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Hooks GM, Ayala JC, Holley CL, Dhulipala V, Beggs GA, Perfect JR, Schumacher MA, Shafer WM, Brennan RG. Hormonal steroids induce multidrug resistance and stress response genes in Neisseria gonorrhoeae by binding to MtrR. Nat Commun 2024; 15:1153. [PMID: 38326294 PMCID: PMC10850145 DOI: 10.1038/s41467-024-45195-1] [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: 08/30/2023] [Accepted: 01/16/2024] [Indexed: 02/09/2024] Open
Abstract
Transcriptional regulator MtrR inhibits the expression of the multidrug efflux pump operon mtrCDE in the pathogenic bacterium Neisseria gonorrhoeae. Here, we show that MtrR binds the hormonal steroids progesterone, β-estradiol, and testosterone, which are present at urogenital infection sites, as well as ethinyl estrogen, a component of some hormonal contraceptives. Steroid binding leads to the decreased affinity of MtrR for cognate DNA, increased mtrCDE expression, and enhanced antimicrobial resistance. Furthermore, we solve crystal structures of MtrR bound to each steroid, thus revealing their binding mechanisms and the conformational changes that induce MtrR.
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Affiliation(s)
- Grace M Hooks
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Julio C Ayala
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, USA
- STD Laboratory Reference and Research Branch, Division of STD Prevention, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Concerta L Holley
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, USA
| | - Vijaya Dhulipala
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, USA
| | - Grace A Beggs
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - John R Perfect
- Division of Infectious Diseases, Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Maria A Schumacher
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - William M Shafer
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, USA
- Laboratories of Microbial Pathogenesis, VA Medical Research Service, Veterans Affairs Medical Center, Decatur, GA, USA
- Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Richard G Brennan
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA.
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2
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Vashishtha S, Thakur S, Singh J, Adhana S, Kundu B. Evolutionarily conserved heat shock protein, HtpX, as an adjunct target against antibiotic-resistant Neisseria gonorrhoeae. J Cell Biochem 2023; 124:1516-1529. [PMID: 37566682 DOI: 10.1002/jcb.30461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 07/09/2023] [Accepted: 07/31/2023] [Indexed: 08/13/2023]
Abstract
The emergence of multiple drug resistance and extreme drug resistance pathogens necessitates the continuous evaluation of the pathogenic genome to identify conserved molecular targets and their respective inhibitors. In this study, we mapped the global mutational landscape of Neisseria gonorrhoeae (an intracellular pathogen notoriously known to cause the sexually transmitted disease gonorrhoea). We identified highly variable amino acid positions in the antibiotic target genes like the penA, ponA, 23s rRNA, rpoB, gyrA, parC, mtrR and porB. Some variations are directly reported to confer resistance to the currently used front-line drugs like ceftriaxone, cefixime, azithromycin and ciprofloxacin. Further, by whole genome comparison and Shannon entropy analysis, we identified a completely conserved protein HtpX in the drug-resistant as well as susceptible isolates of N. gonorrhoeae (NgHtpX). Comparison with the only available information of Escherichia coli HtpX suggested it to be a transmembrane metalloprotease having a role in stress response. The critical zinc-binding residue of NgHtpX was mapped to E141. By applying composite high throughput screening followed by MD simulations, we identified pemirolast and thalidomide as high-energy binding ligands of NgHtpX. Following cloning and expression of the purified metal-binding domain of NgHtpX (NgHtpXd), its Zn2+ -binding (Kd = 0.4 µM) and drug-binding (pemirolast, Kd = 3.47 µM; and thalidomide, Kd = 1.04 µM) potentials were determined using in-vitro fluorescence quenching experiment. When tested on N. gonorrhoeae cultures, both the ligands imposed a dose-dependent reduction in viability. Overall, our results provide high entropy positions in the targets of presently used antibiotics, which can be further explored to understand the AMR mechanism. Additionally, HtpX and its specific inhibitors identified can be utilised effectively in managing gonococcal infections.
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Affiliation(s)
- Shubham Vashishtha
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
| | - Sheetal Thakur
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
| | - Jasdeep Singh
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, New Delhi, India
| | - Sujata Adhana
- Department of Biomedical Sciences, Bhaskaracharya College of Applied Sciences, University of Delhi, New Delhi, India
| | - Bishwajit Kundu
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
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3
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Markota A, Kalamar Ž, Fluher J, Pirkmajer S. Therapeutic hyperthermia for the treatment of infection-a narrative review. Front Physiol 2023; 14:1215686. [PMID: 37565142 PMCID: PMC10410565 DOI: 10.3389/fphys.2023.1215686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 07/14/2023] [Indexed: 08/12/2023] Open
Abstract
Modulating body temperature, mostly through the use of antipyretics, is a commonly employed therapeutic intervention in medical practice. However, emerging evidence suggests that hyperthermia could serve as an adjuvant therapy for patients with infection. We performed a narrative review to explore the application of therapeutic hyperthermia in the treatment of infection. A number of studies have been performed in the pre-antibiotic era, enrolling patients with neurosyphilis and gonococcal infections, with reported cure rates at around 60%-80%. We have outlined the potential molecular and immunological mechanisms explaining the possible beneficial effects of therapeutic hyperthermia. For some pathogens increased temperature exerts a direct negative effect on virulence; however, it is presumed that temperature driven activation of the immune system is probably the most important factor affecting microbial viability. Lastly, we performed a review of modern-era studies where modulation of body temperature has been used as a treatment strategy. In trials of therapeutic hypothermia in patients with infection worse outcomes have been observed in the hypothermia group. Use of antipyretics has not been associated with any improvement in clinical outcomes. In modern-era therapeutic hyperthermia achieved by physical warming has been studied in one pilot trial, and better survival was observed in the hyperthermia group. To conclude, currently there is not enough data to support the use of therapeutic hyperthermia outside clinical trials; however, available studies are in favor of at least a temperature tolerance strategy for non-neurocritical patients.
