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Ataides LS, de Moraes Maia F, Conte FP, Isaac L, Barbosa AS, da Costa Lima-Junior J, Avelar KES, Rodrigues-da-Silva RN. Sph2 (176-191) and Sph2 (446-459): Identification of B-Cell Linear Epitopes in Sphingomyelinase 2 (Sph2), Naturally Recognized by Patients Infected by Pathogenic Leptospires. Vaccines (Basel) 2023; 11:vaccines11020359. [PMID: 36851237 PMCID: PMC9959207 DOI: 10.3390/vaccines11020359] [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: 01/13/2023] [Revised: 01/30/2023] [Accepted: 02/01/2023] [Indexed: 02/09/2023] Open
Abstract
Sphingomyelin is a major constituent of eukaryotic cell membranes, and if degraded by bacteria sphingomyelinases may contribute to the pathogenesis of infection. Among Leptospira spp., there are five sphingomyelinases exclusively expressed by pathogenic leptospires, in which Sph2 is expressed during natural infections, cytotoxic, and implicated in the leptospirosis hemorrhagic complications. Considering this and the lack of information about associations between Sph2 and leptospirosis severity, we use a combination of immunoinformatics approaches to identify its B-cell epitopes, evaluate their reactivity against samples from leptospirosis patients, and investigate the role of antibodies anti-Sph2 in protection against severe leptospirosis. Two B-cell epitopes, Sph2(176-191) and Sph2(446-459), were predicted in Sph2 from L. interrogans serovar Lai, presenting different levels of identity when compared with other pathogenic leptospires. These epitopes were recognized by about 40% of studied patients with a prevalence of IgG antibodies against both Sph2(176-191) and Sph2(446-459). Remarkably, just individuals with low reactivity to Sph2(176-191) presented clinical complications, while high responders had only mild symptoms. Therefore, we identified two B-cell linear epitopes, recognized by antibodies of patients with leptospirosis, that could be further explored in the development of multi-epitope vaccines against leptospirosis.
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Affiliation(s)
- Laura Sant’Anna Ataides
- Laboratório de Tecnologia Imunológica, Instituto de Tecnologia em Imunobiológicos, FIOCRUZ, Rio de Janeiro 21040-900, RJ, Brazil
| | - Fernanda de Moraes Maia
- Laboratório de Tecnologia Imunológica, Instituto de Tecnologia em Imunobiológicos, FIOCRUZ, Rio de Janeiro 21040-900, RJ, Brazil
| | - Fernando Paiva Conte
- Laboratório Piloto Eucariotos, Instituto de Tecnologia em Imunobiológicos, FIOCRUZ, Rio de Janeiro 21040-900, RJ, Brazil
| | - Lourdes Isaac
- Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508-000, SP, Brazil
| | - Angela Silva Barbosa
- Laboratório de Bacteriologia, Instituto Butantan, São Paulo 05503-900, SP, Brazil
| | - Josué da Costa Lima-Junior
- Laboratório de Imunoparasitologia, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro 21040-900, RJ, Brazil
| | - Kátia Eliane Santos Avelar
- Laboratório de Referência Nacional para Leptospirose, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro 21040-900, RJ, Brazil
| | - Rodrigo Nunes Rodrigues-da-Silva
- Laboratório de Tecnologia Imunológica, Instituto de Tecnologia em Imunobiológicos, FIOCRUZ, Rio de Janeiro 21040-900, RJ, Brazil
- Correspondence: or ; Tel.: +55-21982054291
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Tu P, Chi L, Bian X, Gao B, Ru H, Lu K. A Black Raspberry-Rich Diet Protects From Dextran Sulfate Sodium-Induced Intestinal Inflammation and Host Metabolic Perturbation in Association With Increased Aryl Hydrocarbon Receptor Ligands in the Gut Microbiota of Mice. Front Nutr 2022; 9:842298. [PMID: 35734371 PMCID: PMC9208328 DOI: 10.3389/fnut.2022.842298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 04/21/2022] [Indexed: 11/13/2022] Open
Abstract
Dietary modulation of the gut microbiota recently received considerable attention, and ligand activation of aryl hydrocarbon receptor (AHR) plays a pivotal role in intestinal immunity. Importantly, black raspberry (BRB, Rubus occidentalis) is associated with a variety of beneficial health effects. We aim to investigate effects of a BRB-rich diet on dextran sulfate sodium (DSS)-induced intestinal inflammation and to determine whether its consequent anti-inflammatory effects are relevant to modulation of the gut microbiota, especially its production of AHR ligands. A mouse model of DSS-induced intestinal inflammation was used in the present study. C57BL/6J mice were fed either AIN-76A or BRB diet. Composition and functions of the gut microbiota were assessed by 16S rRNA sequencing and comparative metagenome analysis. Metabolic profiles of host and the gut microbiome were assessed by serum and fecal metabolomic profiling and identification. BRB diet was found to ameliorate DSS-induced intestinal inflammation and host metabolic perturbation. BRB diet also protected from DSS-induced perturbation in diversity and composition in the gut microbiota. BRB diet promoted AHR ligand production by the gut microbiota, as revealed by increased levels of fecal AHR activity in addition to increased levels of two known AHR ligands, hemin and biliverdin. Accordingly, enrichment of bacterial genes and pathways responsible for production of hemin and biliverdin were found, specific gut bacteria that are highly correlated with abundances of hemin and biliverdin were also identified. BRB dietary intervention ameliorated intestinal inflammation in mice in association with promotion of AHR ligand production by the gut microbiota.
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Affiliation(s)
- Pengcheng Tu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Liang Chi
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Xiaoming Bian
- Department of Environmental Health Sciences, University of Georgia, Athens, GA, United States
| | - Bei Gao
- Department of Environmental Health Sciences, University of Georgia, Athens, GA, United States
| | - Hongyu Ru
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Kun Lu
- Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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Grassmann AA, Zavala-Alvarado C, Bettin EB, Picardeau M, Benaroudj N, Caimano MJ. The FUR-like regulators PerRA and PerRB integrate a complex regulatory network that promotes mammalian host-adaptation and virulence of Leptospira interrogans. PLoS Pathog 2021; 17:e1009078. [PMID: 34855918 PMCID: PMC8638967 DOI: 10.1371/journal.ppat.1009078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/18/2021] [Indexed: 11/18/2022] Open
Abstract
Leptospira interrogans, the causative agent of most cases of human leptospirosis, must respond to myriad environmental signals during its free-living and pathogenic lifestyles. Previously, we compared L. interrogans cultivated in vitro and in vivo using a dialysis membrane chamber (DMC) peritoneal implant model. From these studies emerged the importance of genes encoding the Peroxide responsive regulators PerRA and PerRB. First described in in Bacillus subtilis, PerRs are widespread in Gram-negative and -positive bacteria, where regulate the expression of gene products involved in detoxification of reactive oxygen species and virulence. Using perRA and perRB single and double mutants, we establish that L. interrogans requires at least one functional PerR for infectivity and renal colonization in a reservoir host. Our finding that the perRA/B double mutant survives at wild-type levels in DMCs is noteworthy as it demonstrates that the loss of virulence is not due to a metabolic lesion (i.e., metal starvation) but instead reflects dysregulation of virulence-related gene products. Comparative RNA-Seq analyses of perRA, perRB and perRA/B mutants cultivated within DMCs identified 106 genes that are dysregulated in the double mutant, including ligA, ligB and lvrA/B sensory histidine kinases. Decreased expression of LigA and LigB in the perRA/B mutant was not due to loss of LvrAB signaling. The majority of genes in the perRA and perRB single and double mutant DMC regulons were differentially expressed only in vivo, highlighting the importance of host signals for regulating gene expression in L. interrogans. Importantly, the PerRA, PerRB and PerRA/B DMC regulons each contain multiple genes related to environmental sensing and/or transcriptional regulation. Collectively, our data suggest that PerRA and PerRB are part of a complex regulatory network that promotes host adaptation by L. interrogans within mammals.
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Affiliation(s)
- André A. Grassmann
- Department of Medicine, University of Connecticut Health, Farmington, Connecticut, United States of America
| | - Crispin Zavala-Alvarado
- Unité de Biologie des Spirochètes, Department of Microbiology, Institut Pasteur, Paris, France
- Université de Paris, Sorbonne Paris Cité, Communauté d’universités et d’établissements (COMUE), Bio Sorbonne Paris Cité (BioSPC), Paris, France
| | - Everton B. Bettin
- Department of Medicine, University of Connecticut Health, Farmington, Connecticut, United States of America
- Programa de Pós-Graduação em Biotecnologia, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas, Pelotas, Rio Grande do Sol, Brazil
| | - Mathieu Picardeau
- Unité de Biologie des Spirochètes, Department of Microbiology, Institut Pasteur, Paris, France
| | - Nadia Benaroudj
- Unité de Biologie des Spirochètes, Department of Microbiology, Institut Pasteur, Paris, France
| | - Melissa J. Caimano
- Department of Medicine, University of Connecticut Health, Farmington, Connecticut, United States of America
- Department of Pediatrics, University of Connecticut Health, Farmington, Connecticut, United States of America
- Department of Molecular Biology and Biophysics, University of Connecticut Health, Farmington, Connecticut, United States of America
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Scott AF, Deery E, Lawrence AD, Warren MJ. Plasmodium falciparum hydroxymethylbilane synthase does not house any cosynthase activity within the haem biosynthetic pathway. MICROBIOLOGY-SGM 2021; 167. [PMID: 34661520 PMCID: PMC8698207 DOI: 10.1099/mic.0.001095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Uroporphyrinogen III, the universal progenitor of macrocyclic, modified tetrapyrroles, is produced from aminolaevulinic acid (ALA) by a conserved pathway involving three enzymes: porphobilinogen synthase (PBGS), hydroxymethylbilane synthase (HmbS) and uroporphyrinogen III synthase (UroS). The gene encoding uroporphyrinogen III synthase has not yet been identified in Plasmodium falciparum, but it has been suggested that this activity is housed inside a bifunctional hybroxymethylbilane synthase (HmbS). Additionally, an unknown protein encoded by PF3D7_1247600 has also been predicted to possess UroS activity. In this study it is demonstrated that neither of these proteins possess UroS activity and the real UroS remains to be identified. This was demonstrated by the failure of codon-optimized genes to complement a defined Escherichia coli hemD− mutant (SASZ31) deficient in UroS activity. Furthermore, HPLC analysis of the oxidized reaction product from recombinant, purified P. falciparum HmbS showed that only uroporphyrin I could be detected (corresponding to hydroxymethylbilane production). No uroporphyrin III was detected, showing that P. falciparum HmbS does not have UroS activity and can only catalyze the formation of hydroxymethylbilane from porphobilinogen.
