51
|
Kint N, Janoir C, Monot M, Hoys S, Soutourina O, Dupuy B, Martin-Verstraete I. The alternative sigma factor σ B plays a crucial role in adaptive strategies of Clostridium difficile during gut infection. Environ Microbiol 2017; 19:1933-1958. [PMID: 28198085 DOI: 10.1111/1462-2920.13696] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 01/19/2017] [Accepted: 01/22/2017] [Indexed: 12/29/2022]
Abstract
Clostridium difficile is a major cause of diarrhoea associated with antibiotherapy. Exposed to stresses in the gut, C. difficile can survive by inducing protection, detoxification and repair systems. In several firmicutes, most of these systems are controlled by the general stress response involving σB . In this work, we studied the role of σB in the physiopathology of C. difficile. We showed that the survival of the sigB mutant during the stationary phase was reduced. Using a transcriptome analysis, we showed that σB controls the expression of ∼25% of genes including genes involved in sporulation, metabolism, cell surface biogenesis and the management of stresses. By contrast, σB does not control toxin gene expression. In agreement with the up-regulation of sporulation genes, the sporulation efficiency is higher in the sigB mutant than in the wild-type strain. sigB inactivation also led to increased sensitivity to acidification, cationic antimicrobial peptides, nitric oxide and ROS. In addition, we showed for the first time that σB also plays a crucial role in oxygen tolerance in this strict anaerobe. Finally, we demonstrated that the fitness of colonisation by the sigB mutant is greatly affected in a dixenic mouse model of colonisation when compared to the wild-type strain.
Collapse
Affiliation(s)
- Nicolas Kint
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Claire Janoir
- EA 4043, Unité Bactéries Pathogènes et Santé (UBaPS), Université Paris-Sud, Université Paris-Saclay, 92290, Châtenay-Malabry, France
| | - Marc Monot
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Sandra Hoys
- EA 4043, Unité Bactéries Pathogènes et Santé (UBaPS), Université Paris-Sud, Université Paris-Saclay, 92290, Châtenay-Malabry, France
| | - Olga Soutourina
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Bruno Dupuy
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Isabelle Martin-Verstraete
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| |
Collapse
|
52
|
Anjuwon-Foster BR, Tamayo R. A genetic switch controls the production of flagella and toxins in Clostridium difficile. PLoS Genet 2017; 13:e1006701. [PMID: 28346491 PMCID: PMC5386303 DOI: 10.1371/journal.pgen.1006701] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 04/10/2017] [Accepted: 03/16/2017] [Indexed: 12/15/2022] Open
Abstract
In the human intestinal pathogen Clostridium difficile, flagella promote adherence to intestinal epithelial cells. Flagellar gene expression also indirectly impacts production of the glucosylating toxins, which are essential to diarrheal disease development. Thus, factors that regulate the expression of the flgB operon will likely impact toxin production in addition to flagellar motility. Here, we report the identification a "flagellar switch" that controls the phase variable production of flagella and glucosylating toxins. The flagellar switch, located upstream of the flgB operon containing the early stage flagellar genes, is a 154 bp invertible sequence flanked by 21 bp inverted repeats. Bacteria with the sequence in one orientation expressed flagellum and toxin genes, produced flagella, and secreted the toxins ("flg phase ON"). Bacteria with the sequence in the inverse orientation were attenuated for flagellar and toxin gene expression, were aflagellate, and showed decreased toxin secretion ("flg phase OFF"). The orientation of the flagellar switch is reversible during growth in vitro. We provide evidence that gene regulation via the flagellar switch occurs post-transcription initiation and requires a C. difficile-specific regulatory factor to destabilize or degrade the early flagellar gene mRNA when the flagellar switch is in the OFF orientation. Lastly, through mutagenesis and characterization of flagellar phase locked isolates, we determined that the tyrosine recombinase RecV, which catalyzes inversion at the cwpV switch, is also responsible for inversion at the flagellar switch in both directions. Phase variable flagellar motility and toxin production suggests that these important virulence factors have both advantageous and detrimental effects during the course of infection.
Collapse
Affiliation(s)
- Brandon R. Anjuwon-Foster
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, United States of America
| |
Collapse
|
53
|
Soutourina O. RNA-based control mechanisms of Clostridium difficile. Curr Opin Microbiol 2017; 36:62-68. [PMID: 28214735 DOI: 10.1016/j.mib.2017.01.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 11/28/2016] [Accepted: 01/08/2017] [Indexed: 01/05/2023]
Abstract
Clostridium difficile (CD)-associated diarrhoea is currently the most prevalent nosocomial diarrhoea worldwide. Many characteristics of CD pathogenicity remain poorly understood. Recent data strongly indicate the importance of an RNA network for the control of gene expression in CD. More than 200 regulatory RNAs have been identified by deep sequencing and targeted approaches, including Hfq-dependent trans riboregulators, cis-antisense RNAs, CRISPR RNAs, and c-di-GMP-responsive riboswitches. These regulatory RNAs are involved in the control of major processes in the CD infection cycle, for example motility, biofilm formation, adhesion, sporulation, stress response, and defence against bacteriophages. We will discuss recent advances in elucidation of the original features of RNA-based mechanisms in this important enteropathogen. This knowledge may pave the way for further discoveries in this emergent field.
