains than nucleotide substitutions. Indels have resulted in presence–absence polymorphism of tRNAArg (ACG) among S. ludwigii mitogenomes. Interestingly, these mitogenomes have undergone recombination, a genetic process that can increase G + C content by GC-biased gene conversion. Finally, the expected equilibrium G + C content under mutation pressure alone is higher than observed G + C content, suggesting existence of mechanisms other than AT-biased mutation operating to increase A/T. Together, our findings shed new lights on mechanisms driving extremely AT-rich genomes.
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Affiliation(s)
- Duong T Nguyen
- Department of Biological Sciences, Wayne State University
| | - Baojun Wu
- Department of Biological Sciences, Wayne State University
| | - Shujie Xiao
- Department of Biological Sciences, Wayne State University
| | - Weilong Hao
- Department of Biological Sciences, Wayne State University
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13
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Bohlin J, Rose B, Brynildsrud O, Birgitte Freiesleben De Blasio. A simple stochastic model describing genomic evolution over time of GC content in microbial symbionts. J Theor Biol 2020; 503:110389. [PMID: 32634385 DOI: 10.1016/j.jtbi.2020.110389] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 04/21/2020] [Accepted: 06/24/2020] [Indexed: 11/29/2022]
Abstract
An organism's genomic base composition is usually summarized by its AT or GC content due to Chargaff's parity laws. Variation in prokaryotic GC content can be substantial between taxa but is generally small within microbial genomes. This variation has been found to correlate with both phylogeny and environmental factors. Since novel single-nucleotide polymorphisms (SNPs) within genomes are at least partially linked to the environment through natural selection, SNP GC content can be considered a compound measure of an organism's environmental influences, lifestyle, phylogeny as well as other more or less random processes. While there are several models describing genomic GC content few, if any, consider AT/GC mutation rates subjected to random perturbations. We present a mathematical model that describes how GC content in microbial genomes evolves over time as a function of the AT → GC and GC → AT mutation rates with Gaussian white noise disturbances. The model, which is suited specifically to non-recombining vertically transmitted prokaryotic symbionts, suggests that small differences in the AT/GC mutation rates can lead to profound differences in outcome due to the ensuing stochastic process. In other words, the model indicates that time to extinction could be a consequence of the mutation rate trajectory on which the symbiont embarked early on in its evolutionary history.
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Affiliation(s)
- Jon Bohlin
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway; Centre for Fertility and Health, Norwegian Institute of Public Health, Oslo, Norway; Department of Production Animals, Faculty of Veterinary Medicine, Norwegian University of Life Science, Oslo, Norway
| | - Brittany Rose
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway; Department of Biostatistics, Oslo Centre for Biostatistics and Epidemiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Ola Brynildsrud
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway; Department of Production Animals, Faculty of Veterinary Medicine, Norwegian University of Life Science, Oslo, Norway
| | - Birgitte Freiesleben De Blasio
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway; Department of Biostatistics, Oslo Centre for Biostatistics and Epidemiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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Adapting Biased Gene Conversion theory to account for intensive GC-content deterioration in the human genome by novel mutations. PLoS One 2020; 15:e0232167. [PMID: 32353016 PMCID: PMC7192473 DOI: 10.1371/journal.pone.0232167] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 04/09/2020] [Indexed: 12/23/2022] Open
Abstract
We examined seventy million well-characterized human mutations, and their impact on G+C-compositional dynamics, in order to understand the formation and maintenance of major genomic nucleotide sequence patterns. Among novel mutations, those that change a strong (S) base pair G:C/C:G to a weak (W) pair A:T/T:A occur at nearly twice the frequency of the opposite mutations. Such imbalance puts strong downward pressure on overall GC-content. However, along protracted paths to fixation, S→W mutations are much less likely to propagate than W→S mutations. The magnitude of relative propagation disadvantages for S→W mutations is inexplicable by any currently-accepted model. This fact forced us to re-examine the quantitative features of Biased Gene Conversion (BGC) theory. Revised parameters of BGC that, per average individual, convert 7–14 W base pairs into S pairs, would account for the S-content turnover differences between new and old mutations, and make BGC an instrumental force for nucleotide dynamics and evolution. BGC should thus be considered seriously in both theories and biomedical practice. In particular, BGC should be taken into account during allele imputations, where missing SNP alleles are computationally predicted based on the information about several neighboring alleles. Finally, we analyzed the effect of neighboring nucleotide context on the mutation frequencies, dynamics, and GC-composition turnover. For this purpose, we examined genomic regions having extremely biased nucleotide compositions (enriched for S-, W-, purine/pyrimidine strand asymmetry, or AC/GT-strand asymmetry). It was found that point mutations in these regions preferentially degrade the nucleotide inhomogeneities, decreasing the sequence biases. Degradation of sequence bias is highest for novel mutations, and considerably lower for older mutations (those widespread across populations). Besides BGC, there may be additional, still uncharacterized molecular mechanisms that either preserve genomic regions with biased nucleotide compositions from mutational degradation or fail to degrade such inhomogeneities in specific chromosomal regions.
