1
|
Sass TH, Lovett ST. The DNA damage response of Escherichia coli, revisited: Differential gene expression after replication inhibition. Proc Natl Acad Sci U S A 2024; 121:e2407832121. [PMID: 38935560 PMCID: PMC11228462 DOI: 10.1073/pnas.2407832121] [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: 04/19/2024] [Accepted: 05/29/2024] [Indexed: 06/29/2024] Open
Abstract
In 1967, in this journal, Evelyn Witkin proposed the existence of a coordinated DNA damage response in Escherichia coli, which later came to be called the "SOS response." We revisited this response using the replication inhibitor azidothymidine (AZT) and RNA-Seq analysis and identified several features. We confirm the induction of classic Save our ship (SOS) loci and identify several genes, including many of the pyrimidine pathway, that have not been previously demonstrated to be DNA damage-inducible. Despite a strong dependence on LexA, these genes lack LexA boxes and their regulation by LexA is likely to be indirect via unknown factors. We show that the transcription factor "stringent starvation protein" SspA is as important as LexA in the regulation of AZT-induced genes and that the genes activated by SspA change dramatically after AZT exposure. Our experiments identify additional LexA-independent DNA damage inducible genes, including 22 small RNA genes, some of which appear to activated by SspA. Motility and chemotaxis genes are strongly down-regulated by AZT, possibly as a result of one of more of the small RNAs or other transcription factors such as AppY and GadE, whose expression is elevated by AZT. Genes controlling the iron siderophore, enterobactin, and iron homeostasis are also strongly induced, independent of LexA. We confirm that IraD antiadaptor protein is induced independent of LexA and that a second antiadaptor, IraM is likewise strongly AZT-inducible, independent of LexA, suggesting that RpoS stabilization via these antiadaptor proteins is an integral part of replication stress tolerance.
Collapse
Affiliation(s)
- Thalia H Sass
- Department of Biology, Brandeis University, Waltham, MA 02454-9110
- Rosenstiel Basic Medical Sciences Research Center MS029, Brandeis University, Waltham, MA 02454-9110
| | - Susan T Lovett
- Department of Biology, Brandeis University, Waltham, MA 02454-9110
- Rosenstiel Basic Medical Sciences Research Center MS029, Brandeis University, Waltham, MA 02454-9110
| |
Collapse
|
2
|
Wagner A. Adaptive evolvability through direct selection instead of indirect, second-order selection. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2022; 338:395-404. [PMID: 34254439 PMCID: PMC9786751 DOI: 10.1002/jez.b.23071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 05/11/2021] [Accepted: 06/04/2021] [Indexed: 12/30/2022]
Abstract
Can evolvability itself be the product of adaptive evolution? To answer this question is challenging, because any DNA mutation that alters only evolvability is subject to indirect, "second order" selection on the future effects of this mutation. Such indirect selection is weaker than "first-order" selection on mutations that alter fitness, in the sense that it can operate only under restrictive conditions. Here I discuss a route to adaptive evolvability that overcomes this challenge. Specifically, a recent evolution experiment showed that some mutations can enhance both fitness and evolvability through a combination of direct and indirect selection. Unrelated evidence from gene duplication and the evolution of gene regulation suggests that mutations with such dual effects may not be rare. Through such mutations, evolvability may increase at least in part because it provides an adaptive advantage. These observations suggest a research program on the adaptive evolution of evolvability, which aims to identify such mutations and to disentangle their direct fitness effects from their indirect effects on evolvability. If evolvability is itself adaptive, Darwinian evolution may have created more than life's diversity. It may also have helped create the very conditions that made the success of Darwinian evolution possible.
Collapse
Affiliation(s)
- Andreas Wagner
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland,Swiss Institute of BioinformaticsQuartier Sorge‐Batiment GenopodeLausanneSwitzerland,The Santa Fe InstituteSanta FeNew MexicoUSA,Stellenbosch Institute for Advanced Study, Wallenberg Research Centre at Stellenbosch UniversityStellenboschSouth Africa
| |
Collapse
|
3
|
Lima-Noronha MA, Fonseca DLH, Oliveira RS, Freitas RR, Park JH, Galhardo RS. Sending out an SOS - the bacterial DNA damage response. Genet Mol Biol 2022; 45:e20220107. [PMID: 36288458 PMCID: PMC9578287 DOI: 10.1590/1678-4685-gmb-2022-0107] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 07/15/2022] [Indexed: 11/04/2022] Open
Abstract
The term “SOS response” was first coined by Radman in 1974, in an intellectual effort to put together the data suggestive of a concerted gene expression program in cells undergoing DNA damage. A large amount of information about this cellular response has been collected over the following decades. In this review, we will focus on a few of the relevant aspects about the SOS response: its mechanism of control and the stressors which activate it, the diversity of regulated genes in different species, its role in mutagenesis and evolution including the development of antimicrobial resistance, and its relationship with mobile genetic elements.
Collapse
Affiliation(s)
- Marco A. Lima-Noronha
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Microbiologia, São Paulo, SP, Brazil
| | - Douglas L. H. Fonseca
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Microbiologia, São Paulo, SP, Brazil
| | - Renatta S. Oliveira
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Microbiologia, São Paulo, SP, Brazil
| | - Rúbia R. Freitas
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Microbiologia, São Paulo, SP, Brazil
| | - Jung H. Park
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Microbiologia, São Paulo, SP, Brazil
| | - Rodrigo S. Galhardo
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Microbiologia, São Paulo, SP, Brazil
| |
Collapse
|
4
|
Merrikh H, Kohli RM. Targeting evolution to inhibit antibiotic resistance. FEBS J 2020; 287:4341-4353. [PMID: 32434280 DOI: 10.1111/febs.15370] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 03/31/2020] [Accepted: 05/15/2020] [Indexed: 12/21/2022]
Abstract
Drug-resistant bacterial infections have led to a global health crisis. Although much effort is placed on the development of new antibiotics or variants that are less subject to existing resistance mechanisms, history shows that this strategy by itself is unlikely to solve the problem of drug resistance. Here, we discuss inhibiting evolution as a strategy that, in combination with antibiotics, may resolve the problem. Although mutagenesis is the main driver of drug resistance development, attacking the drivers of genetic diversification in pathogens has not been well explored. Bacteria possess active mechanisms that increase the rate of mutagenesis, especially at times of stress, such as during replication within eukaryotic host cells, or exposure to antibiotics. We highlight how the existence of these promutagenic proteins (evolvability factors) presents an opportunity that can be capitalized upon for the effective inhibition of drug resistance development. To help move this idea from concept to execution, we first describe a set of criteria that an 'optimal' evolvability factor would likely have to meet to be a viable therapeutic target. We then discuss the intricacies of some of the known mutagenic mechanisms and evaluate their potential as drug targets to inhibit evolution. In principle, and as suggested by recent studies, we argue that the inhibition of these and other evolvability factors should reduce resistance development. Finally, we discuss the challenges of transitioning anti-evolution drugs from the laboratory to the clinic.
