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Aljannat MAK, Oldfield NJ, Albasri HM, Dorrington LKG, Ohri RL, Wooldridge KG, Turner DPJ. The moonlighting peroxiredoxin-glutaredoxin in Neisseria meningitidis binds plasminogen via a C-terminal lysine residue and contributes to survival in a whole blood model. Microb Pathog 2019; 139:103890. [PMID: 31765768 DOI: 10.1016/j.micpath.2019.103890] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 11/20/2019] [Accepted: 11/22/2019] [Indexed: 01/24/2023]
Abstract
Neisseria meningitidis is a human-restricted bacterium that can invade the bloodstream and cross the blood-brain barrier resulting in life-threatening sepsis and meningitis. Meningococci express a cytoplasmic peroxiredoxin-glutaredoxin (Prx5-Grx) hybrid protein that has also been identified on the bacterial surface. Here, recombinant Prx5-Grx was confirmed as a plasminogen (Plg)-binding protein, in an interaction which could be inhibited by the lysine analogue ε-aminocapronic acid. rPrx5-Grx derivatives bearing a substituted C-terminal lysine residue (rPrx5-GrxK244A), but not the active site cysteine residue (rPrx5-GrxC185A) or the sub-terminal rPrx5-GrxK230A lysine residue, exhibited significantly reduced Plg-binding. The absence of Prx5-Grx did not significantly reduce the ability of whole meningococcal cells to bind Plg, but under hydrogen peroxide-mediated oxidative stress, the N. meningitidis Δpxn5-grx mutant survived significantly better than the wild-type or complemented strains. Significantly, using human whole blood as a model of meningococcal bacteremia, it was found that the N. meningitidis Δpxn5-grx mutant had a survival defect compared with the parental or complemented strain, confirming an important role for Prx5-Grx in meningococcal pathogenesis.
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Affiliation(s)
- Mahab A K Aljannat
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Neil J Oldfield
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Hibah M Albasri
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2RD, UK
| | | | - Radhica L Ohri
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Karl G Wooldridge
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2RD, UK
| | - David P J Turner
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2RD, UK.
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2
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Singh A, Blaskovic D, Joo J, Yang Z, Jackson SH, Coleman WG, Yan M. Investigating the Role of Helicobacter pylori PriA Protein. Helicobacter 2016; 21:295-304. [PMID: 26817518 PMCID: PMC8483055 DOI: 10.1111/hel.12283] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND In bacteria, PriA protein, a conserved DEXH-type DNA helicase, plays a central role in replication restart at stalled replication forks. Its unique DNA binding property allows it to recognize and stabilize stalled forks and the structures derived from them. PriA plays a very critical role in replication fork stabilization and DNA repair in E. coli and N. gonorrhoeae. In our in vivo expression technology screen, priA gene was induced in vivo when Helicobacter pylori infects mouse stomach. MATERIALS AND METHODS We decided to elucidate the role of H. pylori PriA protein in survival in mouse stomach, survival in gastric epithelial cells and macrophage cells, DNA repair, acid stress, and oxidative stress. RESULTS The priA null mutant strain was unable to colonize mice stomach mucosa after long-term infections. Mouse colonization was observed after 1 week of infection, but the levels were much lower than the wild-type HpSS1 strain. PriA protein was found to be important for intracellular survival of epithelial cell-/macrophage cell-ingested H. pylori. Also, a priA null mutant was more sensitive to DNA-damaging agents and was much more sensitive to acid and oxidative stress as compared to the wild-type strain. CONCLUSIONS These data suggest that the PriA protein is needed for survival and persistence of H. pylori in mice stomach mucosa.
