1
|
Shen L, Gao L, Swoboda AR, Ouellette SP. Targeted repression of topA by CRISPRi reveals a critical function for balanced DNA topoisomerase I activity in the Chlamydia trachomatis developmental cycle. mBio 2024; 15:e0258423. [PMID: 38265209 PMCID: PMC10865786 DOI: 10.1128/mbio.02584-23] [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: 09/25/2023] [Accepted: 12/06/2023] [Indexed: 01/25/2024] Open
Abstract
Chlamydia trachomatis is an obligate intracellular bacterium that is responsible for the most prevalent bacterial sexually transmitted infection. Changes in DNA topology in this pathogen have been linked to its pathogenicity-associated developmental cycle. Here, evidence is provided that the balanced activity of DNA topoisomerases contributes to controlling Chlamydia developmental processes. Utilizing catalytically inactivated Cas12 (dCas12)-based clustered regularly interspaced short palindromic repeats interference (CRISPRi) technology, we demonstrate targeted knockdown of chromosomal topA transcription in C. trachomatis without detected toxicity of dCas12. Repression of topA impaired the developmental cycle of C. trachomatis mostly through disruption of its differentiation from a replicative form to an infectious form. Consistent with this, expression of late developmental genes of C. trachomatis was downregulated, while early genes maintained their expression. Importantly, the developmental defect associated with topA knockdown was rescued by overexpressing topA at an appropriate degree and time, directly linking the growth patterns to the levels of topA expression. Interestingly, topA knockdown had effects on DNA gyrase expression, indicating a potential compensatory mechanism for survival to offset TopA deficiency. C. trachomatis with topA knocked down displayed hypersensitivity to moxifloxacin that targets DNA gyrase in comparison with the wild type. These data underscore the requirement of integrated topoisomerase actions to support the essential developmental and transcriptional processes of C. trachomatis.IMPORTANCEWe used genetic and chemical tools to demonstrate the relationship of topoisomerase activities and their obligatory role for the chlamydial developmental cycle. Successfully targeting the essential gene topA with a CRISPRi approach, using dCas12, in C. trachomatis indicates that this method will facilitate the characterization of the essential genome. These findings have an important impact on our understanding of the mechanisms by which well-balanced topoisomerase functions in adaptation of C. trachomatis to unfavorable growth conditions imposed by antibiotics.
Collapse
Affiliation(s)
- Li Shen
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Leiqiong Gao
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Abigail R. Swoboda
- Department of Pathology, Microbiology, and Immunology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Scot P. Ouellette
- Department of Pathology, Microbiology, and Immunology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| |
Collapse
|
2
|
Norris V, Kayser C, Muskhelishvili G, Konto-Ghiorghi Y. The roles of nucleoid-associated proteins and topoisomerases in chromosome structure, strand segregation, and the generation of phenotypic heterogeneity in bacteria. FEMS Microbiol Rev 2023; 47:fuac049. [PMID: 36549664 DOI: 10.1093/femsre/fuac049] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 12/06/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022] Open
Abstract
How to adapt to a changing environment is a fundamental, recurrent problem confronting cells. One solution is for cells to organize their constituents into a limited number of spatially extended, functionally relevant, macromolecular assemblies or hyperstructures, and then to segregate these hyperstructures asymmetrically into daughter cells. This asymmetric segregation becomes a particularly powerful way of generating a coherent phenotypic diversity when the segregation of certain hyperstructures is with only one of the parental DNA strands and when this pattern of segregation continues over successive generations. Candidate hyperstructures for such asymmetric segregation in prokaryotes include those containing the nucleoid-associated proteins (NAPs) and the topoisomerases. Another solution to the problem of creating a coherent phenotypic diversity is by creating a growth-environment-dependent gradient of supercoiling generated along the replication origin-to-terminus axis of the bacterial chromosome. This gradient is modulated by transcription, NAPs, and topoisomerases. Here, we focus primarily on two topoisomerases, TopoIV and DNA gyrase in Escherichia coli, on three of its NAPs (H-NS, HU, and IHF), and on the single-stranded binding protein, SSB. We propose that the combination of supercoiling-gradient-dependent and strand-segregation-dependent topoisomerase activities result in significant differences in the supercoiling of daughter chromosomes, and hence in the phenotypes of daughter cells.
Collapse
Affiliation(s)
- Vic Norris
- University of Rouen, Laboratory of Bacterial Communication and Anti-infection Strategies, EA 4312, 76821 Mont Saint Aignan, France
| | - Clara Kayser
- University of Rouen, Laboratory of Bacterial Communication and Anti-infection Strategies, EA 4312, 76821 Mont Saint Aignan, France
| | - Georgi Muskhelishvili
- Agricultural University of Georgia, School of Natural Sciences, 0159 Tbilisi, Georgia
| | - Yoan Konto-Ghiorghi
- University of Rouen, Laboratory of Bacterial Communication and Anti-infection Strategies, EA 4312, 76821 Mont Saint Aignan, France
| |
Collapse
|
3
|
Trouillon J, Attrée I, Elsen S. The regulation of bacterial two-partner secretion systems. Mol Microbiol 2023; 120:159-177. [PMID: 37340956 DOI: 10.1111/mmi.15112] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 06/01/2023] [Accepted: 06/07/2023] [Indexed: 06/22/2023]
Abstract
Two-partner secretion (TPS) systems, also known as Type Vb secretion systems, allow the translocation of effector proteins across the outer membrane of Gram-negative bacteria. By secreting different classes of effectors, including cytolysins and adhesins, TPS systems play important roles in bacterial pathogenesis and host interactions. Here, we review the current knowledge on TPS systems regulation and highlight specific and common regulatory mechanisms across TPS functional classes. We discuss in detail the specific regulatory networks identified in various bacterial species and emphasize the importance of understanding the context-dependent regulation of TPS systems. Several regulatory cues reflecting host environment during infection, such as temperature and iron availability, are common determinants of expression for TPS systems, even across relatively distant species. These common regulatory pathways often affect TPS systems across subfamilies with different effector functions, representing conserved global infection-related regulatory mechanisms.
Collapse
Affiliation(s)
- Julian Trouillon
- Université Grenoble Alpes, CNRS, CEA, IBS UMR 5075, Team Bacterial Pathogenesis and Cellular Responses, Grenoble, France
| | - Ina Attrée
- Université Grenoble Alpes, CNRS, CEA, IBS UMR 5075, Team Bacterial Pathogenesis and Cellular Responses, Grenoble, France
| | - Sylvie Elsen
- Université Grenoble Alpes, CNRS, CEA, IBS UMR 5075, Team Bacterial Pathogenesis and Cellular Responses, Grenoble, France
| |
Collapse
|
4
|
Shen L, Gao L, Swoboda AR, Ouellette SP. Targeted repression of DNA topoisomerase I by CRISPRi reveals a critical function for it in the Chlamydia trachomatis developmental cycle. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.14.532001. [PMID: 36993624 PMCID: PMC10054935 DOI: 10.1101/2023.03.14.532001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Chlamydia trachomatis is an obligate intracellular bacterium that is responsible for the most prevalent bacterial sexually transmitted infections. Changes in DNA topology in this pathogen have been linked to its pathogenicity-associated developmental cycle. Here, evidence is provided that the balanced activity of DNA topoisomerases (Topos) contributes to Chlamydia developmental processes. Utilizing catalytically inactivated Cas12 (dCas12) based-clustered regularly interspaced short palindromic repeats interference (CRISPRi) technology, we demonstrate targeted knockdown of chromosomal topA transcription in C. trachomatis without detected toxicity of dCas12. Repression of topA impaired the growth of C. trachomatis mostly through disruption of its differentiation from a replicative form to an infectious form. Consistent with this, expression of late developmental genes of C. trachomatis was downregulated while early genes maintained their expression. Importantly, the growth defect associated with topA knockdown was rescued by overexpressing topA at an appropriate degree and time, directly linking the growth patterns to the levels of topA expression. Interestingly, topA knockdown had pleiotropic effects on DNA gyrase expression, indicating a potential compensatory mechanism for survival to offset TopA deficiency. C. trachomatis with topA knocked down displayed hypersensitivity to moxifloxacin that targets DNA gyrase in comparison with the wild type. These data underscore the requirement of integrated topoisomerase actions to support the essential development and transcriptional processes of C. trachomatis.
Collapse
Affiliation(s)
- Li Shen
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112
| | - Leiqiong Gao
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112
| | - Abigail R. Swoboda
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Scot P. Ouellette
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| |
Collapse
|
5
|
Pineau M, Martis B. S, Forquet R, Baude J, Villard C, Grand L, Popowycz F, Soulère L, Hommais F, Nasser W, Reverchon S, Meyer S. What is a supercoiling-sensitive gene? Insights from topoisomerase I inhibition in the Gram-negative bacterium Dickeya dadantii. Nucleic Acids Res 2022; 50:9149-9161. [PMID: 35950487 PMCID: PMC9458453 DOI: 10.1093/nar/gkac679] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 07/04/2022] [Accepted: 07/27/2022] [Indexed: 12/24/2022] Open
Abstract
DNA supercoiling is an essential mechanism of bacterial chromosome compaction, whose level is mainly regulated by topoisomerase I and DNA gyrase. Inhibiting either of these enzymes with antibiotics leads to global supercoiling modifications and subsequent changes in global gene expression. In previous studies, genes responding to DNA relaxation induced by DNA gyrase inhibition were categorised as 'supercoiling-sensitive'. Here, we studied the opposite variation of DNA supercoiling in the phytopathogen Dickeya dadantii using the non-marketed antibiotic seconeolitsine. We showed that the drug is active against topoisomerase I from this species, and analysed the first transcriptomic response of a Gram-negative bacterium to topoisomerase I inhibition. We find that the responding genes essentially differ from those observed after DNA relaxation, and further depend on the growth phase. We characterised these genes at the functional level, and also detected distinct patterns in terms of expression level, spatial and orientational organisation along the chromosome. Altogether, these results highlight that the supercoiling-sensitivity is a complex feature, which depends on the action of specific topoisomerases, on the physiological conditions, and on their genomic context. Based on previous in vitro expression data of several promoters, we propose a qualitative model of SC-dependent regulation that accounts for many of the contrasting transcriptomic features observed after DNA gyrase or topoisomerase I inhibition.
