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Ma X, Nugraha DK, Hiramatsu Y, Horiguchi Y. RpoN (sigma factor 54) contributes to bacterial fitness during tracheal colonization of Bordetella bronchiseptica. Microbiol Immunol 2024; 68:36-46. [PMID: 38105571 DOI: 10.1111/1348-0421.13109] [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: 10/11/2023] [Revised: 12/02/2023] [Accepted: 12/03/2023] [Indexed: 12/19/2023]
Abstract
The Gram-negative pathogenic bacterium Bordetella bronchiseptica is a respiratory pathogen closely related to Bordetella pertussis, the causative agent of whooping cough. Despite sharing homologous virulence factors, B. bronchiseptica infects a broad range of mammalian hosts, including some experimental animals, whereas B. pertussis is strictly adapted to humans. Therefore, B. bronchiseptica is often used as a representative model to explore the pathogenicity of Bordetella in infection experiments with laboratory animals. Although Bordetella virulence factors, including toxins and adhesins have been studied well, our recent study implied that unknown virulence factors are involved in tracheal colonization and infection. Here, we investigated bacterial genes contributing to tracheal colonization by high-throughput transposon sequencing (Tn-seq). After the screening, we picked up 151 candidate genes of various functions and found that a rpoN-deficient mutant strain was defective in tracheal colonization when co-inoculated with the wild-type strain. rpoN encodes σ54 , a sigma factor that regulates the transcription of various genes, implying its contribution to various bacterial activities. In fact, we found RpoN of B. bronchiseptica is involved in bacterial motility and initial biofilm formation. From these results, we propose that RpoN supports bacterial colonization by regulating various bacteriological functions.
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Affiliation(s)
- Xingyan Ma
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Dendi K Nugraha
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Yukihiro Hiramatsu
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Yasuhiko Horiguchi
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- Center for Infectious Disease Education and Research, Osaka University, Osaka, Japan
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2
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Hiramatsu Y, Nishida T, Ota N, Tamaki Y, Nugraha DK, Horiguchi Y. DAT, deacylating autotransporter toxin, from Bordetella parapertussis demyristoylates Gα i GTPases and contributes to cough. Proc Natl Acad Sci U S A 2023; 120:e2308260120. [PMID: 37748060 PMCID: PMC10556565 DOI: 10.1073/pnas.2308260120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 08/28/2023] [Indexed: 09/27/2023] Open
Abstract
The pathogenic bacteria Bordetella pertussis and Bordetella parapertussis cause pertussis (whooping cough) and pertussis-like disease, respectively, both of which are characterized by paroxysmal coughing. We previously reported that pertussis toxin (PTx), which inactivates heterotrimeric GTPases of the Gi family through ADP-ribosylation of their α subunits, causes coughing in combination with Vag8 and lipid A in B. pertussis infection. In contrast, the mechanism of cough induced by B. parapertussis, which produces Vag8 and lipopolysaccharide (LPS) containing lipid A, but not PTx, remained to be elucidated. Here, we show that a toxin we named deacylating autotransporter toxin (DAT) of B. parapertussis inactivates heterotrimeric Gi GTPases through demyristoylation of their α subunits and contributes to cough production along with Vag8 and LPS. These results indicate that DAT plays a role in B. parapertussis infection in place of PTx.
