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Gifford DR, Bhattacharyya A, Geim A, Marshall E, Krašovec R, Knight CG. Environmental and genetic influence on the rate and spectrum of spontaneous mutations in Escherichia coli. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001452. [PMID: 38687010 PMCID: PMC11084559 DOI: 10.1099/mic.0.001452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 03/19/2024] [Indexed: 05/02/2024]
Abstract
Spontaneous mutations are the ultimate source of novel genetic variation on which evolution operates. Although mutation rate is often discussed as a single parameter in evolution, it comprises multiple distinct types of changes at the level of DNA. Moreover, the rates of these distinct changes can be independently influenced by genomic background and environmental conditions. Using fluctuation tests, we characterized the spectrum of spontaneous mutations in Escherichia coli grown in low and high glucose environments. These conditions are known to affect the rate of spontaneous mutation in wild-type MG1655, but not in a ΔluxS deletant strain - a gene with roles in both quorum sensing and the recycling of methylation products used in E. coli's DNA repair process. We find an increase in AT>GC transitions in the low glucose environment, suggesting that processes relating to the production or repair of this mutation could drive the response of overall mutation rate to glucose concentration. Interestingly, this increase in AT>GC transitions is maintained by the glucose non-responsive ΔluxS deletant. Instead, an elevated rate of GC>TA transversions, more common in a high glucose environment, leads to a net non-responsiveness of overall mutation rate for this strain. Our results show how relatively subtle changes, such as the concentration of a carbon substrate or loss of a regulatory gene, can substantially influence the amount and nature of genetic variation available to selection.
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Affiliation(s)
- Danna R. Gifford
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Anish Bhattacharyya
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Alexandra Geim
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
- Pembroke College, University of Cambridge, Cambridge, UK
| | - Eleanor Marshall
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Rok Krašovec
- Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Christopher G. Knight
- Department of Earth and Environmental Sciences, School of Natural Sciences, Faculty of Science and Engineering, The University of Manchester, Manchester, UK
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2
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Horton JS, Taylor TB. Mutation bias and adaptation in bacteria. MICROBIOLOGY (READING, ENGLAND) 2023; 169. [PMID: 37943288 DOI: 10.1099/mic.0.001404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2023]
Abstract
Genetic mutation, which provides the raw material for evolutionary adaptation, is largely a stochastic force. However, there is ample evidence showing that mutations can also exhibit strong biases, with some mutation types and certain genomic positions mutating more often than others. It is becoming increasingly clear that mutational bias can play a role in determining adaptive outcomes in bacteria in both the laboratory and the clinic. As such, understanding the causes and consequences of mutation bias can help microbiologists to anticipate and predict adaptive outcomes. In this review, we provide an overview of the mechanisms and features of the bacterial genome that cause mutational biases to occur. We then describe the environmental triggers that drive these mechanisms to be more potent and outline the adaptive scenarios where mutation bias can synergize with natural selection to define evolutionary outcomes. We conclude by describing how understanding mutagenic genomic features can help microbiologists predict areas sensitive to mutational bias, and finish by outlining future work that will help us achieve more accurate evolutionary forecasts.
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Affiliation(s)
- James S Horton
- Milner Centre for Evolution, Department of Life Sciences, University of Bath, BA2 7AY, UK
| | - Tiffany B Taylor
- Milner Centre for Evolution, Department of Life Sciences, University of Bath, BA2 7AY, UK
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3
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Maharjan RP, Sullivan GJ, Adams F, Shah B, Hawkey J, Delgado N, Semenec L, Dinh H, Li L, Short F, Parkhill J, Paulsen I, Barquist L, Eijkelkamp B, Cain A. DksA is a conserved master regulator of stress response in Acinetobacter baumannii. Nucleic Acids Res 2023; 51:6101-6119. [PMID: 37158230 PMCID: PMC10325922 DOI: 10.1093/nar/gkad341] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 04/11/2023] [Accepted: 05/04/2023] [Indexed: 05/10/2023] Open
Abstract
Coordination of bacterial stress response mechanisms is critical for long-term survival in harsh environments for successful host infection. The general and specific stress responses of well-studied Gram-negative pathogens like Escherichia coli are controlled by alternative sigma factors, archetypically RpoS. The deadly hospital pathogen Acinetobacter baumannii is notoriously resistant to environmental stresses, yet it lacks RpoS, and the molecular mechanisms driving this incredible stress tolerance remain poorly defined. Here, using functional genomics, we identified the transcriptional regulator DksA as a master regulator for broad stress protection and virulence in A. baumannii. Transcriptomics, phenomics and in vivo animal studies revealed that DksA controls ribosomal protein expression, metabolism, mutation rates, desiccation, antibiotic resistance, and host colonization in a niche-specific manner. Phylogenetically, DksA was highly conserved and well-distributed across Gammaproteobacteria, with 96.6% containing DksA, spanning 88 families. This study lays the groundwork for understanding DksA as a major regulator of general stress response and virulence in this important pathogen.