Collapse
Affiliation(s)
- Maïwenn Pineau
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 69621 Villeurbanne, France
| | - Shiny Martis B.
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 69621 Villeurbanne, France
| | - Raphaël Forquet
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 69621 Villeurbanne, France
| | - Jessica Baude
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 69621 Villeurbanne, France
| | - Camille Villard
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 69621 Villeurbanne, France
| | - Lucie Grand
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS UMR 5246, Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, 69622 Villeurbanne, France
| | - Florence Popowycz
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS UMR 5246, Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, 69622 Villeurbanne, France
| | - Laurent Soulère
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS UMR 5246, Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, 69622 Villeurbanne, France
| | - Florence Hommais
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 69621 Villeurbanne, France
| | - William Nasser
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 69621 Villeurbanne, France
| | - Sylvie Reverchon
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 69621 Villeurbanne, France
| | - Sam Meyer
- To whom correspondence should be addressed. Tel: +33 4 72 43 85 16;
| |
Collapse
|
6
|
Forquet R, Jiang X, Nasser W, Hommais F, Reverchon S, Meyer S. Mapping the Complex Transcriptional Landscape of the Phytopathogenic Bacterium Dickeya dadantii. mBio 2022; 13:e0052422. [PMID: 35491820 PMCID: PMC9239193 DOI: 10.1128/mbio.00524-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 04/07/2022] [Indexed: 11/21/2022] Open
Abstract
Dickeya dadantii is a phytopathogenic bacterium that causes soft rot in a wide range of plant hosts worldwide and a model organism for studying virulence gene regulation. The present study provides a comprehensive and annotated transcriptomic map of D. dadantii obtained by a computational method combining five independent transcriptomic data sets: (i) paired-end RNA sequencing (RNA-seq) data for a precise reconstruction of the RNA landscape; (ii) DNA microarray data providing transcriptional responses to a broad variety of environmental conditions; (iii) long-read Nanopore native RNA-seq data for isoform-level transcriptome validation and determination of transcription termination sites; (iv) differential RNA sequencing (dRNA-seq) data for the precise mapping of transcription start sites; (v) in planta DNA microarray data for a comparison of gene expression profiles between in vitro experiments and the early stages of plant infection. Our results show that transcription units sometimes coincide with predicted operons but are generally longer, most of them comprising internal promoters and terminators that generate alternative transcripts of variable gene composition. We characterize the occurrence of transcriptional read-through at terminators, which might play a basal regulation role and explain the extent of transcription beyond the scale of operons. We finally highlight the presence of noncontiguous operons and excludons in the D. dadantii genome, novel genomic arrangements that might contribute to the basal coordination of transcription. The highlighted transcriptional organization may allow D. dadantii to finely adjust its gene expression program for a rapid adaptation to fast-changing environments. IMPORTANCE This is the first transcriptomic map of a Dickeya species. It may therefore significantly contribute to further progress in the field of phytopathogenicity. It is also one of the first reported applications of long-read Nanopore native RNA-seq in prokaryotes. Our findings yield insights into basal rules of coordination of transcription that might be valid for other bacteria and may raise interest in the field of microbiology in general. In particular, we demonstrate that gene expression is coordinated at the scale of transcription units rather than operons, which are larger functional genomic units capable of generating transcripts with variable gene composition for a fine-tuning of gene expression in response to environmental changes. In line with recent studies, our findings indicate that the canonical operon model is insufficient to explain the complexity of bacterial transcriptomes.
Collapse
Affiliation(s)
- Raphaël Forquet
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, Villeurbanne, France
| | - Xuejiao Jiang
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, Villeurbanne, France
| | - William Nasser
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, Villeurbanne, France
| | - Florence Hommais
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, Villeurbanne, France
| | - Sylvie Reverchon
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, Villeurbanne, France
| | - Sam Meyer
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, Villeurbanne, France
| |
Collapse
|
7
|
Muskhelishvili G, Sobetzko P, Travers A. Spatiotemporal Coupling of DNA Supercoiling and Genomic Sequence Organization-A Timing Chain for the Bacterial Growth Cycle? Biomolecules 2022; 12:biom12060831. [PMID: 35740956 PMCID: PMC9221221 DOI: 10.3390/biom12060831] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/08/2022] [Accepted: 06/08/2022] [Indexed: 01/25/2023] Open
Abstract
In this article we describe the bacterial growth cycle as a closed, self-reproducing, or autopoietic circuit, reestablishing the physiological state of stationary cells initially inoculated in the growth medium. In batch culture, this process of self-reproduction is associated with the gradual decline in available metabolic energy and corresponding change in the physiological state of the population as a function of "travelled distance" along the autopoietic path. We argue that this directional alteration of cell physiology is both reflected in and supported by sequential gene expression along the chromosomal OriC-Ter axis. We propose that during the E. coli growth cycle, the spatiotemporal order of gene expression is established by coupling the temporal gradient of supercoiling energy to the spatial gradient of DNA thermodynamic stability along the chromosomal OriC-Ter axis.
Collapse
Affiliation(s)
- Georgi Muskhelishvili
- School of Natural Sciences, Biology Program, Agricultural University of Georgia, 0159 Tbilisi, Georgia
- Correspondence:
| | - Patrick Sobetzko
- Synmikro, Loewe Center for Synthetic Microbiology, Philipps-Universität Marburg, 35043 Marburg, Germany;
| | - Andrew Travers
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK;
| |
Collapse
|
8
|
Relationship between the Chromosome Structural Dynamics and Gene Expression—A Chicken and Egg Dilemma? Microorganisms 2022; 10:microorganisms10050846. [PMID: 35630292 PMCID: PMC9144111 DOI: 10.3390/microorganisms10050846] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 04/14/2022] [Indexed: 02/06/2023] Open
Abstract
Prokaryotic transcription was extensively studied over the last half-century. A great deal of data has been accumulated regarding the control of gene expression by transcription factors regulating their target genes by binding at specific DNA sites. However, there is a significant gap between the mechanistic description of transcriptional control obtained from in vitro biochemical studies and the complexity of transcriptional regulation in the context of the living cell. Indeed, recent studies provide ample evidence for additional levels of complexity pertaining to the regulation of transcription in vivo, such as, for example, the role of the subcellular localization and spatial organization of different molecular components involved in the transcriptional control and, especially, the role of chromosome configurational dynamics. The question as to how the chromosome is dynamically reorganized under the changing environmental conditions and how this reorganization is related to gene expression is still far from being clear. In this article, we focus on the relationships between the chromosome structural dynamics and modulation of gene expression during bacterial adaptation. We argue that spatial organization of the bacterial chromosome is of central importance in the adaptation of gene expression to changing environmental conditions and vice versa, that gene expression affects chromosome dynamics.
Collapse
|
9
|
Hugouvieux-Cotte-Pattat N, Royer M, Gueguen E, Le Guen P, Süssmuth RD, Reverchon S, Cociancich S. Specificity and genetic polymorphism in the Vfm quorum sensing system of plant pathogenic bacteria of the genus Dickeya. Environ Microbiol 2022; 24:1467-1483. [PMID: 35014170 PMCID: PMC9306890 DOI: 10.1111/1462-2920.15889] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 12/26/2021] [Indexed: 12/11/2022]
Abstract
The Vfm quorum sensing (QS) system is preponderant for the virulence of different species of the bacterial genus Dickeya. The vfm gene cluster encodes 26 genes involved in the production, sensing or transduction of the QS signal. To date, the Vfm QS signal has escaped detection by analytical chemistry methods. However, we report here a strain‐specific polymorphism in the biosynthesis genes vfmO and vfmP, which is predicted to be related to the production of different analogues of the QS signal. Consequently, the Vfm communication could be impossible between strains possessing different variants of the genes vfmO/P. We constructed three Vfm QS biosensor strains possessing different vfmO/P variants and compared these biosensors for their responses to samples prepared from 34 Dickeya strains possessing different vfmO/P variants. A pattern of specificity was demonstrated, providing evidence that the polymorphism in the genes vfmO/P determines the biosynthesis of different analogues of the QS signal. Unexpectedly, this vfmO/P‐dependent pattern of specificity is linked to a polymorphism in the ABC transporter gene vfmG, suggesting an adaptation of the putative permease VfmG to specifically bind different analogues of the QS signal. Accordingly, we discuss the possible involvement of VfmG as co‐sensor of the Vfm two‐component regulatory system.