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15
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Nwaiwu O, Aduba CC. An in silico analysis of acquired antimicrobial resistance genes in Aeromonas plasmids. AIMS Microbiol 2020; 6:75-91. [PMID: 32226916 PMCID: PMC7099201 DOI: 10.3934/microbiol.2020005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 03/13/2020] [Indexed: 12/17/2022] Open
Abstract
Sequences of 105 Aeromonas species plasmids were probed for acquired anti-microbial resistance (AMR) genes using a bioinformatics approach. The plasmids showed no positive linear correlation between size and GC content and up to 55 acquired AMR genes were found in 39 (37%) plasmids after in silico screening for resistance against 15 antibiotic drug classes. Overall, potential multiple antibiotic resistance (p-MAR) index ranged from 0.07 to 0.53. Up to 18 plasmids were predicted to mediate multiple drug resistance (MDR). Plasmids pS121-1a (A. salmonicida), pWCX23_1 (A. hydrophila) and pASP-a58 (A. veronii) harboured 18, 15 and 14 AMR genes respectively. The five most occurring drug classes for which AMR genes were detected were aminoglycosides (27%), followed by beta-lactams (17%), sulphonamides (13%), fluoroquinolones (13%), and phenicols (10%). The most prevalent genes were a sulphonamide resistant gene Sul1, the gene aac (6')-Ib-cr (aminoglycoside 6'-N-acetyl transferase type Ib-cr) resistant to aminoglycosides and the blaKPC-2 gene, which encodes carbapenemase-production. Plasmid acquisition of AMR genes was mainly inter-genus rather than intra-genus. Eighteen plasmids showed template or host genes acquired from Pseudomonas monteilii, Salmonella enterica or Escherichia coli. The most occurring antimicrobial resistance determinants (ARDs) were beta-lactamase, followed by aminoglycosides acetyl-transferases, and then efflux pumps. Screening of new isolates in vitro and in vivo is required to ascertain the level of phenotypic expression of colistin and other acquired AMR genes detected.