Collapse
Affiliation(s)
- Houra Merrikh
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA.,Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Rahul M Kohli
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| |
Collapse
|
5
|
Erill I, Campoy S, Kılıç S, Barbé J. The Verrucomicrobia LexA-Binding Motif: Insights into the Evolutionary Dynamics of the SOS Response. Front Mol Biosci 2016; 3:33. [PMID: 27489856 PMCID: PMC4951493 DOI: 10.3389/fmolb.2016.00033] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 07/04/2016] [Indexed: 12/20/2022] Open
Abstract
The SOS response is the primary bacterial mechanism to address DNA damage, coordinating multiple cellular processes that include DNA repair, cell division, and translesion synthesis. In contrast to other regulatory systems, the composition of the SOS genetic network and the binding motif of its transcriptional repressor, LexA, have been shown to vary greatly across bacterial clades, making it an ideal system to study the co-evolution of transcription factors and their regulons. Leveraging comparative genomics approaches and prior knowledge on the core SOS regulon, here we define the binding motif of the Verrucomicrobia, a recently described phylum of emerging interest due to its association with eukaryotic hosts. Site directed mutagenesis of the Verrucomicrobium spinosum recA promoter confirms that LexA binds a 14 bp palindromic motif with consensus sequence TGTTC-N4-GAACA. Computational analyses suggest that recognition of this novel motif is determined primarily by changes in base-contacting residues of the third alpha helix of the LexA helix-turn-helix DNA binding motif. In conjunction with comparative genomics analysis of the LexA regulon in the Verrucomicrobia phylum, electrophoretic shift assays reveal that LexA binds to operators in the promoter region of DNA repair genes and a mutagenesis cassette in this organism, and identify previously unreported components of the SOS response. The identification of tandem LexA-binding sites generating instances of other LexA-binding motifs in the lexA gene promoter of Verrucomicrobia species leads us to postulate a novel mechanism for LexA-binding motif evolution. This model, based on gene duplication, successfully addresses outstanding questions in the intricate co-evolution of the LexA protein, its binding motif and the regulatory network it controls.
Collapse
Affiliation(s)
- Ivan Erill
- Erill Lab, Department of Biological Sciences, University of Maryland Baltimore County Baltimore, MD, USA
| | - Susana Campoy
- Unitat de Microbiologia, Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Sefa Kılıç
- Erill Lab, Department of Biological Sciences, University of Maryland Baltimore County Baltimore, MD, USA
| | - Jordi Barbé
- Unitat de Microbiologia, Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona Barcelona, Spain
| |
Collapse
|
6
|
Powers S, DeJongh M, Best AA, Tintle NL. Cautions about the reliability of pairwise gene correlations based on expression data. Front Microbiol 2015; 6:650. [PMID: 26167162 PMCID: PMC4481165 DOI: 10.3389/fmicb.2015.00650] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 06/15/2015] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Rapid growth in the availability of genome-wide transcript abundance levels through gene expression microarrays and RNAseq promises to provide deep biological insights into the complex, genome-wide transcriptional behavior of single-celled organisms. However, this promise has not yet been fully realized. RESULTS We find that computation of pairwise gene associations (correlation; mutual information) across a set of 2782 total genome-wide expression samples from six diverse bacteria produces unexpectedly large variation in estimates of pairwise gene association-regardless of the metric used, the organism under study, or the number and source of the samples. We pinpoint the cause to sampling bias. In particular, in repositories of expression data (e.g., Gene Expression Omnibus, GEO), many individual genes show small differences in absolute gene expression levels across the set of samples. We demonstrate that these small differences are due mainly to "noise" instead of "signal" attributable to environmental or genetic perturbations. We show that downstream analysis using gene expression levels of genes with small differences yields biased estimates of pairwise association. CONCLUSIONS We propose flagging genes with small differences in absolute, RMA-normalized, expression levels (e.g., standard deviation less than 0.5), as potentially yielding biased pairwise association metrics. This strategy has the potential to substantially improve the confidence in genome-wide conclusions about transcriptional behavior in bacterial organisms. Further work is needed to further refine strategies to identify genes with small difference in expression levels prior to computing gene-gene association metrics.
Collapse
Affiliation(s)
- Scott Powers
- Department of Statistics, Stanford University Stanford, CA, USA
| | - Matt DeJongh
- Department of Computer Science, Hope College Holland, MI, USA
| | - Aaron A Best
- Department of Biology, Hope College Holland, MI, USA
| | - Nathan L Tintle
- Department of Mathematics, Statistics and Computer Science, Dordt College Sioux Center, IA, USA
| |
Collapse
|
7
|
Jian H, Xiong L, He Y, Xiao X. The regulatory function of LexA is temperature-dependent in the deep-sea bacterium Shewanella piezotolerans WP3. Front Microbiol 2015; 6:627. [PMID: 26150814 PMCID: PMC4471891 DOI: 10.3389/fmicb.2015.00627] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 06/08/2015] [Indexed: 01/01/2023] Open
Abstract
The SOS response addresses DNA lesions and is conserved in the bacterial domain. The response is governed by the DNA binding protein LexA, which has been characterized in model microorganisms such as Escherichia coli. However, our understanding of its roles in deep-sea bacteria is limited. Here, the influence of LexA on the phenotype and gene transcription of Shewanella piezotolerans WP3 (WP3) was investigated by constructing a lexA deletion strain (WP3ΔlexA), which was compared with the wild-type strain. No growth defect was observed for WP3ΔlexA. A total of 481 and 108 genes were differentially expressed at 20 and 4°C, respectively, as demonstrated by comparative whole genome microarray analysis. Furthermore, the swarming motility and dimethylsulfoxide reduction assay demonstrated that the function of LexA was related to temperature. The transcription of the lexA gene was up-regulated during cold acclimatization and after cold shock, indicating that the higher expression level of LexA at low temperatures may be responsible for its temperature-dependent functions. The deep-sea microorganism S. piezotolerans WP3 is the only bacterial species whose SOS regulator has been demonstrated to be significantly influenced by environmental temperatures to date. Our data support the hypothesis that SOS is a formidable strategy used by bacteria against various environmental stresses.
Collapse
Affiliation(s)
- Huahua Jian
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University Shanghai, China
| | - Lei Xiong
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University Shanghai, China
| | - Ying He
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University Shanghai, China
| | - Xiang Xiao
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University Shanghai, China ; State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University Shanghai, China
| |
Collapse
|
8
|
Baharoglu Z, Mazel D. SOS, the formidable strategy of bacteria against aggressions. FEMS Microbiol Rev 2014; 38:1126-45. [PMID: 24923554 DOI: 10.1111/1574-6976.12077] [Citation(s) in RCA: 247] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 05/01/2014] [Accepted: 05/07/2014] [Indexed: 12/22/2022] Open
Abstract
The presence of an abnormal amount of single-stranded DNA in the bacterial cell constitutes a genotoxic alarm signal that induces the SOS response, a broad regulatory network found in most bacterial species to address DNA damage. The aim of this review was to point out that beyond being a repair process, SOS induction leads to a very strong but transient response to genotoxic stress, during which bacteria can rearrange and mutate their genome, induce several phenotypic changes through differential regulation of genes, and sometimes acquire characteristics that potentiate bacterial survival and adaptation to changing environments. We review here the causes and consequences of SOS induction, but also how this response can be modulated under various circumstances and how it is connected to the network of other important stress responses. In the first section, we review articles describing the induction of the SOS response at the molecular level. The second section discusses consequences of this induction in terms of DNA repair, changes in the genome and gene expression, and sharing of genomic information, with their effects on the bacteria's life and evolution. The third section is about the fine tuning of this response to fit with the bacteria's 'needs'. Finally, we discuss recent findings linking the SOS response to other stress responses. Under these perspectives, SOS can be perceived as a powerful bacterial strategy against aggressions.
Collapse
Affiliation(s)
- Zeynep Baharoglu
- Institut Pasteur, Département Génomes et Génétique, Unité Plasticité du Génome Bactérien, Paris, France; CNRS, UMR3525, Paris, France
| | | |
Collapse
|
9
|
The LexA regulated genes of the Clostridium difficile. BMC Microbiol 2014; 14:88. [PMID: 24713082 PMCID: PMC4234289 DOI: 10.1186/1471-2180-14-88] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 03/27/2014] [Indexed: 01/05/2023] Open
Abstract
Background The SOS response including two main proteins LexA and RecA, maintains the integrity of bacterial genomes after DNA damage due to metabolic or environmental assaults. Additionally, derepression of LexA-regulated genes can result in mutations, genetic exchange and expression of virulence factors. Here we describe the first comprehensive description of the in silico LexA regulon in Clostridium difficile, an important human pathogen. Results We grouped thirty C. difficile strains from different ribotypes and toxinotypes into three clusters according to lexA gene/protein variability. We applied in silico analysis coupled to surface plasmon resonance spectroscopy (SPR) and determined 16 LexA binding sites in C. difficile. Our data indicate that strains within the cluster, as defined by LexA variability, harbour several specific LexA regulon genes. In addition to core SOS genes: lexA, recA, ruvCA and uvrBA, we identified a LexA binding site on the pathogenicity locus (PaLoc) and in the putative promoter region of several genes involved in housekeeping, sporulation and antibiotic resistance. Conclusions Results presented here suggest that in C. difficile LexA is not merely a regulator of the DNA damage response genes but also controls the expression of dozen genes involved in various other biological functions. Our in vitro results indicate that in C. difficile inactivation of LexA repressor depends on repressor`s dissociation from the operators. We report that the repressor`s dissociation rates from operators differentiate, thus the determined LexA-DNA dissociation constants imply on the timing of SOS gene expression in C. difficile.