Collapse
Affiliation(s)
- Olga Soutourina
- Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris Cedex 15, France; Université Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, 25 rue du Dr Roux, 75724 Paris Cedex 15, France; Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette cedex, France.
| |
Collapse
|
54
|
Abstract
Cyclic dinucleotides (CDNs) are highly versatile signalling molecules that control various important biological processes in bacteria. The best-studied example is cyclic di-GMP (c-di-GMP). Known since the late 1980s, it is now recognized as a near-ubiquitous second messenger that coordinates diverse aspects of bacterial growth and behaviour, including motility, virulence, biofilm formation and cell cycle progression. In this Review, we discuss important new insights that have been gained into the molecular principles of c-di-GMP synthesis and degradation, which are mediated by diguanylate cyclases and c-di-GMP-specific phosphodiesterases, respectively, and the cellular functions that are exerted by c-di-GMP-binding effectors and their diverse targets. Finally, we provide a short overview of the signalling versatility of other CDNs, including c-di-AMP and cGMP-AMP (cGAMP).
Collapse
|
55
|
Abt MC, McKenney PT, Pamer EG. Clostridium difficile colitis: pathogenesis and host defence. Nat Rev Microbiol 2016; 14:609-20. [PMID: 27573580 DOI: 10.1038/nrmicro.2016.108] [Citation(s) in RCA: 336] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Clostridium difficile is a major cause of intestinal infection and diarrhoea in individuals following antibiotic treatment. Recent studies have begun to elucidate the mechanisms that induce spore formation and germination and have determined the roles of C. difficile toxins in disease pathogenesis. Exciting progress has also been made in defining the role of the microbiome, specific commensal bacterial species and host immunity in defence against infection with C. difficile. This Review will summarize the recent discoveries and developments in our understanding of C. difficile infection and pathogenesis.
Collapse
Affiliation(s)
- Michael C Abt
- Immunology Program, Lucille Castori Center for Microbes, Inflammation and Cancer, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA
| | - Peter T McKenney
- Immunology Program, Lucille Castori Center for Microbes, Inflammation and Cancer, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA
| | - Eric G Pamer
- Immunology Program, Lucille Castori Center for Microbes, Inflammation and Cancer, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA
| |
Collapse
|
56
|
Maldarelli GA, Piepenbrink KH, Scott AJ, Freiberg JA, Song Y, Achermann Y, Ernst RK, Shirtliff ME, Sundberg EJ, Donnenberg MS, von Rosenvinge EC. Type IV pili promote early biofilm formation by Clostridium difficile. Pathog Dis 2016; 74:ftw061. [PMID: 27369898 DOI: 10.1093/femspd/ftw061] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2016] [Indexed: 12/20/2022] Open
Abstract
Increasing morbidity and mortality from Clostridium difficile infection (CDI) present an enormous challenge to healthcare systems. Clostridium difficile express type IV pili (T4P), but their function remains unclear. Many chronic and recurrent bacterial infections result from biofilms, surface-associated bacterial communities embedded in an extracellular matrix. CDI may be biofilm mediated; T4P are important for biofilm formation in a number of organisms. We evaluate the role of T4P in C. difficile biofilm formation using RNA sequencing, mutagenesis and complementation of the gene encoding the major pilin pilA1, and microscopy. RNA sequencing demonstrates that, in comparison to other growth phenotypes, C. difficile growing in a biofilm has a distinct RNA expression profile, with significant differences in T4P gene expression. Microscopy of T4P-expressing and T4P-deficient strains suggests that T4P play an important role in early biofilm formation. A non-piliated pilA1 mutant forms an initial biofilm of significantly reduced mass and thickness in comparison to the wild type. Complementation of the pilA1 mutant strain leads to formation of a biofilm which resembles the wild-type biofilm. These findings suggest that T4P play an important role in early biofilm formation. Novel strategies for confronting biofilm infections are emerging; our data suggest that similar strategies should be investigated in CDI.
Collapse
Affiliation(s)
- Grace A Maldarelli
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Kurt H Piepenbrink
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Alison J Scott
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Jeffrey A Freiberg
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Yang Song
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Yvonne Achermann
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Mark E Shirtliff
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Eric J Sundberg
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201, USA Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Michael S Donnenberg
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Erik C von Rosenvinge
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA Department of Veterans Affairs, VA Maryland Health Care System, Baltimore, MD 21201, USA
| |
Collapse
|
57
|
Purcell EB, Tamayo R. Cyclic diguanylate signaling in Gram-positive bacteria. FEMS Microbiol Rev 2016; 40:753-73. [PMID: 27354347 DOI: 10.1093/femsre/fuw013] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2016] [Indexed: 12/14/2022] Open
Abstract
The nucleotide second messenger 3'-5' cyclic diguanylate monophosphate (c-di-GMP) is a central regulator of the transition between motile and non-motile lifestyles in bacteria, favoring sessility. Most research investigating the functions of c-di-GMP has focused on Gram-negative species, especially pathogens. Recent work in Gram-positive species has revealed that c-di-GMP plays similar roles in Gram-positives, though the precise targets and mechanisms of regulation may differ. The majority of bacterial life exists in a surface-associated state, with motility allowing bacteria to disseminate and colonize new environments. c-di-GMP signaling regulates flagellum biosynthesis and production of adherence factors and appears to be a primary mechanism by which bacteria sense and respond to surfaces. Ultimately, c-di-GMP influences the ability of a bacterium to alter its transcriptional program, physiology and behavior upon surface contact. This review discusses how bacteria are able to sense a surface via flagella and type IV pili, and the role of c-di-GMP in regulating the response to surfaces, with emphasis on studies of Gram-positive bacteria.