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Affiliation(s)
- Ram P Maharjan
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Geraldine J Sullivan
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Felise G Adams
- College of Science and Engineering, Flinders University, Bedford Park, SA 5042, Australia
| | - Bhumika S Shah
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Jane Hawkey
- Department of Infectious Diseases, Central Clinical School, Monash University, Victoria, Australia
| | - Natasha Delgado
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Lucie Semenec
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Hue Dinh
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Liping Li
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Francesca L Short
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC3800, Australia
| | - Julian Parkhill
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - Ian T Paulsen
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
| | - Lars Barquist
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080Würzburg, Germany
- Faculty of Medicine, University of Würzburg, 97080Würzburg, Germany
| | - Bart A Eijkelkamp
- College of Science and Engineering, Flinders University, Bedford Park, SA 5042, Australia
| | - Amy K Cain
- ARC Centre of Excellence in Synthetic Biology, School of Natural Sciences, Macquarie University, Sydney, NSW2109, Australia
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4
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Ba Q, Zhou J, Li J, Cheng S, Zhang X, Wang H. Mutagenic Characteristics of Six Heavy Metals in Escherichia coli: The Commonality and Specificity. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:13867-13877. [PMID: 36121417 PMCID: PMC9536316 DOI: 10.1021/acs.est.2c04785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 08/27/2022] [Accepted: 08/31/2022] [Indexed: 06/15/2023]
Abstract
The history of long-term environmental exposure to heavy metals can be recorded in the genome as sporadic and specific mutations. Variable environments introduce diverse and adaptive mutations to organisms. To reveal the information hidden in genomes about environmental exposure to heavy metals, we performed long-term mutation accumulation (MA) experiments with Escherichia coli, analyzed genomes from 36 populations across 1650 generations with 6 heavy metal exposure regimes (arsenic, cadmium, chromium, copper, nickel, and lead), and inferred metal-specific evolution modes at the genomic level. All heavy metals induced genetic mutations with a mean rate of 3.459 × 10-9 per nucleotide per generation. The mutational spectrum exhibited distinct signatures; however, heavy metals also shared common mutation signatures prominently associated with all cancer types. The mutated genes showed an average similarity of 54.4% within the same exposure regime, whereas only 38.8% between exposure regimes. In terms of biological insights, mutated genes were enriched to fundamental cellular processes such as metabolism, motility, and transport. Our study elucidates the mutagenic commonality and specificity of environmental heavy metals, which are highly specific at mutational features and locus, but conserved at gene and functional levels, and may play crucial roles in the convergence of adaptation to heavy metals.
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Affiliation(s)
- Qian Ba
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jingqi Zhou
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jingquan Li
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Shujun Cheng
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xiaokang Zhang
- School
of Public Health and Health Management, Gannan Medical University, Ganzhou 341000, China
| | - Hui Wang
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
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5
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Abstract
Mechanisms of evolution and evolution of antibiotic resistance are both fundamental and world health problems. Stress-induced mutagenesis defines mechanisms of mutagenesis upregulated by stress responses, which drive adaptation when cells are maladapted to their environments—when stressed. Work in mutagenesis induced by antibiotics had produced tantalizing clues but not coherent mechanisms. We review recent advances in antibiotic-induced mutagenesis that integrate how reactive oxygen species (ROS), the SOS and general stress responses, and multichromosome cells orchestrate a stress response-induced switch from high-fidelity to mutagenic repair of DNA breaks. Moreover, while sibling cells stay stable, a mutable “gambler” cell subpopulation is induced by differentially generated ROS, which signal the general stress response. We discuss other evolvable subpopulations and consider diverse evolution-promoting molecules as potential targets for drugs to slow evolution of antibiotic resistance, cross-resistance, and immune evasion. An FDA-approved drug exemplifies “stealth” evolution-slowing drugs that avoid selecting resistance to themselves or antibiotics.
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6
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Valencia EY, Barros JP, Ferenci T, Spira B. A Broad Continuum of E. coli Traits in Nature Associated with the Trade-off Between Self-preservation and Nutritional Competence. MICROBIAL ECOLOGY 2022; 83:68-82. [PMID: 33846820 DOI: 10.1007/s00248-021-01751-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 04/05/2021] [Indexed: 06/12/2023]
Abstract
A trade-off between reproduction and survival is a characteristic of many organisms. In bacteria, growth is constrained when cellular resources are channelled towards environmental stress protection. At the core of this trade-off in Escherichia coli is RpoS, a sigma factor that diverts transcriptional resources towards general stress resistance. The constancy of RpoS levels in natural isolates is unknown. A uniform RpoS content in E. coli would impart a narrow range of resistance properties to the species, whereas a diverse set of RpoS levels in nature should result in a diverse range of stress susceptibilities. We explore the diversity of trade-off settings and phenotypes by measuring the level of RpoS protein in strains of E. coli cohabiting in a natural environment. Strains from a stream polluted with domestic waste were investigated in monthly samples. Analyses included E. coli phylogroup classification, RpoS protein level, RpoS-dependent stress phenotypes and the sequencing of rpoS mutations. The most striking finding was the continuum of RpoS levels, with a 100-fold range of RpoS amounts consistently found in individuals in the stream. Approximately 1.8% of the sampled strains carried null or non-synonymous mutations in rpoS. The natural isolates also exhibited a broad (>100-fold) range of stress resistance responses. Our results are consistent with the view that a multiplicity of survival-multiplication trade-off settings is a feature of the species E. coli. The phenotypic diversity resulting from the trade-off permits bet-hedging and the adaptation of E. coli strains to a very broad range of environments.
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Affiliation(s)
- Estela Ynes Valencia
- Departamento de Microbiologia, Instituto de Ciências Biomédicas Universidade de São Paulo, São Paulo, SP, Brazil
| | - Jackeline Pinheiro Barros
- Departamento de Microbiologia, Instituto de Ciências Biomédicas Universidade de São Paulo, São Paulo, SP, Brazil
| | - Thomas Ferenci
- School of Life and Environmental Sciences, University of Sydney, 6/403 Pacific Highway, Sydney, New South Wales, 2070, Australia
| | - Beny Spira
- Departamento de Microbiologia, Instituto de Ciências Biomédicas Universidade de São Paulo, São Paulo, SP, Brazil.
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7
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Shoemaker WR, Polezhaeva E, Givens KB, Lennon JT. Molecular Evolutionary Dynamics of Energy Limited Microorganisms. Mol Biol Evol 2021; 38:4532-4545. [PMID: 34255090 PMCID: PMC8476154 DOI: 10.1093/molbev/msab195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Microorganisms have the unique ability to survive extended periods of time in environments with extremely low levels of exploitable energy. To determine the extent that energy limitation affects microbial evolution, we examined the molecular evolutionary dynamics of a phylogenetically diverse set of taxa over the course of 1,000 days. We found that periodic exposure to energy limitation affected the rate of molecular evolution, the accumulation of genetic diversity, and the rate of extinction. We then determined the degree that energy limitation affected the spectrum of mutations as well as the direction of evolution at the gene level. Our results suggest that the initial depletion of energy altered the direction and rate of molecular evolution within each taxon, though after the initial depletion the rate and direction did not substantially change. However, this consistent pattern became diminished when comparisons were performed across phylogenetically distant taxa, suggesting that while the dynamics of molecular evolution under energy limitation are highly generalizable across the microbial tree of life, the targets of adaptation are specific to a given taxon.