Collapse
|
10
|
Fonseca LS, da Silva JB, Milanez JS, Monteiro-Vitorello CB, Momo L, de Morais ZM, Vasconcellos SA, Marques MV, Ho PL, da Costa RMA. Leptospira interrogans serovar copenhageni harbors two lexA genes involved in SOS response. PLoS One 2013; 8:e76419. [PMID: 24098496 PMCID: PMC3789691 DOI: 10.1371/journal.pone.0076419] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 08/28/2013] [Indexed: 11/24/2022] Open
Abstract
Bacteria activate a regulatory network in response to the challenges imposed by DNA damage to genetic material, known as the SOS response. This system is regulated by the RecA recombinase and by the transcriptional repressor lexA. Leptospira interrogans is a pathogen capable of surviving in the environment for weeks, being exposed to a great variety of stress agents and yet retaining its ability to infect the host. This study aims to investigate the behavior of L. interrogans serovar Copenhageni after the stress induced by DNA damage. We show that L. interrogans serovar Copenhageni genome contains two genes encoding putative LexA proteins (lexA1 and lexA2) one of them being potentially acquired by lateral gene transfer. Both genes are induced after DNA damage, but the steady state levels of both LexA proteins drop, probably due to auto-proteolytic activity triggered in this condition. In addition, seven other genes were up-regulated following UV-C irradiation, recA, recN, dinP, and four genes encoding hypothetical proteins. This set of genes is potentially regulated by LexA1, as it showed binding to their promoter regions. All these regions contain degenerated sequences in relation to the previously described SOS box, TTTGN 5CAAA. On the other hand, LexA2 was able to bind to the palindrome TTGTAN10TACAA, found in its own promoter region, but not in the others. Therefore, the L. interrogans serovar Copenhageni SOS regulon may be even more complex, as a result of LexA1 and LexA2 binding to divergent motifs. New possibilities for DNA damage response in Leptospira are expected, with potential influence in other biological responses such as virulence.
Collapse
Affiliation(s)
- Luciane S Fonseca
- Centro de Biotecnologia, Instituto Butantan, São Paulo, Brazil ; Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Ulrich RL, DeShazer D, Kenny TA, Ulrich MP, Moravusova A, Opperman T, Bavari S, Bowlin TL, Moir DT, Panchal RG. Characterization of the Burkholderia thailandensis SOS response by using whole-transcriptome shotgun sequencing. Appl Environ Microbiol 2013; 79:5830-43. [PMID: 23872555 PMCID: PMC3811356 DOI: 10.1128/aem.00538-13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 07/05/2013] [Indexed: 01/11/2023] Open
Abstract
The bacterial SOS response is a well-characterized regulatory network encoded by most prokaryotic bacterial species and is involved in DNA repair. In addition to nucleic acid repair, the SOS response is involved in pathogenicity, stress-induced mutagenesis, and the emergence and dissemination of antibiotic resistance. Using high-throughput sequencing technology (SOLiD RNA-Seq), we analyzed the Burkholderia thailandensis global SOS response to the fluoroquinolone antibiotic, ciprofloxacin (CIP), and the DNA-damaging chemical, mitomycin C (MMC). We demonstrate that a B. thailandensis recA mutant (RU0643) is ∼4-fold more sensitive to CIP in contrast to the parental strain B. thailandensis DW503. Our RNA-Seq results show that CIP and MMC treatment (P < 0.01) resulted in the differential expression of 344 genes in B. thailandensis and 210 genes in RU0643. Several genes associated with the SOS response were induced and include lexA, uvrA, dnaE, dinB, recX, and recA. At the genome-wide level, we found an overall decrease in gene expression, especially for genes involved in amino acid and carbohydrate transport and metabolism, following both CIP and MMC exposure. Interestingly, we observed the upregulation of several genes involved in bacterial motility and enhanced transcription of a B. thailandensis genomic island encoding a Siphoviridae bacteriophage designated E264. Using B. thailandensis plaque assays and PCR with B. mallei ATCC 23344 as the host, we demonstrate that CIP and MMC exposure in B. thailandensis DW503 induces the transcription and translation of viable bacteriophage in a RecA-dependent manner. This is the first report of the SOS response in Burkholderia spp. to DNA-damaging agents. We have identified both common and unique adaptive responses of B. thailandensis to chemical stress and DNA damage.
Collapse
Affiliation(s)
- Ricky L. Ulrich
- Integrated Toxicology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Maryland, USA
| | - David DeShazer
- Bacteriology Division, USAMRIID, Fort Detrick, Maryland, USA
| | - Tara A. Kenny
- Integrated Toxicology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Maryland, USA
| | - Melanie P. Ulrich
- Edison State College, Math and Science Department, Fort Myers, Florida, USA
| | - Anna Moravusova
- Integrated Toxicology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Maryland, USA
| | | | - Sina Bavari
- Integrated Toxicology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Maryland, USA
| | | | | | - Rekha G. Panchal
- Integrated Toxicology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Maryland, USA
| |
Collapse
|
12
|
Stockwell VO, Davis EW, Carey A, Shaffer BT, Mavrodi DV, Hassan KA, Hockett K, Thomashow LS, Paulsen IT, Loper JE. pA506, a conjugative plasmid of the plant epiphyte Pseudomonas fluorescens A506. Appl Environ Microbiol 2013; 79:5272-82. [PMID: 23811504 PMCID: PMC3753976 DOI: 10.1128/aem.01354-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 06/21/2013] [Indexed: 11/20/2022] Open
Abstract
Conjugative plasmids are known to facilitate the acquisition and dispersal of genes contributing to the fitness of Pseudomonas spp. Here, we report the characterization of pA506, the 57-kb conjugative plasmid of Pseudomonas fluorescens A506, a plant epiphyte used in the United States for the biological control of fire blight disease of pear and apple. Twenty-nine of the 67 open reading frames (ORFs) of pA506 have putative functions in conjugation, including a type IV secretion system related to that of MOBP6 family plasmids and a gene cluster for type IV pili. We demonstrate that pA506 is self-transmissible via conjugation between A506 and strains of Pseudomonas spp. or the Enterobacteriaceae. The origin of vegetative replication (oriV) of pA506 is typical of those in pPT23A family plasmids, which are present in many pathovars of Pseudomonas syringae, but pA506 lacks repA, a defining locus for pPT23A plasmids, and has a novel partitioning region. We selected a plasmid-cured derivative of A506 and compared it to the wild type to identify plasmid-encoded phenotypes. pA506 conferred UV resistance, presumably due to the plasmid-borne rulAB genes, but did not influence epiphytic fitness of A506 on pear or apple blossoms in the field. pA506 does not appear to confer resistance to antibiotics or other toxic elements. Based on the conjugative nature of pA506 and the large number of its genes that are shared with plasmids from diverse groups of environmental bacteria, the plasmid is likely to serve as a vehicle for genetic exchange between A506 and its coinhabitants on plant surfaces.