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Affiliation(s)
- Andrej Markota
- Medical Intensive Care Unit, University Medical Centre Maribor, Maribor, Slovenia
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Žiga Kalamar
- Medical Intensive Care Unit, University Medical Centre Maribor, Maribor, Slovenia
| | - Jure Fluher
- Medical Intensive Care Unit, University Medical Centre Maribor, Maribor, Slovenia
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
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4
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The Pseudomonas aeruginosa RpoH (σ 32) Regulon and Its Role in Essential Cellular Functions, Starvation Survival, and Antibiotic Tolerance. Int J Mol Sci 2023; 24:ijms24021513. [PMID: 36675051 PMCID: PMC9866376 DOI: 10.3390/ijms24021513] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 12/23/2022] [Accepted: 01/10/2023] [Indexed: 01/15/2023] Open
Abstract
The bacterial heat-shock response is regulated by the alternative sigma factor, σ32 (RpoH), which responds to misfolded protein stress and directs the RNA polymerase to the promoters for genes required for protein refolding or degradation. In P. aeruginosa, RpoH is essential for viability under laboratory growth conditions. Here, we used a transcriptomics approach to identify the genes of the RpoH regulon, including RpoH-regulated genes that are essential for P. aeruginosa. We placed the rpoH gene under control of the arabinose-inducible PBAD promoter, then deleted the chromosomal rpoH allele. This allowed transcriptomic analysis of the RpoH (σ32) regulon following a short up-shift in the cellular concentration of RpoH by arabinose addition, in the absence of a sudden change in temperature. The P. aeruginosa ∆rpoH (PBAD-rpoH) strain grew in the absence of arabinose, indicating that some rpoH expression occurred without arabinose induction. When arabinose was added, the rpoH mRNA abundance of P. aeruginosa ∆rpoH (PBAD-rpoH) measured by RT-qPCR increased five-fold within 15 min of arabinose addition. Transcriptome results showed that P. aeruginosa genes required for protein repair or degradation are induced by increased RpoH levels, and that many genes essential for P. aeruginosa growth are induced by RpoH. Other stress response genes induced by RpoH are involved in damaged nucleic acid repair and in amino acid metabolism. Annotation of the hypothetical proteins under RpoH control included proteins that may play a role in antibiotic resistances and in non-ribosomal peptide synthesis. Phenotypic analysis of P. aeruginosa ∆rpoH (PBAD-rpoH) showed that it is impaired in its ability to survive during starvation compared to the wild-type strain. P. aeruginosa ∆rpoH (PBAD-rpoH) also had increased sensitivity to aminoglycoside antibiotics, but not to other classes of antibiotics, whether cultured planktonically or in biofilms. The enhanced aminoglycoside sensitivity of the mutant strain may be due to indirect effects, such as the build-up of toxic misfolded proteins, or to the direct effect of genes, such as aminoglycoside acetyl transferases, that are regulated by RpoH. Overall, the results demonstrate that RpoH regulates genes that are essential for viability of P. aeruginosa, that it protects P. aeruginosa from damage from aminoglycoside antibiotics, and that it is required for survival during nutrient-limiting conditions.
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Liu H, Knox CA, Jakkula LUMR, Wang Y, Peddireddi L, Ganta RR. Evaluating EcxR for Its Possible Role in Ehrlichia chaffeensis Gene Regulation. Int J Mol Sci 2022; 23:12719. [PMID: 36361509 PMCID: PMC9657007 DOI: 10.3390/ijms232112719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/17/2022] [Accepted: 10/19/2022] [Indexed: 04/14/2024] Open
Abstract
Ehrlichia chaffeensis, a tick-transmitted intraphagosomal bacterium, is the causative agent of human monocytic ehrlichiosis. The pathogen also infects several other vertebrate hosts. E. chaffeensis has a biphasic developmental cycle during its growth in vertebrate monocytes/macrophages and invertebrate tick cells. Host- and vector-specific differences in the gene expression from many genes of E. chaffeensis are well documented. It is unclear how the organism regulates gene expression during its developmental cycle and for its adaptation to vertebrate and tick host cell environments. We previously mapped promoters of several E. chaffeensis genes which are recognized by its only two sigma factors: σ32 and σ70. In the current study, we investigated in assessing five predicted E. chaffeensis transcription regulators; EcxR, CtrA, MerR, HU and Tr1 for their possible roles in regulating the pathogen gene expression. Promoter segments of three genes each transcribed with the RNA polymerase containing σ70 (HU, P28-Omp14 and P28-Omp19) and σ32 (ClpB, DnaK and GroES/L) were evaluated by employing multiple independent molecular methods. We report that EcxR binds to all six promoters tested. Promoter-specific binding of EcxR to several gene promoters results in varying levels of gene expression enhancement. This is the first detailed molecular characterization of transcription regulators where we identified EcxR as a gene regulator having multiple promoter-specific interactions.
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Affiliation(s)
| | | | | | | | | | - Roman R. Ganta
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA
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6
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Ayala JC, Balthazar JT, Shafer WM. Transcriptional regulation of the mtrCDE efflux pump operon: importance for Neisseria gonorrhoeae antimicrobial resistance. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35916832 DOI: 10.1099/mic.0.001231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This review focuses on the mechanisms of transcriptional control of an important multidrug efflux pump system (MtrCDE) possessed by Neisseria gonorrhoeae, the aetiological agent of the sexually transmitted infection termed gonorrhoea. The mtrCDE operon that encodes this tripartite protein efflux pump is subject to both cis- and trans-acting transcriptional factors that negatively or positively influence expression. Critically, levels of MtrCDE can influence levels of gonococcal susceptibility to classical antibiotics, host-derived antimicrobials and various biocides. The regulatory systems that control mtrCDE can have profound influences on the capacity of gonococci to resist current and past antibiotic therapy regimens as well as virulence. The emergence, mechanisms of action and clinical significance of the transcriptional regulatory systems that impact mtrCDE expression in gonococci are reviewed here with the aim of linking bacterial antimicrobial resistance with multidrug efflux capability.
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Affiliation(s)
- Julio C Ayala
- Department of Microbiology and Immunology Emory University School of Medicine, Atlanta, Georgia, 30322, USA
| | - Jacqueline T Balthazar
- Department of Microbiology and Immunology Emory University School of Medicine, Atlanta, Georgia, 30322, USA
| | - William M Shafer
- Department of Microbiology and Immunology Emory University School of Medicine, Atlanta, Georgia, 30322, USA.,Laboratories of Bacterial Pathogenesis, VA Medical Center (Atlanta), Decatur, Georgia, 30033, USA.,The Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, Georgia, USA
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7
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Freitas C, Glatter T, Ringgaard S. Specific proteomic adaptation to distinct environments in Vibrio parahaemolyticus includes significant fluctuations in expression of essential proteins. Environ Microbiol 2020; 22:4279-4294. [PMID: 32219943 DOI: 10.1111/1462-2920.14997] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/11/2020] [Accepted: 03/22/2020] [Indexed: 11/28/2022]
Abstract
Bacteria constantly experience changes to their external milieu and need to adapt accordingly to ensure their survival. Certain bacteria adapt by means of cellular differentiation, resulting in the development of a specific cell type that is specialized for life in a distinct environment. Furthermore, to understand how bacteria adapt, it is essential to appreciate the significant changes that occur at the proteomic level. By analysing the proteome of our model organism Vibrio parahaemolyticus from distinct environmental conditions and cellular differential states, we demonstrate that the proteomic expression profile is highly flexible, which likely allows it to adapt to life in different environmental conditions and habitats. We show that, even within the same swarm colony, there are specific zones of cells with distinct expression profiles. Furthermore, our data indicate that cell surface attachment and swarmer cell differentiation are distinct programmes that require specific proteomic expression profiles. This likely allows V. parahaemolyticus to adapt to life in different environmental conditions and habitats. Finally, our analyses reveal that the expression profile of the essential protein pool is highly fluid, with significant fluctuations that dependent on the specific life-style, environment and differentiation state of the bacterium.