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Affiliation(s)
- William R Shoemaker
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA.,Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, 90095, USACurrent affiliation
| | | | - Kenzie B Givens
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA.,Luddy School of Informatics, Computing, and Engineering, Indiana University, Bloomington, IN, 47408, USACurrent affiliation
| | - Jay T Lennon
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
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8
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Schuller A, Cserjan-Puschmann M, Köppl C, Grabherr R, Wagenknecht M, Schiavinato M, Dohm JC, Himmelbauer H, Striedner G. Adaptive Evolution in Producing Microtiter Cultivations Generates Genetically Stable Escherichia coli Production Hosts for Continuous Bioprocessing. Biotechnol J 2020; 16:e2000376. [PMID: 33084246 DOI: 10.1002/biot.202000376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 10/06/2020] [Indexed: 01/01/2023]
Abstract
The production of recombinant proteins usually reduces cell fitness and the growth rate of producing cells. The growth disadvantage favors faster-growing non-producer mutants. Therefore, continuous bioprocessing is hardly feasible in Escherichia coli due to the high escape rate. The stability of E. coli expression systems under long-term production conditions and how metabolic load triggered by recombinant gene expression influences the characteristics of mutations are investigated. Iterated fed-batch-like microbioreactor cultivations are conducted under production conditions. The easy-to-produce green fluorescent protein (GFP) and a challenging antigen-binding fragment (Fab) are used as model proteins, and BL21(DE3) and BL21Q strains as expression hosts. In comparative whole-genome sequencing analyses, mutations that allowed cells to grow unhindered despite recombinant protein production are identified. A T7 RNA polymerase expression system is only conditionally suitable for long-term cultivation under production conditions. Mutations leading to non-producers occur in either the T7 RNA polymerase gene or the T7 promoter. The host RNA polymerase-based BL21Q expression system remains stable in the production of GFP in long-term cultivations. For the production of Fab, mutations in lacI of the BL21Q derivatives have positive effects on long-term stability. The results indicate that adaptive evolution carried out with genome-integrated E. coli expression systems in microtiter cultivations under industrial-relevant production conditions is an efficient strain development tool for production hosts.
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Affiliation(s)
- Artur Schuller
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, A-1190, Austria
| | - Monika Cserjan-Puschmann
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, A-1190, Austria
| | - Christoph Köppl
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, A-1190, Austria
| | - Reingard Grabherr
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, A-1190, Austria
| | - Martin Wagenknecht
- Boehringer Ingelheim RCV GmbH & Co KG, Dr.-Boehringer-Gasse 5-11, Vienna, A-1120, Austria
| | - Matteo Schiavinato
- Department of Biotechnology, Institute of Computational Biology, University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, A-1190, Austria
| | - Juliane C Dohm
- Department of Biotechnology, Institute of Computational Biology, University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, A-1190, Austria
| | - Heinz Himmelbauer
- Department of Biotechnology, Institute of Computational Biology, University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, A-1190, Austria
| | - Gerald Striedner
- Christian Doppler Laboratory for Production of Next-Level Biopharmaceuticals in E. coli, Department of Biotechnology, University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, A-1190, Austria
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9
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Matic I. Mutation Rate Heterogeneity Increases Odds of Survival in Unpredictable Environments. Mol Cell 2020; 75:421-425. [PMID: 31398322 DOI: 10.1016/j.molcel.2019.06.029] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 05/14/2019] [Accepted: 06/19/2019] [Indexed: 11/24/2022]
Abstract
Mutation rates affect both a population's present fitness and its capacity to adapt to future environmental changes. When the available genetic variability limits adaptation to environmental change, natural selection favors high mutations rates. However, constitutively high mutation rates compromise the fitness of a population in stable environments. This problem may be resolved if an increase in mutation rates is limited to times of stress, restricted to some genomic regions, and occurs only in a subpopulation of cells. Such within-population heterogeneity of mutation rates can result from genetic, environmental, and stochastic effects. The presence of subpopulations of transient mutator cells does not jeopardize the overall fitness of a population under stable environmental conditions. However, they can increase the odds of survival in changing environments because they represent reservoirs of increased genetic variability. This article presents evidence that such heterogeneity of mutation rates is more the norm than the exception.
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Affiliation(s)
- Ivan Matic
- Department of Infection, Immunity, and Inflammation, Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Descartes, 75014 Paris, France.
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10
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Ferenci T. Irregularities in genetic variation and mutation rates with environmental stresses. Environ Microbiol 2019; 21:3979-3988. [PMID: 31600848 DOI: 10.1111/1462-2920.14822] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 10/01/2019] [Accepted: 10/03/2019] [Indexed: 11/26/2022]
Abstract
The appearance of new mutations is determined by the equilibrium between DNA error formation and repair. In bacteria like Escherichia coli, stresses are thought shift this balance towards increased mutagenesis. Recent findings, however, suggest a very uneven relationship between stress and mutations. Only a subset of stressful environments increase the net rate of mutation and different forms of nutritional stress (such as oxygen, carbon or phosphorus limitations) result in markedly different mutation rates after similar reductions in growth rate. Moreover, different stresses result in altered mutational spectra, with some increasing transposition and others increasing indel formation. Single-base substitution rates are lower with some stresses than in unstressed bacteria. Indeed, changes to the mix of mutations with stress are more widespread than a marked increase in net mutation rate. Much remains to be learned on how environments have unique mutational signatures and why some stresses are more mutagenic than others. Even beyond stress-induced genetic variation, the fundamental unresolved question in the stress-mutation relationship is the adaptive value of different types of mutations and mutation rates; is transposition, for example, more advantageous under anaerobic conditions? It remains to be investigated whether stress-specific genetic variation impacts on evolvability differentially in distinct environments.