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Affiliation(s)
- Alan F. Scott
- School of Biosciences, University of Kent, Canterbury, Kent, CT2 7NJ, UK
- Present address: School of Chemistry, Cardiff University, Cardiff, CF10 3AT, UK
- *Correspondence: Alan F. Scott,
| | - Evelyne Deery
- School of Biosciences, University of Kent, Canterbury, Kent, CT2 7NJ, UK
| | - Andrew D. Lawrence
- School of Biosciences, University of Kent, Canterbury, Kent, CT2 7NJ, UK
| | - Martin J. Warren
- School of Biosciences, University of Kent, Canterbury, Kent, CT2 7NJ, UK
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, UK
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Haemophagocytic Lymphohistiocytosis with Leptospirosis: A Rare but Devastating Complication. Case Rep Infect Dis 2021; 2021:3451155. [PMID: 34336315 PMCID: PMC8295509 DOI: 10.1155/2021/3451155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/17/2021] [Accepted: 06/29/2021] [Indexed: 11/21/2022] Open
Abstract
Introduction Secondary haemophagocytic lymphohistiocytosis (sHLH), often associated with an array of infections, malignancies, and autoimmune diseases, is rarely seen with leptospirosis, which carries a relatively poor prognosis even with modern state-of-the-art medical care. We describe a patient with leptospirosis complicated by sHLH who succumbed to illness following multiorgan dysfunction. Case Description. A 74-year-old farmer presented with high-grade, unsettling fever for a week. Muddy water exposure and suggestive symptoms prompted investigation and management in the line of leptospirosis (IV ceftriaxone was instituted, and later, MAT (microscopic agglutination test) became positive). Subsequently, he developed severe acute hypoxemia requiring mechanical ventilation and acute renal failure requiring renal replacement therapy. Bone marrow biopsy and markedly elevated serum ferritin and triglyceride levels done on day 10 (with unresolving fever, hepatosplenomegaly, and pancytopaenia) confirmed the diagnosis of HLH. The routine cultures, retroviral studies, CMV, dengue, hanta and mycoplasma antibodies, tuberculosis and COVID-19 PCR, and malaria screening were all normal. There was no improvement of hypoxemia following intravenous methylprednisolone. He died on day 15 despite escalating organ support. Conclusion Leptospirosis is a common zoonotic disease in the tropics with significant morbidity and mortality. In the case of severe leptospirosis, overlapping clinical features with sHLH make the diagnosis of the latter challenging. No assessment tools are available to date to predict the risk of developing sHLH in a patient having leptospirosis. Outcome following sHLH due to leptospirosis still remains majorly ominous. A high index of suspicion and low threshold for specific investigations could possibly alter the outcome following such an occurrence.
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Zavala-Alvarado C, Sismeiro O, Legendre R, Varet H, Bussotti G, Bayram J, G. Huete S, Rey G, Coppée JY, Picardeau M, Benaroudj N. The transcriptional response of pathogenic Leptospira to peroxide reveals new defenses against infection-related oxidative stress. PLoS Pathog 2020; 16:e1008904. [PMID: 33021995 PMCID: PMC7567364 DOI: 10.1371/journal.ppat.1008904] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 10/16/2020] [Accepted: 08/19/2020] [Indexed: 11/19/2022] Open
Abstract
Pathogenic Leptospira spp. are the causative agents of the waterborne zoonotic disease leptospirosis. Leptospira are challenged by numerous adverse conditions, including deadly reactive oxygen species (ROS), when infecting their hosts. Withstanding ROS produced by the host innate immunity is an important strategy evolved by pathogenic Leptospira for persisting in and colonizing hosts. In L. interrogans, genes encoding defenses against ROS are repressed by the peroxide stress regulator, PerR. In this study, RNA sequencing was performed to characterize both the L. interrogans response to low and high concentrations of hydrogen peroxide and the PerR regulon. We showed that Leptospira solicit three main peroxidase machineries (catalase, cytochrome C peroxidase and peroxiredoxin) and heme to detoxify oxidants produced during peroxide stress. In addition, canonical molecular chaperones of the heat shock response and DNA repair proteins from the SOS response were required for Leptospira recovering from oxidative damage. Identification of the PerR regulon upon exposure to H2O2 allowed to define the contribution of this regulator in the oxidative stress response. This study has revealed a PerR-independent regulatory network involving other transcriptional regulators, two-component systems and sigma factors as well as non-coding RNAs that putatively orchestrate, in concert with PerR, the oxidative stress response. We have shown that PerR-regulated genes encoding a TonB-dependent transporter and a two-component system (VicKR) are involved in Leptospira tolerance to superoxide. This could represent the first defense mechanism against superoxide in L. interrogans, a bacterium lacking canonical superoxide dismutase. Our findings provide an insight into the mechanisms required by pathogenic Leptospira to overcome oxidative damage during infection-related conditions. This will participate in framing future hypothesis-driven studies to identify and decipher novel virulence mechanisms in this life-threatening pathogen. Leptospirosis is a zoonotic infectious disease responsible for over one million of severe cases and 60 000 fatalities annually worldwide. This neglected and emerging disease has a worldwide distribution, but it mostly affects populations from developing countries in sub-tropical areas. The causative agents of leptospirosis are pathogenic bacterial Leptospira spp. There is a considerable deficit in our knowledge of these atypical bacteria, including their virulence mechanisms. During infection, Leptospira are confronted with the deadly oxidants produced by the host tissues and immune response. Here, we have identified the leptospiral factors necessary for overcoming infection-related oxidative stress. We found that Leptospira solicit peroxidases to detoxify oxidants as well as chaperones of the heat shock response and DNA repair proteins of the SOS response to recover from oxidative damage. Moreover, our study indicates that the oxidative stress response is orchestrated by a regulatory network involving PerR and other transcriptional regulators, sigma factors, two component systems, and putative non-coding RNAs. These findings provide insights into the mechanisms required by pathogenic Leptospira to tolerate infection-related oxidants and could help identifying novel virulence factors and developing new therapeutic targets.
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Affiliation(s)
- Crispin Zavala-Alvarado
- Unité de Biologie des Spirochètes, Department of Microbiology, Institut Pasteur, Paris, France
- Université de Paris, Sorbonne Paris Cité, COMUE BioSPC, Paris, France
| | - Odile Sismeiro
- Biomics Technological Plateform, Center for Technological Resources and Research, Institut Pasteur, Paris, France
| | - Rachel Legendre
- Biomics Technological Plateform, Center for Technological Resources and Research, Institut Pasteur, Paris, France
- Bioinformatics and Biostatistics Hub, Department of Computational Biology, USR 3756 CNRS, Institut Pasteur, Paris, France
| | - Hugo Varet
- Biomics Technological Plateform, Center for Technological Resources and Research, Institut Pasteur, Paris, France
- Bioinformatics and Biostatistics Hub, Department of Computational Biology, USR 3756 CNRS, Institut Pasteur, Paris, France
| | - Giovanni Bussotti
- Bioinformatics and Biostatistics Hub, Department of Computational Biology, USR 3756 CNRS, Institut Pasteur, Paris, France
| | - Jan Bayram
- Unité de Biologie des Spirochètes, Department of Microbiology, Institut Pasteur, Paris, France
| | - Samuel G. Huete
- Unité de Biologie des Spirochètes, Department of Microbiology, Institut Pasteur, Paris, France
| | - Guillaume Rey
- Unité de Biologie des Spirochètes, Department of Microbiology, Institut Pasteur, Paris, France
| | - Jean-Yves Coppée
- Biomics Technological Plateform, Center for Technological Resources and Research, Institut Pasteur, Paris, France
| | - Mathieu Picardeau
- Unité de Biologie des Spirochètes, Department of Microbiology, Institut Pasteur, Paris, France
| | - Nadia Benaroudj
- Unité de Biologie des Spirochètes, Department of Microbiology, Institut Pasteur, Paris, France
- * E-mail:
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Bhattacharjee S, Mishra AK. The tale of caspase homologues and their evolutionary outlook: deciphering programmed cell death in cyanobacteria. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:4639-4657. [PMID: 32369588 PMCID: PMC7475262 DOI: 10.1093/jxb/eraa213] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 04/28/2020] [Indexed: 06/11/2023]
Abstract
Programmed cell death (PCD), a genetically orchestrated mechanism of cellular demise, is paradoxically required to support life. As in lower eukaryotes and bacteria, PCD in cyanobacteria is poorly appreciated, despite recent biochemical and molecular evidence that supports its existence. Cyanobacterial PCD is an altruistic reaction to stressful conditions that significantly enhances genetic diversity and inclusive fitness of the population. Recent bioinformatic analysis has revealed an abundance of death-related proteases, i.e. orthocaspases (OCAs) and their mutated variants, in cyanobacteria, with the larger genomes of morphologically complex strains harbouring most of them. Sequence analysis has depicted crucial accessory domains along with the proteolytic p20-like sub-domain in OCAs, predicting their functional versatility. However, the cascades involved in sensing death signals, their transduction, and the downstream expression and activation of OCAs remain to be elucidated. Here, we provide a comprehensive description of the attempts to identify mechanisms of PCD and the existence and importance of OCAs based on in silico approaches. We also review the evolutionary and ecological significance of PCD in cyanobacteria. In the future, the analysis of cyanobacterial PCD will identify novel proteins that have varied functional roles in signalling cascades and also help in understanding the incipient mechanism of PCD morphotype(s) from where eukaryotic PCD might have originated.