Collapse
Affiliation(s)
| | - Monique Royer
- CIRAD, UMR PHIM, Montpellier, F-34398, France.,PHIM, Univ Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| | - Erwan Gueguen
- Univ Lyon, Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, UMR5240 MAP, Villeurbanne, F-69622, France
| | - Paul Le Guen
- CIRAD, UMR PHIM, Montpellier, F-34398, France.,PHIM, Univ Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| | - Roderich D Süssmuth
- Institut für Chemie, Technische Universität Berlin, Berlin, D-10623, Germany
| | - Sylvie Reverchon
- Univ Lyon, Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, UMR5240 MAP, Villeurbanne, F-69622, France
| | - Stéphane Cociancich
- CIRAD, UMR PHIM, Montpellier, F-34398, France.,PHIM, Univ Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| |
Collapse
|
10
|
Sarkar S, Dey U, Khohliwe TB, Yella VR, Kumar A. Analysis of nucleoid-associated protein-binding regions reveals DNA structural features influencing genome organization in Mycobacterium tuberculosis. FEBS Lett 2021; 595:2504-2521. [PMID: 34387867 DOI: 10.1002/1873-3468.14178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 08/01/2021] [Accepted: 08/11/2021] [Indexed: 11/10/2022]
Abstract
Nucleoid-associated proteins (NAPs) maintain bacterial nucleoid configuration through their architectural properties of DNA bending, wrapping, and bridging. However, the contribution of DNA structural alterations to DNA-NAP recognition at the genomic scale remains unresolved. Present work dissects the DNA sequence, shape and altered structural preferences at a genomic scale for six NAPs in Mycobacterium tuberculosis. Results suggest narrower minor groove width (MGW) and higher DNA rigidity are marked for the binding sites of EspR and Lsr2, while mIHF, MtHU and NapM have heterogeneous DNA structural predilections. In contrast, WhiB4-DNA-binding sites were characterized by wider MGW, highly deformable and less curved DNA. This work provides systematic insight into NAP-mediated genome organization as a function of DNA structural features.
Collapse
Affiliation(s)
- Sharmilee Sarkar
- Department of Molecular Biology and Biotechnology, Tezpur University, India
| | - Upalabdha Dey
- Department of Molecular Biology and Biotechnology, Tezpur University, India
| | | | - Venkata Rajesh Yella
- Department of Biotechnology, Koneru Lakshmaiah Education Foundation, Guntur, India
| | - Aditya Kumar
- Department of Molecular Biology and Biotechnology, Tezpur University, India
| |
Collapse
|
11
|
Forquet R, Pineau M, Nasser W, Reverchon S, Meyer S. Role of the Discriminator Sequence in the Supercoiling Sensitivity of Bacterial Promoters. mSystems 2021; 6:e0097821. [PMID: 34427530 PMCID: PMC8422995 DOI: 10.1128/msystems.00978-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 08/03/2021] [Indexed: 11/20/2022] Open
Abstract
DNA supercoiling acts as a global transcriptional regulator that contributes to the rapid transcriptional response of bacteria to many environmental changes. Although a large fraction of promoters from phylogenetically distant species respond to superhelical variations, the sequence or structural determinants of this behavior remain elusive. Here, we focus on the sequence of the "discriminator" element that was shown to modulate this response in several promoters. We develop a quantitative thermodynamic model of this regulatory effect, focusing on open complex formation during transcription initiation independently from promoter-specific regulatory proteins. We analyze previous and new expression data and show that the model predictions quantitatively match the in vitro and in vivo supercoiling response of selected promoters with mutated discriminator sequences. We then test the universality of this mechanism by a statistical analysis of promoter sequences from transcriptomes of phylogenetically distant bacteria under conditions of supercoiling variations (i) by gyrase inhibitors, (ii) by environmental stresses, or (iii) inherited in the longest-running evolution experiment. In all cases, we identify a robust and significant sequence signature in the discriminator region, suggesting that supercoiling-modulated promoter opening underpins a ubiquitous regulatory mechanism in the prokaryotic kingdom based on the fundamental mechanical properties of DNA and its basal interaction with RNA polymerase. IMPORTANCE In this study, we highlight the role of the discriminator as a global sensor of supercoiling variations and propose the first quantitative regulatory model of this principle, based on the specific step of promoter opening during transcription initiation. It defines the predictive rule by which DNA supercoiling quantitatively modulates the expression rate of bacterial promoters, depending on the G/C content of their discriminator and independently from promoter-specific regulatory proteins. This basal mechanism affects a wide range of species, which is tested by an extensive analysis of global high-throughput expression data. Altogether, ours results confirm and provide a quantitative framework for the long-proposed notion that the discriminator sequence is a significant determinant of promoter supercoiling sensitivity, underpinning the ubiquitous regulatory action of DNA supercoiling on the core transcriptional machinery, in particular in response to quick environmental changes.
Collapse
Affiliation(s)
- Raphaël Forquet
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, CNRS, UMR5240, MAP, Lyon, France
| | - Maïwenn Pineau
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, CNRS, UMR5240, MAP, Lyon, France
| | - William Nasser
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, CNRS, UMR5240, MAP, Lyon, France
| | - Sylvie Reverchon
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, CNRS, UMR5240, MAP, Lyon, France
| | - Sam Meyer
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, CNRS, UMR5240, MAP, Lyon, France
| |
Collapse
|
12
|
Leonard S, Villard C, Nasser W, Reverchon S, Hommais F. RNA Chaperones Hfq and ProQ Play a Key Role in the Virulence of the Plant Pathogenic Bacterium Dickeya dadantii. Front Microbiol 2021; 12:687484. [PMID: 34248909 PMCID: PMC8264596 DOI: 10.3389/fmicb.2021.687484] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 05/31/2021] [Indexed: 12/01/2022] Open
Abstract
Dickeya dadantii is an important pathogenic bacterium that infects a number of crops including potato and chicory. While extensive works have been carried out on the control of the transcription of its genes encoding the main virulence functions, little information is available on the post-transcriptional regulation of these functions. We investigated the involvement of the RNA chaperones Hfq and ProQ in the production of the main D. dadantii virulence functions. Phenotypic assays on the hfq and proQ mutants showed that inactivation of hfq resulted in a growth defect, a modified capacity for biofilm formation and strongly reduced motility, and in the production of degradative extracellular enzymes (proteases, cellulase, and pectate lyases). Accordingly, the hfq mutant failed to cause soft rot on chicory leaves. The proQ mutant had reduced resistance to osmotic stress, reduced extracellular pectate lyase activity compared to the wild-type strain, and reduced virulence on chicory leaves. Most of the phenotypes of the hfq and proQ mutants were related to the low amounts of mRNA of the corresponding virulence factors. Complementation of the double mutant hfq-proQ by each individual protein and cross-complementation of each chaperone suggested that they might exert their effects via partially overlapping but different sets of targets. Overall, it clearly appeared that the two Hfq and ProQ RNA chaperones are important regulators of pathogenicity in D. dadantii. This underscores that virulence genes are regulated post-transcriptionally by non-coding RNAs.
Collapse
Affiliation(s)
- Simon Leonard
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5240 MAP, Microbiologie, Adaptation, Pathogénie, Villeurbanne, France
| | - Camille Villard
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5240 MAP, Microbiologie, Adaptation, Pathogénie, Villeurbanne, France
| | - William Nasser
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5240 MAP, Microbiologie, Adaptation, Pathogénie, Villeurbanne, France
| | - Sylvie Reverchon
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5240 MAP, Microbiologie, Adaptation, Pathogénie, Villeurbanne, France
| | - Florence Hommais
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5240 MAP, Microbiologie, Adaptation, Pathogénie, Villeurbanne, France
| |
Collapse
|
13
|
Muskhelishvili G, Sobetzko P, Mehandziska S, Travers A. Composition of Transcription Machinery and Its Crosstalk with Nucleoid-Associated Proteins and Global Transcription Factors. Biomolecules 2021; 11:biom11070924. [PMID: 34206477 PMCID: PMC8301835 DOI: 10.3390/biom11070924] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/16/2021] [Accepted: 06/18/2021] [Indexed: 11/24/2022] Open
Abstract
The coordination of bacterial genomic transcription involves an intricate network of interdependent genes encoding nucleoid-associated proteins (NAPs), DNA topoisomerases, RNA polymerase subunits and modulators of transcription machinery. The central element of this homeostatic regulatory system, integrating the information on cellular physiological state and producing a corresponding transcriptional response, is the multi-subunit RNA polymerase (RNAP) holoenzyme. In this review article, we argue that recent observations revealing DNA topoisomerases and metabolic enzymes associated with RNAP supramolecular complex support the notion of structural coupling between transcription machinery, DNA topology and cellular metabolism as a fundamental device coordinating the spatiotemporal genomic transcription. We analyse the impacts of various combinations of RNAP holoenzymes and global transcriptional regulators such as abundant NAPs, on genomic transcription from this viewpoint, monitoring the spatiotemporal patterns of couplons—overlapping subsets of the regulons of NAPs and RNAP sigma factors. We show that the temporal expression of regulons is by and large, correlated with that of cognate regulatory genes, whereas both the spatial organization and temporal expression of couplons is distinctly impacted by the regulons of NAPs and sigma factors. We propose that the coordination of the growth phase-dependent concentration gradients of global regulators with chromosome configurational dynamics determines the spatiotemporal patterns of genomic expression.