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Affiliation(s)
- Thomas Ferenci
- School of Life and Environmental Sciences, University of Sydney, New South Wales, 2006, Australia
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11
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Kozmin SG, Rogozin IB, Moore EA, Abney M, Schaaper RM, Pavlov YI. Comment on "A commensal strain of Staphylococcus epidermidis protects against skin neoplasia" by Nakatsuji et al. SCIENCE ADVANCES 2019; 5:eaaw3915. [PMID: 31535021 PMCID: PMC6739109 DOI: 10.1126/sciadv.aaw3915] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 08/15/2019] [Indexed: 06/10/2023]
Abstract
A recent article in Science Advances described the striking discovery that the commensal Staphylococcus epidermidis strain MO34 displays antimicrobial and antitumor activities by producing a small molecule, identified as the nucleobase analog 6-N-hydroxylaminopurine (6-HAP). However, in contradiction to the literature, the authors claimed that 6-HAP is nonmutagenic and proposed that the toxic effect of 6-HAP results from its ability to inhibit, in its base form, DNA synthesis. To resolve the discrepancy, we proved by genetic experiments with bacteria and yeast that extracts of MO34 do contain a mutagenic compound whose effects are identical to chemically synthesized 6-HAP. The MO34 extract induced the same mutation spectrum as authentic 6-HAP. Notably, the toxic and mutagenic effects of both synthetic and MO34-derived 6-HAP depended on conversion to the corresponding nucleotide. The nucleobase 6-HAP does not inhibit DNA synthesis in vitro, and we conclude that 6-HAP exerts its biological activity when incorporated into DNA.
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Affiliation(s)
- Stanislav G. Kozmin
- National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Igor B. Rogozin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Elizabeth A. Moore
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, USA
| | - Mariah Abney
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, USA
- University of Nebraska at Omaha, Omaha, NE, USA
| | - Roel M. Schaaper
- National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Youri I. Pavlov
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, USA
- Departments of Microbiology and Pathology, Biochemistry and Molecular Biology, Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, USA
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12
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Fitzgerald DM, Rosenberg SM. What is mutation? A chapter in the series: How microbes "jeopardize" the modern synthesis. PLoS Genet 2019; 15:e1007995. [PMID: 30933985 PMCID: PMC6443146 DOI: 10.1371/journal.pgen.1007995] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Mutations drive evolution and were assumed to occur by chance: constantly, gradually, roughly uniformly in genomes, and without regard to environmental inputs, but this view is being revised by discoveries of molecular mechanisms of mutation in bacteria, now translated across the tree of life. These mechanisms reveal a picture of highly regulated mutagenesis, up-regulated temporally by stress responses and activated when cells/organisms are maladapted to their environments-when stressed-potentially accelerating adaptation. Mutation is also nonrandom in genomic space, with multiple simultaneous mutations falling in local clusters, which may allow concerted evolution-the multiple changes needed to adapt protein functions and protein machines encoded by linked genes. Molecular mechanisms of stress-inducible mutation change ideas about evolution and suggest different ways to model and address cancer development, infectious disease, and evolution generally.
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Affiliation(s)
- Devon M. Fitzgerald
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- The Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, United States of America
| | - Susan M. Rosenberg
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- The Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, United States of America
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13
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Shapiro JA. No genome is an island: toward a 21st century agenda for evolution. Ann N Y Acad Sci 2019; 1447:21-52. [DOI: 10.1111/nyas.14044] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 01/17/2019] [Accepted: 02/02/2019] [Indexed: 12/21/2022]
Affiliation(s)
- James A. Shapiro
- Department of Biochemistry and Molecular BiologyUniversity of Chicago Chicago Illinois
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14
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Mutations in sigma 70 transcription factor improves expression of functional eukaryotic membrane proteins in Escherichia coli. Sci Rep 2019; 9:2483. [PMID: 30792443 PMCID: PMC6384906 DOI: 10.1038/s41598-019-39492-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 01/09/2019] [Indexed: 12/11/2022] Open
Abstract
Eukaryotic integral membrane proteins (IMPs) are difficult to study due to low functional expression levels. To investigate factors for efficient biogenesis of eukaryotic IMPs in the prokaryotic model organism Escherichia coli, important, e.g., for isotope-labeling for NMR, we selected for E. coli cells expressing high levels of functional G protein-coupled receptors (GPCRs) by FACS. Utilizing an E. coli strain library with all non-essential genes systematically deleted, we unexpectedly discovered upon whole-genome sequencing that the improved phenotype was not conferred by the deleted genes but by various subtle alterations in the “housekeeping” sigma 70 factor (RpoD). When analyzing effects of the rpoD mutations at the transcriptome level we found that toxic effects incurred on wild-type E. coli during receptor expression were diminished by two independent and synergistic effects: a slower but longer-lasting GPCR biosynthesis and an optimized transcriptional pattern, augmenting growth and expression at low temperature, setting the basis for further bacterial strain engineering.
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15
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Maharjan RP, Ferenci T. The impact of growth rate and environmental factors on mutation rates and spectra in Escherichia coli. ENVIRONMENTAL MICROBIOLOGY REPORTS 2018; 10:626-633. [PMID: 29797781 DOI: 10.1111/1758-2229.12661] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 05/04/2018] [Accepted: 05/11/2018] [Indexed: 06/08/2023]
Abstract
Genetic variation in bacterial populations is remarkably sensitive to environmental influences, including simple, nutritional differences. Not only the rate but also the kind of mutational changes is biased by the nutritional state of bacteria. Here we investigate the mutational consequences of a universal variable for free-living bacteria, namely the growth rate. By controlling growth in chemostats, the rate and mix of mutations was investigated for populations of Escherichia coli subject to different specific growth rates. Both aerobic and anaerobic cultures were compared with see if growth rate is a factor in the commonest respiratory conditions for E. coli. We find mutation rates are raised markedly with decreasing growth rate. Base pair substitutions and 1-bp insertions and deletions increase with reduced growth rate, but less so in anaerobic cultures. Insertion sequence movements are particularly sensitive to growth rate, with IS2 being optimal at intermediate growth rates whereas IS1 and IS150 movements are highest at the slowest tested growth rate. A comprehensive comparison of growth rate effects, as well as six other environmental factors, provides the most complete picture yet of the range of mutational signatures in bacterial genetic variation.