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Affiliation(s)
- Carolina Freitas
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, 35043, Germany
| | - Timo Glatter
- Core Facility for Mass Spectrometry and Proteomics, Max Planck Institute for Terrestrial Microbiology, Marburg, 35043, Germany
| | - Simon Ringgaard
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, 35043, Germany
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Contribution of σ 70 and σ N Factors to Expression of Class II pilE in Neisseria meningitidis. J Bacteriol 2019; 201:JB.00170-19. [PMID: 31331980 PMCID: PMC6755734 DOI: 10.1128/jb.00170-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Accepted: 07/16/2019] [Indexed: 02/06/2023] Open
Abstract
Neisseria meningitidis expresses multicomponent organelles called type four pili (Tfp), which are key virulence factors required for attachment to human cells during carriage and disease. Pilin (PilE) is the main component of Tfp, and N. meningitidis isolates either have a class I pilE locus and express pilins that undergo antigenic variation or have a class II pilE locus and express invariant pilins. The transcriptional regulation of class I pilE has been studied in both N. meningitidis and Neisseria gonorrhoeae, while the control of expression of class II pilE has been elucidated in the nonpathogenic species Neisseria elongata However, the factors that govern the regulation of the class II pilE gene in N. meningitidis are not known. In this work, we have bioinformatically and experimentally identified the class II pilE promoter. We confirmed the presence of conserved σ70 and σN-dependent promoters upstream of pilE in a collection of meningococcal genomes and demonstrated that class II pilE expression initiates from the σ70 family-dependent promoter. By deletion or overexpression of sigma factors, we showed that σN, σH, and σE do not affect class II pilin expression. These findings are consistent with a role of the housekeeping σD in expression of this important component of Tfp. Taken together, our data indicate that the σ-dependent network responsible for the expression of class II pilE has been selected to maintain pilE expression, consistent with the essential roles of Tfp in colonization and pathogenesis.IMPORTANCE The type four pilus (Tfp) of Neisseria meningitidis contributes to fundamental processes such as adhesion, transformation, and disease pathology. Meningococci express one of two distinct classes of Tfp (class I or class II), which can be distinguished antigenically or by the major subunit (pilE) locus and its genetic context. The factors that govern transcription of the class II pilE gene are not known, even though it is present in isolates that cause epidemic disease. Here we show that the transcription of class II pilE is maintained throughout growth and under different stress conditions and is driven by a σ70-dependent promoter. This is distinct from Tfp regulation in nonpathogenic Neisseria spp. and may confer an advantage during host-cell interaction and infection.
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Liu H, Ganta RR. Sequence Determinants Spanning -10 Motif and Spacer Region Implicated in Unique Ehrlichia chaffeensis Sigma 32-Dependent Promoter Activity of dnaK Gene. Front Microbiol 2019; 10:1772. [PMID: 31428069 PMCID: PMC6687850 DOI: 10.3389/fmicb.2019.01772] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 07/18/2019] [Indexed: 11/21/2022] Open
Abstract
Ehrlichia chaffeensis is an obligate intracellular tick-borne bacterium that causes human monocytic ehrlichiosis. Studying Ehrlichia gene regulation is challenge, as this and related rickettsiales lack natural plasmids and mutagenesis experiments are of a limited scope. E. chaffeensis contains only two sigma factors, σ32 and σ70. We previously developed Escherichia coli surrogate system to study transcriptional regulation from RNA polymerase (RNAP) containing Ehrlichia σ32 or σ70. We reported that RNAP binding motifs of E. chaffeensis genes recognized by σ32 or σ70 share extensive homology and that transcription may be initiated by either one of the sigma factors, although transcriptional efficiencies differ. In the current study, we investigated mapping the E. chaffeensis dnaK gene promoter using the pathogen σ32 expressed in E. coli lacking its native σ32. The E. coli surrogate system and our previously described in vitro transcription system aided in defining the unique −10 motif and spacer sequence of the dnaK promoter. We also mapped σ32 amino acids/domains engaged in its promoter regulation in E. chaffeensis. The data reported in this study demonstrate that the −10 and −35 motifs and spacer sequence located between the two motifs of dnaK promoter are critical for the RNAP function. Further, we mapped the importance of all six nucleotide positions of the −10 motif and identified critical determinants within it. In addition, we reported that the lack of C-rich sequence upstream to the −10 motif is unique in driving the pathogen-specific transcription by its σ32 from dnaK gene promoter. This is the first study in defining an E. chaffeensis σ32-dependent promoter and it offers insights about how this and other related rickettsial pathogens regulate stress response genes.
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Affiliation(s)
- Huitao Liu
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, United States
| | - Roman R Ganta
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, United States
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10
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Quillin SJ, Hockenberry AJ, Jewett MC, Seifert HS. Neisseria gonorrhoeae Exposed to Sublethal Levels of Hydrogen Peroxide Mounts a Complex Transcriptional Response. mSystems 2018; 3:e00156-18. [PMID: 30320218 PMCID: PMC6172773 DOI: 10.1128/msystems.00156-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 08/17/2018] [Indexed: 01/13/2023] Open
Abstract
Neisseria gonorrhoeae mounts a substantial transcriptional program in response to hydrogen peroxide (HP), a prominent reactive oxygen species (ROS) encountered during infection. We tested which strain FA1090 genes show differential transcript abundance in response to sublethal amounts of HP to differentiate HP-responsive signaling from widespread cellular death and dysregulation. RNA sequencing (RNA-Seq) revealed that 150 genes were significantly upregulated and 143 genes downregulated following HP exposure. We annotated HP-responsive operons and all transcriptional start sites (TSSs) and identified which TSSs responded to HP treatment. We compared the HP responses and other previously reported genes and found only partial overlapping of other regulatory networks, indicating that the response to HP involves multiple biological functions. Using a representative subset of responsive genes, we validated the RNA-Seq results and found that the HP transcriptome was similar to that of sublethal organic peroxide. None of the genes in the representative subset, however, responded to sublethal levels of HOCl or O2 -. These results support the idea that N. gonorrhoeae may use variations in HP levels as a signal for different stages of infection. IMPORTANCE The strict human pathogen Neisseria gonorrhoeae is the only causative agent of the sexually transmitted disease gonorrhea. This bacterium encounters hydrogen peroxide produced from host cells during infection, but the organism survives in the presence of this antimicrobial agent. This work shows that the bacterium responds to hydrogen peroxide by regulating the expression of many genes involved in multiple processes.