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Affiliation(s)
- Ogueri Nwaiwu
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, United Kingdom
| | - Chiugo Claret Aduba
- Department of Science Laboratory Technology, University of Nigeria, Nsukka, Nigeria
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16
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Bohlin J, Rose B, Pettersson JHO. Estimation of AT and GC content distributions of nucleotide substitution rates in bacterial core genomes. BIG DATA ANALYTICS 2019. [DOI: 10.1186/s41044-019-0042-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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17
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Dietel AK, Merker H, Kaltenpoth M, Kost C. Selective advantages favour high genomic AT-contents in intracellular elements. PLoS Genet 2019; 15:e1007778. [PMID: 31034469 PMCID: PMC6519830 DOI: 10.1371/journal.pgen.1007778] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 05/15/2019] [Accepted: 03/27/2019] [Indexed: 12/27/2022] Open
Abstract
Extrachromosomal genetic elements such as bacterial endosymbionts and plasmids generally exhibit AT-contents that are increased relative to their hosts’ DNA. The AT-bias of endosymbiotic genomes is commonly explained by neutral evolutionary processes such as a mutational bias towards increased A+T. Here we show experimentally that an increased AT-content of host-dependent elements can be selectively favoured. Manipulating the nucleotide composition of bacterial cells by introducing A+T-rich or G+C-rich plasmids, we demonstrate that cells containing GC-rich plasmids are less fit than cells containing AT-rich plasmids. Moreover, the cost of GC-rich elements could be compensated by providing precursors of G+C, but not of A+T, thus linking the observed fitness effects to the cytoplasmic availability of nucleotides. Accordingly, introducing AT-rich and GC-rich plasmids into other bacterial species with different genomic GC-contents revealed that the costs of G+C-rich plasmids decreased with an increasing GC-content of their host’s genomic DNA. Taken together, our work identifies selection as a strong evolutionary force that drives the genomes of intracellular genetic elements toward higher A+T contents. Genomes of endosymbiotic bacteria are commonly more AT-rich than the ones of their free-living relatives. Interestingly, genomes of other intracellular elements like plasmids or bacteriophages also tend to be richer in AT than the genomes of their hosts. The AT-bias of endosymbiotic genomes is commonly explained by neutral evolutionary processes. However, since A+T nucleotides are both more abundant and energetically less expensive than G+C nucleotides, an alternative explanation is that selective advantages drive the nucleotide composition of intracellular elements. Here we provide strong experimental evidence that intracellular elements, whose genome is more AT-rich than the genome of the host, are selectively favoured on the host level. Thus, our results emphasize the importance of selection for shaping the DNA base composition of extrachromosomal genetic elements.
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Affiliation(s)
- Anne-Kathrin Dietel
- Experimental Ecology and Evolution Research Group, Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Holger Merker
- Experimental Ecology and Evolution Research Group, Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Martin Kaltenpoth
- Insect Symbiosis Research Group, Max Planck Institute for Chemical Ecology, Jena, Germany
- * E-mail: (MK); (CK)
| | - Christian Kost
- Experimental Ecology and Evolution Research Group, Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Germany
- * E-mail: (MK); (CK)
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18
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Bohlin J, Pettersson JHO. Evolution of Genomic Base Composition: From Single Cell Microbes to Multicellular Animals. Comput Struct Biotechnol J 2019; 17:362-370. [PMID: 30949307 PMCID: PMC6429543 DOI: 10.1016/j.csbj.2019.03.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 01/07/2023] Open
Abstract
Whole genome sequencing (WGS) of thousands of microbial genomes has provided considerable insight into evolutionary mechanisms in the microbial world. While substantially fewer eukaryotic genomes are available for analyses the number is rapidly increasing. This mini-review summarizes broadly evolutionary dynamics of base composition in the different domains of life from the perspective of prokaryotes. Common and different evolutionary mechanisms influencing genomic base composition in eukaryotes and prokaryotes are discussed. The conclusion from the data currently available suggests that while there are similarities there are also striking differences in how genomic base composition has evolved within prokaryotes and eukaryotes. For instance, homologous recombination appears to increase GC content locally in eukaryotes due to a non-selective process termed GC-biased gene conversion (gBGC). For prokaryotes on the other hand, increase in genomic GC content seems to be driven by the environment and selection. We find that similar phenomena observed for some organisms in each respective domain may be caused by very different mechanisms: while gBGC and recombination rates appear to explain the negative correlation between GC3 (GC content based on the third codon nucleotides) and genome size in some eukaryotes uptake of AT rich DNA sequences is the main reason for a similar negative correlation observed in prokaryotes. We provide further examples that indicate that base composition in prokaryotes and eukaryotes have evolved under very different constraints.