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Affiliation(s)
- Ram P Maharjan
- School of Life and Environmental Sciences, University of Sydney, Sydney, Australia
| | - Thomas Ferenci
- School of Life and Environmental Sciences, University of Sydney, Sydney, Australia
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16
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Maharjan RP, Ferenci T. Escherichia coli mutation rates and spectra with combinations of environmental limitations. MICROBIOLOGY-SGM 2018; 164:1491-1502. [PMID: 30300121 DOI: 10.1099/mic.0.000727] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Micro-organisms often face multiple stresses in natural habitats. Individual stresses are well known to influence mutation rates and the spectra of mutational types, but the extent to which multiple stresses affect the genetic variation in populations is unknown. Here we investigate pair-wise combinations of nutritional stresses in Escherichia coli to determine their effect on mutation rates and mutational types. Environmental interactions modified both the rate and spectrum of mutations in double-limited environments, but the effects were not additive or synergistic relative to single stresses. Generally, bacteria in the mixed environments behaved as if one of the two single-stress stimuli was more dominant and the genetic variation seen with every dual limitation was intermediate between known patterns with individual stresses. The composition of mutational types with double stresses was also intermediate between individual stress patterns. At least with mutations, the single stressor results available are reasonable indicators of stress-induced genetic variation in multifaceted natural habitats. With the influence of 11 conditions available on mutational patterns, we can now also see the clustering of mutational types as a function of these environments.
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Affiliation(s)
- Ram P Maharjan
- School of Life and Environmental Sciences, University of Sydney, NSW 2006, Australia
| | - Thomas Ferenci
- School of Life and Environmental Sciences, University of Sydney, NSW 2006, Australia
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17
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Predicting the evolution of Escherichia coli by a data-driven approach. Nat Commun 2018; 9:3562. [PMID: 30177705 PMCID: PMC6120903 DOI: 10.1038/s41467-018-05807-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 06/12/2018] [Indexed: 12/31/2022] Open
Abstract
A tantalizing question in evolutionary biology is whether evolution can be predicted from past experiences. To address this question, we created a coherent compendium of more than 15,000 mutation events for the bacterium Escherichia coli under 178 distinct environmental settings. Compendium analysis provides a comprehensive view of the explored environments, mutation hotspots and mutation co-occurrence. While the mutations shared across all replicates decrease with the number of replicates, our results argue that the pairwise overlapping ratio remains the same, regardless of the number of replicates. An ensemble of predictors trained on the mutation compendium and tested in forward validation over 35 evolution replicates achieves a 49.2 ± 5.8% (mean ± std) precision and 34.5 ± 5.7% recall in predicting mutation targets. This work demonstrates how integrated datasets can be harnessed to create predictive models of evolution at a gene level and elucidate the effect of evolutionary processes in well-defined environments. How reproducible evolutionary processes are remains an important question in evolutionary biology. Here, the authors compile a compendium of more than 15,000 mutation events for Escherichia coli under 178 distinct environmental settings, and develop an ensemble of predictors to predict evolution at a gene level.
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18
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Robert L, Ollion J, Robert J, Song X, Matic I, Elez M. Mutation dynamics and fitness effects followed in single cells. Science 2018; 359:1283-1286. [DOI: 10.1126/science.aan0797] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 10/19/2017] [Accepted: 01/30/2018] [Indexed: 12/12/2022]
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19
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Sadiq FA, Flint S, Li Y, Ou K, Yuan L, He GQ. Phenotypic and genetic heterogeneity within biofilms with particular emphasis on persistence and antimicrobial tolerance. Future Microbiol 2017; 12:1087-1107. [DOI: 10.2217/fmb-2017-0042] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Phenotypic changes or phase variation within biofilms is an important feature of bacterial dormant life. Enhanced resistance to antimicrobials is one of the distinct features displayed by a fraction of cells within biofilms. It is believed that persisters are mainly responsible for this phenotypic heterogeneity. However, there is still an unresolved debate on the formation of persisters. In this short review, we highlight all known genomic and proteomic changes encountered by bacterial cells within biofilms. We have also described all phenotypic changes displayed by bacterial cells within biofilms with particular emphasis on enhanced antimicrobial tolerance of biofilms with particular reference to persisters. In addition, all currently known models of persistence have been succinctly discussed.