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Affiliation(s)
- Samujjal Bhattacharjee
- Laboratory of Microbial Genetics, Department of Botany, Banaras Hindu University, Varanasi, India
| | - Arun Kumar Mishra
- Laboratory of Microbial Genetics, Department of Botany, Banaras Hindu University, Varanasi, India
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Pappas CJ, Xu H, Motaleb MA. Creating a Library of Random Transposon Mutants in Leptospira. Methods Mol Biol 2020; 2134:77-96. [PMID: 32632861 PMCID: PMC7473121 DOI: 10.1007/978-1-0716-0459-5_8] [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] [Indexed: 06/11/2023]
Abstract
Generation of a random transposon mutant library is advantageous in Leptospira as site-directed mutagenesis remains a challenge, especially in pathogenic species. This procedure is typically completed by transformation of Leptospira with a Himar1 containing plasmid via conjugation with Escherichia coli as a donor cell. Here we describe the methodology to generate random transposon mutants in the saprophyte Leptospira biflexa via conjugation of plasmid pSW29T-TKS2 harbored in E. coli β2163. Determination of transposon insertion site by semi-random nested PCR will also be described. A similar methodology may be employed to generate Tn mutants of pathogenic Leptospira species.
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Affiliation(s)
| | - Hui Xu
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - Md A Motaleb
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC, USA
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Zhang JJ, Hu WL, Yang Y, Li H, Picardeau M, Yan J, Yang XF. The sigma factor σ 54 is required for the long-term survival of Leptospira biflexa in water. Mol Microbiol 2018; 109:10.1111/mmi.13967. [PMID: 29633391 PMCID: PMC6174002 DOI: 10.1111/mmi.13967] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2018] [Indexed: 12/21/2022]
Abstract
Leptospira spp. comprise both pathogenic and free-living saprophytic species. Little is known about the environmental adaptation and survival mechanisms of Leptospira. Alternative sigma factor, σ54 (RpoN) is known to play an important role in environmental and host adaptation in many bacteria. In this study, we constructed an rpoN mutant by allele exchange, and the complemented strain in saprophytic L. biflexa. Transcriptome analysis revealed that expression of several genes involved in nitrogen uptake and metabolism, including amtB1, glnB-amtB2, ntrX and narK, were controlled by σ54 . While wild-type L. biflexa could not grow under nitrogen-limiting conditions but was able to survive under such conditions and recover rapidly, the rpoN mutant was not. The rpoN mutant also had dramatically reduced ability to survive long-term in water. σ54 appears to regulate expression of amtB1, glnK-amtB2, ntrX and narK in an indirect manner. However, we identified a novel nitrogen-related gene, LEPBI_I1011, whose expression was directly under the control of σ54 (herein renamed as rcfA for RpoN-controlled factor A). Taken together, our data reveal that the σ54 regulatory network plays an important role in the long-term environmental survival of Leptospira spp.
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Affiliation(s)
- Jun-Jie Zhang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Wei-Lin Hu
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Medical Microbiology and Parasitology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China
| | - Youyun Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Hongxia Li
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | | | - Jie Yan
- Department of Medical Microbiology and Parasitology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China
| | - X. Frank Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Mehrotra P, Ramakrishnan G, Dhandapani G, Srinivasan N, Madanan MG. Comparison of Leptospira interrogans and Leptospira biflexa genomes: analysis of potential leptospiral-host interactions. MOLECULAR BIOSYSTEMS 2018; 13:883-891. [PMID: 28294222 DOI: 10.1039/c6mb00856a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Leptospirosis, a potentially life-threatening disease, remains the most widespread zoonosis caused by pathogenic species of Leptospira. The pathogenic spirochaete, Leptospira interrogans, is characterized by its ability to permeate human host tissues rapidly and colonize multiple organs in the host. In spite of the efforts taken to comprehend the pathophysiology of the pathogen and the heterogeneity posed by L. interrogans, the current knowledge on the mechanism of pathogenesis is modest. In an attempt to contribute towards the same, we demonstrate the use of an established structure-based protocol coupled with information on subcellular localization of proteins and their tissue-specificity, in recognizing a set of 49 biologically feasible interactions potentially mediated by proteins of L. interrogans in humans. We have also presented means to adjudge the physicochemical viability of the predicted host-pathogen interactions, for selected cases, in terms of interaction energies and geometric shape complementarity of the interacting proteins. Comparative analyses of proteins of L. interrogans and the saprophytic spirochaete, Leptospira biflexa, and their predicted involvement in interactions with human hosts, aided in underpinning the functional relevance of leptospiral-host protein-protein interactions specific to L. interrogans as well as those specific to L. biflexa. Our study presents characteristics of the pathogenic L. interrogans that are predicted to facilitate its ability to persist in human hosts.
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Affiliation(s)
- Prachi Mehrotra
- Indian Institute of Science Mathematics Initiative, Indian Institute of Science, Bangalore 560012, India
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Herman HS, Mehta S, Cárdenas WB, Stewart-Ibarra AM, Finkelstein JL. Micronutrients and Leptospirosis: A Review of the Current Evidence. PLoS Negl Trop Dis 2016; 10:e0004652. [PMID: 27387046 PMCID: PMC4936698 DOI: 10.1371/journal.pntd.0004652] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Leptospirosis is one of the most widespread zoonoses and represents a major threat to human health. Due to the high burden of disease, limitations in diagnostics, and limited coverage and availability of effective human and veterinary vaccines, leptospirosis remains an important neglected zoonotic disease. Improved surveillance and identification of modifiable risk factors for leptospirosis are urgently needed to inform preventive interventions and reduce the risk and severity of Leptospira infection. METHODOLOGY/PRINCIPAL FINDINGS This review was conducted to examine the evidence that links micronutrient status and Leptospira infection. A total of 56 studies were included in this review: 28 in vitro, 17 animal, and 11 observational human studies. Findings indicated that Leptospira infection is associated with higher iron and calcium concentrations and hypomagnesemia. CONCLUSIONS/SIGNIFICANCE Few prospective studies and no randomized trials have been conducted to date to examine the potential role of micronutrients in Leptospira infection. The limited literature in this area constrains our ability to make specific recommendations; however, the roles of iron, calcium, and magnesium in leptospirosis represent important areas for future research. The role of micronutrients in leptospirosis risk and severity needs to be elucidated in larger prospective human studies to inform public health interventions.
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Affiliation(s)
- Heather S. Herman
- Division of Nutritional Sciences, Cornell University, Ithaca, New York, United States of America
| | - Saurabh Mehta
- Division of Nutritional Sciences, Cornell University, Ithaca, New York, United States of America
- St. John's Research Institute, Bangalore, India
| | - Washington B. Cárdenas
- Laboratorio de Biomedicina, Escuela Superior Politécnica del Litoral, ESPOL, Guayaquil, Ecuador
| | - Anna M. Stewart-Ibarra
- Department of Medicine and the Center for Global Health and Translational Science, State University of New York (SUNY) Upstate Medical University, Syracuse, New York, United States of America
| | - Julia L. Finkelstein
- Division of Nutritional Sciences, Cornell University, Ithaca, New York, United States of America
- St. John's Research Institute, Bangalore, India
- * E-mail:
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Multiple Posttranslational Modifications of Leptospira biflexa Proteins as Revealed by Proteomic Analysis. Appl Environ Microbiol 2015; 82:1183-1195. [PMID: 26655756 DOI: 10.1128/aem.03056-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 12/01/2015] [Indexed: 12/12/2022] Open
Abstract
The saprophyte Leptospira biflexa is an excellent model for studying the physiology of the medically important Leptospira genus, the pathogenic members of which are more recalcitrant to genetic manipulation and have significantly slower in vitro growth. However, relatively little is known regarding the proteome of L. biflexa, limiting its utility as a model for some studies. Therefore, we have generated a proteomic map of both soluble and membrane-associated proteins of L. biflexa during exponential growth and in stationary phase. Using these data, we identified abundantly produced proteins in each cellular fraction and quantified the transcript levels from a subset of these genes using quantitative reverse transcription-PCR (RT-PCR). These proteins should prove useful as cellular markers and as controls for gene expression studies. We also observed a significant number of L. biflexa membrane-associated proteins with multiple isoforms, each having unique isoelectric focusing points. L. biflexa cell lysates were examined for several posttranslational modifications suggested by the protein patterns. Methylation and acetylation of lysine residues were predominately observed in the proteins of the membrane-associated fraction, while phosphorylation was detected mainly among soluble proteins. These three posttranslational modification systems appear to be conserved between the free-living species L. biflexa and the pathogenic species Leptospira interrogans, suggesting an important physiological advantage despite the varied life cycles of the different species.