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Affiliation(s)
- Sarah J. Quillin
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Adam J. Hockenberry
- Center for Synthetic Biology, Northwestern University, Evanston, Illinois, USA
- Interdisciplinary Program in Biological Sciences, Northwestern University, Evanston, Illinois, USA
| | - Michael C. Jewett
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois, USA
- Center for Synthetic Biology, Northwestern University, Evanston, Illinois, USA
- Interdisciplinary Program in Biological Sciences, Northwestern University, Evanston, Illinois, USA
| | - H Steven Seifert
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
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11
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Deo P, Chow SH, Hay ID, Kleifeld O, Costin A, Elgass KD, Jiang JH, Ramm G, Gabriel K, Dougan G, Lithgow T, Heinz E, Naderer T. Outer membrane vesicles from Neisseria gonorrhoeae target PorB to mitochondria and induce apoptosis. PLoS Pathog 2018; 14:e1006945. [PMID: 29601598 PMCID: PMC5877877 DOI: 10.1371/journal.ppat.1006945] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 02/21/2018] [Indexed: 01/31/2023] Open
Abstract
Neisseria gonorrhoeae causes the sexually transmitted disease gonorrhoea by evading innate immunity. Colonizing the mucosa of the reproductive tract depends on the bacterial outer membrane porin, PorB, which is essential for ion and nutrient uptake. PorB is also targeted to host mitochondria and regulates apoptosis pathways to promote infections. How PorB traffics from the outer membrane of N. gonorrhoeae to mitochondria and whether it modulates innate immune cells, such as macrophages, remains unclear. Here, we show that N. gonorrhoeae secretes PorB via outer membrane vesicles (OMVs). Purified OMVs contained primarily outer membrane proteins including oligomeric PorB. The porin was targeted to mitochondria of macrophages after exposure to purified OMVs and wild type N. gonorrhoeae. This was associated with loss of mitochondrial membrane potential, release of cytochrome c, activation of apoptotic caspases and cell death in a time-dependent manner. Consistent with this, OMV-induced macrophage death was prevented with the pan-caspase inhibitor, Q-VD-PH. This shows that N. gonorrhoeae utilizes OMVs to target PorB to mitochondria and to induce apoptosis in macrophages, thus affecting innate immunity. Neisseria gonorrhoeae causes the sexually transmitted disease gonorrhoea in more than 100 million people worldwide every year. The bacteria replicate in the reproductive tract by evading innate and adaptive immunity. In the absence of effective vaccines and the rise of antibiotic resistance, understanding the molecular interactions between innate immune cells and N. gonorrhoeae may lead to new strategies to combat bacterial growth and the symptoms of gonorrhoea. It has long been known that the N. gonorrhoeae porin, PorB, promotes bacterial survival but also targets host mitochondria in infections. The mechanism by which PorB traffics form the bacterial outer membrane to host mitochondria remains unclear. Here, we utilized proteomics and super-resolution microscopy to show that N. gonorrhoeae secretes PorB via outer membrane vesicles. These vesicles are taken up by macrophages and deliver PorB to mitochondria. Macrophages treated with N. gonorrhoeae vesicles contained damaged mitochondria and active caspase-3. A caspase inhibitor prevented apoptosis of macrophages treated with N. gonorrhoeae vesicles. This suggests that N. gonorrhoeae secretes membrane vesicles, which are readily detectable in gonorrhoea patients, to target macrophages and to promote infections.
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Affiliation(s)
- Pankaj Deo
- Biomedicine Discovery Institute and Department of Biochemistry & Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Seong H Chow
- Biomedicine Discovery Institute and Department of Biochemistry & Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Iain D Hay
- Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Oded Kleifeld
- Biomedicine Discovery Institute and Department of Biochemistry & Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Adam Costin
- Monash Ramaciotti Centre for Cryo Electron Microscopy, Monash University, Clayton, Victoria, Australia
| | - Kirstin D Elgass
- Monash Micro Imaging, Monash University, Clayton, Victoria, Australia
| | - Jhih-Hang Jiang
- Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Georg Ramm
- Biomedicine Discovery Institute and Department of Biochemistry & Molecular Biology, Monash University, Clayton, Victoria, Australia.,Monash Ramaciotti Centre for Cryo Electron Microscopy, Monash University, Clayton, Victoria, Australia
| | - Kipros Gabriel
- Biomedicine Discovery Institute and Department of Biochemistry & Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Gordon Dougan
- Infection Genomics Program, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Trevor Lithgow
- Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Eva Heinz
- Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, Australia.,Infection Genomics Program, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Thomas Naderer
- Biomedicine Discovery Institute and Department of Biochemistry & Molecular Biology, Monash University, Clayton, Victoria, Australia
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Abstract
The host-adapted human pathogen Neisseria gonorrhoeae is the causative agent of gonorrhoea. Consistent with its proposed evolution from an ancestral commensal bacterium, N. gonorrhoeae has retained features that are common in commensals, but it has also developed unique features that are crucial to its pathogenesis. The continued worldwide incidence of gonorrhoeal infection, coupled with the rising resistance to antimicrobials and the difficulties in controlling the disease in developing countries, highlights the need to better understand the molecular basis of N. gonorrhoeae infection. This knowledge will facilitate disease prevention, surveillance and control, improve diagnostics and may help to facilitate the development of effective vaccines or new therapeutics. In this Review, we discuss sex-related symptomatic gonorrhoeal disease and provide an overview of the bacterial factors that are important for the different stages of pathogenesis, including transmission, colonization and immune evasion, and we discuss the problem of antibiotic resistance.
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Affiliation(s)
- Sarah Jane Quillin
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
| | - H Steven Seifert
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
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Gangaiah D, Raterman EL, Wu H, Fortney KR, Gao H, Liu Y, Jerse AE, Spinola SM. Both MisR (CpxR) and MisS (CpxA) Are Required for Neisseria gonorrhoeae Infection in a Murine Model of Lower Genital Tract Infection. Infect Immun 2017; 85:e00307-17. [PMID: 28652307 PMCID: PMC5563589 DOI: 10.1128/iai.00307-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Accepted: 06/17/2017] [Indexed: 12/29/2022] Open
Abstract
During infection, Neisseria gonorrhoeae senses and responds to stress; such responses may be modulated by MisRS (NGO0177 and NGO0176), a two-component system that is a homolog of CpxRA. In Escherichia coli, CpxRA senses and responds to envelope stress; CpxA is a sensor kinase/phosphatase for CpxR, a response regulator. When a cpxA mutant is grown in medium containing glucose, CpxR is phosphorylated by acetyl phosphate but cannot be dephosphorylated, resulting in constitutive activation. Kandler and coworkers (J. L. Kandler, C. L. Holley, J. L. Reimche, V. Dhulipala, J. T. Balthazar, A. Muszyński, R. W. Carlson, and W. M. Shafer, Antimicrob Agents Chemother 60:4690-4700, 2016, https://doi.org/10.1128/AAC.00823-16) showed that MisR (CpxR) is required for the maintenance of membrane integrity and resistance to antimicrobial peptides, suggesting a role in gonococcal survival in vivo Here, we evaluated the contributions of MisR and MisS (CpxA) to gonococcal infection in a murine model of cervicovaginal colonization and identified MisR-regulated genes using RNA sequencing (RNA-Seq). The deletion of misR or misS severely reduced the capacity of N. gonorrhoeae to colonize mice or maintain infection over a 7-day period and reduced microbial fitness after exposure to heat shock. Compared to the wild type (WT), the inactivation of misR identified 157 differentially regulated genes, most of which encoded putative envelope proteins. The inactivation of misS identified 17 differentially regulated genes compared to the WT and 139 differentially regulated genes compared to the misR mutant, 111 of which overlapped those differentially expressed in the comparison of the WT versus the misR mutant. These data indicate that an intact MisRS system is required for gonococcal infection of mice. Provided the MisR is constitutively phosphorylated in the misS mutant, the data suggest that controlled but not constitutive activation is required for gonococcal infection in mice.