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Affiliation(s)
- Faizan A Sadiq
- College of Biosystems Engineering & Food Science, Zhejiang University, Hangzhou 310058, China
| | - Steve Flint
- School of Food & Nutrition, Massey University, Private Bag 11 222, Palmerston North 4474, New Zealand
| | - YanJun Li
- Research Institute of Food Science, Hangzhou Wahaha Group Co, Ltd, Hangzhou 310018, China
| | - Kai Ou
- Research Institute of Food Science, Hangzhou Wahaha Group Co, Ltd, Hangzhou 310018, China
| | - Lei Yuan
- College of Biosystems Engineering & Food Science, Zhejiang University, Hangzhou 310058, China
| | - Guo Qing He
- College of Biosystems Engineering & Food Science, Zhejiang University, Hangzhou 310058, China
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20
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Moore JM, Correa R, Rosenberg SM, Hastings PJ. Persistent damaged bases in DNA allow mutagenic break repair in Escherichia coli. PLoS Genet 2017; 13:e1006733. [PMID: 28727736 PMCID: PMC5542668 DOI: 10.1371/journal.pgen.1006733] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 08/03/2017] [Accepted: 04/03/2017] [Indexed: 12/31/2022] Open
Abstract
Bacteria, yeast and human cancer cells possess mechanisms of mutagenesis upregulated by stress responses. Stress-inducible mutagenesis potentially accelerates adaptation, and may provide important models for mutagenesis that drives cancers, host pathogen interactions, antibiotic resistance and possibly much of evolution generally. In Escherichia coli repair of double-strand breaks (DSBs) becomes mutagenic, using low-fidelity DNA polymerases under the control of the SOS DNA-damage response and RpoS general stress response, which upregulate and allow the action of error-prone DNA polymerases IV (DinB), II and V to make mutations during repair. Pol IV is implied to compete with and replace high-fidelity DNA polymerases at the DSB-repair replisome, causing mutagenesis. We report that up-regulated Pol IV is not sufficient for mutagenic break repair (MBR); damaged bases in the DNA are also required, and that in starvation-stressed cells, these are caused by reactive-oxygen species (ROS). First, MBR is reduced by either ROS-scavenging agents or constitutive activation of oxidative-damage responses, both of which reduce cellular ROS levels. The ROS promote MBR other than by causing DSBs, saturating mismatch repair, oxidizing proteins, or inducing the SOS response or the general stress response. We find that ROS drive MBR through oxidized guanines (8-oxo-dG) in DNA, in that overproduction of a glycosylase that removes 8-oxo-dG from DNA prevents MBR. Further, other damaged DNA bases can substitute for 8-oxo-dG because ROS-scavenged cells resume MBR if either DNA pyrimidine dimers or alkylated bases are induced. We hypothesize that damaged bases in DNA pause the replisome and allow the critical switch from high fidelity to error-prone DNA polymerases in the DSB-repair replisome, thus allowing MBR. The data imply that in addition to the indirect stress-response controlled switch to MBR, a direct cis-acting switch to MBR occurs independently of DNA breakage, caused by ROS oxidation of DNA potentially regulated by ROS regulators.
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Affiliation(s)
- Jessica M. Moore
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Raul Correa
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Susan M. Rosenberg
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - P. J. Hastings
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, United States of America
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21
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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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22
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Maharjan RP, Ferenci T. A shifting mutational landscape in 6 nutritional states: Stress-induced mutagenesis as a series of distinct stress input-mutation output relationships. PLoS Biol 2017; 15:e2001477. [PMID: 28594817 PMCID: PMC5464527 DOI: 10.1371/journal.pbio.2001477] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 04/15/2017] [Indexed: 12/16/2022] Open
Abstract
Environmental stresses increase genetic variation in bacteria, plants, and human cancer cells. The linkage between various environments and mutational outcomes has not been systematically investigated, however. Here, we established the influence of nutritional stresses commonly found in the biosphere (carbon, phosphate, nitrogen, oxygen, or iron limitation) on both the rate and spectrum of mutations in Escherichia coli. We found that each limitation was associated with a remarkably distinct mutational profile. Overall mutation rates were not always elevated, and nitrogen, iron, and oxygen limitation resulted in major spectral changes but no net increase in rate. Our results thus suggest that stress-induced mutagenesis is a diverse series of stress input-mutation output linkages that is distinct in every condition. Environment-specific spectra resulted in the differential emergence of traits needing particular mutations in these settings. Mutations requiring transpositions were highest under iron and oxygen limitation, whereas base-pair substitutions and indels were highest under phosphate limitation. The unexpected diversity of input-output effects explains some important phenomena in the mutational biases of evolving genomes. The prevalence of bacterial insertion sequence transpositions in the mammalian gut or in anaerobically stored cultures is due to environmentally determined mutation availability. Likewise, the much-discussed genomic bias towards transition base substitutions in evolving genomes can now be explained as an environment-specific output. Altogether, our conclusion is that environments influence genetic variation as well as selection.
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Affiliation(s)
- Ram P. Maharjan
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Thomas Ferenci
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
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23
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Iwase T, Matsuo T, Nishioka S, Tajima A, Mizunoe Y. Hydrophobicity of Residue 128 of the Stress-Inducible Sigma Factor RpoS Is Critical for Its Activity. Front Microbiol 2017; 8:656. [PMID: 28491053 PMCID: PMC5405132 DOI: 10.3389/fmicb.2017.00656] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 03/30/2017] [Indexed: 11/29/2022] Open
Abstract
RpoS is a key stress-inducible sigma factor that regulates stress resistance genes in Escherichia coli, such as the katE gene encoding catalase HPII and the glg genes encoding glycogen synthesis proteins. Monitoring RpoS activity can provide information on the stress sensitivity of E. coli isolates in clinical settings because the RpoS in these isolates is often mutated. In the present study, we found a novel, missense point mutation at RpoS residue 128 in a clinical Shiga toxin-producing E. coli (STEC) isolate. This mutation caused RpoS dysfunction and increased stress sensitivity. A mutant rpoS was cloned from a clinical STEC that is vulnerable to cold temperature and oxidative stresses. Mutant RpoS protein expression was detected in the clinical isolate, and this RpoS was non-functional according to HPII activity and glycogen levels, which are positively regulated by RpoS and thus are used as indicators for RpoS function. A reporter assay with β-galactosidase indicated that the dysfunction occurred at the transcriptional level of genes regulated by RpoS. Furthermore, substitution analysis indicated that the hydrophobicity of the amino acid at residue 128 was critical for RpoS activity; the simulation analysis indicated that the amino acids of RNA polymerase (RNAP) that interact with RpoS residue 128 are hydrophobic, suggesting that this hydrophobic interaction is critical for RpoS activity. In addition, substitution of Ile128 to Pro128 abolished RpoS activity, possibly as a result of disruption of the secondsary structure around residue 128, indicating that the structure is also a crucial factor for RpoS activity. These results indicate that only one point mutation at a hydrophobic residue of the complex formed during transcription leads to a critical change in RpoS regulation. Moreover, we found that Ile128 is widely conserved among various bacteria: several bacterial strains have Met128 or Leu128, which are hydrophobic residues, and these strains had similar or higher RpoS activity than that observed with Ile128 in this study. These data indicate that the hydrophobicity of the amino acid at residue 128 is critical for RpoS activity and is consequently important for bacterial survival. Taken together, these findings may contribute to a deeper understanding of protein functional mechanisms and bacterial stress responses.