Collapse
Affiliation(s)
- Virginia O. Stockwell
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | - Edward W. Davis
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
- Agricultural Research Service, U.S. Department of Agriculture, Corvallis, Oregon, USA
| | - Alyssa Carey
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
- Agricultural Research Service, U.S. Department of Agriculture, Corvallis, Oregon, USA
| | - Brenda T. Shaffer
- Agricultural Research Service, U.S. Department of Agriculture, Corvallis, Oregon, USA
| | - Dmitri V. Mavrodi
- Department of Plant Pathology, Washington State University, Pullman, Washington, USA
| | - Karl A. Hassan
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, Australia
| | - Kevin Hockett
- Agricultural Research Service, U.S. Department of Agriculture, Corvallis, Oregon, USA
| | - Linda S. Thomashow
- Department of Plant Pathology, Washington State University, Pullman, Washington, USA
- Agricultural Research Service, U.S. Department of Agriculture, Pullman, Washington, USA
| | - Ian T. Paulsen
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, Australia
| | - Joyce E. Loper
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
- Agricultural Research Service, U.S. Department of Agriculture, Corvallis, Oregon, USA
| |
Collapse
|
13
|
Abstract
The Bacillus thuringiensis temperate phage GIL01 does not integrate into the host chromosome but exists stably as an independent linear replicon within the cell. Similar to that of the lambdoid prophages, the lytic cycle of GIL01 is induced as part of the cellular SOS response to DNA damage. However, no CI-like maintenance repressor has been detected in the phage genome, suggesting that GIL01 uses a novel mechanism to maintain lysogeny. To gain insights into the GIL01 regulatory circuit, we isolated and characterized a set of 17 clear plaque (cp) mutants that are unable to lysogenize. Two phage-encoded proteins, gp1 and gp7, are required for stable lysogen formation. Analysis of cp mutants also identified a 14-bp palindromic dinBox1 sequence within the P1-P2 promoter region that resembles the known LexA-binding site of Gram-positive bacteria. Mutations at conserved positions in dinBox1 result in a cp phenotype. Genomic analysis identified a total of three dinBox sites within GIL01 promoter regions. To investigate the possibility that the host LexA regulates GIL01, phage induction was measured in a host carrying a noncleavable lexA (Ind(-)) mutation. GIL01 formed stable lysogens in this host, but lytic growth could not be induced by treatment with mitomycin C. Also, mitomycin C induced β-galactosidase expression from GIL01-lacZ promoter fusions, and induction was similarly blocked in the lexA (Ind(-)) mutant host. These data support a model in which host LexA binds to dinBox sequences in GIL01, repressing phage gene expression during lysogeny and providing the switch necessary to enter lytic development.
Collapse
|
14
|
Cagle CA, Shearer JES, Summers AO. Regulation of the integrase and cassette promoters of the class 1 integron by nucleoid-associated proteins. MICROBIOLOGY-SGM 2011; 157:2841-2853. [PMID: 21778209 DOI: 10.1099/mic.0.046987-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The integrase IntI1 catalyses recombination of antibiotic-resistance gene cassettes in the integron, a widely found bacterial mobile element active in spreading antibiotic multi-resistance. We have previously shown that resistance cassette recombination rate and specificity depend on the amount of intracellular integrase. Here, we used in vivo and in vitro methods to examine convergent expression of the integrase promoter (P(int)) and of the cassette promoters (P(c) and P(2)) in the prototypical plasmid-borne class 1 integron, In2. Highly conserved P(int) has near consensus -10 and -35 hexamers for σ(70) RNA polymerase, but there are 11 naturally occurring arrangements of P(c) alone or combinations of the P(c)+P(2) cassette promoters (note that P(2) occurs with a 14 or 17 bp spacer). Using a bi-directional reporter vector, we found that P(int) is a strong promoter in vivo, but its expression is reduced by converging transcription from P(c) and P(2). In addition to cis-acting convergence control of integrase expression, the regulator site prediction program, prodoric 8.9, identified sites for global regulators FIS, LexA, IHF and H-NS in and near the integron promoters. In strains mutated in each global regulator, we found that: (1) FIS repressed integrase and cassette expression; (2) LexA repressed P(int) and P(2) with the 14 bp spacer version of P(2) and FIS was necessary for maximum LexA repression; (3) IHF activated P(int) when it faced the strong 17 bp spacer P(2) but did not elevate its expression versus LexA-repressed P(2) with the 14 bp spacer; and (4) H-NS repressed both P(int) and the 14 bp P(2) but activated the 17 bp P(2) cassette promoters. Mobility shift assays showed that FIS and IHF interact directly with the promoter regions and DNase I footprinting confirmed extensive protection by FIS of wild-type In2 integron promoter sequence. Thus, nucleoid-associated proteins, known to act directly in site-specific recombination, also control integron gene expression directly and possibly indirectly.
Collapse
Affiliation(s)
- Caran A Cagle
- Department of Microbiology, The University of Georgia, Athens, GA 30602-2605, USA
| | - Julia E S Shearer
- Department of Microbiology, The University of Georgia, Athens, GA 30602-2605, USA
| | - Anne O Summers
- Department of Microbiology, The University of Georgia, Athens, GA 30602-2605, USA
| |
Collapse
|
15
|
Cambray G, Sanchez-Alberola N, Campoy S, Guerin É, Da Re S, González-Zorn B, Ploy MC, Barbé J, Mazel D, Erill I. Prevalence of SOS-mediated control of integron integrase expression as an adaptive trait of chromosomal and mobile integrons. Mob DNA 2011; 2:6. [PMID: 21529368 PMCID: PMC3108266 DOI: 10.1186/1759-8753-2-6] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 04/30/2011] [Indexed: 11/26/2022] Open
Abstract
Background Integrons are found in hundreds of environmental bacterial species, but are mainly known as the agents responsible for the capture and spread of antibiotic-resistance determinants between Gram-negative pathogens. The SOS response is a regulatory network under control of the repressor protein LexA targeted at addressing DNA damage, thus promoting genetic variation in times of stress. We recently reported a direct link between the SOS response and the expression of integron integrases in Vibrio cholerae and a plasmid-borne class 1 mobile integron. SOS regulation enhances cassette swapping and capture in stressful conditions, while freezing the integron in steady environments. We conducted a systematic study of available integron integrase promoter sequences to analyze the extent of this relationship across the Bacteria domain. Results Our results showed that LexA controls the expression of a large fraction of integron integrases by binding to Escherichia coli-like LexA binding sites. In addition, the results provide experimental validation of LexA control of the integrase gene for another Vibrio chromosomal integron and for a multiresistance plasmid harboring two integrons. There was a significant correlation between lack of LexA control and predicted inactivation of integrase genes, even though experimental evidence also indicates that LexA regulation may be lost to enhance expression of integron cassettes. Conclusions Ancestral-state reconstruction on an integron integrase phylogeny led us to conclude that the ancestral integron was already regulated by LexA. The data also indicated that SOS regulation has been actively preserved in mobile integrons and large chromosomal integrons, suggesting that unregulated integrase activity is selected against. Nonetheless, additional adaptations have probably arisen to cope with unregulated integrase activity. Identifying them may be fundamental in deciphering the uneven distribution of integrons in the Bacteria domain.