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Affiliation(s)
- Aparna Singh
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Dusan Blaskovic
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Jungsoo Joo
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Zhen Yang
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Sharon H. Jackson
- National Institute on Minority Health and Health Disparities, National Institutes of Health, Bethesda, MD
| | - William G. Coleman
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD,National Institute on Minority Health and Health Disparities, National Institutes of Health, Bethesda, MD
| | - Ming Yan
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
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3
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D'Argenio V, Casaburi G, Precone V, Pagliuca C, Colicchio R, Sarnataro D, Discepolo V, Kim SM, Russo I, Del Vecchio Blanco G, Horner DS, Chiara M, Pesole G, Salvatore P, Monteleone G, Ciacci C, Caporaso GJ, Jabrì B, Salvatore F, Sacchetti L. Metagenomics Reveals Dysbiosis and a Potentially Pathogenic N. flavescens Strain in Duodenum of Adult Celiac Patients. Am J Gastroenterol 2016; 111:879-90. [PMID: 27045926 PMCID: PMC4897008 DOI: 10.1038/ajg.2016.95] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Revised: 02/01/2016] [Accepted: 02/01/2016] [Indexed: 12/11/2022]
Abstract
OBJECTIVES Celiac disease (CD)-associated duodenal dysbiosis has not yet been clearly defined, and the mechanisms by which CD-associated dysbiosis could concur to CD development or exacerbation are unknown. In this study, we analyzed the duodenal microbiome of CD patients. METHODS The microbiome was evaluated in duodenal biopsy samples of 20 adult patients with active CD, 6 CD patients on a gluten-free diet, and 15 controls by DNA sequencing of 16S ribosomal RNA libraries. Bacterial species were cultured, isolated and identified by mass spectrometry. Isolated bacterial species were used to infect CaCo-2 cells, and to stimulate normal duodenal explants and cultured human and murine dendritic cells (DCs). Inflammatory markers and cytokines were evaluated by immunofluorescence and ELISA, respectively. RESULTS Proteobacteria was the most abundant and Firmicutes and Actinobacteria the least abundant phyla in the microbiome profiles of active CD patients. Members of the Neisseria genus (Betaproteobacteria class) were significantly more abundant in active CD patients than in the other two groups (P=0.03). Neisseria flavescens (CD-Nf) was the most abundant Neisseria species in active CD duodenum. Whole-genome sequencing of CD-Nf and control-Nf showed genetic diversity of the iron acquisition systems and of some hemoglobin-related genes. CD-Nf was able to escape the lysosomal compartment in CaCo-2 cells and to induce an inflammatory response in DCs and in ex-vivo mucosal explants. CONCLUSIONS Marked dysbiosis and an abundance of a peculiar CD-Nf strain characterize the duodenal microbiome in active CD patients thus suggesting that the CD-associated microbiota could contribute to the many inflammatory signals in this disorder.
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Affiliation(s)
- Valeria D'Argenio
- CEINGE-Biotecnologie Avanzate, Naples, Italy.,Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy
| | | | - Vincenza Precone
- CEINGE-Biotecnologie Avanzate, Naples, Italy.,Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy
| | - Chiara Pagliuca
- CEINGE-Biotecnologie Avanzate, Naples, Italy.,Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy
| | - Roberta Colicchio
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy
| | - Daniela Sarnataro
- CEINGE-Biotecnologie Avanzate, Naples, Italy.,Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy
| | - Valentina Discepolo
- CEINGE-Biotecnologie Avanzate, Naples, Italy.,Department of Medical Translational Sciences and European Laboratory for the Investigation of Food Induced Diseases, University of Naples Federico II, Naples, Italy
| | - Sangman M Kim
- Department of Medicine and the University of Chicago Celiac Disease Center, University of Chicago, Chicago, Illinois, USA
| | - Ilaria Russo
- Department of Medicine and Surgery, University of Salerno, Salerno, Italy
| | | | - David S Horner
- Department of Biosciences, University of Milan, Milan, Italy
| | - Matteo Chiara
- Department of Biosciences, University of Milan, Milan, Italy
| | - Graziano Pesole
- Institute of Biomembranes and Bioenergetics, National Research Council, Bari, Italy.,Department of Biochemistry and Molecular Biology, University of Bari A. Moro, Bari, Italy
| | - Paola Salvatore
- CEINGE-Biotecnologie Avanzate, Naples, Italy.,Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy
| | | | - Carolina Ciacci
- Department of Medicine and Surgery, University of Salerno, Salerno, Italy
| | | | - Bana Jabrì
- Department of Medicine and the University of Chicago Celiac Disease Center, University of Chicago, Chicago, Illinois, USA
| | - Francesco Salvatore