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Affiliation(s)
- Dharanesh Gangaiah
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Erica L Raterman
- Department of Microbiology and Immunology, F. Edward Herbert School of Medicine, Uniformed Services University, Bethesda, Maryland, USA
| | - Hong Wu
- Department of Microbiology and Immunology, F. Edward Herbert School of Medicine, Uniformed Services University, Bethesda, Maryland, USA
| | - Kate R Fortney
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Hongyu Gao
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Yunlong Liu
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Ann E Jerse
- Department of Microbiology and Immunology, F. Edward Herbert School of Medicine, Uniformed Services University, Bethesda, Maryland, USA
| | - Stanley M Spinola
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Kenyon LJ, Meulia T, Sabree ZL. Habitat visualization and genomic analysis of "Candidatus Pantoea carbekii," the primary symbiont of the brown marmorated stink bug. Genome Biol Evol 2015; 7:620-35. [PMID: 25587021 PMCID: PMC4350177 DOI: 10.1093/gbe/evv006] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Phytophagous pentatomid insects can negatively impact agricultural productivity and the brown marmorated stink bug (Halyomorpha halys) is an emerging invasive pest responsible for damage to many fruit crops and ornamental plants in North America. Many phytophagous stink bugs, including H. halys, harbor gammaproteobacterial symbionts that likely contribute to host development, and characterization of symbiont transmission/acquisition and their contribution to host fitness may offer alternative strategies for managing pest species. “Candidatus Pantoea carbekii” is the primary occupant of gastric ceca lumina flanking the distal midgut of H. halys insects and it is acquired each generation when nymphs feed on maternal extrachorion secretions following hatching. Insects prevented from symbiont uptake exhibit developmental delays and aberrant behaviors. To infer contributions of Ca. P. carbekii to H. halys, the complete genome was sequenced and annotated from a North American H. halys population. Overall, the Ca. P. carbekii genome is nearly one-fourth (1.2 Mb) that of free-living congenerics, and retains genes encoding many functions that are potentially host-supportive. Gene content reflects patterns of gene loss/retention typical of intracellular mutualists of plant-feeding insects. Electron and fluorescence in situ microscopic imaging of H. halys egg surfaces revealed that maternal extrachorion secretions were populated with Ca. P. carbekii cells. The reported findings detail a transgenerational mode of symbiont transmission distinct from that observed for intracellular insect mutualists and illustrate the potential additive functions contributed by the bacterial symbiont to this important agricultural pest.
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Affiliation(s)
- Laura J Kenyon
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University
| | - Tea Meulia
- Molecular and Cellular Imaging Center, Ohio Agricultural Research and Development Center and the Department of Plant Pathology, The Ohio State University
| | - Zakee L Sabree
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University
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15
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Purification and biochemical characterization of DnaK and its transcriptional activator RpoH from Neisseria gonorrhoeae. Mol Biol Rep 2014; 41:7945-53. [PMID: 25156536 DOI: 10.1007/s11033-014-3689-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Accepted: 08/21/2014] [Indexed: 10/24/2022]
Abstract
DnaK plays a central role in stress response in the important human pathogen Neisseria gonorrhoeae. The genes encoding the DnaK chaperone machine (DnaK/DnaJ/GrpE) in N. gonorrhoeae are transcribed from RpoH (σ(32))-dependent promoters. In this study, we cloned, purified and biochemically characterised N. gonorrhoeae DnaK (NgDnaK) and RpoH. The NgDnaK and RpoH sequences are 73 and 50 % identical to the sequences of their respective E. coli counterparts. Similar to EcDnaK, nucleotide-free NgDnaK exists as a mix of monomers, dimers and higher oligomeric species in solution, and dissociates into monomers on addition of ATP. Like E. coli σ(32), RpoH of N. gonorrhoeae is monomeric in solution. Kinetic analysis of the basal ATPase activity of purified NgDnaK revealed a V max of 193 pmol phosphate released per minute per microgram DnaK (which is significantly higher than reported basal ATPase activity of EcDnaK), and the turnover number against ATP was 0.4 min(-1) under our assay conditions. Nucleotide-free NgDnaK bound a short model substrate, NR-peptide, with micromolar affinity close to that reported for EcDnaK. Our analysis showed that interaction between N. gonorrhoeae RpoH and DnaK appears to be ATP-dependent and non-specific, in stark contrast to the E. coli DnaK system where σ(32) and DnaK interact as monomers even in the absence of ATP. Sequence comparison showed that the DnaK-binding site of σ(32) is not conserved in RpoH. Our findings suggest that the mechanism of DnaK/RpoH recognition in N. gonorrhoeae is different from that in E. coli.
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16
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Transcription of Ehrlichia chaffeensis genes is accomplished by RNA polymerase holoenzyme containing either sigma 32 or sigma 70. PLoS One 2013; 8:e81780. [PMID: 24278458 PMCID: PMC3836757 DOI: 10.1371/journal.pone.0081780] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 10/22/2013] [Indexed: 11/19/2022] Open
Abstract
Bacterial gene transcription is initiated by RNA polymerase containing a sigma factor. To understand gene regulation in Ehrlichia chaffeensis, an important tick-transmitted rickettsiae responsible for human monocytic ehrlichiosis, we initiated studies evaluating the transcriptional machinery of several genes of this organism. We mapped the transcription start sites of 10 genes and evaluated promoters of five genes (groE, dnaK, hup, p28-Omp14 and p28-Omp19 genes). We report here that the RNA polymerase binding elements of E. chaffeensis gene promoters are highly homologous for its only two transcription regulators, sigma 32 and sigma 70, and that gene expression is accomplished by either of the transcription regulators. RNA analysis revealed that although transcripts for both sigma 32 and sigma 70 are upregulated during the early replicative stage, their expression patterns remained similar for the entire replication cycle. We further present evidence demonstrating that the organism’s -35 motifs are essential to transcription initiations. The data suggest that E. chaffeensis gene regulation has evolved to support the organism’s growth, possibly to facilitate its intraphagosomal growth. Considering the limited availability of genetic tools, this study offers a novel alternative in defining gene regulation in E. chaffeensis and other related intracellular pathogens.
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Piek S, Kahler CM. A comparison of the endotoxin biosynthesis and protein oxidation pathways in the biogenesis of the outer membrane of Escherichia coli and Neisseria meningitidis. Front Cell Infect Microbiol 2012; 2:162. [PMID: 23267440 PMCID: PMC3526765 DOI: 10.3389/fcimb.2012.00162] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 12/01/2012] [Indexed: 01/13/2023] Open
Abstract
The Gram-negative bacterial cell envelope consists of an inner membrane (IM) that surrounds the cytoplasm and an asymmetrical outer-membrane (OM) that forms a protective barrier to the external environment. The OM consists of lipopolysaccahride (LPS), phospholipids, outer membrane proteins (OMPs), and lipoproteins. Oxidative protein folding mediated by periplasmic oxidoreductases is required for the biogenesis of the protein components, mainly constituents of virulence determinants such as pili, flagella, and toxins, of the Gram-negative OM. Recently, periplasmic oxidoreductases have been implicated in LPS biogenesis of Escherichia coli and Neisseria meningitidis. Differences in OM biogenesis, in particular the transport pathways for endotoxin to the OM, the composition and role of the protein oxidation, and isomerization pathways and the regulatory networks that control them have been found in these two Gram-negative species suggesting that although form and function of the OM is conserved, the pathways required for the biosynthesis of the OM and the regulatory circuits that control them have evolved to suit the lifestyle of each organism.