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O'Flynn C, Deusch O, Darling AE, Eisen JA, Wallis C, Davis IJ, Harris SJ. Comparative Genomics of the Genus Porphyromonas Identifies Adaptations for Heme Synthesis within the Prevalent Canine Oral Species Porphyromonas cangingivalis. Genome Biol Evol 2015; 7:3397-413. [PMID: 26568374 PMCID: PMC4700951 DOI: 10.1093/gbe/evv220] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Porphyromonads play an important role in human periodontal disease and recently have been shown to be highly prevalent in canine mouths. Porphyromonas cangingivalis is the most prevalent canine oral bacterial species in both plaque from healthy gingiva and plaque from dogs with early periodontitis. The ability of P. cangingivalis to flourish in the different environmental conditions characterized by these two states suggests a degree of metabolic flexibility. To characterize the genes responsible for this, the genomes of 32 isolates (including 18 newly sequenced and assembled) from 18 Porphyromonad species from dogs, humans, and other mammals were compared. Phylogenetic trees inferred using core genes largely matched previous findings; however, comparative genomic analysis identified several genes and pathways relating to heme synthesis that were present in P. cangingivalis but not in other Porphyromonads. Porphyromonas cangingivalis has a complete protoporphyrin IX synthesis pathway potentially allowing it to synthesize its own heme unlike pathogenic Porphyromonads such as Porphyromonas gingivalis that acquire heme predominantly from blood. Other pathway differences such as the ability to synthesize siroheme and vitamin B12 point to enhanced metabolic flexibility for P. cangingivalis, which may underlie its prevalence in the canine oral cavity.
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Affiliation(s)
- Ciaran O'Flynn
- The WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, United Kingdom
| | - Oliver Deusch
- The WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, United Kingdom
| | - Aaron E Darling
- The ithree Institute, University of Technology Sydney, Ultimo, New South Wales, Australia
| | - Jonathan A Eisen
- Department of Evolution and Ecology, University of California, Davis Department of Medical Microbiology and Immunology, University of California, Davis UC Davis Genome Center, University of California, Davis
| | - Corrin Wallis
- The WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, United Kingdom
| | - Ian J Davis
- The WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, United Kingdom
| | - Stephen J Harris
- The WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, United Kingdom
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14
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Narayanavari SA, Lourdault K, Sritharan M, Haake DA, Matsunaga J. Role of sph2 Gene Regulation in Hemolytic and Sphingomyelinase Activities Produced by Leptospira interrogans. PLoS Negl Trop Dis 2015; 9:e0003952. [PMID: 26274394 PMCID: PMC4537108 DOI: 10.1371/journal.pntd.0003952] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 07/06/2015] [Indexed: 12/19/2022] Open
Abstract
Pathogenic members of the genus Leptospira are the causative agents of leptospirosis, a neglected disease of public and veterinary health concern. Leptospirosis is a systemic disease that in its severest forms leads to renal insufficiency, hepatic dysfunction, and pulmonary failure. Many strains of Leptospira produce hemolytic and sphingomyelinase activities, and a number of candidate leptospiral hemolysins have been identified based on sequence similarity to well-characterized bacterial hemolysins. Five of the putative hemolysins are sphingomyelinase paralogs. Although recombinant forms of the sphingomyelinase Sph2 and other hemolysins lyse erythrocytes, none have been demonstrated to contribute to the hemolytic activity secreted by leptospiral cells. In this study, we examined the regulation of sph2 and its relationship to hemolytic and sphingomyelinase activities produced by several L. interrogans strains cultivated under the osmotic conditions found in the mammalian host. The sph2 gene was poorly expressed when the Fiocruz L1-130 (serovar Copenhageni), 56601 (sv. Lai), and L495 (sv. Manilae) strains were cultivated in the standard culture medium EMJH. Raising EMJH osmolarity to physiological levels with sodium chloride enhanced Sph2 production in all three strains. In addition, the Pomona subtype kennewicki strain LC82-25 produced substantially greater amounts of Sph2 during standard EMJH growth than the other strains, and sph2 expression increased further by addition of salt. When 10% rat serum was present in EMJH along with the sodium chloride supplement, Sph2 production increased further in all strains. Osmotic regulation and differences in basal Sph2 production in the Manilae L495 and Pomona strains correlated with the levels of secreted hemolysin and sphingomyelinase activities. Finally, a transposon insertion in sph2 dramatically reduced hemolytic and sphingomyelinase activities during incubation of L. interrogans at physiologic osmolarity. Complementation of the mutation with the sph2 gene partially restored production of hemolytic and sphingomyelinase activities. These results indicate that the sph2 gene product contributes to the hemolytic and sphingomyelinase activities secreted by L. interrogans and most likely dominates those functions under the culture condition tested. The spirochete Leptospira causes leptospirosis, a potentially deadly disease of humans and animals. Candidate factors that promote infection include hemolysins encoded by several leptospiral genes. Hemolysins rupture red blood cells in vitro. Some hemolysins are sphingomyelinases, which target sphingomyelin in the host cell membrane. Hemolysins have the potential to disrupt organ function during infection. It is not known which hemolysins and sphingomyelinases are responsible for the hemolytic and sphingomyelinase activities secreted by L. interrogans. We found that the production of hemolytic activity is regulated and is tied to expression of sph2, which encodes a hemolysin with sphingomyelinase, cytotoxic, and fibronectin-binding activities. Hemolytic and sphingomyelinase activities and sph2 expression were higher when the osmolarity of the culture medium was raised to the level found in the mammalian host. Similarly, sph2 expression was substantially higher in an L. interrogans strain that secreted large amounts of hemolytic and sphingomyelinase activities than in a strain that generated negligible amounts. Most importantly, disruption of the sph2 gene eliminated hemolysin production and yielded substantially less sphingomyelinase than the wild-type strain. Our findings indicate that sph2 is a major contributor to the hemolytic and sphingomyelinase activities secreted by L. interrogans and that the hemolytic and sphingomyelinase activities measured in standard L. interrogans cultures may underestimate the levels produced during infection.
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Affiliation(s)
| | - Kristel Lourdault
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America; Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, California, United States of America
| | - Manjula Sritharan
- Department of Animal Biology, University of Hyderabad, Hyderabad, India
| | - David A Haake
- Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, California, United States of America; Department of Urology, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, California, United States of America; Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, California, United States of America; Division of Infectious Diseases, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America
| | - James Matsunaga
- Research Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States of America; Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, California, United States of America
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Abstract
The mechanisms of disease pathogenesis in leptospirosis are poorly defined. Recent developments in the application of genetic tools in the study of Leptospira have advanced our understanding by allowing the assessment of mutants in animal models. As a result, a small number of essential virulence factors have been identified, though most do not have a clearly defined function. Significant advances have also been made in the in vitro characterization of leptospiral interaction with host structures, including extracellular matrix proteins (such as laminin, elastin, fibronectin, collagens), proteins related to hemostasis (fibrinogen, plasmin), and soluble mediators of complement resistance (factor H, C4b-binding protein), although none of these in vitro findings has been translated to the host animal. Binding to host structures may permit colonization of the host, prevention of blood clotting may contribute to hemorrhage, while interaction with complement resistance mediators may contribute to survival in serum. While not a classical intracellular pathogen, the interaction of leptospires and phagocytic cells appears complex, with bacteria surviving uptake and promoting apoptosis; mutants relating to these processes (such as cell invasion and oxidative stress resistance) are attenuated in vivo. Another feature of leptospiral biology is the high degree of functional redundancy and the surprising lack of attenuation of mutants in what appear to be certain virulence factors, such as LipL32 and LigB. While many advances have been made, there remains a lack of understanding of how Leptospira causes tissue pathology. It is likely that leptospires have many novel pathogenesis mechanisms that are yet to be identified.
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16
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Morero NR, Botti H, Nitta KR, Carrión F, Obal G, Picardeau M, Buschiazzo A. HemR is an OmpR/PhoB-like response regulator from Leptospira, which simultaneously effects transcriptional activation and repression of key haem metabolism genes. Mol Microbiol 2014; 94:340-52. [PMID: 25145397 DOI: 10.1111/mmi.12763] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2014] [Indexed: 02/06/2023]
Abstract
Several Leptospira species cause leptospirosis, the most extended zoonosis worldwide. In bacteria, two-component systems constitute key signalling pathways, some of which are involved in pathogenesis. The physiological roles of two-component systems in Leptospira are largely unknown, despite identifying several dozens within their genomes. Biochemical confirmation of an operative phosphorelaying two-component system has been obtained so far only for the Hklep/Rrlep pair. It is known that hklep/rrlep knockout strains of Leptospira biflexa result in haem auxotrophy, although their de novo biosynthesis machinery remains fully functional. Haem is essential for Leptospira, but information about Hklep/Rrlep effector function(s) and target(s) is still lacking. We are now reporting a thorough molecular characterization of this system, which we rename HemK/HemR. The DNA HemR-binding motif was determined, and found within the genomes of saprophyte and pathogenic Leptospira. In this way, putative HemR-regulated genes were pinpointed, including haem catabolism-related (hmuO - haem oxygenase) and biosynthesis-related (the hemA/C/D/B/L/E/N/G operon). Specific HemR binding to these two promoters was quantified, and a dual function was observed in vivo, inversely repressing the hmuO, while activating the hemA operon transcription. The crystal structure of HemR receiver domain was determined, leading to a mechanistic model for its dual regulatory role.