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Affiliation(s)
- Yukihiro Hiramatsu
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka565-0871, Japan
| | - Takashi Nishida
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka565-0871, Japan
| | - Natsuko Ota
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka565-0871, Japan
| | - Yuki Tamaki
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka565-0871, Japan
| | - Dendi K. Nugraha
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka565-0871, Japan
| | - Yasuhiko Horiguchi
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka565-0871, Japan
- Center for Infectious Disease Education and Research, Osaka University, Suita, Osaka565-0871, Japan
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Badhai J, Das SK. Genomic evidence and virulence properties decipher the extra-host origin of Bordetella bronchiseptica. J Appl Microbiol 2023; 134:lxad200. [PMID: 37660236 DOI: 10.1093/jambio/lxad200] [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: 05/05/2023] [Revised: 08/12/2023] [Accepted: 08/30/2023] [Indexed: 09/04/2023]
Abstract
Until recently, members of the classical Bordetella species comprised only pathogenic bacteria that were thought to live exclusively in warm-blooded animals. The close phylogenetic relationship of Bordetella with Achromobacter and Alcaligenes, which include primarily environmental bacteria, suggests that the ancestral Bordetellae were probably free-living. Eventually, the Bordetella species evolved to infect and live within warm-blooded animals. The modern history of pathogens related to the genus Bordetella started towards the end of the 19th century when it was discovered in the infected respiratory epithelium of mammals, including humans. The first identified member was Bordetella pertussis, which causes whooping cough, a fatal disease in young children. In due course, B. bronchiseptica was recovered from the trachea and bronchi of dogs with distemper. Later, a second closely related human pathogen, B. parapertussis, was described as causing milder whooping cough. The classical Bordetellae are strictly host-associated pathogens transmitted via the host-to-host aerosol route. Recently, the B. bronchiseptica strain HT200 has been reported from a thermal spring exhibiting unique genomic features that were not previously observed in clinical strains. Therefore, it advocates that members of classical Bordetella species have evolved from environmental sources. This organism can be transmitted via environmental reservoirs as it can survive nutrient-limiting conditions and possesses a motile flagellum. This study aims to review the molecular basis of origin and virulence properties of obligate host-restricted and environmental strains of classical Bordetella.
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Affiliation(s)
- Jhasketan Badhai
- Department of Biotechnology, Institute of Life Sciences, Nalco Square, Bhubaneswar-751023, India
| | - Subrata K Das
- Department of Biotechnology, Institute of Life Sciences, Nalco Square, Bhubaneswar-751023, India
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Clarke KR, Hor L, Pilapitiya A, Luirink J, Paxman JJ, Heras B. Phylogenetic Classification and Functional Review of Autotransporters. Front Immunol 2022; 13:921272. [PMID: 35860281 PMCID: PMC9289746 DOI: 10.3389/fimmu.2022.921272] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 06/06/2022] [Indexed: 11/30/2022] Open
Abstract
Autotransporters are the core component of a molecular nano-machine that delivers cargo proteins across the outer membrane of Gram-negative bacteria. Part of the type V secretion system, this large family of proteins play a central role in controlling bacterial interactions with their environment by promoting adhesion to surfaces, biofilm formation, host colonization and invasion as well as cytotoxicity and immunomodulation. As such, autotransporters are key facilitators of fitness and pathogenesis and enable co-operation or competition with other bacteria. Recent years have witnessed a dramatic increase in the number of autotransporter sequences reported and a steady rise in functional studies, which further link these proteins to multiple virulence phenotypes. In this review we provide an overview of our current knowledge on classical autotransporter proteins, the archetype of this protein superfamily. We also carry out a phylogenetic analysis of their functional domains and present a new classification system for this exquisitely diverse group of bacterial proteins. The sixteen phylogenetic divisions identified establish sensible relationships between well characterized autotransporters and inform structural and functional predictions of uncharacterized proteins, which may guide future research aimed at addressing multiple unanswered aspects in this group of therapeutically important bacterial factors.