Collapse
Affiliation(s)
- Georgi Muskhelishvili
- School of Natural Sciences, Agricultural University of Georgia, David Aghmashenebeli Alley 24, Tbilisi 0159, Georgia
- Correspondence:
| | - Patrick Sobetzko
- Department of Chromosome Biology, Philipps-Universität Marburg, LOEWE-Zentrum für Synthetische Mikrobiologie, Hans-Meerwein-Straße, 35043 Marburg, Germany;
| | - Sanja Mehandziska
- School of Engineering and Science, Campus Ring 1, Jacobs University Bremen, 28759 Bremen, Germany;
| | - Andrew Travers
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK;
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
| |
Collapse
|
14
|
Reverchon S, Meyer S, Forquet R, Hommais F, Muskhelishvili G, Nasser W. The nucleoid-associated protein IHF acts as a 'transcriptional domainin' protein coordinating the bacterial virulence traits with global transcription. Nucleic Acids Res 2021; 49:776-790. [PMID: 33337488 PMCID: PMC7826290 DOI: 10.1093/nar/gkaa1227] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 11/30/2020] [Accepted: 12/07/2020] [Indexed: 02/04/2023] Open
Abstract
Bacterial pathogenic growth requires a swift coordination of pathogenicity function with various kinds of environmental stress encountered in the course of host infection. Among the factors critical for bacterial adaptation are changes of DNA topology and binding effects of nucleoid-associated proteins transducing the environmental signals to the chromosome and coordinating the global transcriptional response to stress. In this study, we use the model phytopathogen Dickeya dadantii to analyse the organisation of transcription by the nucleoid-associated heterodimeric protein IHF. We inactivated the IHFα subunit of IHF thus precluding the IHFαβ heterodimer formation and determined both phenotypic effects of ihfA mutation on D. dadantii virulence and the transcriptional response under various conditions of growth. We show that ihfA mutation reorganises the genomic expression by modulating the distribution of chromosomal DNA supercoils at different length scales, thus affecting many virulence genes involved in both symptomatic and asymptomatic phases of infection, including those required for pectin catabolism. Altogether, we propose that IHF heterodimer is a 'transcriptional domainin' protein, the lack of which impairs the spatiotemporal organisation of transcriptional stress-response domains harbouring various virulence traits, thus abrogating the pathogenicity of D. dadantii.
Collapse
Affiliation(s)
- Sylvie Reverchon
- Univ Lyon, Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, UMR5240 MAP, F-69622, France
| | - Sam Meyer
- Univ Lyon, Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, UMR5240 MAP, F-69622, France
| | - Raphaël Forquet
- Univ Lyon, Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, UMR5240 MAP, F-69622, France
| | - Florence Hommais
- Univ Lyon, Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, UMR5240 MAP, F-69622, France
| | - Georgi Muskhelishvili
- Agricultural University of Georgia, School of Natural Sciences, 0159 Tbilisi, Georgia
| | - William Nasser
- Univ Lyon, Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, UMR5240 MAP, F-69622, France
| |
Collapse
|
15
|
Duprey A, Groisman EA. FEDS: a Novel Fluorescence-Based High-Throughput Method for Measuring DNA Supercoiling In Vivo. mBio 2020; 11:e01053-20. [PMID: 32723920 PMCID: PMC7387798 DOI: 10.1128/mbio.01053-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 06/24/2020] [Indexed: 11/20/2022] Open
Abstract
DNA supercoiling (DS) is essential for life because it controls critical processes, including transcription, replication, and recombination. Current methods to measure DNA supercoiling in vivo are laborious and unable to examine single cells. Here, we report a method for high-throughput measurement of bacterial DNA supercoiling in vivoFluorescent evaluation of DNA supercoiling (FEDS) utilizes a plasmid harboring the gene for a green fluorescent protein transcribed by a discovered promoter that responds exclusively to DNA supercoiling and the gene for a red fluorescent protein transcribed by a constitutive promoter as the internal standard. Using FEDS, we uncovered single-cell heterogeneity in DNA supercoiling and established that, surprisingly, population-level decreases in DNA supercoiling result from a low-mean/high-variance DNA supercoiling subpopulation rather than from a homogeneous shift in supercoiling of the whole population. In addition, we identified a regulatory loop in which a gene that decreases DNA supercoiling is transcriptionally repressed when DNA supercoiling increases.IMPORTANCE DNA represents the chemical support of genetic information in all forms of life. In addition to its linear sequence of nucleotides, it bears critical information in its structure. This information, called DNA supercoiling, is central to all fundamental DNA processes, such as transcription and replication, and defines cellular physiology. Unlike reading of a nucleotide sequence, DNA supercoiling determinations have been laborious. We have now developed a method for rapid measurement of DNA supercoiling and established its utility by identifying a novel regulator of DNA supercoiling in the bacterium Salmonella enterica as well as behaviors that could not have been discovered with current methods.
Collapse
Affiliation(s)
- Alexandre Duprey
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
| | - Eduardo A Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
- Yale Microbial Sciences Institute, West Haven, Connecticut, USA
| |
Collapse
|
16
|
Fan J, Ma L, Zhao C, Yan J, Che S, Zhou Z, Wang H, Yang L, Hu B. Transcriptome of Pectobacterium carotovorum subsp. carotovorum PccS1 infected in calla plants in vivo highlights a spatiotemporal expression pattern of genes related to virulence, adaptation, and host response. MOLECULAR PLANT PATHOLOGY 2020; 21:871-891. [PMID: 32267092 PMCID: PMC7214478 DOI: 10.1111/mpp.12936] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 02/14/2020] [Accepted: 02/29/2020] [Indexed: 06/11/2023]
Abstract
Bacterial pathogens from the genus Pectobacterium cause soft rot in various plants, and result in important economic losses worldwide. We understand much about how these pathogens digest their hosts and protect themselves against plant defences, as well as some regulatory networks in these processes. However, the spatiotemporal expression of genome-wide infection of Pectobacterium remains unclear, although researchers analysed this in some phytopathogens. In the present work, comparing the transcriptome profiles from cellular infection with growth in minimal and rich media, RNA-Seq analyses revealed that the differentially expressed genes (log2 -fold ratio ≥ 1.0) in the cells of Pectobacterium carotovorum subsp. carotovorum PccS1 recovered at a series of time points after inoculation in the host in vivo covered approximately 50% of genes in the genome. Based on the dynamic expression changes in infection, the significantly differentially expressed genes (log2 -fold ratio ≥ 2.0) were classified into five types, and the main expression pattern of the genes for carbohydrate metabolism underlying the processes of infection was identified. The results are helpful to our understanding of the inducement of host plant and environmental adaption of Pectobacterium. In addition, our results demonstrate that maceration caused by PccS1 is due to the depression of callose deposition in the plant for resistance by the pathogenesis-related genes and the superlytic ability of pectinolytic enzymes produced in PccS1, rather than the promotion of plant cell death elicited by the T3SS of bacteria as described in previous work.
Collapse
Affiliation(s)
- Jiaqin Fan
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Lin Ma
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Chendi Zhao
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Jingyuan Yan
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Shu Che
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Zhaowei Zhou
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Huan Wang
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Liuke Yang
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| | - Baishi Hu
- Laboratory of BacteriologyDepartment of Plant PathologyNanjing Agricultural UniversityNanjingChina
| |
Collapse
|
17
|
Kosmidis K, Jablonski KP, Muskhelishvili G, Hütt MT. Chromosomal origin of replication coordinates logically distinct types of bacterial genetic regulation. NPJ Syst Biol Appl 2020; 6:5. [PMID: 32066730 PMCID: PMC7026169 DOI: 10.1038/s41540-020-0124-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 01/21/2020] [Indexed: 01/16/2023] Open
Abstract
For a long time it has been hypothesized that bacterial gene regulation involves an intricate interplay of the transcriptional regulatory network (TRN) and the spatial organization of genes in the chromosome. Here we explore this hypothesis both on a structural and on a functional level. On the structural level, we study the TRN as a spatially embedded network. On the functional level, we analyze gene expression patterns from a network perspective (“digital control”), as well as from the perspective of the spatial organization of the chromosome (“analog control”). Our structural analysis reveals the outstanding relevance of the symmetry axis defined by the origin (Ori) and terminus (Ter) of replication for the network embedding and, thus, suggests the co-evolution of two regulatory infrastructures, namely the transcriptional regulatory network and the spatial arrangement of genes on the chromosome, to optimize the cross-talk between two fundamental biological processes: genomic expression and replication. This observation is confirmed by the functional analysis based on the differential gene expression patterns of more than 4000 pairs of microarray and RNA-Seq datasets for E. coli from the Colombos Database using complex network and machine learning methods. This large-scale analysis supports the notion that two logically distinct types of genetic control are cooperating to regulate gene expression in a complementary manner. Moreover, we find that the position of the gene relative to the Ori is a feature of very high predictive value for gene expression, indicating that the Ori–Ter symmetry axis coordinates the action of distinct genetic control mechanisms.