Collapse
Affiliation(s)
- Guillaume Cambray
- Institut Pasteur, Unité Plasticité du Génome Bactérien, CNRS URA 2171, 75015 Paris, France
| | - Neus Sanchez-Alberola
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.,Department of Biological Sciences, University of Maryland Baltimore County, Baltimore 21228, USA
| | - Susana Campoy
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Émilie Guerin
- Université de Limoges, Faculté de Médecine, EA3175, INSERM, Equipe Avenir, Limoges 87000, France
| | - Sandra Da Re
- Université de Limoges, Faculté de Médecine, EA3175, INSERM, Equipe Avenir, Limoges 87000, France
| | - Bruno González-Zorn
- Departamento de Sanidad Animal, Facultad de Veterinaria, and VISAVET, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Marie-Cécile Ploy
- Université de Limoges, Faculté de Médecine, EA3175, INSERM, Equipe Avenir, Limoges 87000, France
| | - Jordi Barbé
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore 21228, USA
| | - Didier Mazel
- Institut Pasteur, Unité Plasticité du Génome Bactérien, CNRS URA 2171, 75015 Paris, France
| | - Ivan Erill
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore 21228, USA
| |
Collapse
|
16
|
Li S, Xu M, Su Z. Computational analysis of LexA regulons in Cyanobacteria. BMC Genomics 2010; 11:527. [PMID: 20920248 PMCID: PMC3091678 DOI: 10.1186/1471-2164-11-527] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Accepted: 09/29/2010] [Indexed: 12/13/2022] Open
Abstract
Background The transcription factor LexA plays an important role in the SOS response in Escherichia coli and many other bacterial species studied. Although the lexA gene is encoded in almost every bacterial group with a wide range of evolutionary distances, its precise functions in each group/species are largely unknown. More recently, it has been shown that lexA genes in two cyanobacterial genomes Nostoc sp. PCC 7120 and Synechocystis sp. PCC 6803 might have distinct functions other than the regulation of the SOS response. To gain a general understanding of the functions of LexA and its evolution in cyanobacteria, we conducted the current study. Results Our analysis indicates that six of 33 sequenced cyanobacterial genomes do not harbor a lexA gene although they all encode the key SOS response genes, suggesting that LexA is not an indispensable transcription factor in these cyanobacteria, and that their SOS responses might be regulated by different mechanisms. Our phylogenetic analysis suggests that lexA was lost during the course of evolution in these six cyanobacterial genomes. For the 26 cyanobacterial genomes that encode a lexA gene, we have predicted their LexA-binding sites and regulons using an efficient binding site/regulon prediction algorithm that we developed previously. Our results show that LexA in most of these 26 genomes might still function as the transcriptional regulator of the SOS response genes as seen in E. coli and other organisms. Interestingly, putative LexA-binding sites were also found in some genomes for some key genes involved in a variety of other biological processes including photosynthesis, drug resistance, etc., suggesting that there is crosstalk between the SOS response and these biological processes. In particular, LexA in both Synechocystis sp. PCC6803 and Gloeobacter violaceus PCC7421 has largely diverged from those in other cyanobacteria in the sequence level. It is likely that LexA is no longer a regulator of the SOS response in Synechocystis sp. PCC6803. Conclusions In most cyanobacterial genomes that we analyzed, LexA appears to function as the transcriptional regulator of the key SOS response genes. There are possible couplings between the SOS response and other biological processes. In some cyanobacteria, LexA has adapted distinct functions, and might no longer be a regulator of the SOS response system. In some other cyanobacteria, lexA appears to have been lost during the course of evolution. The loss of lexA in these genomes might lead to the degradation of its binding sites.
Collapse
Affiliation(s)
- Shan Li
- Bioinformatics Research Center, Department of Bioinformatics and Genomics, the University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | | | | |
Collapse
|
17
|
Baumbach J. On the power and limits of evolutionary conservation--unraveling bacterial gene regulatory networks. Nucleic Acids Res 2010; 38:7877-84. [PMID: 20699275 PMCID: PMC3001071 DOI: 10.1093/nar/gkq699] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The National Center for Biotechnology Information (NCBI) recently announced ‘1000 prokaryotic genomes are now completed and available in the Genome database’. The increasing trend will provide us with thousands of sequenced microbial organisms over the next years. However, this is only the first step in understanding how cells survive, reproduce and adapt their behavior while being exposed to changing environmental conditions. One major control mechanism is transcriptional gene regulation. Here, striking is the direct juxtaposition of the handful of bacterial model organisms to the 1000 prokaryotic genomes. Next-generation sequencing technologies will further widen this gap drastically. However, several computational approaches have proven to be helpful. The main idea is to use the known transcriptional regulatory network of reference organisms as template in order to unravel evolutionarily conserved gene regulations in newly sequenced species. This transfer essentially depends on the reliable identification of several types of conserved DNA sequences. We decompose this problem into three computational processes, review the state of the art and illustrate future perspectives.
Collapse
Affiliation(s)
- Jan Baumbach
- Algorithms Group, International Computer Science Institute, Berkeley, USA.
| |
Collapse
|
18
|
Identification of a methylase required for 2-methylhopanoid production and implications for the interpretation of sedimentary hopanes. Proc Natl Acad Sci U S A 2010; 107:8537-42. [PMID: 20421508 DOI: 10.1073/pnas.0912949107] [Citation(s) in RCA: 172] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The rise of atmospheric oxygen has driven environmental change and biological evolution throughout much of Earth's history and was enabled by the evolution of oxygenic photosynthesis in the cyanobacteria. Dating this metabolic innovation using inorganic proxies from sedimentary rocks has been difficult and one important approach has been to study the distributions of fossil lipids, such as steranes and 2-methylhopanes, as biomarkers for this process. 2-methylhopanes arise from degradation of 2-methylbacteriohopanepolyols (2-MeBHPs), lipids thought to be synthesized primarily by cyanobacteria. The discovery that 2-MeBHPs are produced by an anoxygenic phototroph, however, challenged both their taxonomic link with cyanobacteria and their functional link with oxygenic photosynthesis. Here, we identify a radical SAM methylase encoded by the hpnP gene that is required for methylation at the C-2 position in hopanoids. This gene is found in several, but not all, cyanobacteria and also in alpha -proteobacteria and acidobacteria. Thus, one cannot extrapolate from the presence of 2-methylhopanes alone, in modern environments or ancient sedimentary rocks, to a particular taxonomic group or metabolism. To understand the origin of this gene, we reconstructed the evolutionary history of HpnP. HpnP proteins from cyanobacteria, Methylobacterium species, and other alpha-proteobacteria form distinct phylogenetic clusters, but the branching order of these clades could not be confidently resolved. Hence,it is unclear whether HpnP, and 2-methylhopanoids, originated first in the cyanobacteria. In summary, existing evidence does not support the use of 2-methylhopanes as biomarkers for oxygenic photosynthesis.
Collapse
|
19
|
Jochmann N, Kurze AK, Czaja LF, Brinkrolf K, Brune I, Hüser AT, Hansmeier N, Pühler A, Borovok I, Tauch A. Genetic makeup of the Corynebacterium glutamicum LexA regulon deduced from comparative transcriptomics and in vitro DNA band shift assays. MICROBIOLOGY-SGM 2009; 155:1459-1477. [PMID: 19372162 DOI: 10.1099/mic.0.025841-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The lexA gene of Corynebacterium glutamicum ATCC 13032 was deleted to create the mutant strain C. glutamicum NJ2114, which has an elongated cell morphology and an increased doubling time. To characterize the SOS regulon in C. glutamicum, the transcriptomes of NJ2114 and a DNA-damage-induced wild-type strain were compared with that of a wild-type control using DNA microarray hybridization. The expression data were combined with bioinformatic pattern searches for LexA binding sites, leading to the detection of 46 potential SOS boxes located upstream of differentially expressed transcription units. Binding of a hexahistidyl-tagged LexA protein to 40 double-stranded oligonucleotides containing the potential SOS boxes was demonstrated in vitro by DNA band shift assays. It turned out that LexA binds not only to SOS boxes in the promoter-operator region of upregulated genes, but also to SOS boxes detected upstream of downregulated genes. These results demonstrated that LexA controls directly the expression of at least 48 SOS genes organized in 36 transcription units. The deduced genes encode a variety of physiological functions, many of them involved in DNA repair and survival after DNA damage, but nearly half of them have hitherto unknown functions. Alignment of the LexA binding sites allowed the corynebacterial SOS box consensus sequence TcGAA(a/c)AnnTGTtCGA to be deduced. Furthermore, the common intergenic region of lexA and the differentially expressed divS-nrdR operon, encoding a cell division suppressor and a regulator of deoxyribonucleotide biosynthesis, was characterized in detail. Promoter mapping revealed differences in divS-nrdR expression during SOS response and normal growth conditions. One of the four LexA binding sites detected in the intergenic region is involved in regulating divS-nrdR transcription, whereas the other sites are apparently used for negative autoregulation of lexA expression.