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Affiliation(s)
- Kaitlin R. Clarke
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
| | - Lilian Hor
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
| | - Akila Pilapitiya
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
| | - Joen Luirink
- Department of Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit, Amsterdam, Netherlands
| | - Jason J. Paxman
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
- *Correspondence: Begoña Heras, ; Jason J. Paxman,
| | - Begoña Heras
- Department of Biochemistry and Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
- *Correspondence: Begoña Heras, ; Jason J. Paxman,
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Categorizing sequences of concern by function to better assess mechanisms of microbial pathogenesis. Infect Immun 2021; 90:e0033421. [PMID: 34780277 PMCID: PMC9119117 DOI: 10.1128/iai.00334-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
To identify sequences with a role in microbial pathogenesis, we assessed the adequacy of their annotation by existing controlled vocabularies and sequence databases. Our goal was to regularize descriptions of microbial pathogenesis for improved integration with bioinformatic applications. Here, we review the challenges of annotating sequences for pathogenic activity. We relate the categorization of more than 2,750 sequences of pathogenic microbes through a controlled vocabulary called Functions of Sequences of Concern (FunSoCs). These allow for an ease of description by both humans and machines. We provide a subset of 220 fully annotated sequences in the supplemental material as examples. The use of this compact (∼30 terms), controlled vocabulary has potential benefits for research in microbial genomics, public health, biosecurity, biosurveillance, and the characterization of new and emerging pathogens.
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Novák J, Jurnečka D, Linhartová I, Holubová J, Staněk O, Štipl D, Dienstbier A, Večerek B, Azevedo N, Provazník J, Beneš V, Šebo P. A Mutation Upstream of the rplN-rpsD Ribosomal Operon Downregulates Bordetella pertussis Virulence Factor Production without Compromising Bacterial Survival within Human Macrophages. mSystems 2020; 5:e00612-20. [PMID: 33293402 PMCID: PMC7742992 DOI: 10.1128/msystems.00612-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 11/06/2020] [Indexed: 11/20/2022] Open
Abstract
The BvgS/BvgA two-component system controls expression of ∼550 genes of Bordetella pertussis, of which, ∼245 virulence-related genes are positively regulated by the BvgS-phosphorylated transcriptional regulator protein BvgA (BvgA∼P). We found that a single G-to-T nucleotide transversion in the 5'-untranslated region (5'-UTR) of the rplN gene enhanced transcription of the ribosomal protein operon and of the rpoA gene and provoked global dysregulation of B. pertussis genome expression. This comprised overproduction of the alpha subunit (RpoA) of the DNA-dependent RNA polymerase, downregulated BvgA and BvgS protein production, and impaired production and secretion of virulence factors by the mutant. Nonetheless, the mutant survived like the parental bacteria for >2 weeks inside infected primary human macrophages and persisted within infected mouse lungs for a longer period than wild-type B. pertussis These observations suggest that downregulation of virulence factor production by bacteria internalized into host cells may enable persistence of the whooping cough agent in the airways.IMPORTANCE We show that a spontaneous mutation that upregulates transcription of an operon encoding ribosomal proteins and causes overproduction of the downstream-encoded α subunit (RpoA) of RNA polymerase causes global effects on gene expression levels and proteome composition of Bordetella pertussis Nevertheless, the resulting important downregulation of the BvgAS-controlled expression of virulence factors of the whooping cough agent did not compromise its capacity to persist for prolonged periods inside primary human macrophage cells, and it even enhanced its capacity to persist in infected mouse lungs. These observations suggest that the modulation of BvgAS-controlled expression of virulence factors may occur also during natural infections of human airways by Bordetella pertussis and may possibly account for long-term persistence of the pathogen within infected cells of the airways.