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Affiliation(s)
- Jon Bohlin
- Norwegian Institute of Public Health, Division of Infection Control and Environmental Health, Department of Infectious Disease Epidemiology and Modelling, Lovisenberggata 8, 0456 Oslo, Norway.,Centre for Fertility and Health, Norwegian Institute of Public Health, PO-Box 222 Skøyen, N-0213 Oslo, Norway.,Norwegian University of Life Sciences, Faculty of Veterinary Sciences, Production Animal Clinical Sciences, Ullevålsveien 72, 0454 Oslo, Norway
| | - John H-O Pettersson
- Marie Bashir Institute for Infectious Diseases and Biosecurity, Charles Perkins Centre, School of Life and Environmental Sciences and Sydney Medical School the University of Sydney, New South Wales 2006, Australia.,Zoonosis Science Center, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.,Public Health Agency of Sweden, Nobels vg 18, SE-171 82 Solna, Sweden
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19
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Aslam S, Lan XR, Zhang BW, Chen ZL, Wang L, Niu DK. Aerobic prokaryotes do not have higher GC contents than anaerobic prokaryotes, but obligate aerobic prokaryotes have. BMC Evol Biol 2019; 19:35. [PMID: 30691392 PMCID: PMC6350292 DOI: 10.1186/s12862-019-1365-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 01/17/2019] [Indexed: 12/17/2022] Open
Abstract
Background Among the four bases, guanine is the most susceptible to damage from oxidative stress. Replication of DNA containing damaged guanines results in G to T mutations. Therefore, the mutations resulting from oxidative DNA damage are generally expected to predominantly consist of G to T (and C to A when the damaged guanine is not in the reference strand) and result in decreased GC content. However, the opposite pattern was reported 16 years ago in a study of prokaryotic genomes. Although that result has been widely cited and confirmed by nine later studies with similar methods, the omission of the effect of shared ancestry requires a re-examination of the reliability of the results. Results When aerobic and obligate aerobic prokaryotes were mixed together and anaerobic and obligate anaerobic prokaryotes were mixed together, phylogenetic controlled analyses did not detect significant difference in GC content between aerobic and anaerobic prokaryotes. This result is consistent with two generally neglected studied that had accounted for the phylogenetic relationship. However, when obligate aerobic prokaryotes were compared with aerobic prokaryotes, anaerobic prokaryotes, and obligate anaerobic prokaryotes separately using phylogenetic regression analysis, a significant positive association was observed between aerobiosis and GC content, no matter it was calculated from whole genome sequences or the 4-fold degenerate sites of protein-coding genes. Obligate aerobes have significantly higher GC content than aerobes, anaerobes, and obligate anaerobes. Conclusions The positive association between aerobiosis and GC content could be attributed to a mutational force resulting from incorporation of damaged deoxyguanosine during DNA replication rather than oxidation of the guanine nucleotides within DNA sequences. Our results indicate a grade in the aerobiosis-associated mutational force, strong in obligate aerobes, moderate in aerobes, weak in anaerobes and obligate anaerobes. Electronic supplementary material The online version of this article (10.1186/s12862-019-1365-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sidra Aslam
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Xin-Ran Lan
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Bo-Wen Zhang
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Zheng-Lin Chen
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Li Wang
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
| | - Deng-Ke Niu
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing, 100875, China.