Collapse
Affiliation(s)
- Erin B Purcell
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| |
Collapse
|
58
|
Martin-Verstraete I, Peltier J, Dupuy B. The Regulatory Networks That Control Clostridium difficile Toxin Synthesis. Toxins (Basel) 2016; 8:E153. [PMID: 27187475 PMCID: PMC4885068 DOI: 10.3390/toxins8050153] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Revised: 05/03/2016] [Accepted: 05/05/2016] [Indexed: 12/19/2022] Open
Abstract
The pathogenic clostridia cause many human and animal diseases, which typically arise as a consequence of the production of potent exotoxins. Among the enterotoxic clostridia, Clostridium difficile is the main causative agent of nosocomial intestinal infections in adults with a compromised gut microbiota caused by antibiotic treatment. The symptoms of C. difficile infection are essentially caused by the production of two exotoxins: TcdA and TcdB. Moreover, for severe forms of disease, the spectrum of diseases caused by C. difficile has also been correlated to the levels of toxins that are produced during host infection. This observation strengthened the idea that the regulation of toxin synthesis is an important part of C. difficile pathogenesis. This review summarizes our current knowledge about the regulators and sigma factors that have been reported to control toxin gene expression in response to several environmental signals and stresses, including the availability of certain carbon sources and amino acids, or to signaling molecules, such as the autoinducing peptides of quorum sensing systems. The overlapping regulation of key metabolic pathways and toxin synthesis strongly suggests that toxin production is a complex response that is triggered by bacteria in response to particular states of nutrient availability during infection.
Collapse
Affiliation(s)
- Isabelle Martin-Verstraete
- Laboratoire Pathogenèse des Bactéries Anaérobes, Department of Microbiology, Institut Pasteur, 25 rue du Dr Roux Paris, Paris 75015, France.
- UFR Sciences du vivant, University Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, Paris 75015, France.
| | - Johann Peltier
- Laboratoire Pathogenèse des Bactéries Anaérobes, Department of Microbiology, Institut Pasteur, 25 rue du Dr Roux Paris, Paris 75015, France.
| | - Bruno Dupuy
- Laboratoire Pathogenèse des Bactéries Anaérobes, Department of Microbiology, Institut Pasteur, 25 rue du Dr Roux Paris, Paris 75015, France.
| |
Collapse
|
59
|
Kariisa AT, Weeks K, Tamayo R. The RNA Domain Vc1 Regulates Downstream Gene Expression in Response to Cyclic Diguanylate in Vibrio cholerae. PLoS One 2016; 11:e0148478. [PMID: 26849223 PMCID: PMC4744006 DOI: 10.1371/journal.pone.0148478] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 01/19/2016] [Indexed: 11/18/2022] Open
Abstract
In many bacterial species, including the aquatic bacterium and human pathogen Vibrio cholerae, the second messenger cyclic diguanylate (c-di-GMP) modulates processes such as biofilm formation, motility, and virulence factor production. By interacting with various effectors, c-di-GMP regulates gene expression or protein function. One type of c-di-GMP receptor is the class I riboswitch, representatives of which have been shown to bind c-di-GMP in vitro. Herein, we examined the in vitro and in vivo function of the putative class I riboswitch in Vibrio cholerae, Vc1, which lies upstream of the gene encoding GbpA, a colonization factor that contributes to attachment of V. cholerae to environmental and host surfaces containing N-acetylglucosamine moieties. We provide evidence that Vc1 RNA interacts directly with c-di-GMP in vitro, and that nucleotides conserved among this class of riboswitch are important for binding. Yet the mutation of these conserved residues individually in the V. cholerae chromosome inconsistently affects the expression of gbpA and production of the GbpA protein. By isolating the regulatory function of Vc1, we show that the Vc1 element positively regulates downstream gene expression in response to c-di-GMP. Together these data suggest that the Vc1 element responds to c-di-GMP in vivo. Positive regulation of gbpA expression by c-di-GMP via Vc1 may influence the ability of V. cholerae to associate with chitin in the aquatic environment and the host intestinal environment.
Collapse
Affiliation(s)
- Ankunda T. Kariisa
- Department of Microbiology and Immunology, University of North Carolina Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Kevin Weeks
- Department of Chemistry, University of North Carolina Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
| |
Collapse
|