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Affiliation(s)
- Susannah Piek
- Department of Pathology and Laboratory Medicine, The University of Western Australia Perth, WA, Australia
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18
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Dual RpoH sigma factors and transcriptional plasticity in a symbiotic bacterium. J Bacteriol 2012; 194:4983-94. [PMID: 22773790 DOI: 10.1128/jb.00449-12] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Sinorhizobium meliloti can live as a soil saprophyte and can engage in a nitrogen-fixing symbiosis with plant roots. To succeed in such diverse environments, the bacteria must continually adjust gene expression. Transcriptional plasticity in eubacteria is often mediated by alternative sigma (σ) factors interacting with core RNA polymerase. The S. meliloti genome encodes 14 of these alternative σ factors, including two putative RpoH ("heat shock") σ factors. We used custom Affymetrix symbiosis chips to characterize the global transcriptional response of S. meliloti rpoH1, rpoH2, and rpoH1 rpoH2 mutants during heat shock and stationary-phase growth. Under these conditions, expression of over 300 genes is dependent on rpoH1 and rpoH2. We mapped transcript start sites of 69 rpoH-dependent genes using 5' RACE (5' rapid amplification of cDNA ends), which allowed us to determine putative RpoH1-dependent, RpoH2-dependent, and dual-promoter (RpoH1- and RpoH2-dependent) consensus sequences that were each used to search the genome for other potential direct targets of RpoH. The inferred S. meliloti RpoH promoter consensus sequences share features of Escherichia coli RpoH promoters but lack extended -10 motifs.
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19
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Jiang JH, Davies JK, Lithgow T, Strugnell RA, Gabriel K. Targeting of Neisserial PorB to the mitochondrial outer membrane: an insight on the evolution of β-barrel protein assembly machines. Mol Microbiol 2011; 82:976-87. [DOI: 10.1111/j.1365-2958.2011.07880.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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20
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Isabella VM, Clark VL. Deep sequencing-based analysis of the anaerobic stimulon in Neisseria gonorrhoeae. BMC Genomics 2011; 12:51. [PMID: 21251255 PMCID: PMC3032703 DOI: 10.1186/1471-2164-12-51] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Accepted: 01/20/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Maintenance of an anaerobic denitrification system in the obligate human pathogen, Neisseria gonorrhoeae, suggests that an anaerobic lifestyle may be important during the course of infection. Furthermore, mounting evidence suggests that reduction of host-produced nitric oxide has several immunomodulary effects on the host. However, at this point there have been no studies analyzing the complete gonococcal transcriptome response to anaerobiosis. Here we performed deep sequencing to compare the gonococcal transcriptomes of aerobically and anaerobically grown cells. Using the information derived from this sequencing, we discuss the implications of the robust transcriptional response to anaerobic growth. RESULTS We determined that 198 chromosomal genes were differentially expressed (~10% of the genome) in response to anaerobic conditions. We also observed a large induction of genes encoded within the cryptic plasmid, pJD1. Validation of RNA-seq data using translational-lacZ fusions or RT-PCR demonstrated the RNA-seq results to be very reproducible. Surprisingly, many genes of prophage origin were induced anaerobically, as well as several transcriptional regulators previously unknown to be involved in anaerobic growth. We also confirmed expression and regulation of a small RNA, likely a functional equivalent of fnrS in the Enterobacteriaceae family. We also determined that many genes found to be responsive to anaerobiosis have also been shown to be responsive to iron and/or oxidative stress. CONCLUSIONS Gonococci will be subject to many forms of environmental stress, including oxygen-limitation, during the course of infection. Here we determined that the anaerobic stimulon in gonococci was larger than previous studies would suggest. Many new targets for future research have been uncovered, and the results derived from this study may have helped to elucidate factors or mechanisms of virulence that may have otherwise been overlooked.
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Affiliation(s)
- Vincent M Isabella
- Department of Microbiology and Immunology, School of Medicine and Dentistry, University of Rochester, Box 672, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Virginia L Clark
- Department of Microbiology and Immunology, School of Medicine and Dentistry, University of Rochester, Box 672, 601 Elmwood Avenue, Rochester, NY 14642, USA
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Evolution of the RpoS regulon: origin of RpoS and the conservation of RpoS-dependent regulation in bacteria. J Mol Evol 2010; 70:557-71. [PMID: 20506020 DOI: 10.1007/s00239-010-9352-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Accepted: 05/03/2010] [Indexed: 10/19/2022]
Abstract
The RpoS sigma factor in proteobacteria regulates genes in stationary phase and in response to stress. Although of conserved function, the RpoS regulon may have different gene composition across species due to high genomic diversity and to known environmental conditions that select for RpoS mutants. In this study, the distribution of RpoS homologs in prokaryotes and the differential dependence of regulon members on RpoS for expression in two gamma-proteobacteria (Escherichia coli and Pseudomonas aeruginosa) were examined. Using a maximum-likelihood phylogeny and reciprocal best hits analysis, we show that the RpoS sigma factor is conserved within gamma-, beta-, and delta-proteobacteria. Annotated RpoS of Borrelia and the enteric RpoS are postulated to have separate evolutionary origins. To determine the conservation of RpoS-dependent gene expression across species, reciprocal best hits analysis was used to identify orthologs of the E. coli RpoS regulon in the RpoS regulon of P. aeruginosa. Of the 186 RpoS-dependent genes of E. coli, 50 proteins have an ortholog within the P. aeruginosa genome. Twelve genes of the 50 orthologs are RpoS-dependent in both species, and at least four genes are regulated by RpoS in other gamma-proteobacteria. Despite RpoS conservation in gamma-, beta-, and delta-proteobacteria, RpoS regulon composition is subject to modification between species. Environmental selection for RpoS mutants likely contributes to the evolutionary divergence and specialization of the RpoS regulon within different bacterial genomes.
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22
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Kaparakis M, Turnbull L, Carneiro L, Firth S, Coleman HA, Parkington HC, Le Bourhis L, Karrar A, Viala J, Mak J, Hutton ML, Davies JK, Crack PJ, Hertzog PJ, Philpott DJ, Girardin SE, Whitchurch CB, Ferrero RL. Bacterial membrane vesicles deliver peptidoglycan to NOD1 in epithelial cells. Cell Microbiol 2009; 12:372-85. [PMID: 19888989 DOI: 10.1111/j.1462-5822.2009.01404.x] [Citation(s) in RCA: 306] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Gram-negative bacterial peptidoglycan is specifically recognized by the host intracellular sensor NOD1, resulting in the generation of innate immune responses. Although epithelial cells are normally refractory to external stimulation with peptidoglycan, these cells have been shown to respond in a NOD1-dependent manner to Gram-negative pathogens that can either invade or secrete factors into host cells. In the present work, we report that Gram-negative bacteria can deliver peptidoglycan to cytosolic NOD1 in host cells via a novel mechanism involving outer membrane vesicles (OMVs). We purified OMVs from the Gram-negative mucosal pathogens: Helicobacter pylori, Pseudomonas aeruginosa and Neisseria gonorrhoea and demonstrated that these peptidoglycan containing OMVs upregulated NF-kappaB and NOD1-dependent responses in vitro. These OMVs entered epithelial cells through lipid rafts thereby inducing NOD1-dependent responses in vitro. Moreover, OMVs delivered intragastrically to mice-induced innate and adaptive immune responses via a NOD1-dependent but TLR-independent mechanism. Collectively, our findings identify OMVs as a generalized mechanism whereby Gram-negative bacteria deliver peptidoglycan to cytosolic NOD1. We propose that OMVs released by bacteria in vivo may promote inflammation and pathology in infected hosts.