Collapse
Affiliation(s)
- Nina Jochmann
- International NRW Graduate School in Bioinformatics and Genome Research, Centrum für Biotechnologie, Universität Bielefeld, Universitätsstraße 25, D-33615 Bielefeld, Germany.,Institut für Genomforschung und Systembiologie, Centrum für Biotechnologie, Universität Bielefeld, Universitätsstraße 27, D-33615 Bielefeld, Germany
| | - Anna-Katharina Kurze
- Institut für Genomforschung und Systembiologie, Centrum für Biotechnologie, Universität Bielefeld, Universitätsstraße 27, D-33615 Bielefeld, Germany
| | - Lisa F Czaja
- Institut für Genomforschung und Systembiologie, Centrum für Biotechnologie, Universität Bielefeld, Universitätsstraße 27, D-33615 Bielefeld, Germany
| | - Karina Brinkrolf
- Institut für Genomforschung und Systembiologie, Centrum für Biotechnologie, Universität Bielefeld, Universitätsstraße 27, D-33615 Bielefeld, Germany
| | - Iris Brune
- Institut für Genomforschung und Systembiologie, Centrum für Biotechnologie, Universität Bielefeld, Universitätsstraße 27, D-33615 Bielefeld, Germany
| | - Andrea T Hüser
- Institut für Genomforschung und Systembiologie, Centrum für Biotechnologie, Universität Bielefeld, Universitätsstraße 27, D-33615 Bielefeld, Germany
| | - Nicole Hansmeier
- Department of Physics, Arizona State University, Tempe, AZ 85287-1504, USA
| | - Alfred Pühler
- Institut für Genomforschung und Systembiologie, Centrum für Biotechnologie, Universität Bielefeld, Universitätsstraße 27, D-33615 Bielefeld, Germany
| | - Ilya Borovok
- George S. Wise Faculty of Life Sciences, Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Andreas Tauch
- Institut für Genomforschung und Systembiologie, Centrum für Biotechnologie, Universität Bielefeld, Universitätsstraße 27, D-33615 Bielefeld, Germany
| |
Collapse
|
20
|
Balleza E, López-Bojorquez LN, Martínez-Antonio A, Resendis-Antonio O, Lozada-Chávez I, Balderas-Martínez YI, Encarnación S, Collado-Vides J. Regulation by transcription factors in bacteria: beyond description. FEMS Microbiol Rev 2009; 33:133-51. [PMID: 19076632 PMCID: PMC2704942 DOI: 10.1111/j.1574-6976.2008.00145.x] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Transcription is an essential step in gene expression and its understanding has been one of the major interests in molecular and cellular biology. By precisely tuning gene expression, transcriptional regulation determines the molecular machinery for developmental plasticity, homeostasis and adaptation. In this review, we transmit the main ideas or concepts behind regulation by transcription factors and give just enough examples to sustain these main ideas, thus avoiding a classical ennumeration of facts. We review recent concepts and developments: cis elements and trans regulatory factors, chromosome organization and structure, transcriptional regulatory networks (TRNs) and transcriptomics. We also summarize new important discoveries that will probably affect the direction of research in gene regulation: epigenetics and stochasticity in transcriptional regulation, synthetic circuits and plasticity and evolution of TRNs. Many of the new discoveries in gene regulation are not extensively tested with wetlab approaches. Consequently, we review this broad area in Inference of TRNs and Dynamical Models of TRNs. Finally, we have stepped backwards to trace the origins of these modern concepts, synthesizing their history in a timeline schema.
Collapse
Affiliation(s)
- Enrique Balleza
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Baumbach J, Tauch A, Rahmann S. Towards the integrated analysis, visualization and reconstruction of microbial gene regulatory networks. Brief Bioinform 2008; 10:75-83. [PMID: 19074493 DOI: 10.1093/bib/bbn055] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
To handle changing environmental surroundings and to manage unfavorable conditions, microbial organisms have evolved complex transcriptional regulatory networks. To comprehensively analyze these gene regulatory networks, several online available databases and analysis platforms have been implemented and established. In this article, we address the typical cycle of scientific knowledge exploration and integration in the area of procaryotic transcriptional gene regulation. We briefly review five popular, publicly available systems that support (i) the integration of existing knowledge, (ii) visualization capabilities and (iii) computer analysis to predict promising wet lab targets. We exemplify the benefits of such integrated data analysis platforms by means of four application cases exemplarily performed with the corynebacterial reference database CoryneRegNet.
Collapse
Affiliation(s)
- Jan Baumbach
- International Computer Science Institute, Berkeley, USA.
| | | | | |
Collapse
|
22
|
Thompson W, Conlan S, McCue LA, Lawrence CE. Using the Gibbs Motif Sampler for phylogenetic footprinting. Methods Mol Biol 2008; 395:403-24. [PMID: 17993688 DOI: 10.1007/978-1-59745-514-5_25] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/15/2023]
Abstract
The Gibbs Motif Sampler (Gibbs) is a software package used to predict conserved elements in biopolymer sequences. Although the software can be used to locate conserved motifs in protein sequences, its most common use is the prediction of transcription factor binding sites (TFBSs) in promoters upstream of gene sequences. We will describe approaches that use Gibbs to locate TFBSs in a collection of orthologous nucleotide sequences, i.e., phylogenetic footprinting. To illustrate this technique, we present examples that use Gibbs to detect binding sites for the transcription factor LexA in orthologous sequence data from representative species belonging to two different proteobacterial divisions.
Collapse
|
23
|
Janky R, van Helden J. Evaluation of phylogenetic footprint discovery for predicting bacterial cis-regulatory elements and revealing their evolution. BMC Bioinformatics 2008; 9:37. [PMID: 18215291 PMCID: PMC2248561 DOI: 10.1186/1471-2105-9-37] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Accepted: 01/23/2008] [Indexed: 11/24/2022] Open
Abstract
Background The detection of conserved motifs in promoters of orthologous genes (phylogenetic footprints) has become a common strategy to predict cis-acting regulatory elements. Several software tools are routinely used to raise hypotheses about regulation. However, these tools are generally used as black boxes, with default parameters. A systematic evaluation of optimal parameters for a footprint discovery strategy can bring a sizeable improvement to the predictions. Results We evaluate the performances of a footprint discovery approach based on the detection of over-represented spaced motifs. This method is particularly suitable for (but not restricted to) Bacteria, since such motifs are typically bound by factors containing a Helix-Turn-Helix domain. We evaluated footprint discovery in 368 Escherichia coli K12 genes with annotated sites, under 40 different combinations of parameters (taxonomical level, background model, organism-specific filtering, operon inference). Motifs are assessed both at the levels of correctness and significance. We further report a detailed analysis of 181 bacterial orthologs of the LexA repressor. Distinct motifs are detected at various taxonomical levels, including the 7 previously characterized taxon-specific motifs. In addition, we highlight a significantly stronger conservation of half-motifs in Actinobacteria, relative to Firmicutes, suggesting an intermediate state in specificity switching between the two Gram-positive phyla, and thereby revealing the on-going evolution of LexA auto-regulation. Conclusion The footprint discovery method proposed here shows excellent results with E. coli and can readily be extended to predict cis-acting regulatory signals and propose testable hypotheses in bacterial genomes for which nothing is known about regulation.