- CEINGE-Biotecnologie Avanzate, Naples, Italy.,Department of Molecular Medicine and Medical Biotechnologies, University of Naples Federico II, Naples, Italy.,IRCCS-Fondazione SDN, Naples, Italy
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4
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Colicchio R, Pagliuca C, Pastore G, Cicatiello AG, Pagliarulo C, Talà A, Scaglione E, Sammartino JC, Bucci C, Alifano P, Salvatore P. Fitness Cost of Rifampin Resistance in Neisseria meningitidis: In Vitro Study of Mechanisms Associated with rpoB H553Y Mutation. Antimicrob Agents Chemother 2015; 59:7637-49. [PMID: 26416867 PMCID: PMC4649176 DOI: 10.1128/aac.01746-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 09/23/2015] [Indexed: 12/14/2022] Open
Abstract
Rifampin chemoprophylaxis against Neisseria meningitidis infections led to the onset of rifampin resistance in clinical isolates harboring point mutations in the rpoB gene, coding for the RNA polymerase β chain. These resistant strains are rare in medical practice, suggesting their decreased fitness in the human host. In this study, we isolated rifampin-resistant rpoB mutants from hypervirulent serogroup C strain 93/4286 and analyzed their different properties, including the ability to grow/survive in different culture media and in differentiated THP-1 human monocytes and to compete with the wild-type strain in vitro. Our results demonstrate that different rpoB mutations (H553Y, H553R, and S549F) may have different effects, ranging from low- to high-cost effects, on bacterial fitness in vitro. Moreover, we found that the S549F mutation confers temperature sensitivity, possibly explaining why it is observed very rarely in clinical isolates. Comparative high-throughput RNA sequencing analysis of bacteria grown in chemically defined medium demonstrated that the low-cost H553Y substitution resulted in global transcriptional changes that functionally mimic the stringent response. Interestingly, many virulence-associated genes, including those coding for meningococcal type IV pili, porin A, adhesins/invasins, IgA protease, two-partner secretion system HrpA/HrpB, enzymes involved in resistance to oxidative injury, lipooligosaccharide sialylation, and capsular polysaccharide biosynthesis, were downregulated in the H553Y mutant compared to their level of expression in the wild-type strain. These data might account for the reduced capacity of this mutant to grow/survive in differentiated THP-1 cells and explain the rarity of H553Y mutants among clinical isolates.
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Affiliation(s)
- Roberta Colicchio
- Department of Molecular Medicine and Medical Biotechnology, Federico II University Medical School, Naples, Italy SDN-Foundation, Naples, Italy
| | - Chiara Pagliuca
- Department of Molecular Medicine and Medical Biotechnology, Federico II University Medical School, Naples, Italy Ceinge Advanced Biotechnologies, Naples, Italy
| | - Gabiria Pastore
- Department of Sciences and Technologies, University of Sannio, Benevento, Italy
| | | | - Caterina Pagliarulo
- Department of Sciences and Technologies, University of Sannio, Benevento, Italy
| | - Adelfia Talà
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy
| | - Elena Scaglione
- Department of Molecular Medicine and Medical Biotechnology, Federico II University Medical School, Naples, Italy
| | - Josè Camilla Sammartino
- Department of Molecular Medicine and Medical Biotechnology, Federico II University Medical School, Naples, Italy
| | - Cecilia Bucci
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy
| | - Pietro Alifano
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy
| | - Paola Salvatore
- Department of Molecular Medicine and Medical Biotechnology, Federico II University Medical School, Naples, Italy Ceinge Advanced Biotechnologies, Naples, Italy
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Abstract
Neisseria meningitidis (meningococcus) is a major causative organism of meningitis and sepsis and Neisseria gonorrhoeae (gonococcus) is the causative organism of the sexually transmitted disease gonorrhea. Infections caused by meningococci are vaccine-preventable, whereas gonococcal vaccine research and development has languished for decades and the correlates of protection are still largely unknown. In the past two decades, complementary 'omic' platforms have been developed to interrogate Neisseria genomes and gene products. Proteomic techniques applied to whole Neisseria bacteria, outer membranes and outer membrane vesicle vaccines have generated protein maps and also allowed the examination of environmental stresses on protein expression. In particular, immuno-proteomics has identified proteins whose expression is correlated with the development of human natural immunity to meningococcal infection and colonization and following vaccination. Neisseria proteomic techniques have produced a catalog of potential vaccine antigens and investigating the functional and biological properties of these proteins could finally provide 'universal' Neisseria vaccines.