Collapse
Affiliation(s)
- Kosmas Kosmidis
- Division of Theoretical Physics, Physics Department, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece.,PharmaInformatics Unit, Research Center ATHENA, Athens, Greece
| | - Kim Philipp Jablonski
- Department of Life Sciences and Chemistry, Jacobs University, Bremen, Germany.,Department of Biosystems Science and Engineering, ETH Zürich, Zürich, Switzerland
| | | | - Marc-Thorsten Hütt
- Department of Life Sciences and Chemistry, Jacobs University, Bremen, Germany.
| |
Collapse
|
18
|
Travers A, Muskhelishvili G. Chromosomal Organization and Regulation of Genetic Function in Escherichia coli Integrates the DNA Analog and Digital Information. EcoSal Plus 2020; 9:10.1128/ecosalplus.ESP-0016-2019. [PMID: 32056535 PMCID: PMC11168577 DOI: 10.1128/ecosalplus.esp-0016-2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Indexed: 12/22/2022]
Abstract
In this article, we summarize our current understanding of the bacterial genetic regulation brought about by decades of studies using the Escherichia coli model. It became increasingly evident that the cellular genetic regulation system is organizationally closed, and a major challenge is to describe its circular operation in quantitative terms. We argue that integration of the DNA analog information (i.e., the probability distribution of the thermodynamic stability of base steps) and digital information (i.e., the probability distribution of unique triplets) in the genome provides a key to understanding the organizational logic of genetic control. During bacterial growth and adaptation, this integration is mediated by changes of DNA supercoiling contingent on environmentally induced shifts in intracellular ionic strength and energy charge. More specifically, coupling of dynamic alterations of the local intrinsic helical repeat in the structurally heterogeneous DNA polymer with structural-compositional changes of RNA polymerase holoenzyme emerges as a fundamental organizational principle of the genetic regulation system. We present a model of genetic regulation integrating the genomic pattern of DNA thermodynamic stability with the gene order and function along the chromosomal OriC-Ter axis, which acts as a principal coordinate system organizing the regulatory interactions in the genome.
Collapse
Affiliation(s)
- Andrew Travers
- Department of Biochemistry, University of Cambridge, Cambridge, UK
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | | |
Collapse
|
19
|
Muskhelishvili G, Forquet R, Reverchon S, Meyer S, Nasser W. Coherent Domains of Transcription Coordinate Gene Expression During Bacterial Growth and Adaptation. Microorganisms 2019; 7:microorganisms7120694. [PMID: 31847191 PMCID: PMC6956064 DOI: 10.3390/microorganisms7120694] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 11/28/2019] [Accepted: 12/09/2019] [Indexed: 01/07/2023] Open
Abstract
Recent studies strongly suggest that in bacteria, both the genomic pattern of DNA thermodynamic stability and the order of genes along the chromosomal origin-to-terminus axis are highly conserved and that this spatial organization plays a crucial role in coordinating genomic transcription. In this article, we explore the relationship between genomic sequence organization and transcription in the commensal bacterium Escherichia coli and the plant pathogen Dickeya. We argue that, while in E. coli the gradient of DNA thermodynamic stability and gene order along the origin-to-terminus axis represent major organizational features orchestrating temporal gene expression, the genomic sequence organization of Dickeya is more complex, demonstrating extended chromosomal domains of thermodynamically distinct DNA sequences eliciting specific transcriptional responses to various kinds of stress encountered during pathogenic growth. This feature of the Dickeya genome is likely an adaptation to the pathogenic lifestyle utilizing differences in genomic sequence organization for the selective expression of virulence traits. We propose that the coupling of DNA thermodynamic stability and genetic function provides a common organizational principle for the coordinated expression of genes during both normal and pathogenic bacterial growth.
Collapse
Affiliation(s)
| | - Raphaël Forquet
- INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, Univ. Lyon, Université Lyon 1, F-69622 Villeurbanne, France; (R.F.); (S.R.); (S.M.)
| | - Sylvie Reverchon
- INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, Univ. Lyon, Université Lyon 1, F-69622 Villeurbanne, France; (R.F.); (S.R.); (S.M.)
| | - Sam Meyer
- INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, Univ. Lyon, Université Lyon 1, F-69622 Villeurbanne, France; (R.F.); (S.R.); (S.M.)
| | - William Nasser
- INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, Univ. Lyon, Université Lyon 1, F-69622 Villeurbanne, France; (R.F.); (S.R.); (S.M.)
- Correspondence:
| |
Collapse
|
20
|
Leonard S, Meyer S, Lacour S, Nasser W, Hommais F, Reverchon S. APERO: a genome-wide approach for identifying bacterial small RNAs from RNA-Seq data. Nucleic Acids Res 2019; 47:e88. [PMID: 31147705 PMCID: PMC6735904 DOI: 10.1093/nar/gkz485] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 05/06/2019] [Accepted: 05/20/2019] [Indexed: 12/02/2022] Open
Abstract
Small non-coding RNAs (sRNAs) regulate numerous cellular processes in all domains of life. Several approaches have been developed to identify them from RNA-seq data, which are efficient for eukaryotic sRNAs but remain inaccurate for the longer and highly structured bacterial sRNAs. We present APERO, a new algorithm to detect small transcripts from paired-end bacterial RNA-seq data. In contrast to previous approaches that start from the read coverage distribution, APERO analyzes boundaries of individual sequenced fragments to infer the 5′ and 3′ ends of all transcripts. Since sRNAs are about the same size as individual fragments (50–350 nucleotides), this algorithm provides a significantly higher accuracy and robustness, e.g., with respect to spontaneous internal breaking sites. To demonstrate this improvement, we develop a comparative assessment on datasets from Escherichia coli and Salmonella enterica, based on experimentally validated sRNAs. We also identify the small transcript repertoire of Dickeya dadantii including putative intergenic RNAs, 5′ UTR or 3′ UTR-derived RNA products and antisense RNAs. Comparisons to annotations as well as RACE-PCR experimental data confirm the precision of the detected transcripts. Altogether, APERO outperforms all existing methods in terms of sRNA detection and boundary precision, which is crucial for comprehensive genome annotations. It is freely available as an open source R package on https://github.com/Simon-Leonard/APERO
Collapse
Affiliation(s)
- Simon Leonard
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, 11 avenue Jean Capelle, F-69621 Villeurbanne, France
| | - Sam Meyer
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, 11 avenue Jean Capelle, F-69621 Villeurbanne, France
| | - Stephan Lacour
- Univ. Grenoble Alpes, CNRS, Inria, LiPhy (UMR5588), 38000 Grenoble, France
| | - William Nasser
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, 11 avenue Jean Capelle, F-69621 Villeurbanne, France
| | - Florence Hommais
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, 11 avenue Jean Capelle, F-69621 Villeurbanne, France
| | - Sylvie Reverchon
- Université de Lyon, INSA-Lyon, Université Claude Bernard Lyon1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation, Pathogénie, 11 avenue Jean Capelle, F-69621 Villeurbanne, France
| |
Collapse
|
21
|
Martis B S, Forquet R, Reverchon S, Nasser W, Meyer S. DNA Supercoiling: an Ancestral Regulator of Gene Expression in Pathogenic Bacteria? Comput Struct Biotechnol J 2019; 17:1047-1055. [PMID: 31452857 PMCID: PMC6700405 DOI: 10.1016/j.csbj.2019.07.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 07/17/2019] [Accepted: 07/24/2019] [Indexed: 12/28/2022] Open
Abstract
DNA supercoiling acts as a global and ancestral regulator of bacterial gene expression. In this review, we advocate that it plays a pivotal role in host-pathogen interactions by transducing environmental signals to the bacterial chromosome and coordinating its transcriptional response. We present available evidence that DNA supercoiling is modulated by environmental stress conditions relevant to the infection process according to ancestral mechanisms, in zoopathogens as well as phytopathogens. We review the results of transcriptomics studies obtained in widely distant bacterial species, showing that such structural transitions of the chromosome are associated to a complex transcriptional response affecting a large fraction of the genome. Mechanisms and computational models of the transcriptional regulation by DNA supercoiling are then discussed, involving both basal interactions of RNA Polymerase with promoter DNA, and more specific interactions with regulatory proteins. A final part is specifically focused on the regulation of virulence genes within pathogenicity islands of several pathogenic bacterial species.
Collapse
Affiliation(s)
- Shiny Martis B
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 11 avenue Jean Capelle, 69621 Villeurbanne, France
| | - Raphaël Forquet
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 11 avenue Jean Capelle, 69621 Villeurbanne, France
| | - Sylvie Reverchon
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 11 avenue Jean Capelle, 69621 Villeurbanne, France
| | - William Nasser
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 11 avenue Jean Capelle, 69621 Villeurbanne, France
| | - Sam Meyer
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 11 avenue Jean Capelle, 69621 Villeurbanne, France
| |
Collapse
|
22
|
El Houdaigui B, Forquet R, Hindré T, Schneider D, Nasser W, Reverchon S, Meyer S. Bacterial genome architecture shapes global transcriptional regulation by DNA supercoiling. Nucleic Acids Res 2019; 47:5648-5657. [PMID: 31216038 PMCID: PMC6582348 DOI: 10.1093/nar/gkz300] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 04/15/2019] [Accepted: 04/16/2019] [Indexed: 01/20/2023] Open
Abstract
DNA supercoiling acts as a global transcriptional regulator in bacteria, that plays an important role in adapting their expression programme to environmental changes, but for which no quantitative or even qualitative regulatory model is available. Here, we focus on spatial supercoiling heterogeneities caused by the transcription process itself, which strongly contribute to this regulation mode. We propose a new mechanistic modeling of the transcription-supercoiling dynamical coupling along a genome, which allows simulating and quantitatively reproducing in vitro and in vivo transcription assays, and highlights the role of genes' local orientation in their supercoiling sensitivity. Consistently with predictions, we show that chromosomal relaxation artificially induced by gyrase inhibitors selectively activates convergent genes in several enterobacteria, while conversely, an increase in DNA supercoiling naturally selected in a long-term evolution experiment with Escherichia coli favours divergent genes. Simulations show that these global expression responses to changes in DNA supercoiling result from fundamental mechanical constraints imposed by transcription, independently from more specific regulation of each promoter. These constraints underpin a significant and predictable contribution to the complex rules by which bacteria use DNA supercoiling as a global but fine-tuned transcriptional regulator.