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Affiliation(s)
- Natalia R Morero
- Institut Pasteur de Montevideo, Unit of Protein Crystallography, 2020 Mataojo, 11400, Montevideo, Uruguay
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A model system for studying the transcriptomic and physiological changes associated with mammalian host-adaptation by Leptospira interrogans serovar Copenhageni. PLoS Pathog 2014; 10:e1004004. [PMID: 24626166 PMCID: PMC3953431 DOI: 10.1371/journal.ppat.1004004] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 02/01/2014] [Indexed: 12/23/2022] Open
Abstract
Leptospirosis, an emerging zoonotic disease with worldwide distribution, is caused by spirochetes belonging to the genus Leptospira. More than 500,000 cases of severe leptospirosis are reported annually, with >10% of these being fatal. Leptospires can survive for weeks in suitably moist conditions before encountering a new host. Reservoir hosts, typically rodents, exhibit little to no signs of disease but shed large numbers of organisms in their urine. Transmission occurs when mucosal surfaces or abraded skin come into contact with infected urine or urine-contaminated water or soil. In humans, leptospires can cause a variety of clinical manifestations, ranging from asymptomatic or mild fever to severe icteric (Weil's) disease and pulmonary haemorrhage. Currently, little is known about how Leptospira persist within a reservoir host. Prior in vitro studies have suggested that leptospires alter their transcriptomic and proteomic profiles in response to environmental signals encountered during mammalian infection. However, no study has examined gene expression by leptospires within a mammalian host-adapted state. To obtain a more faithful representation of how leptospires respond to host-derived signals, we used RNA-Seq to compare the transcriptome of L. interrogans cultivated within dialysis membrane chambers (DMCs) implanted into the peritoneal cavities of rats with that of organisms grown in vitro. In addition to determining the relative expression levels of “core” housekeeping genes under both growth conditions, we identified 166 genes that are differentially-expressed by L. interrogans in vivo. Our analyses highlight physiological aspects of host adaptation by leptospires relating to heme uptake and utilization. We also identified 11 novel non-coding transcripts that are candidate small regulatory RNAs. The DMC model provides a facile system for studying the transcriptional and antigenic changes associated with mammalian host-adaption, selection of targets for mutagenesis, and the identification of previously unrecognized virulence determinants. Leptospirosis, a global disease caused by the unusual bacterium Leptospira, is transmitted from animals to humans. Pathogenic species of Leptospira are excreted in urine from infected animals and can continue to survive in suitable environments before coming into contact with a new reservoir or accidental host. Leptospires have an inherent ability to survive a wide range of conditions encountered in nature during transmission and within mammals. However, we know very little about the regulatory pathways and gene products that promote mammalian host adaptation and enable leptospires to establish infection. In this study, we used a novel system whereby leptospires are cultivated in dialysis membrane chambers implanted into the peritoneal cavities of rats to compare the gene expression profiles of mammalian host-adapted and in vitro-cultivated organisms. In addition to providing a facile system for studying the transcriptional and physiologic changes leptospires undergo during mammalian infection, our data provide a rational basis for selecting new targets for mutagenesis.
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Bung N, Pradhan M, Srinivasan H, Bulusu G. Structural insights into E. coli porphobilinogen deaminase during synthesis and exit of 1-hydroxymethylbilane. PLoS Comput Biol 2014; 10:e1003484. [PMID: 24603363 PMCID: PMC3945110 DOI: 10.1371/journal.pcbi.1003484] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 01/08/2014] [Indexed: 11/19/2022] Open
Abstract
Porphobilinogen deaminase (PBGD) catalyzes the formation of 1-hydroxymethylbilane (HMB), a crucial intermediate in tetrapyrrole biosynthesis, through a step-wise polymerization of four molecules of porphobilinogen (PBG), using a unique dipyrromethane (DPM) cofactor. Structural and biochemical studies have suggested residues with catalytic importance, but their specific role in the mechanism and the dynamic behavior of the protein with respect to the growing pyrrole chain remains unknown. Molecular dynamics simulations of the protein through the different stages of pyrrole chain elongation suggested that the compactness of the overall protein decreases progressively with addition of each pyrrole ring. Essential dynamics showed that domains move apart while the cofactor turn region moves towards the second domain, thus creating space for the pyrrole rings added at each stage. Residues of the flexible active site loop play a significant role in its modulation. Steered molecular dynamics was performed to predict the exit mechanism of HMB from PBGD at the end of the catalytic cycle. Based on the force profile and minimal structural changes the proposed path for the exit of HMB is through the space between the domains flanking the active site loop. Residues reported as catalytically important, also play an important role in the exit of HMB. Further, upon removal of HMB, the structure of PBGD gradually relaxes to resemble its initial stage structure, indicating its readiness to resume a new catalytic cycle. Heme is the prosthetic group at the core of the oxygen carrier metalloprotein hemoglobin. Heme consists of a tetrapyrrole called porphyrin bound to an iron ion. It is synthesized by the heme biosynthetic pathway, which is common to all eukaryotes and most prokaryotes. Porphobilinogen deaminase, an enzyme in the heme biosynthetic pathway, catalyzes the formation of a linear tetrapyrrole product, 1-hydroxymethylbilane, from four units of porphobilinogen. In this study we carried out molecular dynamics simulations to understand the structural changes that the enzyme undergoes while catalyzing this reaction. There are three segments to the study: 1) understanding the changes in the enzyme when the porphobilinogen units get attached to the dipyrromethane cofactor, thereby forming a polypyrrole chain; 2) exit of the product from the active site of the enzyme via steered molecular dynamics; and 3) the relaxation of the enzyme to the initial stage to resume its catalytic cycle. Molecular dynamics simulations of the protein through the different stages of pyrrole chain elongation gives insight into the motions of domains, active site loop and role of conserved active site residues in facilitating the accommodation of the polypyrrole chain. In addition to this, we propose a possible exit path for the product and demonstrate the relaxation of the enzyme after the exit of the product to resume the catalytic cycle.
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Affiliation(s)
- Navneet Bung
- TCS Innovation Labs-Hyderabad (Life Sciences Division), Tata Consultancy Services Limited, Hyderabad, India
| | - Meenakshi Pradhan
- TCS Innovation Labs-Hyderabad (Life Sciences Division), Tata Consultancy Services Limited, Hyderabad, India
| | - Harini Srinivasan
- TCS Innovation Labs-Hyderabad (Life Sciences Division), Tata Consultancy Services Limited, Hyderabad, India
| | - Gopalakrishnan Bulusu
- TCS Innovation Labs-Hyderabad (Life Sciences Division), Tata Consultancy Services Limited, Hyderabad, India
- * E-mail:
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19
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Runyen-Janecky LJ. Role and regulation of heme iron acquisition in gram-negative pathogens. Front Cell Infect Microbiol 2013; 3:55. [PMID: 24116354 PMCID: PMC3792355 DOI: 10.3389/fcimb.2013.00055] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 09/10/2013] [Indexed: 12/14/2022] Open
Abstract
Bacteria that reside in animal tissues and/or cells must acquire iron from their host. However, almost all of the host iron is sequestered in iron-containing compounds and proteins, the majority of which is found within heme molecules. Thus, likely iron sources for bacterial pathogens (and non-pathogenic symbionts) are free heme and heme-containing proteins. Furthermore, the cellular location of the bacterial within the host (intra or extracellular) influences the amount and nature of the iron containing compounds available for transport. The low level of free iron in the host, coupled with the presence of numerous different heme sources, has resulted in a wide range of high-affinity iron acquisition strategies within bacteria. However, since excess iron and heme are toxic to bacteria, expression of these acquisition systems is highly regulated. Precise expression in the correct host environment at the appropriate times enables heme iron acquisitions systems to contribute to the growth of bacterial pathogens within the host. This mini-review will highlight some of the recent findings in these areas for gram-negative pathogens.
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20
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Evangelista KV, Coburn J. Leptospira as an emerging pathogen: a review of its biology, pathogenesis and host immune responses. Future Microbiol 2011; 5:1413-25. [PMID: 20860485 DOI: 10.2217/fmb.10.102] [Citation(s) in RCA: 196] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Leptospirosis, the most widespread zoonosis in the world, is an emerging public health problem, particularly in large urban centers of developing countries. Several pathogenic species of the genus Leptospira can cause a wide range of clinical manifestations, from a mild, flu-like illness to a severe disease form characterized by multiorgan system complications leading to death. However, the mechanisms of pathogenesis of Leptospira are largely unknown. This article will address the animal models of acute and chronic leptospire infections, and the recent developments in the genetic manipulation of the bacteria, which facilitate the identification of virulence factors involved in pathogenesis and the assessment of their potential values in the control and prevention of leptospirosis.