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Affiliation(s)
- Maria Kaparakis
- Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
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Dietrich M, Munke R, Gottschald M, Ziska E, Boettcher JP, Mollenkopf H, Friedrich A. The effect of hfq on global gene expression and virulence in Neisseria gonorrhoeae. FEBS J 2009; 276:5507-20. [PMID: 19691497 DOI: 10.1111/j.1742-4658.2009.07234.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hfq is an RNA chaperone that functions as a pleiotropic regulator for RNA metabolism in bacteria. In several pathogenic bacteria, Hfq contributes indirectly to virulence by binding to riboregulators that modulate the stability or translation efficiency of RNA transcripts. To characterize the role of Hfq in the pathogenicity of Neisseria gonorrhoeae, we generated an N. gonorrhoeae hfq mutant. Infectivity and global changes in gene expression caused by the hfq mutation in N. gonorrhoeae strain MS11 were analyzed. Transcriptional analysis using a custom-made N. gonorrhoeae microarray revealed that 369 ORFs were differentially regulated in the hfq mutant, MS11hfq, in comparison with the wild-type strain (202 were upregulated, and 167 were downregulated). The loss-of-function mutation in hfq led to pleiotropic phenotypic effects, including an altered bacterial growth rate and reduced adherence to epithelial cells. Twitching motility and microcolony formation were not affected. Hfq also appears to play a minor role in inducing the inflammatory response of infected human epithelial cells. Interleukin-8 production was slightly decreased, and activation of c-Jun N-terminal kinase, a mitogen-activated protein kinase, was reduced in MS11hfq-infected epithelial cells in comparison with wild type-infected cells. However, activation of nuclear factor kappa B, extracellular signal-regulated kinase 1/2 and p38 remained unchanged. The data presented suggest that Hfq plays an important role as a post-transcriptional regulator in N. gonorrhoeae strain MS11 but does not contribute significantly to its virulence in cell culture models.
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Affiliation(s)
- Manuela Dietrich
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
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24
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Grall N, Livny J, Waldor M, Barel M, Charbit A, Meibom KL. Pivotal role of the Francisella tularensis heat-shock sigma factor RpoH. MICROBIOLOGY-SGM 2009; 155:2560-2572. [PMID: 19443547 DOI: 10.1099/mic.0.029058-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Francisella tularensis is a highly infectious pathogen that infects animals and humans to cause the disease tularemia. The primary targets of this bacterium are macrophages, in which it replicates in the cytoplasm after escaping the initial phagosomal compartment. The ability to replicate within macrophages relies on the tightly regulated expression of a series of genes. One of the most commonly used means of coordinating the regulation of multiple genes in bacteria consists of the association of dedicated alternative sigma factors with the core of the RNA polymerase (RNAP). In silico analysis of the F. tularensis LVS genome led us to identify, in addition to the genes encoding the RNAP core (comprising the alpha1, alpha2, beta, beta' and omega subunits), one gene (designated rpoD) encoding the major sigma factor sigma(70), and a unique gene (FTL_0851) encoding a putative alternative sigma factor homologue of the sigma(32) heat-shock family (designated rpoH). Hence, F. tularensis represents one of the minority of bacterial species that possess only one or no alternative sigma factor in addition to the main factor sigma(70). In the present work, we show that FTL_0851 encodes a genuine sigma(32) factor. Transcriptomic analyses of the F. tularensis LVS heat-stress response allowed the identification of a series of orthologues of known heat-shock genes (including those for Hsp40, GroEL, GroES, DnaK, DnaJ, GrpE, ClpB and ClpP) and a number of genes implicated in Francisella virulence. A bioinformatic analysis was used to identify genes preceded by a putative sigma(32)-binding site, revealing both similarities to and differences from RpoH-mediated gene expression in Escherichia coli. Our results suggest that RpoH is an essential protein of F. tularensis, and positively regulates a subset of genes involved in the heat-shock response.
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Affiliation(s)
- Nathalie Grall
- INSERM, U570, Unit of Pathogenesis of Systemic Infections, F-75015 Paris, France.,Université Paris Descartes, Faculté de Médecine Necker-Enfants Malades, F-75015 Paris, France
| | - Jonathan Livny
- Channing Laboratories, Brigham and Women's Hospital, Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA
| | - Matthew Waldor
- Howard Hughes Medical Institute, 4000 Jones Bridge Road, Chevy Chase, MD 20815-6789, USA.,Channing Laboratories, Brigham and Women's Hospital, Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA
| | - Monique Barel
- INSERM, U570, Unit of Pathogenesis of Systemic Infections, F-75015 Paris, France.,Université Paris Descartes, Faculté de Médecine Necker-Enfants Malades, F-75015 Paris, France
| | - Alain Charbit
- INSERM, U570, Unit of Pathogenesis of Systemic Infections, F-75015 Paris, France.,Université Paris Descartes, Faculté de Médecine Necker-Enfants Malades, F-75015 Paris, France
| | - Karin L Meibom
- INSERM, U570, Unit of Pathogenesis of Systemic Infections, F-75015 Paris, France.,Université Paris Descartes, Faculté de Médecine Necker-Enfants Malades, F-75015 Paris, France
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Jordan PW, Saunders NJ. Host iron binding proteins acting as niche indicators for Neisseria meningitidis. PLoS One 2009; 4:e5198. [PMID: 19352437 PMCID: PMC2662411 DOI: 10.1371/journal.pone.0005198] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Accepted: 03/09/2009] [Indexed: 12/13/2022] Open
Abstract
Neisseria meningitidis requires iron, and in the absence of iron alters its gene expression to increase iron acquisition and to make the best use of the iron it has. During different stages of colonization and infection available iron sources differ, particularly the host iron-binding proteins haemoglobin, transferrin, and lactoferrin. This study compared the transcriptional responses of N. meningitidis, when grown in the presence of these iron donors and ferric iron, using microarrays. Specific transcriptional responses to the different iron sources were observed, including genes that are not part of the response to iron restriction. Comparisons between growth on haemoglobin and either transferrin or lactoferrin identified changes in 124 and 114 genes, respectively, and 33 genes differed between growth on transferrin or lactoferrin. Comparison of gene expression from growth on haemoglobin or ferric iron showed that transcription is also affected by the entry of either haem or ferric iron into the cytoplasm. This is consistent with a model in which N. meningitidis uses the relative availability of host iron donor proteins as niche indicators. Growth in the presence of haemoglobin is associated with a response likely to be adaptive to survival within the bloodstream, which is supported by serum killing assays that indicate growth on haemoglobin significantly increases survival, and the response to lactoferrin is associated with increased expression of epithelial cell adhesins and oxidative stress response molecules. The transferrin receptor is the most highly transcribed receptor and has the fewest genes specifically induced in its presence, suggesting this is the favoured iron source for the bacterium. Most strikingly, the responses to haemoglobin, which is associated with unrestricted growth, indicates a low iron transcriptional profile, associated with an aggressive phenotype that may be adaptive to access host iron sources but which may also underlie the lethal features of meningococcal septicaemia, when haemoglobin may become a major source of iron.
