1
|
Phoka T, Fule L, Da Fonseca JP, Cokelaer T, Picardeau M, Patarakul K. Investigating the role of the carbon storage regulator A (CsrA) in Leptospira spp. PLoS One 2021; 16:e0260981. [PMID: 34898610 PMCID: PMC8668096 DOI: 10.1371/journal.pone.0260981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 11/20/2021] [Indexed: 01/08/2023] Open
Abstract
Carbon Storage Regulator A (CsrA) is a well-characterized post-transcriptional global regulator that plays a critical role in response to environmental changes in many bacteria. CsrA has been reported to regulate several metabolic pathways, motility, biofilm formation, and virulence-associated genes. The role of csrA in Leptospira spp., which are able to survive in different environmental niches and infect a wide variety of reservoir hosts, has not been characterized. To investigate the role of csrA as a gene regulator in Leptospira, we generated a L. biflexa csrA deletion mutant (ΔcsrA) and csrA overexpressing Leptospira strains. The ΔcsrA L. biflexa displayed poor growth under starvation conditions. RNA sequencing revealed that in rich medium only a few genes, including the gene encoding the flagellar filament protein FlaB3, were differentially expressed in the ΔcsrA mutant. In contrast, 575 transcripts were differentially expressed when csrA was overexpressed in L. biflexa. Electrophoretic mobility shift assay (EMSA) confirmed the RNA-seq data in the ΔcsrA mutant, showing direct binding of recombinant CsrA to flaB3 mRNA. In the pathogen L. interrogans, we were not able to generate a csrA mutant. We therefore decided to overexpress csrA in L. interrogans. In contrast to the overexpressing strain of L. biflexa, the overexpressing L. interrogans strain had poor motility on soft agar. The overexpressing strain of L. interrogans also showed significant upregulation of the flagellin flaB1, flaB2, and flaB4. The interaction of L. interrogans rCsrA and flaB4 was confirmed by EMSA. Our results demonstrated that CsrA may function as a global regulator in Leptospira spp. under certain conditions that cause csrA overexpression. Interestingly, the mechanisms of action and gene targets of CsrA may be different between non-pathogenic and pathogenic Leptospira strains.
Collapse
Affiliation(s)
- Theerapat Phoka
- Medical Microbiology, Interdisciplinary and International Program, Graduate School, Chulalongkorn University, Bangkok, Thailand
| | - Lenka Fule
- Institut Pasteur, Biology of Spirochetes Unit, French National Reference Centre for Leptospirosis, Paris, France
| | - Juliana Pipoli Da Fonseca
- Plate-forme Technologique Biomics, Centre de Ressources et Recherches Technologiques (C2RT), Institut Pasteur, Paris, France
| | - Thomas Cokelaer
- Plate-forme Technologique Biomics, Centre de Ressources et Recherches Technologiques (C2RT), Institut Pasteur, Paris, France
- Hub de Bioinformatique et Biostatistique – Département Biologie Computationnelle, Institut Pasteur, Paris, France
| | - Mathieu Picardeau
- Institut Pasteur, Biology of Spirochetes Unit, French National Reference Centre for Leptospirosis, Paris, France
| | - Kanitha Patarakul
- Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Pathumwan, Bangkok, Thailand
- Chula Vaccine Research Center (Chula VRC), Center of Excellence in Vaccine Research and Development, Chulalongkorn University, Bangkok, Thailand
- * E-mail: ,
| |
Collapse
|
2
|
MB T, AF T, ALTO N. The leptospiral LipL21 and LipL41 proteins exhibit a broad spectrum of interactions with host cell components. Virulence 2021; 12:2798-2813. [PMID: 34719356 PMCID: PMC8632080 DOI: 10.1080/21505594.2021.1993427] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 09/08/2021] [Accepted: 10/08/2021] [Indexed: 01/09/2023] Open
Abstract
Leptospirosis is a globally prevalent zoonotic disease, and is caused by pathogenic spirochetes from the genus Leptospira. LipL21 and LipL41 are lipoproteins expressed strongly on the outer membrane of pathogenic Leptospira spp. Many studies have shown that both proteins are interesting targets for vaccines and diagnosis. However, their role in host-pathogen interactions remains underexplored. Therefore, we evaluated the capacity of LipL21 and LipL41 to bind with glycosaminoglycans (GAGs), the cell receptors and extracellular matrix, and plasma components by ELISA. Both proteins interacted with collagen IV, laminin, E-cadherin, and elastin dose-dependently. A broad-spectrum binding to plasma components was also observed. Only LipL21 interacted with all the GAG components tested, whereas LipL41 presented a concentration-dependent binding only for chondroitin 4 sulfate. Although, both proteins have the ability to interact with fibrinogen, only LipL21 inhibited fibrin clot formation partially. Both proteins exhibited a decrease in plasminogen binding in the presence of amino caproic acid (ACA), a competitive inhibitor of lysine residues, suggesting that their binding occurs via the kringle domains of plasminogen. LipL41, but not LipL21, was able to convert plasminogen to plasmin, and recruit plasminogen from normal human serum, suggesting that the interaction of this protein with plasminogen may occur in physiological conditions. This work provides the first report demonstrating the capacity of LipL21 and LipL41 to interact with a broad range of host components, highlighting their importance in host-Leptospira interactions.