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Affiliation(s)
- Karen V Evangelista
- Department of Microbiology & Molecular Genetics, Medical College of Wisconsin, Milwaukee, USA
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Xue F, Dong H, Wu J, Wu Z, Hu W, Sun A, Troxell B, Yang XF, Yan J. Transcriptional responses of Leptospira interrogans to host innate immunity: significant changes in metabolism, oxygen tolerance, and outer membrane. PLoS Negl Trop Dis 2010; 4:e857. [PMID: 21049008 PMCID: PMC2964297 DOI: 10.1371/journal.pntd.0000857] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 09/27/2010] [Indexed: 12/31/2022] Open
Abstract
Background Leptospira interrogans is the major causative agent of leptospirosis. Phagocytosis plays important roles in the innate immune responses to L. interrogans infection, and L. interrogans can evade the killing of phagocytes. However, little is known about the adaptation of L. interrogans during this process. Methodology/Principal Findings To better understand the interaction of pathogenic Leptospira and innate immunity, we employed microarray and comparative genomics analyzing the responses of L. interrogans to macrophage-derived cells. During this process, L. interrogans altered expressions of many genes involved in carbohydrate and lipid metabolism, energy production, signal transduction, transcription and translation, oxygen tolerance, and outer membrane proteins. Among them, the catalase gene expression was significantly up-regulated, suggesting it may contribute to resisting the oxidative pressure of the macrophages. The expressions of several major outer membrane protein (OMP) genes (e.g., ompL1, lipL32, lipL41, lipL48 and ompL47) were dramatically down-regulated (10–50 folds), consistent with previous observations that the major OMPs are differentially regulated in vivo. The persistent down-regulations of these major OMPs were validated by immunoblotting. Furthermore, to gain initial insight into the gene regulation mechanisms in L. interrogans, we re-defined the transcription factors (TFs) in the genome and identified the major OmpR TF gene (LB333) that is concurrently regulated with the major OMP genes, suggesting a potential role of LB333 in OMPs regulation. Conclusions/Significance This is the first report on global responses of pathogenic Leptospira to innate immunity, which revealed that the down-regulation of the major OMPs may be an immune evasion strategy of L. interrogans, and a putative TF may be involved in governing these down-regulations. Alterations of the leptospiral OMPs up interaction with host antigen-presenting cells (APCs) provide critical information for selection of vaccine candidates. In addition, genome-wide annotation and comparative analysis of TFs set a foundation for further studying regulatory networks in Leptospira spp. Leptospirosis is an important tropical disease around the world, particularly in humid tropical and subtropical countries. As a major pathogen of this disease, Leptospira interrogans can be shed from the urine of reservoir hosts, survive in soil and water, and infect humans through broken skin or mucous membranes. Recently, host adaptability and immune evasion of L. interrogans to host innate immunity was partially elucidated in infection or animal models. A better understanding of the molecular mechanisms of L. interrogans in response to host innate immunity is required to learn the nature of early leptospirosis. This study focused on the transcriptome of L. interrogans during host immune cells interaction. Significant changes in energy metabolism, oxygen tolerance and outer membrane protein profile were identified as potential immune evasion strategies by pathogenic Leptospira during the early stage of infection. The major outer membrane proteins (OMPs) of L. interrogans may be regulated by the major OmpR specific transcription factor (LB333). These results provide a foundation for further studying the pathogenesis of leptospirosis, as well as identifying gene regulatory networks in Leptospira spp.
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Affiliation(s)
- Feng Xue
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital of Medical College, Zhejiang University, Hangzhou, China
- Department of Medical Microbiology and Parasitology, Medical College, Zhejiang University School of Medicine, Hangzhou, China
| | - Haiyan Dong
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital of Medical College, Zhejiang University, Hangzhou, China
- Department of Medical Microbiology and Parasitology, Medical College, Zhejiang University School of Medicine, Hangzhou, China
| | - Jinyu Wu
- Zhejiang Provincial Key Laboratory of Medical Genetics, Institute of Biomedical Informatics, Wenzhou Medical College, Wenzhou, China
| | - Zuowei Wu
- Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Weilin Hu
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital of Medical College, Zhejiang University, Hangzhou, China
- Department of Medical Microbiology and Parasitology, Medical College, Zhejiang University School of Medicine, Hangzhou, China
| | - Aihua Sun
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital of Medical College, Zhejiang University, Hangzhou, China
- Department of Medical Microbiology and Parasitology, Medical College, Zhejiang University School of Medicine, Hangzhou, China
| | - Bryan Troxell
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - X. Frank Yang
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Jie Yan
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital of Medical College, Zhejiang University, Hangzhou, China
- Department of Medical Microbiology and Parasitology, Medical College, Zhejiang University School of Medicine, Hangzhou, China
- * E-mail:
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Niller HH. Myelodysplastic syndrome (MDS) as a late stage of subclinical hemophagocytic lymphohistiocytosis (HLH): a putative role for Leptospira infection. A hypothesis. Acta Microbiol Immunol Hung 2010; 57:181-9. [PMID: 20870590 DOI: 10.1556/amicr.57.2010.3.3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
It is proposed that hemophagocytic lymphohistiocytosis (HLH) and myelodysplastic syndromes (MDS) may be temporally distinct phases of pathophysiologically related disease processes. A significant subgroup of MDS may develop from subclinical HLH. In that case, HLH-like disease would chronically proceed with little disease activity or under occasional flares only, until it first becomes clinically apparent at the MDS stage. At the MDS stage, however, HLH activity may be easily overlooked by histological or cytogenetic means, since hemophagocytosis has fallen already largely silent. Current treatment options for HLH, like high-dose intravenous immunoglobulins (IVIG), may turn out to be helpful in MDS patients as well. In rare and extreme cases, Leptospira infection causes severe and life-threatening HLH. Thus, this proposal also implies that an insufficient, dysfunctional or misdirected immunological response to Leptospira infection may lead to MDS in the long run in a significant number of cases, which have not been recognized as Leptospira -triggered events in the first place. Infections by agents other than Leptospira may lead to subclinical HLH-like disease with MDS as a late stage as well.
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Affiliation(s)
- H H Niller
- Universität Regensburg, Institut für Medizinische Mikrobiologie und Hygiene, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany.
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Transcriptional response of Leptospira interrogans to iron limitation and characterization of a PerR homolog. Infect Immun 2010; 78:4850-9. [PMID: 20805337 DOI: 10.1128/iai.00435-10] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Leptospirosis is a globally significant zoonosis caused by Leptospira spp. Iron is essential for growth of most bacterial species. Since iron availability is low in the host, pathogens have evolved complex iron acquisition mechanisms to survive and establish infection. In many bacteria, expression of iron uptake and storage proteins is regulated by Fur. L. interrogans encodes four predicted Fur homologs; we have constructed a mutation in one of these, la1857. We conducted microarray analysis to identify iron-responsive genes and to study the effects of la1857 mutation on gene expression. Under iron-limiting conditions, 43 genes were upregulated and 49 genes were downregulated in the wild type. Genes encoding proteins with predicted involvement in inorganic ion transport and metabolism (including TonB-dependent proteins and outer membrane transport proteins) were overrepresented in the upregulated list, while 54% of differentially expressed genes had no known function. There were 16 upregulated genes of unknown function which are absent from the saprophyte L. biflexa and which therefore may encode virulence-associated factors. Expression of iron-responsive genes was not significantly affected by mutagenesis of la1857, indicating that LA1857 is not a global regulator of iron homeostasis. Upregulation of heme biosynthetic genes and a putative catalase in the mutant suggested that LA1857 is more similar to PerR, a regulator of the oxidative stress response. Indeed, the la1857 mutant was more resistant to peroxide stress than the wild type. Our results provide insights into the role of iron in leptospiral metabolism and regulation of the oxidative stress response, including genes likely to be important for virulence.
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Overcoming the heme paradox: heme toxicity and tolerance in bacterial pathogens. Infect Immun 2010; 78:4977-89. [PMID: 20679437 DOI: 10.1128/iai.00613-10] [Citation(s) in RCA: 208] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Virtually all bacterial pathogens require iron to infect vertebrates. The most abundant source of iron within vertebrates is in the form of heme as a cofactor of hemoproteins. Many bacterial pathogens have elegant systems dedicated to the acquisition of heme from host hemoproteins. Once internalized, heme is either degraded to release free iron or used intact as a cofactor in catalases, cytochromes, and other bacterial hemoproteins. Paradoxically, the high redox potential of heme makes it a liability, as heme is toxic at high concentrations. Although a variety of mechanisms have been proposed to explain heme toxicity, the mechanisms by which heme kills bacteria are not well understood. Nonetheless, bacteria employ various strategies to protect against and eliminate heme toxicity. Factors involved in heme acquisition and detoxification have been found to contribute to virulence, underscoring the physiological relevance of heme stress during pathogenesis. Herein we describe the current understanding of the mechanisms of heme toxicity and how bacterial pathogens overcome the heme paradox during infection.
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Vargas PD, Furuyama K, Sassa S, Shibahara S. Hypoxia decreases the expression of the two enzymes responsible for producing linear and cyclic tetrapyrroles in the heme biosynthetic pathway. FEBS J 2009; 275:5947-59. [PMID: 19021769 DOI: 10.1111/j.1742-4658.2008.06723.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Heme is synthesized in all cell types in aerobic organisms. Hydroxymethylbilane synthase (HMBS) and uroporphyrinogen III synthase (UROS) catalyze two consecutive reactions in the heme biosynthetic pathway, generating the first linear and the first cyclic tetrapyrroles, respectively. Each of the HMBS and UROS genes contains the two separate promoters that generate ubiquitous and erythroid-specific mRNAs. Despite the functional significance of HMBS and UROS, regulation of their gene expression remains to be investigated. Here, we showed that hypoxia (1% O(2)) decreased the expression of ubiquitous mRNAs for HMBS and UROS by three- and twofold, respectively, in human hepatic cells (HepG2 and Hep3B), whereas the expression of ubiquitous and erythroid HMBS and UROS mRNAs remained unchanged in erythroid cells (YN-1 and K562). Unexpectedly, hypoxia did not decrease the half-life of HMBS mRNA (8.4 h under normoxia versus 9.1 h under hypoxia) or UROS mRNA (9.0 versus 10.4 h) in hepatic cells. It is therefore unlikely that a change in mRNA stability is responsible for the hypoxia-mediated decrease in the expression levels of these mRNAs. Furthermore, expression levels of HMBS and UROS mRNAs were decreased under normoxia by treatment with deferoxamine or cobalt chloride in hepatic cells, while hypoxia-inducible factor 1alpha was accumulated. Thus, the decrease in the expression of ubiquitous HMBS and UROS mRNAs is associated with accumulation of hypoxia-inducible factor 1alpha protein. In conclusion, the expression of HMBS and UROS mRNAs may be coordinately regulated, which represents a newly identified mechanism that is important for heme homeostasis.