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Affiliation(s)
- Tadayuki Iwase
- Department of Bacteriology, The Jikei University School of MedicineTokyo, Japan
| | - Takashi Matsuo
- Graduate School of Materials Science, Nara Institute of Science and TechnologyNara, Japan
| | - Saiko Nishioka
- Department of Bacteriology, The Jikei University School of MedicineTokyo, Japan
| | - Akiko Tajima
- Department of Bacteriology, The Jikei University School of MedicineTokyo, Japan
| | - Yoshimitsu Mizunoe
- Department of Bacteriology, The Jikei University School of MedicineTokyo, Japan
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24
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Fitzgerald DM, Hastings PJ, Rosenberg SM. Stress-Induced Mutagenesis: Implications in Cancer and Drug Resistance. ANNUAL REVIEW OF CANCER BIOLOGY 2017; 1:119-140. [PMID: 29399660 PMCID: PMC5794033 DOI: 10.1146/annurev-cancerbio-050216-121919] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Genomic instability underlies many cancers and generates genetic variation that drives cancer initiation, progression, and therapy resistance. In contrast with classical assumptions that mutations occur purely stochastically at constant, gradual rates, microbes, plants, flies, and human cancer cells possess mechanisms of mutagenesis that are upregulated by stress responses. These generate transient, genetic-diversity bursts that can propel evolution, specifically when cells are poorly adapted to their environments-that is, when stressed. We review molecular mechanisms of stress-response-dependent (stress-induced) mutagenesis that occur from bacteria to cancer, and are activated by starvation, drugs, hypoxia, and other stressors. We discuss mutagenic DNA break repair in Escherichia coli as a model for mechanisms in cancers. The temporal regulation of mutagenesis by stress responses and spatial restriction in genomes are common themes across the tree of life. Both can accelerate evolution, including the evolution of cancers. We discuss possible anti-evolvability drugs, aimed at targeting mutagenesis and other variation generators, that could be used to delay the evolution of cancer progression and therapy resistance.
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Affiliation(s)
- Devon M Fitzgerald
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston Texas 77030
- The Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas 77030
| | - P J Hastings
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- The Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas 77030
| | - Susan M Rosenberg
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston Texas 77030
- The Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas 77030
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25
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The Small RNA GcvB Promotes Mutagenic Break Repair by Opposing the Membrane Stress Response. J Bacteriol 2016; 198:3296-3308. [PMID: 27698081 PMCID: PMC5116933 DOI: 10.1128/jb.00555-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 09/22/2016] [Indexed: 12/19/2022] Open
Abstract
Microbes and human cells possess mechanisms of mutagenesis activated by stress responses. Stress-inducible mutagenesis mechanisms may provide important models for mutagenesis that drives host-pathogen interactions, antibiotic resistance, and possibly much of evolution generally. In Escherichia coli, repair of DNA double-strand breaks is switched to a mutagenic mode, using error-prone DNA polymerases, via the SOS DNA damage and general (σS) stress responses. We investigated small RNA (sRNA) clients of Hfq, an RNA chaperone that promotes mutagenic break repair (MBR), and found that GcvB promotes MBR by allowing a robust σS response, achieved via opposing the membrane stress (σE) response. Cells that lack gcvB were MBR deficient and displayed reduced σS-dependent transcription but not reduced σS protein levels. The defects in MBR and σS-dependent transcription in ΔgcvB cells were alleviated by artificially increasing σS levels, implying that GcvB promotes mutagenesis by allowing a normal σS response. ΔgcvB cells were highly induced for the σE response, and blocking σE response induction restored both mutagenesis and σS-promoted transcription. We suggest that GcvB may promote the σS response and mutagenesis indirectly, by promoting membrane integrity, which keeps σE levels lower. At high levels, σE might outcompete σS for binding RNA polymerase and so reduce the σS response and mutagenesis. The data show the delicate balance of stress response modulation of mutagenesis. IMPORTANCE Mutagenesis mechanisms upregulated by stress responses promote de novo antibiotic resistance and cross-resistance in bacteria, antifungal drug resistance in yeasts, and genome instability in cancer cells under hypoxic stress. This paper describes the role of a small RNA (sRNA) in promoting a stress-inducible-mutagenesis mechanism, mutagenic DNA break repair in Escherichia coli The roles of many sRNAs in E. coli remain unknown. This study shows that ΔgcvB cells, which lack the GcvB sRNA, display a hyperactivated membrane stress response and reduced general stress response, possibly because of sigma factor competition for RNA polymerase. This results in a mutagenic break repair defect. The data illuminate a function of GcvB sRNA in opposing the membrane stress response, and thus indirectly upregulating mutagenesis.
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26
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Moura de Sousa JA, Alpedrinha J, Campos PRA, Gordo I. Competition and fixation of cohorts of adaptive mutations under Fisher geometrical model. PeerJ 2016; 4:e2256. [PMID: 27547562 PMCID: PMC4975028 DOI: 10.7717/peerj.2256] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 06/23/2016] [Indexed: 11/24/2022] Open
Abstract
One of the simplest models of adaptation to a new environment is Fisher’s Geometric Model (FGM), in which populations move on a multidimensional landscape defined by the traits under selection. The predictions of this model have been found to be consistent with current observations of patterns of fitness increase in experimentally evolved populations. Recent studies investigated the dynamics of allele frequency change along adaptation of microbes to simple laboratory conditions and unveiled a dramatic pattern of competition between cohorts of mutations, i.e., multiple mutations simultaneously segregating and ultimately reaching fixation. Here, using simulations, we study the dynamics of phenotypic and genetic change as asexual populations under clonal interference climb a Fisherian landscape, and ask about the conditions under which FGM can display the simultaneous increase and fixation of multiple mutations—mutation cohorts—along the adaptive walk. We find that FGM under clonal interference, and with varying levels of pleiotropy, can reproduce the experimentally observed competition between different cohorts of mutations, some of which have a high probability of fixation along the adaptive walk. Overall, our results show that the surprising dynamics of mutation cohorts recently observed during experimental adaptation of microbial populations can be expected under one of the oldest and simplest theoretical models of adaptation—FGM.