Collapse
Affiliation(s)
- Takahashi MB
- Laboratório de Desenvolvimento de Vacinas, Instituto Butantan, São Paulo, Brazil
- Programa de Pós-Graduação Interunidades Em Biotecnologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Teixeira AF
- Laboratório de Desenvolvimento de Vacinas, Instituto Butantan, São Paulo, Brazil
| | - Nascimento ALTO
- Laboratório de Desenvolvimento de Vacinas, Instituto Butantan, São Paulo, Brazil
| |
Collapse
|
3
|
Heterologous Expression of the Pathogen-Specific LIC11711 Gene in the Saprophyte L. biflexa Increases Bacterial Binding to Laminin and Plasminogen. Pathogens 2020; 9:pathogens9080599. [PMID: 32707797 PMCID: PMC7460275 DOI: 10.3390/pathogens9080599] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 07/13/2020] [Accepted: 07/17/2020] [Indexed: 12/13/2022] Open
Abstract
Leptospirosis is a febrile disease and the etiological agents are pathogenic bacteria of the genus Leptospira. The leptospiral virulence mechanisms are not fully understood and the application of genetic tools is still limited, despite advances in molecular biology techniques. The leptospiral recombinant protein LIC11711 has shown interaction with several host components, indicating a potential function in virulence. This study describes a system for heterologous expression of the L. interrogans gene lic11711 using the saprophyte L. biflexa serovar Patoc as a surrogate, aiming to investigate its possible activity in bacterial virulence. Heterologous expression of LIC11711 was performed using the pMaOri vector under regulation of the lipL32 promoter. The protein was found mainly on the leptospiral outer surface, confirming its location. The lipL32 promoter enhanced the expression of LIC11711 in L. biflexa compared to the pathogenic strain, indicating that this strategy may be used to overexpress low-copy proteins. The presence of LIC11711 enhanced the capacity of L. biflexa to adhere to laminin (Lam) and plasminogen (Plg)/plasmin (Pla) in vitro, suggesting the involvement of this protein in bacterial pathogenesis. We show for the first time that the expression of LIC11711 protein of L. interrogans confers a virulence-associated phenotype on L. biflexa, pointing out possible mechanisms used by pathogenic leptospires.
Collapse
|
4
|
Sasoni N, Ferrero DML, Guerrero SA, Iglesias AA, Arias DG. First evidence of glutathione metabolism in Leptospira interrogans. Free Radic Biol Med 2019; 143:366-374. [PMID: 31465831 DOI: 10.1016/j.freeradbiomed.2019.08.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 07/08/2019] [Accepted: 08/24/2019] [Indexed: 11/28/2022]
Abstract
BACKGROUND Glutathione (GSH) plays a role as a main antioxidant metabolite in all eukaryotes and many prokaryotes. Most of the organisms synthesize GSH by a pathway involving two enzymatic reactions, each one consuming one molecule of ATP. In a first step mediated by glutamate-cysteine ligase (GCL), the carboxylate of l-glutamic acid reacts with l-cysteine to form the dipeptide γ-glutamylcysteine (γ-GC). The second step involves the addition of glycine to the C-terminal of γ-GC catalyzed by glutathione synthetase (GS). In many bacteria, such as in the pathogen Leptospira interrogans, the main intracellular thiol has not yet been identified and the presence of GSH is not clear. METHODS We performed the molecular cloning of the genes gshA and gshB from L. interrogans; which respectively code for GCL and GS. After heterologous expression of the cloned genes we recombinantly produced the respective proteins with high degree of purity. These enzymes were exhaustively characterized in their biochemical properties. In addition, we determined the contents of GSH and the activity of related enzymes (and proteins) in cell extracts of the bacterium. RESULTS We functionally characterized GCL and GS, the two enzymes putatively involved in GSH synthesis in L. interrogans serovar Copenhageni. LinGCL showed higher substrate promiscuity (was active in presence of l-glutamic acid, l-cysteine and ATP, and also with GTP, l-aspartic acid and l-serine in lower proportion) unlike LinGS (which was only active with γ-GC, l-glycine and ATP). LinGCL is significantly inhibited by γ-GC and GSH, the respective intermediate and final product of the synthetic pathway. GSH showed inhibitory effect over LinGS but with a lower potency than LinGCL. Going further, we detected the presence of GSH in L. interrogans cells grown under basal conditions and also determined enzymatic activity of several GSH-dependent/related proteins in cell extracts. CONCLUSIONS and General Significance. Our results contribute with novel insights concerning redox metabolism in L. interrogans, mainly supporting that GSH is part of the antioxidant defense in the bacterium.