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20
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Bohlin J, Eldholm V, Brynildsrud O, Petterson JHO, Alfsnes K. Modeling of the GC content of the substituted bases in bacterial core genomes. BMC Genomics 2018; 19:589. [PMID: 30081825 PMCID: PMC6080486 DOI: 10.1186/s12864-018-4984-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 07/31/2018] [Indexed: 12/13/2022] Open
Abstract
Background The purpose of the present study was to examine the GC content of substituted bases (sbGC) in the core genomes of 35 bacterial species. Each species, or core genome, constituted genomes from at least 10 strains. We also wanted to explore whether sbGC for each strain was associated with the corresponding species’ core genome GC content (cgGC). We present a simple mathematical model that estimates sbGC from cgGC. The model assumes only that the estimated sbGC is a function of cgGC proportional to fixed AT→GC (α) and GC → AT (β) mutation rates. Non-linear regression was used to estimate parameters α and β from the empirical data described above. Results We found that sbGC for each strain showed a non-linear association with the corresponding cgGC with a bias towards higher GC content for most core genomes (66.3% of the strains), assuming as a null-hypothesis that sbGC should be approximately equal to cgGC. The most GC rich core genomes (i.e. approximately %GC > 60), on the other hand, exhibited slightly less GC-biased sbGC than expected. The best fitted regression model indicates that GC → AT mutation rates β = (1.91 ± 0.13) p < 0.001 are approximately (1.91/0.79) = 2.42 times as high, on average, as AT→GC α = (− 0.79 ± 0.25) p < 0.001 mutation rates. Whether the observed sbGC GC-bias for all but the most GC-rich prokaryotic species is due to selection, compensating for the GC → AT mutation bias, and/or selective neutral processes is currently debated. Residual standard error was found to be σ = 0.076 indicating estimated errors of sbGC to be approximately within ±15.2% GC (95% confidence interval) for the strains of all species in the study. Conclusion Not only did our mathematical model give reasonable estimates of sbGC it also provides further support to previous observations that mutation rates in prokaryotes exhibit a universal GC → AT bias that appears to be remarkably consistent between taxa. Electronic supplementary material The online version of this article (10.1186/s12864-018-4984-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jon Bohlin
- Norwegian Institute of Public Health, Lovisenberggata 8, P.O. Box 4404, 0403, Oslo, Norway.
| | - Vegard Eldholm
- Norwegian Institute of Public Health, Lovisenberggata 8, P.O. Box 4404, 0403, Oslo, Norway
| | - Ola Brynildsrud
- Norwegian Institute of Public Health, Lovisenberggata 8, P.O. Box 4404, 0403, Oslo, Norway
| | - John H-O Petterson
- Norwegian Institute of Public Health, Lovisenberggata 8, P.O. Box 4404, 0403, Oslo, Norway
| | - Kristian Alfsnes
- Norwegian Institute of Public Health, Lovisenberggata 8, P.O. Box 4404, 0403, Oslo, Norway
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21
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Almpanis A, Swain M, Gatherer D, McEwan N. Correlation between bacterial G+C content, genome size and the G+C content of associated plasmids and bacteriophages. Microb Genom 2018; 4:e000168. [PMID: 29633935 PMCID: PMC5989581 DOI: 10.1099/mgen.0.000168] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/06/2018] [Indexed: 02/06/2023] Open
Abstract
Based on complete bacterial genome sequence data, we demonstrate a correlation between bacterial chromosome length and the G+C content of the genome, with longer genomes having higher G+C contents. The correlation value decreases at shorter genome sizes, where there is a wider spread of G+C values. However, although significant (P<0.001), the correlation value (Pearson R=0.58) suggests that other factors also have a significant influence. A similar pattern was seen for plasmids; longer plasmids had higher G+C values, although the large number of shorter plasmids had a wide spread of G+C values. There was also a significant (P<0.0001) correlation between the G+C content of plasmids and the G+C content of their bacterial host. Conversely, the G+C content of bacteriophages tended to reduce with larger genome sizes, and although there was a correlation between host genome G+C content and that of the bacteriophage, it was not as strong as that seen between plasmids and their hosts.
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Affiliation(s)
- Apostolos Almpanis
- Aberystwyth University, Aberystwyth, UK
- Newcastle University, Newcastle-upon-Tyne, UK
| | | | | | - Neil McEwan
- Aberystwyth University, Aberystwyth, UK
- School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, UK
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22
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Gil R, Vargas-Chavez C, López-Madrigal S, Santos-García D, Latorre A, Moya A. Tremblaya phenacola PPER: an evolutionary beta-gammaproteobacterium collage. THE ISME JOURNAL 2018; 12:124-135. [PMID: 28914880 PMCID: PMC5739004 DOI: 10.1038/ismej.2017.144] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 05/31/2017] [Accepted: 07/28/2017] [Indexed: 02/07/2023]
Abstract
Many insects rely on bacterial endosymbionts to obtain nutrients that are scarce in their highly specialized diets. The most surprising example corresponds to the endosymbiotic system found in mealybugs from subfamily Pseudococcinae in which two bacteria, the betaproteobacterium 'Candidatus Tremblaya princeps' and a gammaproteobacterium, maintain a nested endosymbiotic consortium. In the sister subfamily Phenacoccinae, however, a single beta-endosymbiont, 'Candidatus Tremblaya phenacola', has been described. In a previous study, we detected a trpB gene of gammaproteobacterial origin in 'Ca. Tremblaya phenacola' from two Phenacoccus species, apparently indicating an unusual case of horizontal gene transfer (HGT) in a bacterial endosymbiont. What we found by sequencing the genome of 'Ca. Tremblaya phenacola' PPER, single endosymbiont of Phenacoccus peruvianus, goes beyond a HGT phenomenon. It rather represents a genome fusion between a beta and a gammaproteobacterium, followed by massive rearrangements and loss of redundant genes, leading to an unprecedented evolutionary collage. Mediated by the presence of several repeated sequences, there are many possible genome arrangements, and different subgenomic sequences might coexist within the same population.