Collapse
Affiliation(s)
- Bilal El Houdaigui
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 69621 Villeurbanne, France
| | - Raphaël Forquet
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 69621 Villeurbanne, France
| | - Thomas Hindré
- Université Grenoble-Alpes, CNRS, Grenoble INP, TIMC-IMAG, 38000 Grenoble, France
| | - Dominique Schneider
- Université Grenoble-Alpes, CNRS, Grenoble INP, TIMC-IMAG, 38000 Grenoble, France
| | - William Nasser
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 69621 Villeurbanne, France
| | - Sylvie Reverchon
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 69621 Villeurbanne, France
| | - Sam Meyer
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 69621 Villeurbanne, France
| |
Collapse
|
23
|
Functional Metagenomics Reveals an Overlooked Diversity and Novel Features of Soil-Derived Bacterial Phosphatases and Phytases. mBio 2019; 10:mBio.01966-18. [PMID: 30696742 PMCID: PMC6355987 DOI: 10.1128/mbio.01966-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phosphatases, including phytases, play a major role in cell metabolism, phosphorus cycle, biotechnology, and pathogenic processes. Nevertheless, their discovery by functional metagenomics is challenging. Here, soil metagenomic libraries were successfully screened for genes encoding phosphatase activity. In this context, we report the largest number and diversity of phosphatase genes derived from functional metagenome analysis. Two of the detected gene products carry domains which have never been associated with phosphatase activity before. One of these domains, the SNARE-associated domain DedA, harbors a so-far-overlooked motif present in numerous bacterial SNARE-associated proteins. Our analysis revealed a previously unreported phytase activity of the alkaline phosphatase and sulfatase superfamily (cl23718) and of purple acid phosphatases from nonvegetal origin. This suggests that the classical concept comprising four classes of phytases should be modified and indicates high performance of our screening method for retrieving novel types of phosphatases/phytases hidden in metagenomes of complex environments.IMPORTANCE Phosphorus (P) is a key element involved in numerous cellular processes and essential to meet global food demand. Phosphatases play a major role in cell metabolism and contribute to control the release of P from phosphorylated organic compounds, including phytate. Apart from the relationship with pathogenesis and the enormous economic relevance, phosphatases/phytases are also important for reduction of phosphorus pollution. Almost all known functional phosphatases/phytases are derived from cultured individual microorganisms. We demonstrate here for the first time the potential of functional metagenomics to exploit the phosphatase/phytase pools hidden in environmental soil samples. The recovered diversity of phosphatases/phytases comprises new types and proteins exhibiting largely unknown characteristics, demonstrating the potential of the screening method for retrieving novel target enzymes. The insights gained into the unknown diversity of genes involved in the P cycle highlight the power of function-based metagenomic screening strategies to study Earth's phosphatase pools.
Collapse
|
24
|
Golanowska M, Potrykus M, Motyka-Pomagruk A, Kabza M, Bacci G, Galardini M, Bazzicalupo M, Makalowska I, Smalla K, Mengoni A, Hugouvieux-Cotte-Pattat N, Lojkowska E. Comparison of Highly and Weakly Virulent Dickeya solani Strains, With a View on the Pangenome and Panregulon of This Species. Front Microbiol 2018; 9:1940. [PMID: 30233505 PMCID: PMC6127512 DOI: 10.3389/fmicb.2018.01940] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 07/31/2018] [Indexed: 11/30/2022] Open
Abstract
Bacteria belonging to the genera Dickeya and Pectobacterium are responsible for significant economic losses in a wide variety of crops and ornamentals. During last years, increasing losses in potato production have been attributed to the appearance of Dickeya solani. The D. solani strains investigated so far share genetic homogeneity, although different virulence levels were observed among strains of various origins. The purpose of this study was to investigate the genetic traits possibly related to the diverse virulence levels by means of comparative genomics. First, we developed a new genome assembly pipeline which allowed us to complete the D. solani genomes. Four de novo sequenced and ten publicly available genomes were used to identify the structure of the D. solani pangenome, in which 74.8 and 25.2% of genes were grouped into the core and dispensable genome, respectively. For D. solani panregulon analysis, we performed a binding site prediction for four transcription factors, namely CRP, KdgR, PecS and Fur, to detect the regulons of these virulence regulators. Most of the D. solani potential virulence factors were predicted to belong to the accessory regulons of CRP, KdgR, and PecS. Thus, some differences in gene expression could exist between D. solani strains. The comparison between a highly and a low virulent strain, IFB0099 and IFB0223, respectively, disclosed only small differences between their genomes but significant differences in the production of virulence factors like pectinases, cellulases and proteases, and in their mobility. The D. solani strains also diverge in the number and size of prophages present in their genomes. Another relevant difference is the disruption of the adhesin gene fhaB2 in the highly virulent strain. Strain IFB0223, which has a complete adhesin gene, is less mobile and less aggressive than IFB0099. This suggests that in this case, mobility rather than adherence is needed in order to trigger disease symptoms. This study highlights the utility of comparative genomics in predicting D. solani traits involved in the aggressiveness of this emerging plant pathogen.
Collapse
Affiliation(s)
- Malgorzata Golanowska
- Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Marta Potrykus
- Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Agata Motyka-Pomagruk
- Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Michal Kabza
- Department of Integrative Genomics, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
| | - Giovanni Bacci
- Department of Biology, University of Florence, Florence, Italy
| | - Marco Galardini
- EMBL, EBI, Wellcome Trust Genome Campus, Cambridge, United Kingdom
| | | | - Izabela Makalowska
- Department of Integrative Genomics, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
| | - Kornelia Smalla
- Department of Epidemiology and Pathogen Diagnostics, Julius Kühn-Institut - Federal Research Centre for Cultivated Plants, Braunschweig, Germany
| | - Alessio Mengoni
- Department of Biology, University of Florence, Florence, Italy
| | - Nicole Hugouvieux-Cotte-Pattat
- UMR5240 Microbiologie Adaptation et Pathogénie, Univ Lyon, CNRS, Univ Claude Bernard Lyon 1, INSA Lyon, Villeurbanne, France
| | - Ewa Lojkowska
- Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| |
Collapse
|
25
|
Martín-Galiano AJ, Ferrándiz MJ, de la Campa AG. Bridging Chromosomal Architecture and Pathophysiology of Streptococcus pneumoniae. Genome Biol Evol 2018; 9:350-361. [PMID: 28158485 PMCID: PMC5381641 DOI: 10.1093/gbe/evw299] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/22/2016] [Indexed: 11/14/2022] Open
Abstract
The chromosome of Streptococcus pneumoniae is organized into topological domains based on its transcriptional response to DNA relaxation: Up-regulated (UP), down-regulated (DOWN), nonregulated (NR), and AT-rich. In the present work, NR genes found to have highly conserved chromosomal locations (17% of the genome) were categorized as members of position-conserved nonregulated (pcNR) domains, while NR genes with a variable position (36% of the genome) were classified as members of position-variable nonregulated (pvNR) domains. On average, pcNR domains showed high transcription rates, optimized codon usage, and were found to contain only a small number of RUP/BOX/SPLICE repeats. They were also poor in exogenous genes but enriched in leading strand genes that code for proteins involved in primary metabolism with central roles within the interactome. In contrast, pvNR genes coding for cell wall proteins, paralogs, virulence factors and immunogenic candidates for protein-based vaccines were found to be overrepresented. DOWN domains were enriched in genes essential for infection. Many UP and DOWN domain genes were seen to be activated during different stages of competence, whereas pcNR genes tended to be repressed until the competence was switched off. Pneumococcal genes appear to be subject to a topology-driven selection pressure that defines the chromosomal location of genes involved in metabolism, virulence and competence. The pcNR domains are interleaved between UP and DOWN domains according to a pattern that suggests the existence of macrodomain entities. The term “topogenomics” is here proposed to describe the study of the topological rules of genomes and their relationship with physiology.
Collapse
Affiliation(s)
- Antonio J Martín-Galiano
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Majadahonda, Spain
| | - María J Ferrándiz
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Majadahonda, Spain
| | - Adela G de la Campa
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Majadahonda, Spain.,Unidad de Genética Bacteriana, Presidencia, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| |
Collapse
|
26
|
Junier I, Frémont P, Rivoire O. Universal and idiosyncratic characteristic lengths in bacterial genomes. Phys Biol 2018; 15:035001. [PMID: 29512518 DOI: 10.1088/1478-3975/aab4ac] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In condensed matter physics, simplified descriptions are obtained by coarse-graining the features of a system at a certain characteristic length, defined as the typical length beyond which some properties are no longer correlated. From a physics standpoint, in vitro DNA has thus a characteristic length of 300 base pairs (bp), the Kuhn length of the molecule beyond which correlations in its orientations are typically lost. From a biology standpoint, in vivo DNA has a characteristic length of 1000 bp, the typical length of genes. Since bacteria live in very different physico-chemical conditions and since their genomes lack translational invariance, whether larger, universal characteristic lengths exist is a non-trivial question. Here, we examine this problem by leveraging the large number of fully sequenced genomes available in public databases. By analyzing GC content correlations and the evolutionary conservation of gene contexts (synteny) in hundreds of bacterial chromosomes, we conclude that a fundamental characteristic length around 10-20 kb can be defined. This characteristic length reflects elementary structures involved in the coordination of gene expression, which are present all along the genome of nearly all bacteria. Technically, reaching this conclusion required us to implement methods that are insensitive to the presence of large idiosyncratic genomic features, which may co-exist along these fundamental universal structures.