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Affiliation(s)
- Jakub Novák
- Laboratory of Molecular Biology of Bacterial Pathogens, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - David Jurnečka
- Laboratory of Molecular Biology of Bacterial Pathogens, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Irena Linhartová
- Laboratory of Molecular Biology of Bacterial Pathogens, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jana Holubová
- Laboratory of Molecular Biology of Bacterial Pathogens, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Ondřej Staněk
- Laboratory of Molecular Biology of Bacterial Pathogens, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Daniel Štipl
- Laboratory of Post-Transcriptional Control of Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Ana Dienstbier
- Laboratory of Post-Transcriptional Control of Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Branislav Večerek
- Laboratory of Post-Transcriptional Control of Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Nayara Azevedo
- Genomics Core Facility, European Molecular Biology Laboratory, Services and Technology Unit, Heidelberg, Germany
| | - Jan Provazník
- Genomics Core Facility, European Molecular Biology Laboratory, Services and Technology Unit, Heidelberg, Germany
| | - Vladimír Beneš
- Genomics Core Facility, European Molecular Biology Laboratory, Services and Technology Unit, Heidelberg, Germany
| | - Peter Šebo
- Laboratory of Molecular Biology of Bacterial Pathogens, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
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7
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Novak J, Fabrik I, Jurnecka D, Holubova J, Stanek O, Sebo P. Bordetella pertussis Acetylome is Shaped by Lysine Deacetylase Bkd1. J Proteome Res 2020; 19:3680-3696. [PMID: 32674575 DOI: 10.1021/acs.jproteome.0c00178] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Post-translational modifications of proteins enable swift physiological adaptation of cells to altered growth conditions and stress. Aside from protein phosphorylation, acetylation on ε-amino groups of lysine residues (N-ε-lysine acetylation) represents another important post-translational modification of proteins. For many bacterial pathogens, including the whooping cough agent Bordetella pertussis, the role and extent of protein acetylation remain to be defined. We expressed in Escherichia coli the BP0960 and BP3063 genes encoding two putative deacetylases of B. pertussis and show that BP0960 encodes a lysine deacetylase enzyme, named Bkd1, that regulates acetylation of a range of B. pertussis proteins. Comparison of the proteome and acetylome of a Δbkd1 mutant with the proteome and acetylome of wild-type B. pertussis (PRIDE ID. PXD016384) revealed that acetylation on lysine residues may modulate activities or stabilities of proteins involved in bacterial metabolism and histone-like proteins. However, increased acetylation of the BvgA response regulator protein of the B. pertussis master virulence-regulating BvgAS two-component system affected neither the total levels of produced BvgA nor its phosphorylation status. Indeed, the Δbkd1 mutant was not impaired in the production of key virulence factors and its survival within human macrophages in vitro was not affected. The Δbkd1 mutant exhibited an increased growth rate under carbon source-limiting conditions and its virulence in the in vivo mouse lung infection model was somewhat affected. These results indicate that the lysine deacetylase Bkd1 and N-ε-lysine acetylation primarily modulate the general metabolism rather than the virulence of B. pertussis.
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Affiliation(s)
- Jakub Novak
- Institute of Microbiology of the Czech Academy of Sciences, Prague 14220, Czech Republic.,Faculty of Science, Charles University, Prague 11636, Czech Republic
| | - Ivo Fabrik
- Biomedical Research Center, University Hospital Hradec Kralove, Hradec Kralove 50005, Czech Republic
| | - David Jurnecka
- Institute of Microbiology of the Czech Academy of Sciences, Prague 14220, Czech Republic.,Faculty of Science, Charles University, Prague 11636, Czech Republic
| | - Jana Holubova
- Institute of Microbiology of the Czech Academy of Sciences, Prague 14220, Czech Republic
| | - Ondrej Stanek
- Institute of Microbiology of the Czech Academy of Sciences, Prague 14220, Czech Republic
| | - Peter Sebo
- Institute of Microbiology of the Czech Academy of Sciences, Prague 14220, Czech Republic
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8
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Kilgore PE, Salim AM, Zervos MJ, Schmitt HJ. Pertussis: Microbiology, Disease, Treatment, and Prevention. Clin Microbiol Rev 2016; 29:449-86. [PMID: 27029594 PMCID: PMC4861987 DOI: 10.1128/cmr.00083-15] [Citation(s) in RCA: 226] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Pertussis is a severe respiratory infection caused by Bordetella pertussis, and in 2008, pertussis was associated with an estimated 16 million cases and 195,000 deaths globally. Sizeable outbreaks of pertussis have been reported over the past 5 years, and disease reemergence has been the focus of international attention to develop a deeper understanding of pathogen virulence and genetic evolution of B. pertussis strains. During the past 20 years, the scientific community has recognized pertussis among adults as well as infants and children. Increased recognition that older children and adolescents are at risk for disease and may transmit B. pertussis to younger siblings has underscored the need to better understand the role of innate, humoral, and cell-mediated immunity, including the role of waning immunity. Although recognition of adult pertussis has increased in tandem with a better understanding of B. pertussis pathogenesis, pertussis in neonates and adults can manifest with atypical clinical presentations. Such disease patterns make pertussis recognition difficult and lead to delays in treatment. Ongoing research using newer tools for molecular analysis holds promise for improved understanding of pertussis epidemiology, bacterial pathogenesis, bioinformatics, and immunology. Together, these advances provide a foundation for the development of new-generation diagnostics, therapeutics, and vaccines.