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Affiliation(s)
- Myron Christodoulides
- Neisseria Research Group, Molecular Microbiology, Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, University of Southampton, Faculty of Medicine, Southampton General Hospital, Southampton, SO16 6YD, UK
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6
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Serogroup-specific interaction of Neisseria meningitidis capsular polysaccharide with host cell microtubules and effects on tubulin polymerization. Infect Immun 2013; 82:265-74. [PMID: 24166951 DOI: 10.1128/iai.00501-13] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
We have previously shown that during late stages of the infectious process, serogroup B meningococci (MenB) are able to escape the phagosome of in vitro-infected human epithelial cells. They then multiply in the cytosolic environment and spread intracellularly and to surrounding cells by exploiting the microtubule cytoskeleton, as suggested by results of infections in the presence of microtubule inhibitors and evidence of nanotubes connecting neighboring cells. In this study, by using microtubule binding assays with purified microtubule asters and bundles and microtubule bundles synthesized in vitro, we demonstrate that the MenB capsule directly mediates the interaction between bacteria and microtubules. The direct interaction between the microtubules and the MenB capsular polysaccharide was confirmed by coimmunoprecipitation experiments. Unexpectedly, serogroup C meningococci (MenC), which have a capsular polysaccharide that differs from that of MenB only by its anomeric linkage, α(2→9) instead of α(2→8), were not able to interact with the microtubules, and the lack of interaction was not due to capsular polysaccharide O-acetylation that takes place in most MenC strains but not in MenB strains. Moreover, we demonstrate that the MenB capsular polysaccharide inhibits tubulin polymerization in vitro. Thus, at variance with MenC, MenB may interfere with microtubule dynamics during cell infection.
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7
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Sunchu B, Berg L, Ward HE, Lopper ME. Identification of a small molecule PriA helicase inhibitor. Biochemistry 2012. [PMID: 23193948 DOI: 10.1021/bi301100w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PriA helicase catalyzes the initial steps of replisome reloading onto repaired DNA replication forks in bacterial DNA replication restart pathways. We have used a high-throughput screen to identify a small molecule inhibitor of PriA-catalyzed duplex DNA unwinding. The compound, CGS 15943, targets Neisseria gonorrhoeae PriA helicase with an IC(50) of 114 ± 24 μM. The PriA helicase of Escherichia coli is also inhibited, although to a lesser extent than N. gonorrhoeae PriA. CGS 15943 decreases rates of PriA-catalyzed ATP hydrolysis and reduces the affinity with which PriA binds DNA. Steady-state kinetic data indicate that CGS 15943 inhibits PriA through a mixed mode of inhibition with respect to ATP and with respect to DNA, indicating that it binds to a site on PriA that participates in both substrate binding and catalysis. Inhibitor binding constants derived from steady-state kinetic experiments reveal that CGS 15943 has the highest binding affinity for the PriA·PriB·ATP complex, intermediate binding affinity for the PriA·PriB·DNA complex, and the lowest binding affinity for the PriA·PriB·DNA·ATP complex, suggesting that PriA assumes different conformations in each of these complexes. We propose that CGS 15943 binds to PriA at a site distinct from the DNA and primary ATP binding sites, perhaps at PriA's weak nucleotide binding site, and induces a conformational change in PriA that renders it less catalytically proficient or prevents conformational changes in PriA that are necessary for ATP hydrolysis and duplex DNA unwinding.