Collapse
Affiliation(s)
- Ivan Junier
- CNRS, TIMC-IMAG, Grenoble, France. Univ. Grenoble Alpes, TIMC-IMAG, Grenoble, France
| | | | | |
Collapse
|
27
|
Cameron ADS, Dillon SC, Kröger C, Beran L, Dorman CJ. Broad-scale redistribution of mRNA abundance and transcriptional machinery in response to growth rate in Salmonella enterica serovar Typhimurium. Microb Genom 2017; 3:e000127. [PMID: 29177086 PMCID: PMC5695205 DOI: 10.1099/mgen.0.000127] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 07/12/2017] [Indexed: 11/18/2022] Open
Abstract
We have investigated the connection between the four-dimensional architecture of the bacterial nucleoid and the organism's global gene expression programme. By localizing the transcription machinery and the transcriptional outputs across the genome of the model bacterium Salmonella enterica serovar Typhimurium at different stages of the growth cycle, a surprising disconnection between gene dosage and transcriptional output was revealed. During exponential growth, gene output occurred chiefly in the Ori (origin), Ter (terminus) and NSL (non-structured left) domains, whereas the Left macrodomain remained transcriptionally quiescent at all stages of growth. The apparently high transcriptional output in Ter was correlated with an enhanced stability of the RNA expressed there during exponential growth, suggesting that longer mRNA half-lives compensate for low gene dosage. During exponential growth, RNA polymerase (RNAP) was detected everywhere, whereas in stationary phase cells, RNAP was concentrated in the Ter macrodomain. The alternative sigma factors RpoE, RpoH and RpoN were not required to drive transcription in these growth conditions, consistent with their observed binding to regions away from RNAP and regions of active transcription. Specifically, these alternative sigma factors were found in the Ter macrodomain during exponential growth, whereas they were localized at the Ori macrodomain in stationary phase.
Collapse
Affiliation(s)
- Andrew D S Cameron
- 1Institute of Microbial Systems and Society, University of Regina, Regina, SK, S4S 0A2, Canada.,2Department of Biology, University of Regina, Regina, SK, S4S 0A2, Canada
| | - Shane C Dillon
- 3School of Biological Sciences, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland
| | - Carsten Kröger
- 4Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Laurens Beran
- 1Institute of Microbial Systems and Society, University of Regina, Regina, SK, S4S 0A2, Canada
| | - Charles J Dorman
- 4Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
| |
Collapse
|
28
|
Chromosomal organization of transcription: in a nutshell. Curr Genet 2017; 64:555-565. [PMID: 29184972 DOI: 10.1007/s00294-017-0785-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 11/20/2017] [Accepted: 11/20/2017] [Indexed: 01/25/2023]
Abstract
Early studies of transcriptional regulation focused on individual gene promoters defined specific transcription factors as central agents of genetic control. However, recent genome-wide data propelled a different view by linking spatially organized gene expression patterns to chromosomal dynamics. Therefore, the major problem in contemporary molecular genetics concerned with transcriptional gene regulation is to establish a unifying model that reconciles these two views. This problem, situated at the interface of polymer physics and network theory, requires development of an integrative methodology. In this review, we discuss recent achievements in classical model organism E. coli and provide some novel insights gained from studies of a bacterial plant pathogen, D. dadantii. We consider DNA topology and the basal transcription machinery as key actors of regulation, in which activation of functionally relevant genes is coupled to and coordinated with the establishment of extended chromosomal domains of coherent transcription. We argue that the spatial organization of genome plays a fundamental role in its own regulation.
Collapse
|
29
|
de la Campa AG, Ferrándiz MJ, Martín-Galiano AJ, García MT, Tirado-Vélez JM. The Transcriptome of Streptococcus pneumoniae Induced by Local and Global Changes in Supercoiling. Front Microbiol 2017; 8:1447. [PMID: 28824578 PMCID: PMC5534458 DOI: 10.3389/fmicb.2017.01447] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 07/17/2017] [Indexed: 01/28/2023] Open
Abstract
The bacterial chromosome is compacted in a manner optimal for DNA transactions to occur. The degree of compaction results from the level of DNA-supercoiling and the presence of nucleoid-binding proteins. DNA-supercoiling is homeostatically maintained by the opposing activities of relaxing DNA topoisomerases and negative supercoil-inducing DNA gyrase. DNA-supercoiling acts as a general cis regulator of transcription, which can be superimposed upon other types of more specific trans regulatory mechanism. Transcriptomic studies on the human pathogen Streptococcus pneumoniae, which has a relatively small genome (∼2 Mb) and few nucleoid-binding proteins, have been performed under conditions of local and global changes in supercoiling. The response to local changes induced by fluoroquinolone antibiotics, which target DNA gyrase subunit A and/or topoisomerase IV, involves an increase in oxygen radicals which reduces cell viability, while the induction of global supercoiling changes by novobiocin (a DNA gyrase subunit B inhibitor), or by seconeolitsine (a topoisomerase I inhibitor), has revealed the existence of topological domains that specifically respond to such changes. The control of DNA-supercoiling in S. pneumoniae occurs mainly via the regulation of topoisomerase gene transcription: relaxation triggers the up-regulation of gyrase and the down-regulation of topoisomerases I and IV, while hypernegative supercoiling down-regulates the expression of topoisomerase I. Relaxation affects 13% of the genome, with the majority of the genes affected located in 15 domains. Hypernegative supercoiling affects 10% of the genome, with one quarter of the genes affected located in 12 domains. However, all the above domains overlap, suggesting that the chromosome is organized into topological domains with fixed locations. Based on its response to relaxation, the pneumococcal chromosome can be said to be organized into five types of domain: up-regulated, down-regulated, position-conserved non-regulated, position-variable non-regulated, and AT-rich. The AT content is higher in the up-regulated than in the down-regulated domains. Genes within the different domains share structural and functional characteristics. It would seem that a topology-driven selection pressure has defined the chromosomal location of the metabolism, virulence and competence genes, which suggests the existence of topological rules that aim to improve bacterial fitness.
Collapse
Affiliation(s)
- Adela G de la Campa
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos IIIMadrid, Spain.,Presidencia, Consejo Superior de Investigaciones CientíficasMadrid, Spain
| | - María J Ferrándiz
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos IIIMadrid, Spain
| | - Antonio J Martín-Galiano
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos IIIMadrid, Spain
| | - María T García
- Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad ComplutenseMadrid, Spain
| | - Jose M Tirado-Vélez
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos IIIMadrid, Spain
| |
Collapse
|
30
|
Leonard S, Hommais F, Nasser W, Reverchon S. Plant-phytopathogen interactions: bacterial responses to environmental and plant stimuli. Environ Microbiol 2017; 19:1689-1716. [DOI: 10.1111/1462-2920.13611] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 11/09/2016] [Accepted: 11/16/2016] [Indexed: 01/06/2023]
Affiliation(s)
- Simon Leonard
- University of Lyon, Université Claude Bernard Lyon 1; INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, 10 rue Raphaël Dubois Villeurbanne F-69622 France
| | - Florence Hommais
- University of Lyon, Université Claude Bernard Lyon 1; INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, 10 rue Raphaël Dubois Villeurbanne F-69622 France
| | - William Nasser
- University of Lyon, Université Claude Bernard Lyon 1; INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, 10 rue Raphaël Dubois Villeurbanne F-69622 France
| | - Sylvie Reverchon
- University of Lyon, Université Claude Bernard Lyon 1; INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, 10 rue Raphaël Dubois Villeurbanne F-69622 France
| |
Collapse
|
31
|
González C, Lazcano M, Valdés J, Holmes DS. Bioinformatic Analyses of Unique (Orphan) Core Genes of the Genus Acidithiobacillus: Functional Inferences and Use As Molecular Probes for Genomic and Metagenomic/Transcriptomic Interrogation. Front Microbiol 2016; 7:2035. [PMID: 28082953 PMCID: PMC5186765 DOI: 10.3389/fmicb.2016.02035] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 12/02/2016] [Indexed: 01/06/2023] Open
Abstract
Using phylogenomic and gene compositional analyses, five highly conserved gene families have been detected in the core genome of the phylogenetically coherent genus Acidithiobacillus of the class Acidithiobacillia. These core gene families are absent in the closest extant genus Thermithiobacillus tepidarius that subtends the Acidithiobacillus genus and roots the deepest in this class. The predicted proteins encoded by these core gene families are not detected by a BLAST search in the NCBI non-redundant database of more than 90 million proteins using a relaxed cut-off of 1.0e−5. None of the five families has a clear functional prediction. However, bioinformatic scrutiny, using pI prediction, motif/domain searches, cellular location predictions, genomic context analyses, and chromosome topology studies together with previously published transcriptomic and proteomic data, suggests that some may have functions associated with membrane remodeling during cell division perhaps in response to pH stress. Despite the high level of amino acid sequence conservation within each family, there is sufficient nucleotide variation of the respective genes to permit the use of the DNA sequences to distinguish different species of Acidithiobacillus, making them useful additions to the armamentarium of tools for phylogenetic analysis. Since the protein families are unique to the Acidithiobacillus genus, they can also be leveraged as probes to detect the genus in environmental metagenomes and metatranscriptomes, including industrial biomining operations, and acid mine drainage (AMD).