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Affiliation(s)
- Paul E Kilgore
- Department of Pharmacy Practice, Eugene Applebaum Collage of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan, USA Department of Family Medicine and Public Health Sciences, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Abdulbaset M Salim
- Department of Pharmacy Practice, Eugene Applebaum Collage of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan, USA
| | - Marcus J Zervos
- Division of Infectious Diseases, Department of Internal Medicine, Henry Ford Health System and Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Heinz-Josef Schmitt
- Medical and Scientific Affairs, Pfizer Vaccines, Paris, France Department of Pediatrics, Johannes Gutenberg-University, Mainz, Germany
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9
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Cherry JD, Paddock CD. Pathogenesis and histopathology of pertussis: implications for immunization. Expert Rev Vaccines 2014; 13:1115-23. [PMID: 24992986 DOI: 10.1586/14760584.2014.935766] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Pertussis is a unique infectious disease in that it can be severe and fatal but occurs without fever and other evidence of an inflammatory illness. The authors with others have studied the histopathology of fatal pertussis and also the unique characteristics of severe pertussis in young infants. Histopathologic observations from approximately 100 years ago, and from recent evaluation, indicate that the histopathologic changes of the upper respiratory tract of patients with fatal pertussis are often relatively normal unless there is a secondary bacterial infection. Bordetella pertussis contains many protein antigens and perhaps a polysaccharide capsule which contribute to the infectious process. However, only two of these antigens contribute to clinical illness. These antigens are pertussis toxin and the yet to be identified 'cough toxin'. The authors speculate as to the nature of the 'cough toxin' and discuss the implications of their observations and concepts for the future control of pertussis.
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Affiliation(s)
- James D Cherry
- Department of Pediatrics, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC 22-442, Los Angeles, CA 90095, USA
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10
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Abstract
Pertussis, also known as whooping cough, has recently re-emerged as a major public health threat despite high levels of vaccination against the aetiological agent Bordetella pertussis. In this Review, we describe the pathogenesis of this disease, with a focus on recent mechanistic insights into B. pertussis virulence-factor function. We also discuss the changing epidemiology of pertussis and the challenges facing vaccine development. Despite decades of research, many aspects of B. pertussis physiology and pathogenesis remain poorly understood. We highlight knowledge gaps that must be addressed to develop improved vaccines and therapeutic strategies.
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Mason E, Henderson MW, Scheller EV, Byrd MS, Cotter PA. Evidence for phenotypic bistability resulting from transcriptional interference of bvgAS in Bordetella bronchiseptica. Mol Microbiol 2013; 90:716-33. [PMID: 24007341 PMCID: PMC4216693 DOI: 10.1111/mmi.12394] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2013] [Indexed: 11/27/2022]
Abstract
Bordetella species cause respiratory infections in mammals. Their master regulatory system BvgAS controls expression of at least three distinct phenotypic phases in response to environmental cues. The Bvg⁺ phase is necessary and sufficient for respiratory infection while the Bvg⁻ phase is required for survival ex vivo. We obtained large colony variants (LCVs) from the lungs of mice infected with B. bronchiseptica strain RBX9, which contains an in-frame deletion mutation in fhaB, encoding filamentous haemagglutinin. RBX9 also yielded LCVs when switched from Bvg⁻ phase conditions to Bvg⁺ phase conditions in vitro. We determined that LCVs are composed of both Bvg⁺ and Bvg⁻ phase bacteria and that they result from defective bvgAS positive autoregulation. The LCV phenotype was linked to the presence of a divergent promoter 5' to bvgAS, suggesting a previously undescribed mechanism of transcriptional interference that, in this case, leads to feedback-based bistability (FBM). Our results also indicate that a small proportion of RBX9 bacteria modulates to the Bvg⁻ phase in vivo. In addition to providing insight into transcriptional interference and FBM, our data provide an example of an in-frame deletion mutation exerting a 'polar' effect on nearby genes.