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Affiliation(s)
- Philip W. Jordan
- The Bacterial Pathogenesis and Functional Genomics Group, The Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Nigel J. Saunders
- The Bacterial Pathogenesis and Functional Genomics Group, The Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
- * E-mail:
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26
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Nichols CE, Sainsbury S, Ren J, Walter TS, Verma A, Stammers DK, Saunders NJ, Owens RJ. The structure of NMB1585, a MarR-family regulator from Neisseria meningitidis. Acta Crystallogr Sect F Struct Biol Cryst Commun 2009; 65:204-9. [PMID: 19255465 PMCID: PMC2650471 DOI: 10.1107/s174430910900414x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Accepted: 02/04/2009] [Indexed: 11/21/2022]
Abstract
The structure of the MarR-family regulator NMB1585 from N. meningitidis has been solved using data extending to 2.1 Å resolution. The structure of the MarR-family transcription factor NMB1585 from Neisseria meningitidis has been solved using data extending to a resolution of 2.1 Å. Overall, the dimeric structure resembles those of other MarR proteins, with each subunit comprising a winged helix–turn–helix (wHtH) domain connected to an α-helical dimerization domain. The spacing of the recognition helices of the wHtH domain indicates that NMB1585 is pre-configured for DNA binding, with a putative inducer pocket that is largely occluded by the side chains of two aromatic residues (Tyr29 and Trp53). NMB1585 was shown to bind to its own promoter region in a gel-shift assay, indicating that the protein acts as an auto-repressor.
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Affiliation(s)
- Charles E Nichols
- Wellcome Trust Centre for Human Genetics, University of Oxford, England
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MtrR modulates rpoH expression and levels of antimicrobial resistance in Neisseria gonorrhoeae. J Bacteriol 2008; 191:287-97. [PMID: 18978065 DOI: 10.1128/jb.01165-08] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The MtrR transcriptional-regulatory protein is known to repress transcription of the mtrCDE operon, which encodes a multidrug efflux pump possessed by Neisseria gonorrhoeae that is important in the ability of gonococci to resist certain hydrophobic antibiotics, detergents, dyes, and host-derived antimicrobials. In order to determine whether MtrR can exert regulatory action on other gonococcal genes, we performed a whole-genome microarray analysis using total RNA extracted from actively growing broth cultures of isogenic MtrR-positive and MtrR-negative gonococci. We determined that, at a minimum, 69 genes are directly or indirectly subject to MtrR control, with 47 being MtrR repressed and 22 being MtrR activated. rpoH, which encodes the general stress response sigma factor RpoH (sigma 32), was found by DNA-binding studies to be directly repressed by MtrR, as it was found to bind to a DNA sequence upstream of rpoH that included sites within the rpoH promoter. MtrR also repressed the expression of certain RpoH-regulated genes, but this regulation was likely indirect and a reflection of MtrR control of rpoH expression. Inducible expression of MtrR was found to repress rpoH expression and to increase gonococcal susceptibility to hydrogen peroxide (H(2)O(2)) and an antibiotic (erythromycin) recognized by the MtrC-MtrD-MtrE efflux pump system. We propose that, apart from its ability to control the expression of the mtrCDE-encoded efflux pump operon and, as a consequence, levels of gonococcal resistance to host antimicrobials (e.g., antimicrobial peptides) recognized by the efflux pump, the ability of MtrR to regulate the expression levels of rpoH and RpoH-regulated genes also modulates levels of gonococcal susceptibility to H(2)O(2).
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Abstract
Two-component regulatory systems are involved in processes important for bacterial pathogenesis. Inactivation of the misR/misS system in Neisseria meningitidis results in the loss of phosphorylation of the lipooligosaccharide inner core and causes attenuation in a mouse model of meningococcal infection. One hundred seventeen (78 up-regulated and 39 down-regulated) potential regulatory targets of the MisR/MisS (MisR/S) system were identified by transcriptional profiling of the NMBmisR mutant and the parental wild-type meningococcal strain NMB. The regulatory effect was further confirmed in a subset of target genes by quantitative real-time PCR and beta-galactosidase transcriptional fusion reporter assays. The MisR regulon includes genes encoding proteins necessary for protein folding in the bacterial cytoplasm and periplasm, transcriptional regulation, metabolism, iron assimilation, and type I protein transport. Mutation in the MisR/S system caused increased sensitivity to oxidative stress and also resulted in decreased susceptibility to complement-mediated killing by normal human serum. To identify the direct targets of MisR regulation, electrophoretic mobility shift assays were carried out using purified MisR-His(6) protein. Among 22 genes examined, misR directly interacted with 14 promoter regions. Six promoters were further investigated by DNase I protection assays, and a MisR-binding consensus sequence was proposed. Thus, the direct regulatory targets of MisR and the minimal regulon of the meningococcal MisR/S two-component signal transduction system were characterized. These data indicate that the MisR/S system influences a wide range of biological functions in N. meningitidis either directly or via intermediate regulators.
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Ren J, Sainsbury S, Combs SE, Capper RG, Jordan PW, Berrow NS, Stammers DK, Saunders NJ, Owens RJ. The Structure and Transcriptional Analysis of a Global Regulator from Neisseria meningitidis. J Biol Chem 2007; 282:14655-64. [PMID: 17374605 DOI: 10.1074/jbc.m701082200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neisseria meningitidis, a causative agent of bacterial meningitis, has a relatively small repertoire of transcription factors, including NMB0573 (annotated AsnC), a member of the Lrp-AsnC family of regulators that are widely expressed in both Bacteria and Archaea. In the present study we show that NMB0573 binds to l-leucine and l-methionine and have solved the structure of the protein with and without bound amino acids. This has shown, for the first time that amino acid binding does not induce significant conformational changes in the structure of an AsnC/Lrp regulator although it does appear to stabilize the octameric assembly of the protein. Transcriptional profiling of wild-type and NMB0573 knock-out strains of N. meningitidis has shown that NMB0573 is associated with an adaptive response to nutrient poor conditions reflected in a reduction in major surface protein expression. On the basis of its structure and the transcriptional response, we propose that NMB0573 is a global regulator in Neisseria controlling responses to nutrient availability through indicators of general amino acid abundance: leucine and methionine.
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Affiliation(s)
- Jingshan Ren
- Oxford Protein Production Facility and Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford, UK
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Slamti L, Livny J, Waldor MK. Global gene expression and phenotypic analysis of a Vibrio cholerae rpoH deletion mutant. J Bacteriol 2006; 189:351-62. [PMID: 17085549 PMCID: PMC1797412 DOI: 10.1128/jb.01297-06] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio cholerae, the cause of cholera, can grow in a variety of environments outside of human hosts. During infection, this pathogen must adapt to significant environmental alterations, including the elevated temperature of the human gastrointestinal tract. Sigma(32), an alternative sigma factor encoded by rpoH, activates transcription of genes involved in the heat shock response in several bacterial species. Here, we assessed the role of sigma(32) in V. cholerae physiology. In aggregate, our findings suggest that sigma(32) promotes V. cholerae growth at temperatures ranging at least from 15 degrees C to 42 degrees C. Growth of the rpoH mutant was severely attenuated within the suckling mouse intestine, suggesting that sigma(32)-regulated genes are critical for V. cholerae adaptation to conditions within the gastrointestinal tract. We defined the V. cholerae RpoH regulon by comparing the whole-genome transcription profiles of the wild-type and rpoH mutant strains after a temperature up-shift. Most of the V. cholerae genes expressed in an RpoH-dependent manner after heat shock encode proteins that influence protein fate, such as proteases and chaperones, or are of unknown function. Bioinformatic analyses of the microarray data were used to define a putative sigma(32) consensus binding sequence and subsequently to identify genes that are likely to be directly regulated by RpoH in the whole V. cholerae genome.
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Affiliation(s)
- Leyla Slamti
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA
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