Collapse
Affiliation(s)
- Carolina González
- Center for Bioinformatics and Genome Biology, Fundación Ciencia & VidaSantiago, Chile; Facultad de Ciencias Biologicas, Universidad Andres BelloSantiago, Chile
| | - Marcelo Lazcano
- Center for Bioinformatics and Genome Biology, Fundación Ciencia & VidaSantiago, Chile; Facultad de Ciencias Biologicas, Universidad Andres BelloSantiago, Chile
| | - Jorge Valdés
- Center for Genomics and Bioinformatics, Faculty of Sciences, Universidad Mayor Santiago, Chile
| | - David S Holmes
- Center for Bioinformatics and Genome Biology, Fundación Ciencia & VidaSantiago, Chile; Facultad de Ciencias Biologicas, Universidad Andres BelloSantiago, Chile
| |
Collapse
|
32
|
Hugouvieux-Cotte-Pattat N. Metabolism and Virulence Strategies in Dickeya-Host Interactions. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 142:93-129. [PMID: 27571693 DOI: 10.1016/bs.pmbts.2016.05.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Dickeya, a genus of the Enterobacteriaceae family, all cause plant diseases. They are aggressive necrotrophs that have both a wide geographic distribution and a wide host range. As a plant pathogen, Dickeya has had to adapt to a vegetarian diet. Plants constitute a large storage of carbohydrates; they contain substantial amounts of soluble sugars and the plant cell wall is composed of long polysaccharides. Metabolic functions used by Dickeya in order to multiply during infection are essential aspects of pathogenesis. Dickeya is able to catabolize a large range of oligosaccharides and glycosides of plant origin. Glucose, fructose, and sucrose are all efficiently metabolized by the bacteria. To avoid the formation of acidic products, their final catabolism involves the butanediol pathway, a nonacidifying fermentative pathway. The assimilation of plant polysaccharides necessitates their prior cleavage into oligomers. Notably, the Dickeya virulence strategy is based on its capacity to dissociate the plant cell wall and, for this, the bacteria secrete an extensive set of polysaccharide degrading enzymes, composed mostly of pectinases. Since pectic polymers have a major role in plant tissue cohesion, pectinase action results in plant rot. The pectate lyases secreted by Dickeya play a double role as virulence factors and as nutrient providers. This dual function implies that the pel gene expression is regulated by both metabolic and virulence regulators. The control of sugar assimilation by specific or global regulators enables Dickeya to link its nutritional status to virulence, a coupling that optimizes the different phases of infection.
Collapse
Affiliation(s)
- N Hugouvieux-Cotte-Pattat
- Microbiology Adaptation and Pathogenesis, CNRS, University of Lyon, University Claude Bernard Lyon 1, INSA Lyon, Villeurbanne, France.
| |
Collapse
|
33
|
Reverchon S, Muskhelisvili G, Nasser W. Virulence Program of a Bacterial Plant Pathogen: The Dickeya Model. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 142:51-92. [PMID: 27571692 DOI: 10.1016/bs.pmbts.2016.05.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The pectinolytic Dickeya spp. are Gram-negative bacteria causing severe disease in a wide range of plant species. Although the Dickeya genus was initially restricted to tropical and subtropical areas, two Dickeya species (D. dianthicola and D. solani) emerged recently in potato cultures in Europe. Soft-rot, the visible symptoms, is caused by plant cell wall degrading enzymes, mainly pectate lyases (Pels) that cleave the pectin polymer. However, an efficient colonization of the host requires many additional elements including early factors (eg, flagella, lipopolysaccharide, and exopolysaccharide) that allow adhesion of the bacteria and intermediate factors involved in adaptation to new growth conditions encountered in the host (eg, oxidative stress, iron starvation, and toxic compounds). To facilitate this adaptation, Dickeya have developed complex regulatory networks ensuring appropriate expression of virulence genes. This review presents recent advances in our understanding of the signals and genetic circuits impacting the expression of virulence determinants. Special attention is paid to integrated control of virulence functions by variations in the superhelical density of chromosomal DNA, and the global and specific regulators, making the regulation of Dickeya virulence an especially attractive model for those interested in relationships between the chromosomal dynamics and gene regulatory networks.
Collapse
Affiliation(s)
- S Reverchon
- Department of Biology, University of Lyon, INSA-Lyon, Villeurbanne, Lyon, France.
| | - G Muskhelisvili
- Department of Biology, University of Lyon, INSA-Lyon, Villeurbanne, Lyon, France
| | - W Nasser
- Department of Biology, University of Lyon, INSA-Lyon, Villeurbanne, Lyon, France
| |
Collapse
|
34
|
Junier I, Rivoire O. Conserved Units of Co-Expression in Bacterial Genomes: An Evolutionary Insight into Transcriptional Regulation. PLoS One 2016; 11:e0155740. [PMID: 27195891 PMCID: PMC4873041 DOI: 10.1371/journal.pone.0155740] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 05/03/2016] [Indexed: 12/18/2022] Open
Abstract
Genome-wide measurements of transcriptional activity in bacteria indicate that the transcription of successive genes is strongly correlated beyond the scale of operons. Here, we analyze hundreds of bacterial genomes to identify supra-operonic segments of genes that are proximal in a large number of genomes. We show that these synteny segments correspond to genomic units of strong transcriptional co-expression. Structurally, the segments contain operons with specific relative orientations (co-directional or divergent) and nucleoid-associated proteins are found to bind at their boundaries. Functionally, operons inside a same segment are highly co-expressed even in the apparent absence of regulatory factors at their promoter regions. Remote operons along DNA can also be co-expressed if their corresponding segments share a transcriptional or sigma factor, without requiring these factors to bind directly to the promoters of the operons. As evidence that these results apply across the bacterial kingdom, we demonstrate them both in the Gram-negative bacterium Escherichia coli and in the Gram-positive bacterium Bacillus subtilis. The underlying process that we propose involves only RNA-polymerases and DNA: it implies that the transcription of an operon mechanically enhances the transcription of adjacent operons. In support of a primary role of this regulation by facilitated co-transcription, we show that the transcription en bloc of successive operons as a result of transcriptional read-through is strongly and specifically enhanced in synteny segments. Finally, our analysis indicates that facilitated co-transcription may be evolutionary primitive and may apply beyond bacteria.
Collapse
Affiliation(s)
- Ivan Junier
- CNRS, TIMC-IMAG, F-38000 Grenoble, France.,Univ. Grenoble Alpes, TIMC-IMAG, F-38000 Grenoble, France
| | - Olivier Rivoire
- CNRS, LIPhy, F-38000 Grenoble, France.,Univ. Grenoble Alpes, LIPhy, F-38000 Grenoble, France
| |
Collapse
|
35
|
Jiang X, Zghidi-Abouzid O, Oger-Desfeux C, Hommais F, Greliche N, Muskhelishvili G, Nasser W, Reverchon S. Global transcriptional response of Dickeya dadantii to environmental stimuli relevant to the plant infection. Environ Microbiol 2016; 18:3651-3672. [PMID: 26940633 DOI: 10.1111/1462-2920.13267] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Accepted: 02/14/2016] [Indexed: 11/28/2022]
Abstract
Dickeya species are soft rot disease-causing bacterial plant pathogens and an emerging agricultural threat in Europe. Environmental modulation of gene expression is critical for Dickeya dadantii pathogenesis. While the bacterium uses various environmental cues to distinguish between its habitats, an intricate transcriptional control system coordinating the expression of virulence genes ensures efficient infection. Understanding of this behaviour requires a detailed knowledge of expression patterns under a wide range of environmental conditions, which is currently lacking. To obtain a comprehensive picture of this adaptive response, we devised a strategy to examine the D. dadantii transcriptome in a series of 32 infection-relevant conditions encountered in the hosts. We propose a temporal map of the bacterial response to various stress conditions and show that D. dadantii elicits complex genetic behaviour combining common stress-response genes with distinct sets of genes specifically induced under each particular stress. Comparison of our dataset with an in planta expression profile reveals the combined impact of stress factors and enables us to predict the major stress confronting D. dadantii at a particular stage of infection. We provide a comprehensive catalog of D. dadantii genomic responses to environmentally relevant stimuli, thus facilitating future studies of this important plant pathogen.
Collapse
Affiliation(s)
- Xuejiao Jiang
- Univ Lyon, Université Lyon 1, INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, Département Biologie, F-69622, Villeurbanne, France
| | - Ouafa Zghidi-Abouzid
- Univ Lyon, Université Lyon 1, INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, Département Biologie, F-69622, Villeurbanne, France
| | - Christine Oger-Desfeux
- Univ Lyon, Université Lyon 1, Pôle Rhône-Alpes de Bioinformatique, Département Biologie, F-69622, Villeurbanne, France
| | - Florence Hommais
- Univ Lyon, Université Lyon 1, INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, Département Biologie, F-69622, Villeurbanne, France
| | - Nicolas Greliche
- Univ Lyon, Université Lyon 1, INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, Département Biologie, F-69622, Villeurbanne, France
| | - Georgi Muskhelishvili
- Univ Lyon, Université Lyon 1, INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, Département Biologie, F-69622, Villeurbanne, France
| | - William Nasser
- Univ Lyon, Université Lyon 1, INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, Département Biologie, F-69622, Villeurbanne, France
| | - Sylvie Reverchon
- Univ Lyon, Université Lyon 1, INSA-Lyon, CNRS, UMR5240, Microbiologie, Adaptation, Pathogénie, Département Biologie, F-69622, Villeurbanne, France
| |
Collapse
|