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Affiliation(s)
- Rosario Gil
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva (ICBiBE), Universitat de València, Valencia, Spain
- Evolutionary Systems Biology of Symbionts Research Program, Institute for Integrative Systems Biology, Universitat de València/CSIC, Paterna (Valencia), Spain
- Institute for Integrative Systems Biology, Universitat de València/CSIC, C/Catedrático José Beltrán 2, 46980 Paterna (Valencia), Spain. E-mail:
| | - Carlos Vargas-Chavez
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva (ICBiBE), Universitat de València, Valencia, Spain
- Evolutionary Systems Biology of Symbionts Research Program, Institute for Integrative Systems Biology, Universitat de València/CSIC, Paterna (Valencia), Spain
| | - Sergio López-Madrigal
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva (ICBiBE), Universitat de València, Valencia, Spain
| | - Diego Santos-García
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva (ICBiBE), Universitat de València, Valencia, Spain
| | - Amparo Latorre
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva (ICBiBE), Universitat de València, Valencia, Spain
- Evolutionary Systems Biology of Symbionts Research Program, Institute for Integrative Systems Biology, Universitat de València/CSIC, Paterna (Valencia), Spain
- Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana, Valencia, Spain
| | - Andrés Moya
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva (ICBiBE), Universitat de València, Valencia, Spain
- Evolutionary Systems Biology of Symbionts Research Program, Institute for Integrative Systems Biology, Universitat de València/CSIC, Paterna (Valencia), Spain
- Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana, Valencia, Spain
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Abstract
Organisms often encounter stressful conditions, some of which damage their DNA. In response, some organisms show a high expression of error-prone DNA repair machinery, causing a temporary increase in the genome-wide mutation rate. Although we now have a detailed map of the molecular mechanisms underlying such stress-induced mutagenesis (SIM), it has been hotly debated whether SIM alters evolutionary dynamics. Key to this controversy is our poor understanding about which stresses increase mutagenesis and their long-term consequences for adaptation. In a new study with Escherichia coli, Maharjan and Ferenci show that while only some nutritional stresses (phosphorous and carbon limitation) increase total mutation rates, each stress generates a unique spectrum of mutations. Their results suggest the potential for specific stresses to shape evolutionary dynamics and highlight the necessity for explicit tests of the long-term evolutionary impacts of SIM.