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Affiliation(s)
- Patrick D Vargas
- Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Miyagi, Japan
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Abstract
The genus Leptospira belongs to the order Spirochaetales and is composed of both saprophytic and pathogenic members, such as Leptospira biflexa and L. interrogans, respectively. A major factor contributing to our ignorance of spirochetal biology has been the lack of methods available for genetic analysis of these organisms. In recent years, an E. coli-L. biflexa shuttle vector has been constructed and a system for targeted mutagenesis and random transposon mutagenesis of the saprophyte L. biflexa has been developed. These studies enable the use of L. biflexa as a model bacterium among spirochetes.
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Affiliation(s)
- Hélène Louvel
- Unité de Biologie des Spirochètes Institut Pasteur, Paris, France
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Cavallaro G, Decaria L, Rosato A. Genome-Based Analysis of Heme Biosynthesis and Uptake in Prokaryotic Systems. J Proteome Res 2008; 7:4946-54. [DOI: 10.1021/pr8004309] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gabriele Cavallaro
- Magnetic Resonance Center (CERM), University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy, and Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
| | - Leonardo Decaria
- Magnetic Resonance Center (CERM), University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy, and Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
| | - Antonio Rosato
- Magnetic Resonance Center (CERM), University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy, and Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
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Targeted mutagenesis in pathogenic Leptospira species: disruption of the LigB gene does not affect virulence in animal models of leptospirosis. Infect Immun 2008; 76:5826-33. [PMID: 18809657 DOI: 10.1128/iai.00989-08] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The pathogenic mechanisms of Leptospira interrogans, the causal agent of leptospirosis, remain largely unknown. This is mainly due to the lack of tools for genetically manipulating pathogenic Leptospira species. Thus, homologous recombination between introduced DNA and the corresponding chromosomal locus has never been demonstrated for this pathogen. Leptospiral immunoglobulin-like repeat (Lig) proteins were previously identified as putative Leptospira virulence factors. In this study, a ligB mutant was constructed by allelic exchange in L. interrogans; in this mutant a spectinomycin resistance (Spc(r)) gene replaced a portion of the ligB coding sequence. Gene disruption was confirmed by PCR, immunoblot analysis, and immunofluorescence studies. The ligB mutant did not show decrease virulence compared to the wild-type strain in the hamster model of leptospirosis. In addition, inoculation of rats with the ligB mutant induced persistent colonization of the kidneys. Finally, LigB was not required to mediate bacterial adherence to cultured cells. Taken together, our data provide the first evidence of site-directed homologous recombination in pathogenic Leptospira species. Furthermore, our data suggest that LigB does not play a major role in dissemination of the pathogen in the host and in the development of acute disease manifestations or persistent renal colonization.
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Murray GL, Ellis KM, Lo M, Adler B. Leptospira interrogans requires a functional heme oxygenase to scavenge iron from hemoglobin. Microbes Infect 2008; 10:791-7. [PMID: 18524663 DOI: 10.1016/j.micinf.2008.04.010] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Revised: 03/25/2008] [Accepted: 04/16/2008] [Indexed: 11/18/2022]
Abstract
The transposon TnSC189 was used to construct a mutant in the putative heme oxygenase gene hemO (LB186) of Leptospira interrogans. Unlike its parent strain, the mutant grew poorly in medium in which hemoglobin was the sole iron source. The putative heme oxygenase was over expressed in a His-tagged form, purified and was demonstrated to degrade heme in vitro. Unexpectedly, it was also found that the L. interrogans growth rate was significantly increased when medium was supplemented with hemoglobin, but only if ferrous iron sources were absent. This result was mirrored in the expression of some iron-related genes and suggests the presence of regulatory mechanisms detecting Fe2+ and hemoglobin. This is the first demonstration of a functional heme oxygenase from a spirochete.
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Affiliation(s)
- Gerald L Murray
- Australian Bacterial Pathogenesis Program, Department of Microbiology, Monash University, VIC, Australia
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Louvel H, Betton JM, Picardeau M. Heme rescues a two-component system Leptospira biflexa mutant. BMC Microbiol 2008; 8:25. [PMID: 18234085 PMCID: PMC2266917 DOI: 10.1186/1471-2180-8-25] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Accepted: 01/30/2008] [Indexed: 11/18/2022] Open
Abstract
Background Heme is typically a major iron source for bacteria, but little is known about how bacteria of the Leptospira genus, composed of both saprophytic and pathogenic species, access heme. Results In this study, we analysed a two-component system of the saprophyte Leptospira biflexa. In vitro phosphorylation and site-directed mutagenesis assays showed that Hklep is a histidine kinase which, after autophosphorylation of a conserved histidine, transfers the phosphate to an essential aspartate of the response regulator Rrlep. Hklep/Rrlep two-component system mutants were generated in L. biflexa. The mutants could only grow in medium supplemented with hemin or δ-aminolevulinic acid (ALA). In the pathogen L. interrogans, the hklep and rrlep orthologous genes are located between hemE and hemL genes, which encode proteins involved in heme biosynthesis. The L. biflexa hklep mutant could be complemented with a replicative plasmid harbouring the L. interrogans orthologous gene, suggesting that these two-component systems are functionally similar. By real-time quantitative reverse transcription-PCR, we also observed that this two-component system might influence the expression of heme biosynthetic genes. Conclusion These findings demonstrate that the Hklep/Rrlep regulatory system is critical for the in vitro growth of L. biflexa, and suggest that this two-component system is involved in a complex mechanism that regulates the heme biosynthetic pathway.
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Affiliation(s)
- Hélène Louvel
- Unité de Biologie des Spirochètes, Institut Pasteur, Paris, France.
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31
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Nagaraj VA, Arumugam R, Gopalakrishnan B, Jyothsna YS, Rangarajan PN, Padmanaban G. Unique properties of Plasmodium falciparum porphobilinogen deaminase. J Biol Chem 2007; 283:437-444. [PMID: 17962188 DOI: 10.1074/jbc.m706861200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The hybrid pathway for heme biosynthesis in the malarial parasite proposes the involvement of parasite genome-coded enzymes of the pathway localized in different compartments such as apicoplast, mitochondria, and cytosol. However, knowledge on the functionality and localization of many of these enzymes is not available. In this study, we demonstrate that porphobilinogen deaminase encoded by the Plasmodium falciparum genome (PfPBGD) has several unique biochemical properties. Studies carried out with PfPBGD partially purified from parasite membrane fraction, as well as recombinant PfPBGD lacking N-terminal 64 amino acids expressed and purified from Escherichia coli cells (DeltaPfPBGD), indicate that both the proteins are catalytically active. Surprisingly, PfPBGD catalyzes the conversion of porphobilinogen to uroporphyrinogen III (UROGEN III), indicating that it also possesses uroporphyrinogen III synthase (UROS) activity, catalyzing the next step. This obviates the necessity to have a separate gene for UROS that has not been so far annotated in the parasite genome. Interestingly, DeltaPfP-BGD gives rise to UROGEN III even after heat treatment, although UROS from other sources is known to be heat-sensitive. Based on the analysis of active site residues, a DeltaPfPBGDL116K mutant enzyme was created and the specific activity of this recombinant mutant enzyme is 5-fold higher than DeltaPfPBGD. More interestingly, DeltaPfPBGDL116K catalyzes the formation of uroporphyrinogen I (UROGEN I) in addition to UROGEN III, indicating that with increased PBGD activity the UROS activity of PBGD may perhaps become rate-limiting, thus leading to non-enzymatic cyclization of preuroporphyrinogen to UROGEN I. PfPBGD is localized to the apicoplast and is catalytically very inefficient compared with the host red cell enzyme.
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Affiliation(s)
| | - Rajavel Arumugam
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Bulusu Gopalakrishnan
- Life Sciences Division, Innovation Labs Hyderabad, Tata Consultancy Services, Hyderabad 500081, India
| | - Yeleswarapu Sri Jyothsna
- Life Sciences Division, Innovation Labs Hyderabad, Tata Consultancy Services, Hyderabad 500081, India
| | - Pundi N Rangarajan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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Asuthkar S, Velineni S, Stadlmann J, Altmann F, Sritharan M. Expression and characterization of an iron-regulated hemin-binding protein, HbpA, from Leptospira interrogans serovar Lai. Infect Immun 2007; 75:4582-91. [PMID: 17576761 PMCID: PMC1951163 DOI: 10.1128/iai.00324-07] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In an earlier study, based on the ferric enterobactin receptor FepA of Escherichia coli, we identified and modeled a TonB-dependent outer membrane receptor protein (LB191) from the genome of Leptospira interrogans serovar Lai. Based on in silico analysis, we hypothesized that this protein was an iron-dependent hemin-binding protein. In this study, we provide experimental evidence to prove that this protein, termed HbpA (hemin-binding protein A), is indeed an iron-regulated hemin-binding protein. We cloned and expressed the full-length 81-kDa recombinant rHbpA protein and a truncated 55-kDa protein from L. interrogans serovar Lai, both of which bind hemin-agarose. Assay of hemin-associated peroxidase activity and spectrofluorimetric analysis provided confirmatory evidence of hemin binding by HbpA. Immunofluorescence studies by confocal microscopy and the microscopic agglutination test demonstrated the surface localization and the iron-regulated expression of HbpA in L. interrogans. Southern blot analysis confirmed our earlier observation that the hbpA gene was present only in some of the pathogenic serovars and was absent in Leptospira biflexa. Hemin-agarose affinity studies showed another hemin-binding protein with a molecular mass of approximately 44 kDa, whose expression was independent of iron levels. This protein was seen in several serovars, including nonpathogenic L. biflexa. Sequence analysis and immunoreactivity with specific antibodies showed this protein to be LipL41.