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Affiliation(s)
- Bharath Sunchu
- Department of Chemistry, University of Dayton, 300 College Park, Dayton, OH 45469, USA
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8
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Talà A, Monaco C, Nagorska K, Exley RM, Corbett A, Zychlinsky A, Alifano P, Tang CM. Glutamate utilization promotes meningococcal survival in vivo through avoidance of the neutrophil oxidative burst. Mol Microbiol 2011; 81:1330-42. [PMID: 21777301 PMCID: PMC3755445 DOI: 10.1111/j.1365-2958.2011.07766.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Polymorphonuclear neutrophil leucocytes (PMNs) are a critical part of innate immune defence against bacterial pathogens, and only a limited subset of microbes can escape killing by these phagocytic cells. Here we show that Neisseria meningitidis, a leading cause of septicaemia and meningitis, can avoid killing by PMNs and this is dependent on the ability of the bacterium to acquire L-glutamate through its GltT uptake system. We demonstrate that the uptake of available L-glutamate promotes N. meningitidis evasion of PMN reactive oxygen species produced by the oxidative burst. In the meningococcus, L-glutamate is converted to glutathione, a key molecule for maintaining intracellular redox potential, which protects the bacterium from reactive oxygen species such as hydrogen peroxide. We show that this mechanism contributes to the ability of N. meningitidis to cause bacteraemia, a critical step in the disease process during infections caused by this important human pathogen.
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Affiliation(s)
- Adelfia Talà
- Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali (DiSTeBA), Università del Salento, Via Provinciale Monteroni, 73100 Lecce, Italy
| | - Caterina Monaco
- Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali (DiSTeBA), Università del Salento, Via Provinciale Monteroni, 73100 Lecce, Italy
| | - Krzysztofa Nagorska
- Centre for Molecular Microbiology and Infection, Department of Microbiology, Imperial College London, England, UK
| | - Rachel M. Exley
- Centre for Molecular Microbiology and Infection, Department of Microbiology, Imperial College London, England, UK
| | - Anne Corbett
- Centre for Molecular Microbiology and Infection, Department of Microbiology, Imperial College London, England, UK
| | - Arturo Zychlinsky
- Department of Cellular Microbiology, Max Planck Institute for Infection Biology, 10117 Berlin, Germany
| | - Pietro Alifano
- Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali (DiSTeBA), Università del Salento, Via Provinciale Monteroni, 73100 Lecce, Italy
| | - Christoph M. Tang
- Centre for Molecular Microbiology and Infection, Department of Microbiology, Imperial College London, England, UK
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9
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Feng C, Sunchu B, Greenwood ME, Lopper ME. A bacterial PriB with weak single-stranded DNA binding activity can stimulate the DNA unwinding activity of its cognate PriA helicase. BMC Microbiol 2011; 11:189. [PMID: 21861872 PMCID: PMC3179954 DOI: 10.1186/1471-2180-11-189] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 08/23/2011] [Indexed: 12/05/2022] Open
Abstract
Background Bacterial DNA replication restart pathways facilitate reinitiation of DNA replication following disruptive encounters of a replisome with DNA damage, thereby allowing complete and faithful duplication of the genome. In Neisseria gonorrhoeae, the primosome proteins that catalyze DNA replication restart differ from the well-studied primosome proteins of E. coli with respect to the number of proteins involved and the affinities of their physical interactions: the PriA:PriB interaction is weak in E. coli, but strong in N. gonorrhoeae, and the PriB:DNA interaction is strong in E. coli, but weak in N. gonorrhoeae. In this study, we investigated the functional consequences of this affinity reversal. Results We report that N. gonorrhoeae PriA's DNA binding and unwinding activities are similar to those of E. coli PriA, and N. gonorrhoeae PriA's helicase activity is stimulated by its cognate PriB, as it is in E. coli. This finding is significant because N. gonorrhoeae PriB's single-stranded DNA binding activity is weak relative to that of E. coli PriB, and in E. coli, PriB's single-stranded DNA binding activity is important for PriB stimulation of PriA helicase. Furthermore, a N. gonorrhoeae PriB variant defective for binding single-stranded DNA can stimulate PriA's helicase activity, suggesting that DNA binding by PriB might not be important for PriB stimulation of PriA helicase in N. gonorrhoeae. We also demonstrate that N. gonorrhoeae PriB stimulates ATP hydrolysis catalyzed by its cognate PriA. This activity of PriB has not been observed in E. coli, and could be important for PriB stimulation of PriA helicase in N. gonorrhoeae. Conclusions The results of this study demonstrate that a bacterial PriB homolog with weak single-stranded DNA binding activity can stimulate the DNA unwinding activity of its cognate PriA helicase. While it remains unclear if N. gonorrhoeae PriB's weak DNA binding activity is required for PriB stimulation of PriA helicase, the ability of PriB to stimulate PriA-catalyzed ATP hydrolysis could play an important role. Thus, the weak interaction between N. gonorrhoeae PriB and DNA might be compensated for by the strong interaction between PriB and PriA, which could result in allosteric activation of PriA's ATPase activity.