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24
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Wang B. Human Skin RNases Offer Dual Protection against Invading Bacteria. Front Microbiol 2017; 8:624. [PMID: 28443087 PMCID: PMC5386971 DOI: 10.3389/fmicb.2017.00624] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 03/27/2017] [Indexed: 12/25/2022] Open
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25
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Bohlin J, Eldholm V, Pettersson JHO, Brynildsrud O, Snipen L. The nucleotide composition of microbial genomes indicates differential patterns of selection on core and accessory genomes. BMC Genomics 2017; 18:151. [PMID: 28187704 PMCID: PMC5303225 DOI: 10.1186/s12864-017-3543-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 02/02/2017] [Indexed: 12/02/2022] Open
Abstract
Background The core genome consists of genes shared by the vast majority of a species and is therefore assumed to have been subjected to substantially stronger purifying selection than the more mobile elements of the genome, also known as the accessory genome. Here we examine intragenic base composition differences in core genomes and corresponding accessory genomes in 36 species, represented by the genomes of 731 bacterial strains, to assess the impact of selective forces on base composition in microbes. We also explore, in turn, how these results compare with findings for whole genome intragenic regions. Results We found that GC content in coding regions is significantly higher in core genomes than accessory genomes and whole genomes. Likewise, GC content variation within coding regions was significantly lower in core genomes than in accessory genomes and whole genomes. Relative entropy in coding regions, measured as the difference between observed and expected trinucleotide frequencies estimated from mononucleotide frequencies, was significantly higher in the core genomes than in accessory and whole genomes. Relative entropy was positively associated with coding region GC content within the accessory genomes, but not within the corresponding coding regions of core or whole genomes. Conclusion The higher intragenic GC content and relative entropy, as well as the lower GC content variation, observed in the core genomes is most likely associated with selective constraints. It is unclear whether the positive association between GC content and relative entropy in the more mobile accessory genomes constitutes signatures of selection or selective neutral processes. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3543-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jon Bohlin
- Infectious Disease Control and Environmental Health, Norwegian Institute of Public Health, Lovisenberggata 8, P.O. Box 4404, 0403, Oslo, Norway.
| | - Vegard Eldholm
- Infectious Disease Control and Environmental Health, Norwegian Institute of Public Health, Lovisenberggata 8, P.O. Box 4404, 0403, Oslo, Norway
| | - John H O Pettersson
- Infectious Disease Control and Environmental Health, Norwegian Institute of Public Health, Lovisenberggata 8, P.O. Box 4404, 0403, Oslo, Norway
| | - Ola Brynildsrud
- Infectious Disease Control and Environmental Health, Norwegian Institute of Public Health, Lovisenberggata 8, P.O. Box 4404, 0403, Oslo, Norway
| | - Lars Snipen
- Department of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences, 1430, Ås, Norway
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Shotgun Metagenomic Profiles Have a High Capacity To Discriminate Samples of Activated Sludge According to Wastewater Type. Appl Environ Microbiol 2016; 82:5186-96. [PMID: 27316957 DOI: 10.1128/aem.00916-16] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 06/10/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED This study was conducted to investigate whether functions encoded in the metagenome could improve our ability to understand the link between microbial community structures and functions in activated sludge. By analyzing data sets from six industrial and six municipal wastewater treatment plants (WWTPs), covering different configurations, operational conditions, and geographic regions, we found that wastewater influent composition was an overriding factor shaping the metagenomic composition of the activated sludge samples. Community GC content profiles were conserved within treatment plants on a time scale of years and between treatment plants with similar influent wastewater types. Interestingly, GC contents of the represented phyla covaried with the average GC contents of the corresponding WWTP metagenome. This suggests that the factors influencing nucleotide composition act similarly across taxa and thus the variation in nucleotide contents is driven by environmental differences between WWTPs. While taxonomic richness and functional richness were correlated, shotgun metagenomics complemented taxon-based analyses in the task of classifying microbial communities involved in wastewater treatment systems. The observed taxonomic dissimilarity between full-scale WWTPs receiving influent types with varied compositions, as well as the inferred taxonomic and functional assignment of recovered genomes from each metagenome, were consistent with underlying differences in the abundance of distinctive sets of functional categories. These conclusions were robust with respect to plant configuration, operational and environmental conditions, and even differences in laboratory protocols. IMPORTANCE This work contributes to the elucidation of drivers of microbial community assembly in wastewater treatment systems. Our results are significant because they provide clear evidence that bacterial communities in WWTPs assemble mainly according to influent wastewater characteristics. Differences in bacterial community structures between WWTPs were consistent with differences in the abundance of distinctive sets of functional categories, which were related to the metabolic potential that would be expected according to the source of the wastewater.