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Affiliation(s)
- Swapna Asuthkar
- School of Life Sciences, University of Hyderabad, Gachibowli, Hyderabad 500046, India
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33
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Louvel H, Bommezzadri S, Zidane N, Boursaux-Eude C, Creno S, Magnier A, Rouy Z, Médigue C, Saint Girons I, Bouchier C, Picardeau M. Comparative and functional genomic analyses of iron transport and regulation in Leptospira spp. J Bacteriol 2006; 188:7893-904. [PMID: 16980464 PMCID: PMC1636298 DOI: 10.1128/jb.00711-06] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The spirochetes of the Leptospira genus contain saprophytic and pathogenic members, the latter being responsible for leptospirosis. Despite the recent sequencing of the genome of the pathogen L. interrogans, the slow growth of these bacteria, their virulence in humans, and a lack of genetic tools make it difficult to work with these pathogens. In contrast, the development of numerous genetic tools for the saprophyte L. biflexa enables its use as a model bacterium. Leptospira spp. require iron for growth. In this work, we show that Leptospira spp. can acquire iron from different sources, including siderophores. A comparative genome analysis of iron uptake systems and their regulation in the saprophyte L. biflexa and the pathogen L. interrogans is presented in this study. Our data indicated that, for instance, L. biflexa and L. interrogans contain 8 and 12 genes, respectively, whose products share homology with proteins that have been shown to be TonB-dependent receptors. We show that some genes involved in iron uptake were differentially expressed in response to iron. In addition, we were able to disrupt several putative genes involved in iron acquisition systems or iron regulation in L. biflexa. Comparative genomics, in combination with gene inactivation, gives us significant functional information on iron homeostasis in Leptospira spp.
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Affiliation(s)
- H Louvel
- Laboratoire des Spirochètes, Institut Pasteur, 28 rue du docteur Roux, 75724 Paris Cedex 15, France
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Abstract
PURPOSE OF REVIEW Leptospirosis, a spirochaetal zoonotic disease, has been recognized as an important emerging infectious disease in the last 10 years. This review addresses the issues in the epidemiology, diagnosis and clinical management which confront public health responses, and highlights the progress made towards understanding the Leptospira genome, biology and pathogenesis. RECENT FINDINGS Leptospirosis has spread from its traditional rural base to become the cause of epidemics in poor urban slum communities in developing countries. Mortality from severe disease forms, Weil's disease and severe pulmonary haemorrhage syndrome, is high (>10% and >50%, respectively) even when optimal treatment is provided. Moreover, the overall disease burden is underestimated, since leptospirosis is a significant cause of undifferentiated fever and frequently not recognized. Barriers to addressing this problem have been the lack of an adequate diagnostic test and effective control measures. China and Brazil, countries in which leptospirosis is a major health problem, have completed the sequence of the Leptospira interrogans genome. Together with new genetic tools and proteomics, new insights have been made into the biology of Leptospira and the mechanisms used to adapt to host and external environments. Surface-exposed proteins and putative virulence determinants have been identified which may serve as sub-unit vaccine candidates. SUMMARY Major progress has been made in the basic research of leptospirosis. Future challenges will be to translate these advances into public health measures for developing countries. Yet the most effective responses may be interventions that directly address the determinants of poverty, such as poor sanitation, which are often responsible for transmission.
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Affiliation(s)
- Alan J A McBride
- Gonçalo Moniz Research Centre, Oswaldo Cruz Foundation, Ministry of Health, Rua Waldemar Falcão 121, 40295-001 Salvador, Bahia, Brazil
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Bourhy P, Frangeul L, Couvé E, Glaser P, Saint Girons I, Picardeau M. Complete nucleotide sequence of the LE1 prophage from the spirochete Leptospira biflexa and characterization of its replication and partition functions. J Bacteriol 2005; 187:3931-40. [PMID: 15937155 PMCID: PMC1151745 DOI: 10.1128/jb.187.12.3931-3940.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The first and, to date, only extrachromosomal circular replicon identified in the spirochete Leptospira is the LE1 prophage from Leptospira biflexa. The 74-kb LE1 genome has a GC content of 36%, which is similar to the GC content of Leptospira spp. Most of the 79 predicted open reading frames (ORFs) showed no similarities to known ORFs. However 21 ORFs appeared to be organized in clusters that could code for head and tail structural proteins and immunity repressor proteins. In addition, the pattern of gene expression showed that several LE1 genes are expressed specifically either in LE1 prophage or in L. biflexa late after infection. Since the LE1 prophage replicates autonomously as a circular replicon in L. biflexa, we were able to engineer an L. biflexa-Escherichia coli shuttle vector from a 5.3-kb DNA fragment of LE1 (Saint Girons et al., J. Bacteriol. 182:5700-5705, 2000), opening this genus to genetic manipulation. In this study, base compositional asymmetry confirms the location of the LE1 replication region and suggests that LE1 replicates via a bidirectional Theta-like replication mechanism from this unique origin. By subcloning experiments, the replication region can be narrowed down to a 1-kb region. This minimal replication region consists of a rep encoding a protein of 180 amino acids. Upstream from rep, putative partitioning genes, called parA and parB, were found to be similar to the par loci in Borrelia plasmids. A significant increase of plasmid stability in L. biflexa can be seen only when both parA and parB are present. These results enable the construction of new shuttle vectors for studying the genetics of Leptospira spp. This study will also contribute to a better knowledge of phages unrelated to lambdoid phages.
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Affiliation(s)
- Pascale Bourhy
- Laboratoire des Spirochètes, Institut Pasteur, 25 rue du docteur Roux, 75724 Paris Cedex 15, France
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Bourhy P, Louvel H, Saint Girons I, Picardeau M. Random insertional mutagenesis of Leptospira interrogans, the agent of leptospirosis, using a mariner transposon. J Bacteriol 2005; 187:3255-8. [PMID: 15838053 PMCID: PMC1082815 DOI: 10.1128/jb.187.9.3255-3258.2005] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The recent availability of the complete genome sequences of Leptospira interrogans, the agent of leptospirosis, has allowed the identification of several putative virulence factors. However, to our knowledge, attempts to carry out gene transfer in pathogenic Leptospira spp. have failed so far. In this study, we show that the Himar1 mariner transposon permits random mutagenesis in the pathogen L. interrogans. We have identified genes that have been interrupted by Himar1 insertion in 35 L. interrogans mutants. This approach of transposon mutagenesis will be useful for understanding the spirochetal physiology and the pathogenic mechanisms of Leptospira, which remain largely unknown.
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Affiliation(s)
- Pascale Bourhy
- Laboratoire des Spirochètes, Institut Pasteur, 28 rue du docteur Roux, 75724 Paris Cedex 15, France
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Louvel H, Saint Girons I, Picardeau M. Isolation and characterization of FecA- and FeoB-mediated iron acquisition systems of the spirochete Leptospira biflexa by random insertional mutagenesis. J Bacteriol 2005; 187:3249-54. [PMID: 15838052 PMCID: PMC1082814 DOI: 10.1128/jb.187.9.3249-3254.2005] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The specific mechanisms by which Leptospira spp. acquire iron from their ecological niches are unknown. A major factor contributing to our ignorance of spirochetal biology is the lack of methods for genetic analysis of these organisms. In this study, we have developed a system for random transposon mutagenesis of Leptospira biflexa using a mariner transposon, Himar1. To demonstrate the validity of Himar1 in vivo transposon mutagenesis in L. biflexa, a screen of mutants for clones impaired in amino acid biosynthesis was first performed, enabling the identification of tryptophan and glutamate auxotrophs. To investigate iron transporters, 2,000 L. biflexa transposon mutants were screened onto media with and without hemin, thus allowing the identification of five hemin-requiring mutants, and the putative genes responsible for this phenotype were identified. Three mutants had distinct insertions in a gene encoding a protein which shares homology with the TonB-dependent receptor FecA, involved in ferric citrate transport. We also identified two mutants with a Himar1 insertion into a feoB-like gene, the product of which is required for ferrous iron uptake in many bacterial organisms. Interestingly, the growth inhibition exhibited by the fecA and feoB mutants was relieved by deferoxamine, suggesting the presence of a ferric hydroxamate transporter. These results confirm the importance of iron for the growth of Leptospira and its ability to use multiple iron sources.
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Affiliation(s)
- Hélène Louvel
- Laboratoire des Spirochètes, Institut Pasteur, 28 rue du docteur Roux, 75724 Paris Cedex 15, France
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Nascimento ALTO, Verjovski-Almeida S, Van Sluys MA, Monteiro-Vitorello CB, Camargo LEA, Digiampietri LA, Harstkeerl RA, Ho PL, Marques MV, Oliveira MC, Setubal JC, Haake DA, Martins EAL. Genome features of Leptospira interrogans serovar Copenhageni. Braz J Med Biol Res 2004; 37:459-77. [PMID: 15064809 PMCID: PMC2666282 DOI: 10.1590/s0100-879x2004000400003] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We report novel features of the genome sequence of Leptospira interrogans serovar Copenhageni, a highly invasive spirochete. Leptospira species colonize a significant proportion of rodent populations worldwide and produce life-threatening infections in mammals. Genomic sequence analysis reveals the presence of a competent transport system with 13 families of genes encoding for major transporters including a three-member component efflux system compatible with the long-term survival of this organism. The leptospiral genome contains a broad array of genes encoding regulatory system, signal transduction and methyl-accepting chemotaxis proteins, reflecting the organism's ability to respond to diverse environmental stimuli. The identification of a complete set of genes encoding the enzymes for the cobalamin biosynthetic pathway and the novel coding genes related to lipopolysaccharide biosynthesis should bring new light to the study of Leptospira physiology. Genes related to toxins, lipoproteins and several surface-exposed proteins may facilitate a better understanding of the Leptospira pathogenesis and may serve as potential candidates for vaccine.
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