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Affiliation(s)
- Cui Feng
- Department of Chemistry, University of Dayton, 300 College Park, Dayton, OH 45469, USA
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10
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Kozlova EV, Khajanchi BK, Sha J, Chopra AK. Quorum sensing and c-di-GMP-dependent alterations in gene transcripts and virulence-associated phenotypes in a clinical isolate of Aeromonas hydrophila. Microb Pathog 2011; 50:213-23. [PMID: 21256953 DOI: 10.1016/j.micpath.2011.01.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2010] [Revised: 01/10/2011] [Accepted: 01/12/2011] [Indexed: 01/16/2023]
Abstract
Recently, we demonstrated that the LuxS-based quorum sensing (QS) system (AI-2) negatively regulated the virulence of a diarrheal isolate SSU of Aeromonas hydrophila, while the ahyRI-based (AI-1) N-acyl-homoserine lactone system was a positive regulator of bacterial virulence. Thus, these QS systems had opposing effects on modulating biofilm formation and bacterial motility in vitro models and in vivo virulence in a speticemic mouse model of infection. In this study, we linked these two QS systems with the bacterial second messenger cyclic diguanosine monophosphate (c-di-GMP) in the regulation of virulence in A. hydrophila SSU. To accomplish this, we examined the effect of overproducing a protein with GGDEF domain, which increases c-di-GMP levels in bacteria, on the phenotype and transcriptional profiling of genes involved in biofilm formation and bacterial motility in wild-type (WT) versus its QS null mutants. We provided evidence that c-di-GMP overproduction dramatically enhanced biofilm formation and reduced motility of the WT A. hydrophila SSU, which was equitable with that of the ΔluxS mutant. On the contrary, the ∆ahyRI mutant exhibited only a marginal increase in the biofilm formation with no effect on motility when c-di-GMP was overproduced. Overall, our data indicated that c-di-GMP overproduction modulated transcriptional levels of genes involved in biofilm formation and motility phenotype in A. hydrophila SSU in a QS-dependent manner, involving both AI-1 and AI-2 systems.
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Affiliation(s)
- Elena V Kozlova
- Department of Microbiology & Immunology, University of Texas Medical Branch, UTMB, Galveston, TX 77555, USA
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11
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Gabbai CB, Marians KJ. Recruitment to stalled replication forks of the PriA DNA helicase and replisome-loading activities is essential for survival. DNA Repair (Amst) 2010; 9:202-9. [PMID: 20097140 DOI: 10.1016/j.dnarep.2009.12.009] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PriA, a 3'-->5' superfamily 2 DNA helicase, acts to remodel stalled replication forks and as a specificity factor for origin-independent assembly of a new replisome at the stalled fork. The ability of PriA to initiate replication at stalled forked structures ensures complete genome replication and helps to protect the cell from illegitimate recombination events. This review focuses on the activities of PriA and its role in replication fork assembly and maintaining genomic integrity.
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Affiliation(s)
- Carolina B Gabbai
- Molecular Biology Program, Weill-Cornell Graduate School of Medical Sciences, New York, NY, USA.