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Matsumoto T, John A, Baeza-Centurion P, Li B, Akashi H. Codon Usage Selection Can Bias Estimation of the Fraction of Adaptive Amino Acid Fixations. Mol Biol Evol 2016; 33:1580-9. [PMID: 26873577 DOI: 10.1093/molbev/msw027] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A growing number of molecular evolutionary studies are estimating the proportion of adaptive amino acid substitutions (α) from comparisons of ratios of polymorphic and fixed DNA mutations. Here, we examine how violations of two of the model assumptions, neutral evolution of synonymous mutations and stationary base composition, affect α estimation. We simulated the evolution of coding sequences assuming weak selection on synonymous codon usage bias and neutral protein evolution, α = 0. We show that weak selection on synonymous mutations can give polymorphism/divergence ratios that yield α-hat (estimated α) considerably larger than its true value. Nonstationary evolution (changes in population size, selection, or mutation) can exacerbate such biases or, in some scenarios, give biases in the opposite direction, α-hat < α. These results demonstrate that two factors that appear to be prevalent among taxa, weak selection on synonymous mutations and non-steady-state nucleotide composition, should be considered when estimating α. Estimates of the proportion of adaptive amino acid fixations from large-scale analyses of Drosophila melanogaster polymorphism and divergence data are positively correlated with codon usage bias. Such patterns are consistent with α-hat inflation from weak selection on synonymous mutations and/or mutational changes within the examined gene trees.
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Affiliation(s)
- Tomotaka Matsumoto
- Division of Evolutionary Genetics, National Institute of Genetics, Yata, Mishima, Shizuoka, Japan
| | - Anoop John
- Division of Evolutionary Genetics, National Institute of Genetics, Yata, Mishima, Shizuoka, Japan
| | - Pablo Baeza-Centurion
- Division of Evolutionary Genetics, National Institute of Genetics, Yata, Mishima, Shizuoka, Japan
| | - Boyang Li
- Division of Evolutionary Genetics, National Institute of Genetics, Yata, Mishima, Shizuoka, Japan
| | - Hiroshi Akashi
- Division of Evolutionary Genetics, National Institute of Genetics, Yata, Mishima, Shizuoka, Japan Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Yata, Mishima, Shizuoka, Japan
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28
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Reichenberger ER, Rosen G, Hershberg U, Hershberg R. Prokaryotic nucleotide composition is shaped by both phylogeny and the environment. Genome Biol Evol 2015; 7:1380-9. [PMID: 25861819 PMCID: PMC4453058 DOI: 10.1093/gbe/evv063] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2015] [Indexed: 02/07/2023] Open
Abstract
The causes of the great variation in nucleotide composition of prokaryotic genomes have long been disputed. Here, we use extensive metagenomic and whole-genome data to demonstrate that both phylogeny and the environment shape prokaryotic nucleotide content. We show that across environments, various phyla are characterized by different mean guanine and cytosine (GC) values as well as by the extent of variation on that mean value. At the same time, we show that GC-content varies greatly as a function of environment, in a manner that cannot be entirely explained by disparities in phylogenetic composition. We find environmentally driven differences in nucleotide content not only between highly diverged environments (e.g., soil, vs. aquatic vs. human gut) but also within a single type of environment. More specifically, we demonstrate that some human guts are associated with a microbiome that is consistently more GC-rich across phyla, whereas others are associated with a more AT-rich microbiome. These differences appear to be driven both by variations in phylogenetic composition and by environmental differences-which are independent of these phylogenetic composition differences. Combined, our results demonstrate that both phylogeny and the environment significantly affect nucleotide composition and that the environmental differences affecting nucleotide composition are far subtler than previously appreciated.
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Affiliation(s)
- Erin R Reichenberger
- Department of Biomedical Engineering, Science & Health Systems, Drexel University
| | - Gail Rosen
- Department of Computer and Electrical Engineering, Drexel University
| | - Uri Hershberg
- Department of Biomedical Engineering, Science & Health Systems, Drexel University Department of Microbiology and Immunology, Drexel University College of Medicine
| | - Ruth Hershberg
- Rachel and Menachem Mendelovitch Evolutionary Processes of Mutation and Natural Selection Research Laboratory, Department of Genetics and Developmental Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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