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Affiliation(s)
- Eliza Mason
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7290, USA
| | - Michael W. Henderson
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7290, USA
| | - Erich V. Scheller
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7290, USA
| | - Matthew S. Byrd
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7290, USA
| | - Peggy A. Cotter
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7290, USA
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The Helicobacter pylori autotransporter ImaA (HP0289) modulates the immune response and contributes to host colonization. Infect Immun 2012; 80:2286-96. [PMID: 22566509 DOI: 10.1128/iai.00312-12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The human pathogen Helicobacter pylori employs a diverse collection of outer membrane proteins to colonize, persist, and drive disease within the acidic gastric environment. In this study, we sought to elucidate the function of the host-induced gene HP0289, which encodes an uncharacterized outer membrane protein. We first generated an isogenic H. pylori mutant that lacks HP0289 and found that the mutant has a colonization defect in single-strain infections and is greatly outcompeted in mouse coinfection experiments with wild-type H. pylori. Furthermore, we used protease assays and biochemical fractionation coupled with an HP0289-targeted peptide antibody to verify that the HP0289 protein resides in the outer membrane. Our previous findings showed that the HP0289 promoter is upregulated in the mouse stomach, and here we demonstrate that HP0289 expression is induced under acidic conditions in an ArsRS-dependent manner. Finally, we have shown that the HP0289 mutant induces greater expression of the chemokine interleukin-8 (IL-8) and the cytokine tumor necrosis factor alpha (TNF-α) in gastric carcinoma cells (AGS). Similarly, transcription of the IL-8 homolog keratinocyte-derived chemokine (KC) is elevated in murine infections with the HP0289 mutant than in murine infections with wild-type H. pylori. On the basis of this phenotype, we renamed HP0289 ImaA for immunomodulatory autotransporter protein. Our work has revealed that genes induced in vivo play an important role in H. pylori pathogenesis. Specifically, the outer membrane protein ImaA modulates a component of the host inflammatory response, and thus may allow H. pylori to fine tune the host immune response based on ImaA expression.
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13
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A novel sensor kinase is required for Bordetella bronchiseptica to colonize the lower respiratory tract. Infect Immun 2011; 79:3216-28. [PMID: 21606184 DOI: 10.1128/iai.00005-11] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Bacterial virulence is influenced by the activity of two-component regulator systems (TCSs), which consist of membrane-bound sensor kinases that allow bacteria to sense the external environment and cytoplasmic, DNA-binding response regulator proteins that control appropriate gene expression. Respiratory pathogens of the Bordetella genus require the well-studied TCS BvgAS to control the expression of many genes required for colonization of the mammalian respiratory tract. Here we describe the identification of a novel gene in Bordetella bronchiseptica, plrS, the product of which shares sequence homology to several NtrY-family sensor kinases and is required for B. bronchiseptica to colonize and persist in the lower, but not upper, respiratory tract in rats and mice. The plrS gene is located immediately 5' to and presumably cotranscribed with a gene encoding a putative response regulator, supporting the idea that PlrS and the product of the downstream gene may compose a TCS. Consistent with this hypothesis, the PlrS-dependent colonization phenotype requires a conserved histidine that serves as the site of autophosphorylation in other sensor kinases, and in strains lacking plrS, the production and/or cellular localization of several immune-recognized proteins is altered in comparison to that in the wild-type strain. Because plrS is required for colonization and persistence only in the lower respiratory tract, a site where innate and adaptive immune mechanisms actively target infectious agents, we hypothesize that its role may be to allow Bordetella to resist the host immune response.
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