Collapse
Affiliation(s)
- Rekin's Janky
- Laboratoire de Bioinformatique des Génomes et des Réseaux, Université Libre de Bruxelles (ULB), Campus Plaine, CP 263, Boulevard du Triomphe, 1050 Bruxelles, Belgium.
| | | |
Collapse
|
24
|
Erill I, Campoy S, Barbé J. Aeons of distress: an evolutionary perspective on the bacterial SOS response. FEMS Microbiol Rev 2007; 31:637-56. [PMID: 17883408 DOI: 10.1111/j.1574-6976.2007.00082.x] [Citation(s) in RCA: 243] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The SOS response of bacteria is a global regulatory network targeted at addressing DNA damage. Governed by the products of the lexA and recA genes, it co-ordinates a comprehensive response against DNA lesions and its description in Escherichia coli has stood for years as a textbook paradigm of stress-response systems in bacteria. In this paper we review the current state of research on the SOS response outside E. coli. By retracing research on the identification of multiple diverging LexA-binding motifs across the Bacteria Domain, we show how this work has led to the description of a minimum regulon core, but also of a heterogeneous collection of SOS regulatory networks that challenges many tenets of the E. coli model. We also review recent attempts at reconstructing the evolutionary history of the SOS network that have cast new light on the SOS response. Exploiting the newly gained knowledge on LexA-binding motifs and the tight association of LexA with a recently described mutagenesis cassette, these works put forward likely evolutionary scenarios for the SOS response, and we discuss their relevance on the ultimate nature of this stress-response system and the evolutionary pressures driving its evolution.
Collapse
Affiliation(s)
- Ivan Erill
- Biomedical Applications Group, Centro Nacional de Microelectrónica, Barcelona, Spain
| | | | | |
Collapse
|
25
|
Abstract
In contrast to the vast majority of the members of the domain Bacteria, several Pseudomonas and Xanthomonas species have two lexA genes, whose products have been shown to recognize different LexA binding motifs, making them an interesting target for studying the interplay between cohabiting LexA regulons in a single species. Here we report an analysis of the genetic composition of the two LexA regulons of Pseudomonas putida KT2440 performed with a genomic microarray. The data obtained indicate that one of the two LexA proteins (LexA1) seems to be in control of the conventional Escherichia coli-like SOS response, while the other LexA protein (LexA2) regulates only its own transcriptional unit, which includes the imuA, imuB, and dnaE2 genes, and a gene (PP_3901) from a resident P. putida prophage. Furthermore, PP_3901 is also regulated by LexA1 and is required for DNA damage-mediated induction of several P. putida resident prophage genes. In silico searches suggested that this marked asymmetry in regulon contents also occurs in other Pseudomonas species with two lexA genes, and the implications of this asymmetry in the evolution of the SOS network are discussed.
Collapse
|
26
|
Sycheva LV, Permina EA, Gelfand MS. Taxon-specific regulation of the SOS response in γ-proteobacteria. Mol Biol 2007. [DOI: 10.1134/s0026893307050160] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
27
|
Andersson SA, Lagergren J. Motif Yggdrasil: sampling sequence motifs from a tree mixture model. J Comput Biol 2007; 14:682-97. [PMID: 17683268 DOI: 10.1089/cmb.2007.r010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In phylogenetic foot-printing, putative regulatory elements are found in upstream regions of orthologous genes by searching for common motifs. Motifs in different upstream sequences are subject to mutations along the edges of the corresponding phylogenetic tree, consequently taking advantage of the tree in the motif search is an appealing idea. We describe the Motif Yggdrasil sampler; the first Gibbs sampler based on a general tree that uses unaligned sequences. Previous tree-based Gibbs samplers have assumed a star-shaped tree or partially aligned upstream regions. We give a probabilistic model (MY model) describing upstream sequences with regulatory elements and build a Gibbs sampler with respect to this model. The model allows toggling, i.e., the restriction of a position to a subset of nucleotides, but does not require aligned sequences nor edge lengths, which may be difficult to come by. We apply the collapsing technique to eliminate the need to sample nuisance parameters, and give a derivation of the predictive update formula. We show that the MY model improves the modeling of difficult motif instances and that the use of the tree achieves a substantial increase in nucleotide level correlation coefficient both for synthetic data and 37 bacterial lexA genes. We investigate the sensitivity to errors in the tree and show that using random trees MY sampler still has a performance similar to the original version.
Collapse
Affiliation(s)
- Samuel A Andersson
- Stockholm Bioinformatics Center and School of Computer Science and Communication, Royal Institute of Technology, Stockholm, Sweden.
| | | |
Collapse
|
28
|
Enikeeva FN, Kotelnikova EA, Gelfand MS, Makeev VJ. A model of evolution with constant selective pressure for regulatory DNA sites. BMC Evol Biol 2007; 7:125. [PMID: 17662135 PMCID: PMC1978210 DOI: 10.1186/1471-2148-7-125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Accepted: 07/27/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Molecular evolution is usually described assuming a neutral or weakly non-neutral substitution model. Recently, new data have become available on evolution of sequence regions under a selective pressure, e.g. transcription factor binding sites. To reconstruct the evolutionary history of such sequences, one needs evolutionary models that take into account a substantial constant selective pressure. RESULTS We present a simple evolutionary model with a single preferred (consensus) nucleotide and the neutral substitution model adopted for all other nucleotides. This evolutionary model has a rate matrix in which all substitutions that do not involve the consensus nucleotide occur with the same rate. The model has two time scales for achieving a stationary distribution; in the general case only one of the two rate parameters can be evaluated from the stationary distribution. In the middle-time zone, a counterintuitive behavior was observed for some parameter values, with a probability of conservation for a non-consensus nucleotide greater than that for the consensus nucleotide. Such an effect can be observed only in the case of weak preference for the consensus nucleotide, when the probability to observe the consensus nucleotide in the stationary distribution is less than 1/2. If the substitution rate is represented as a product of mutation and fixation, only the fixation can be calculated from the stationary distribution. The exhibited conservation of non-consensus nucleotides does not take place if the elements of mutation matrix are identical, and can be related to the reduced mutation rate between the non-consensus nucleotides. This bias can have no effect on the stationary distribution of nucleotide frequencies calculated over the ensemble of multiple alignments, e.g. transcription factor binding sites upstream of different sets of co-regulated orthologous genes. CONCLUSION The derived model can be used as a null model when analyzing the evolution of orthologous transcription factor binding sites. In particular, our findings show that a nucleotide preferred at some position of a multiple alignment of binding sites for some transcription factor in the same genome is not necessarily the most conserved nucleotide in an alignment of orthologous sites from different species. However, this effect can take place only in the case of a mutation matrix whose elements are not identical.
Collapse
Affiliation(s)
- Farida N Enikeeva
- Institute for Information Transmission Problems (the Kharkevich Institute) of RAS, Bolshoi Karetny pereulok, 19, GSP-4, Moscow, 127994, Russia
| | - Ekaterina A Kotelnikova
- State Research Institute of Genetics and Selection of Industrial Microorganisms, 1st Dorozhnyj proezd, 1, Moscow, 113535, Russia
- Ariadne Genomics Inc. 9700 Great Seneca Highway, Suite 113, Rockville, MD 20850, USA
| | - Mikhail S Gelfand
- Institute for Information Transmission Problems (the Kharkevich Institute) of RAS, Bolshoi Karetny pereulok, 19, GSP-4, Moscow, 127994, Russia
- Faculty of Bioengineering and Bioinformatics, Moscow State University, Vorobyevy Gory 1-73, Moscow, 119992, Russia
| | - Vsevolod J Makeev
- State Research Institute of Genetics and Selection of Industrial Microorganisms, 1st Dorozhnyj proezd, 1, Moscow, 113535, Russia
- Engelgardt Institute of Molecular Biology of RAS, Vavilova 32, Moscow, 119991, Russia
| |
Collapse
|
29
|
Baumbach J, Wittkop T, Rademacher K, Rahmann S, Brinkrolf K, Tauch A. CoryneRegNet 3.0—An interactive systems biology platform for the analysis of gene regulatory networks in corynebacteria and Escherichia coli. J Biotechnol 2007; 129:279-89. [PMID: 17229482 DOI: 10.1016/j.jbiotec.2006.12.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Revised: 11/22/2006] [Accepted: 12/04/2006] [Indexed: 11/30/2022]
Abstract
CoryneRegNet is an ontology-based data warehouse for the reconstruction and visualization of transcriptional regulatory interactions in prokaryotes. To extend the biological content of CoryneRegNet, we added comprehensive data on transcriptional regulations in the model organism Escherichia coli K-12, originally deposited in the international reference database RegulonDB. The enhanced web interface of CoryneRegNet offers several types of search options. The results of a search are displayed in a table-based style and include a visualization of the genetic organization of the respective gene region. Information on DNA binding sites of transcriptional regulators is depicted by sequence logos. The results can also be displayed by several layouters implemented in the graphical user interface GraphVis, allowing, for instance, the visualization of genome-wide network reconstructions and the homology-based inter-species comparison of reconstructed gene regulatory networks. In an application example, we compare the composition of the gene regulatory networks involved in the SOS response of E. coli and Corynebacterium glutamicum. CoryneRegNet is available at the following URL: http://www.cebitec.uni-bielefeld.de/groups/gi/software/coryneregnet/.