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12
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Fook LW, Chow VTK. Transcriptome profiling of host-microbe interactions by differential display RT-PCR. Methods Mol Biol 2010; 630:33-47. [PMID: 20300989 DOI: 10.1007/978-1-60761-629-0_3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In recent years, DNA microarray has become increasingly popular as a tool to investigate global expression patterns compared to differential display RT-PCR. Although differential display RT-PCR can be labour-intensive, it has its own merits over those of DNA microarray. While the latter usually consists of a well-defined set of species-specific genes, differential display RT-PCR allows the investigation of host-microbe interactions without bias towards any mRNA transcripts. This means that the regulated transcript expression of both host and pathogen can be analysed simultaneously. In addition, novel transcripts and alternate splicing variants pertaining to the infection can also be discovered. We have investigated the response of rhabdomyosarcoma cells to infection with a neurovirulent strain of enterovirus 71 (EV71) at different time-points during the infection process compared with uninfected cells. Using differential display RT-PCR, we identified mRNAs that were up- or down-regulated. Less than half of the clones match known genes including those involved in mediating the cytoskeleton, cell cycle, cell death, protein translational machinery and cellular transport. The rest of the clones do not match any known genes, of which several are novel genes. Noteworthy is the discovery of an alternate splicing form of TRIP7, which is down-regulated during EV71 infection. The differential display technique has potentially wide applicability to elucidate the gene expression or transcriptomic profiles of host-microbe interactions, which can provide a better understanding of microbial pathogenesis.
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Affiliation(s)
- Leong Wai Fook
- Institute of Molecular and Cell Biology, Proteos, Singapore
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13
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Dong J, George NP, Duckett KL, DeBeer MAP, Lopper ME. The crystal structure of Neisseria gonorrhoeae PriB reveals mechanistic differences among bacterial DNA replication restart pathways. Nucleic Acids Res 2009; 38:499-509. [PMID: 19906704 PMCID: PMC2811003 DOI: 10.1093/nar/gkp1031] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Reactivation of repaired DNA replication forks is essential for complete duplication of bacterial genomes. However, not all bacteria encode homologs of the well-studied Escherichia coli DNA replication restart primosome proteins, suggesting that there might be distinct mechanistic differences among DNA replication restart pathways in diverse bacteria. Since reactivation of repaired DNA replication forks requires coordinated DNA and protein binding by DNA replication restart primosome proteins, we determined the crystal structure of Neisseria gonorrhoeae PriB at 2.7 A resolution and investigated its ability to physically interact with DNA and PriA helicase. Comparison of the crystal structures of PriB from N. gonorrhoeae and E. coli reveals a well-conserved homodimeric structure consisting of two oligosaccharide/oligonucleotide-binding (OB) folds. In spite of their overall structural similarity, there is significant species variation in the type and distribution of surface amino acid residues. This correlates with striking differences in the affinity with which each PriB homolog binds single-stranded DNA and PriA helicase. These results provide evidence that mechanisms of DNA replication restart are not identical across diverse species and that these pathways have likely become specialized to meet the needs of individual organisms.
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Affiliation(s)
- Jinlan Dong
- Department of Chemistry, University of Dayton, 300 College Park, Dayton, OH 45469, USA
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Immunoproteomic analysis of the development of natural immunity in subjects colonized by Neisseria meningitidis reveals potential vaccine candidates. Infect Immun 2009; 77:5080-9. [PMID: 19737898 DOI: 10.1128/iai.00701-09] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The potential protective effect of existing vaccines against serogroup B meningococci, based on outer membrane proteins, is limited by strain restriction and apparent short duration of immune responses. In contrast, meningococcal colonization is known to stimulate the production of cross-protective antibodies as defined by the development of serum bactericidal activity (SBA) against heterologous serogroup B strains. In the current study, a resource of human serum samples and meningococcal carriage strains from studies of longitudinal carriage has been subjected to immunoproteomic analysis to investigate the outer membrane protein antigens associated with the development of SBA to both homologous and heterologous meningococcal serogroup B strains. Proteins from outer membranes of homologous and heterologous strains were separated by two-dimensional electrophoresis and reacted with paired sera which showed an increase in SBA following colonization. Individuals showed differing patterns of reactivity upon colonization, with an increase in SBA being associated with increases in the number of spots detected before and after colonization and/or with increases in the intensity of individual spots. Analysis of immunoreactive spots by mass spectrometry resulted in the identification of 43 proteins potentially associated with the development of SBA against both homologous and heterologous strains. The list of protein immunogens generated included not only well-established antigens but also novel proteins that represent potentially new candidates for inclusion in defined, multicomponent serogroup B vaccines.