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Affiliation(s)
| | | | - Paulo R A Campos
- Departamento de Fisica, Cidade Universitária, Universidade Federal de Pernambuco , Recife , Pernambuco , Brazil
| | - Isabel Gordo
- Instituto Gulbenkian de Ciência , Oeiras , Portugal
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27
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Feugeas JP, Tourret J, Launay A, Bouvet O, Hoede C, Denamur E, Tenaillon O. Links between Transcription, Environmental Adaptation and Gene Variability in Escherichia coli: Correlations between Gene Expression and Gene Variability Reflect Growth Efficiencies. Mol Biol Evol 2016; 33:2515-29. [PMID: 27352853 DOI: 10.1093/molbev/msw105] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Gene expression is known to be the principle factor explaining how fast genes evolve. Highly transcribed genes evolve slowly because any negative impact caused by a particular mutation is magnified by protein abundance. However, gene expression is a phenotype that depends both on the environment and on the strains or species. We studied this phenotypic plasticity by analyzing the transcriptome profiles of four Escherichia coli strains grown in three different culture media, and explored how expression variability was linked to gene allelic diversity. Genes whose expression changed according to the media and not to the strains were less polymorphic than other genes. Genes for which transcription depended predominantly on the strain were more polymorphic than other genes and were involved in sensing and responding to environmental changes, with an overrepresentation of two-component system genes. Surprisingly, we found that the correlation between transcription and gene diversity was highly variable among growth conditions and could be used to quantify growth efficiency of a strain in a medium. Genetic variability was found to increase with gene expression in poor growth conditions. As such conditions are also characterized by down-regulation of all DNA repair systems, including transcription-coupled repair, we suggest that gene expression under stressful conditions may be mutagenic and thus leads to a variability in mutation rate among genes in the genome which contributes to the pattern of protein evolution.
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Affiliation(s)
- Jean-Paul Feugeas
- INSERM, UMR 1137, Infection, Antimicrobiens, Modélisation, Evolution (IAME), Paris, France Faculté de Médecine, Universités Paris Diderot et Paris Nord-Sorbonne Paris Cité, Paris, France
| | - Jerome Tourret
- INSERM, UMR 1137, Infection, Antimicrobiens, Modélisation, Evolution (IAME), Paris, France Faculté de Médecine, Universités Paris Diderot et Paris Nord-Sorbonne Paris Cité, Paris, France AP-HP, Unité de Transplantation, GH Pitié-Salpêtrière Charles Foix et Université Pierre et Marie Curie, Paris, France
| | - Adrien Launay
- INSERM, UMR 1137, Infection, Antimicrobiens, Modélisation, Evolution (IAME), Paris, France Faculté de Médecine, Universités Paris Diderot et Paris Nord-Sorbonne Paris Cité, Paris, France
| | - Odile Bouvet
- INSERM, UMR 1137, Infection, Antimicrobiens, Modélisation, Evolution (IAME), Paris, France Faculté de Médecine, Universités Paris Diderot et Paris Nord-Sorbonne Paris Cité, Paris, France
| | - Claire Hoede
- INRA, MIAT, Plateforme Bio-Informatique GenoToul, Castanet-Tolosan Cedex, France
| | - Erick Denamur
- INSERM, UMR 1137, Infection, Antimicrobiens, Modélisation, Evolution (IAME), Paris, France Faculté de Médecine, Universités Paris Diderot et Paris Nord-Sorbonne Paris Cité, Paris, France AP-HP, Laboratoire de Génétique Moléculaire, GH Paris Nord Val de Seine, Paris, France
| | - Olivier Tenaillon
- INSERM, UMR 1137, Infection, Antimicrobiens, Modélisation, Evolution (IAME), Paris, France Faculté de Médecine, Universités Paris Diderot et Paris Nord-Sorbonne Paris Cité, Paris, France
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28
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Rates and mechanisms of bacterial mutagenesis from maximum-depth sequencing. Nature 2016; 534:693-6. [PMID: 27338792 PMCID: PMC4940094 DOI: 10.1038/nature18313] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 05/05/2016] [Indexed: 01/09/2023]
Abstract
In 1943, Luria and Delbrück used a phage resistance assay to establish spontaneous mutation as a driving force of microbial diversity1. Mutation rates are still studied using such assays, but these can only examine the small minority of mutations conferring survival in a particular condition. Newer approaches, such as long-term evolution followed by whole-genome sequencing 2, 3, may be skewed by mutational “hot” or “cold” spots 3, 4. Both approaches are affected by numerous caveats 5, 6, 7 (see Supplemental Information). We devise a method, Maximum-Depth Sequencing (MDS), to detect extremely rare variants in a population of cells through error-corrected, high-throughput sequencing. We directly measure locus-specific mutation rates in E. coli and show that they vary across the genome by at least an order of magnitude. Our data suggest that certain types of nucleotide misincorporation occur 104-fold more frequently than the basal rate of mutations, but are repaired in vivo. Our data also suggest specific mechanisms of antibiotic-induced mutagenesis, including downregulation of mismatch repair via oxidative stress; transcription-replication conflicts; and in the case of fluoroquinolones, direct damage to DNA.
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29
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Fosse R, Joseph J, Jones M. Schizophrenia: A critical view on genetic effects. PSYCHOSIS-PSYCHOLOGICAL SOCIAL AND INTEGRATIVE APPROACHES 2015. [DOI: 10.1080/17522439.2015.1081269] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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30
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De-convoluting the Genetic Adaptations of E. coli C41(DE3) in Real Time Reveals How Alleviating Protein Production Stress Improves Yields. Cell Rep 2015; 10:1758-1766. [DOI: 10.1016/j.celrep.2015.02.029] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 01/29/2015] [Accepted: 02/08/2015] [Indexed: 11/20/2022] Open
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