Collapse
Affiliation(s)
- Jan Baumbach
- Algorithms and Statistics for Systems Biology Group, Genominformatik, Technische Fakultät, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany
| | | | | | | | | | | |
Collapse
|
30
|
Mazón G, Campoy S, Fernández de Henestrosa AR, Barbé J. Insights into the LexA regulon of Thermotogales. Antonie Van Leeuwenhoek 2006; 90:123-37. [PMID: 16897562 DOI: 10.1007/s10482-006-9066-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Accepted: 02/09/2006] [Indexed: 10/24/2022]
Abstract
The lexA genes of Thermotoga maritima and Petrotoga miotherma, both members of the Order Thermotogales, have been cloned and their transcriptional organization, as well as the functional characteristics of their encoded products, analyzed. In both bacterial species, the lexA gene was found to be co-transcribed together with another four (T. maritima) or three (P. miotherma) upstream open-reading frames. The P. miotherma LexA was able to bind promoters of both the cognate lexA encoding operon and the uvrA gene but not to that of the recA. Conversely, LexA protein and crude cell extracts from T. maritima were unable to bind promoters governing the expression of either its lexA or recA genes. In agreement with these observations, no functional copy of the P. miotherma LexA box, corresponding to the GANTN(6)GANNAC motif, seems to be present in the T. maritima genome. Giving support to the proposal that the evolutionary branching order of the Order Thermotogales is very close to that of Gram-positive bacteria, the P. miotherma LexA protein was still able to recognize the previously described LexA-binding sequence for Gram-positive bacteria.
Collapse
Affiliation(s)
- Gerard Mazón
- Centre de Recerca en Sanitat Animal, 08193 Bellaterra, Spain
| | | | | | | |
Collapse
|
31
|
Mazón G, Campoy S, Erill I, Barbé J. Identification of the Acidobacterium capsulatum LexA box reveals a lateral acquisition of the Alphaproteobacteria lexA gene. MICROBIOLOGY-SGM 2006; 152:1109-1118. [PMID: 16549674 DOI: 10.1099/mic.0.28376-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Acidobacterium capsulatum is the most thoroughly studied species of a new bacterial phylogenetic group designated the phylum Acidobacteria. Through a tblastn search, the A. capsulatum lexA gene has been identified, and its product purified. Electrophoretic mobility shift assays have shown that A. capsulatum LexA protein binds specifically to the direct repeat GTTCN(7)GTTC motif. Strikingly, this is also the LexA box of the Alphaproteobacteria, but had not previously been described outside this subclass of the Proteobacteria. In addition, a phylogenetic analysis of the LexA protein clusters together Acidobacterium and the Alphaproteobacteria, moving the latter away from their established phylogenetic position as a subclass of the Proteobacteria, and pointing to a lateral gene transfer of the lexA gene from the phylum Acidobacteria, or an immediate ancestor, to the Alphaproteobacteria. Lastly, in vivo experiments demonstrate that the A. capsulatum recA gene is DNA-damage inducible, despite the fact that a LexA-binding sequence is not present in its promoter region.
Collapse
Affiliation(s)
- Gerard Mazón
- Centre de Recerca en Sanitat Animal (CReSA), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Susana Campoy
- Centre de Recerca en Sanitat Animal (CReSA), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Ivan Erill
- Biomedical Applications Group, Centro Nacional de Microelectrónica, 08193 Bellaterra, Spain
| | - Jordi Barbé
- Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
- Centre de Recerca en Sanitat Animal (CReSA), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| |
Collapse
|
32
|
Oliveira P, Lindblad P. LexA, a transcription regulator binding in the promoter region of the bidirectional hydrogenase in the cyanobacterium Synechocystis sp. PCC 6803. FEMS Microbiol Lett 2006; 251:59-66. [PMID: 16102913 DOI: 10.1016/j.femsle.2005.07.024] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2005] [Revised: 07/15/2005] [Accepted: 07/20/2005] [Indexed: 11/23/2022] Open
Abstract
The unicellular cyanobacterium Synechocystis PCC 6803 contains a single pentameric bidirectional hydrogenase encoded by hoxEFUYH. Transcriptional experiments demonstrated that the five hox genes are part of a single transcript together with three ORFs with unknown functions. The transcription start point was localized by 5' RACE to 168bp upstream the hoxE ATG start codon. DNA affinity assays demonstrated a specific interaction between the hox regulatory promoter region and a protein which, using mass spectrometry, was identified to be LexA. Overexpressed His-tagged Synechocystis LexA and EMSA showed a specific binding to the promoter region of the hox operon. Increasing concentrations of the purified LexA resulted in two retarded LexA-DNA complexes, in agreement with the presence of two putative LexA binding sites upstream the determined TSP.
Collapse
Affiliation(s)
- Paulo Oliveira
- Department of Physiological Botany, EBC, Uppsala University, Villavägen 6, SE-752 36 Uppsala, Sweden.
| | | |
Collapse
|
33
|
Erill I, Campoy S, Mazon G, Barbé J. Dispersal and regulation of an adaptive mutagenesis cassette in the bacteria domain. Nucleic Acids Res 2006; 34:66-77. [PMID: 16407325 PMCID: PMC1326238 DOI: 10.1093/nar/gkj412] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Recently, a multiple gene cassette with mutagenic translation synthesis activity was identified and shown to be under LexA regulation in several proteobacteria species. In this work, we have traced down instances of this multiple gene cassette across the bacteria domain. Phylogenetic analyses show that this cassette has undergone several reorganizations since its inception in the actinobacteria, and that it has dispersed across the bacterial domain through a combination of vertical inheritance, lateral gene transfer and duplication. In addition, our analyses show that LexA regulation of this multiple gene cassette is persistent in all the phyla in which it has been detected, and suggest that this regulation is prompted by the combined activity of two of its constituent genes: a polymerase V homolog and an alpha subunit of the DNA polymerase III.
Collapse
Affiliation(s)
| | - Susana Campoy
- Centre de Recerca en Sanitat Animal (CReSA)08193 Bellaterra, Spain
| | - Gerard Mazon
- Centre de Recerca en Sanitat Animal (CReSA)08193 Bellaterra, Spain
| | - Jordi Barbé
- Centre de Recerca en Sanitat Animal (CReSA)08193 Bellaterra, Spain
- Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona 08193 BellaterraSpain
- To whom correspondence should be addressed at Departament de Genètica i Microbiologia, Ed. C, Universitat Autònoma de Barcelona 08193 Bellaterra, Spain. Tel: +34 93 581 1837; Fax: +34 93 581 2387;
| |
Collapse
|