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15
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Colicchio R, Ricci S, Lamberti F, Pagliarulo C, Pagliuca C, Braione V, Braccini T, Talà A, Montanaro D, Tripodi S, Cintorino M, Troncone G, Bucci C, Pozzi G, Bruni CB, Alifano P, Salvatore P. The meningococcal ABC-Type L-glutamate transporter GltT is necessary for the development of experimental meningitis in mice. Infect Immun 2009; 77:3578-87. [PMID: 19528209 PMCID: PMC2737999 DOI: 10.1128/iai.01424-08] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 01/21/2009] [Accepted: 06/05/2009] [Indexed: 11/20/2022] Open
Abstract
Experimental animal models of bacterial meningitis are useful to study the host-pathogen interactions occurring at the cerebral level and to analyze the pathogenetic mechanisms behind this life-threatening disease. In this study, we have developed a mouse model of meningococcal meningitis based on the intracisternal inoculation of bacteria. Experiments were performed with mouse-passaged serogroup C Neisseria meningitidis. Survival and clinical parameters of infected mice and microbiological and histological analysis of the brain demonstrated the establishment of meningitis with features comparable to those of the disease in humans. When using low bacterial inocula, meningococcal replication in the brain was very efficient, with a 1,000-fold increase of viable counts in 18 h. Meningococci were also found in the blood, spleens, and livers of infected mice, and bacterial loads in different organs were dependent on the infectious dose. As glutamate uptake from the host has been implicated in meningococcal virulence, mice were infected intracisternally with an isogenic strain deficient in the ABC-type L-glutamate transporter GltT. Noticeably, the mutant was attenuated in virulence in mixed infections, indicating that wild-type bacteria outcompeted the GltT-deficient meningococci. The data show that the GltT transporter plays a role in meningitis and concomitant systemic infection, suggesting that meningococci may use L-glutamate as a nutrient source and as a precursor to synthesize the antioxidant glutathione.
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16
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Ambur OH, Davidsen T, Frye SA, Balasingham SV, Lagesen K, Rognes T, Tønjum T. Genome dynamics in major bacterial pathogens. FEMS Microbiol Rev 2009; 33:453-70. [PMID: 19396949 PMCID: PMC2734928 DOI: 10.1111/j.1574-6976.2009.00173.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Pathogenic bacteria continuously encounter multiple forms of stress in their hostile environments, which leads to DNA damage. With the new insight into biology offered by genome sequences, the elucidation of the gene content encoding proteins provides clues toward understanding the microbial lifestyle related to habitat and niche. Campylobacter jejuni, Haemophilus influenzae, Helicobacter pylori, Mycobacterium tuberculosis, the pathogenic Neisseria, Streptococcus pneumoniae, Streptococcus pyogenes and Staphylococcus aureus are major human pathogens causing detrimental morbidity and mortality at a global scale. An algorithm for the clustering of orthologs was established in order to identify whether orthologs of selected genes were present or absent in the genomes of the pathogenic bacteria under study. Based on the known genes for the various functions and their orthologs in selected pathogenic bacteria, an overview of the presence of the different types of genes was created. In this context, we focus on selected processes enabling genome dynamics in these particular pathogens, namely DNA repair, recombination and horizontal gene transfer. An understanding of the precise molecular functions of the enzymes participating in DNA metabolism and their importance in the maintenance of bacterial genome integrity has also, in recent years, indicated a future role for these enzymes as targets for therapeutic intervention.
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Affiliation(s)
- Ole Herman Ambur
- Centre for Molecular Biology and Neuroscience, Institute of Microbiology, University of Oslo, Oslo University Hospital, Norway
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