Collapse
Affiliation(s)
- Natalia Sasoni
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Facultad de Bioquímica y Ciencias Biológicas (FBCB), Centro Científico Tecnológico CONICET Santa Fe, Colectora Ruta Nacional Nº 168 km 0, Santa Fe, 3000, Argentina
| | - Danisa M L Ferrero
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Facultad de Bioquímica y Ciencias Biológicas (FBCB), Centro Científico Tecnológico CONICET Santa Fe, Colectora Ruta Nacional Nº 168 km 0, Santa Fe, 3000, Argentina
| | - Sergio A Guerrero
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Facultad de Bioquímica y Ciencias Biológicas (FBCB), Centro Científico Tecnológico CONICET Santa Fe, Colectora Ruta Nacional Nº 168 km 0, Santa Fe, 3000, Argentina
| | - Alberto A Iglesias
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Facultad de Bioquímica y Ciencias Biológicas (FBCB), Centro Científico Tecnológico CONICET Santa Fe, Colectora Ruta Nacional Nº 168 km 0, Santa Fe, 3000, Argentina
| | - Diego G Arias
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Facultad de Bioquímica y Ciencias Biológicas (FBCB), Centro Científico Tecnológico CONICET Santa Fe, Colectora Ruta Nacional Nº 168 km 0, Santa Fe, 3000, Argentina.
| |
Collapse
|
5
|
Hillman C, Stewart PE, Strnad M, Stone H, Starr T, Carmody A, Evans TJ, Carracoi V, Wachter J, Rosa PA. Visualization of Spirochetes by Labeling Membrane Proteins With Fluorescent Biarsenical Dyes. Front Cell Infect Microbiol 2019; 9:287. [PMID: 31482073 PMCID: PMC6710359 DOI: 10.3389/fcimb.2019.00287] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 07/24/2019] [Indexed: 01/06/2023] Open
Abstract
Numerous methods exist for fluorescently labeling proteins either as direct fusion proteins (GFP, RFP, YFP, etc.—attached to the protein of interest) or utilizing accessory proteins to produce fluorescence (SNAP-tag, CLIP-tag), but the significant increase in size that these accompanying proteins add may hinder or impede proper protein folding, cellular localization, or oligomerization. Fluorescently labeling proteins with biarsenical dyes, like FlAsH, circumvents this issue by using a short 6-amino acid tetracysteine motif that binds the membrane-permeable dye and allows visualization of living cells. Here, we report the successful adaptation of FlAsH dye for live-cell imaging of two genera of spirochetes, Leptospira and Borrelia, by labeling inner or outer membrane proteins tagged with tetracysteine motifs. Visualization of labeled spirochetes was possible by fluorescence microscopy and flow cytometry. A subsequent increase in fluorescent signal intensity, including prolonged detection, was achieved by concatenating two copies of the 6-amino acid motif. Overall, we demonstrate several positive attributes of the biarsenical dye system in that the technique is broadly applicable across spirochete genera, the tetracysteine motif is stably retained and does not interfere with protein function throughout the B. burgdorferi infectious cycle, and the membrane-permeable nature of the dyes permits fluorescent detection of proteins in different cellular locations without the need for fixation or permeabilization. Using this method, new avenues of investigation into spirochete morphology and motility, previously inaccessible with large fluorescent proteins, can now be explored.
Collapse
Affiliation(s)
- Chadwick Hillman
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Philip E Stewart
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Martin Strnad
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States.,Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czechia.,Faculty of Science, University of South Bohemia in České Budějovice, České Budějovice, Czechia
| | - Hunter Stone
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Tregei Starr
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Aaron Carmody
- Research Technologies Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Tyler J Evans
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Valentina Carracoi
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Jenny Wachter
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| | - Patricia A Rosa
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, United States
| |
Collapse
|
6
|
Fernandes LGV, Guaman LP, Vasconcellos SA, Heinemann MB, Picardeau M, Nascimento ALTO. Gene silencing based on RNA-guided catalytically inactive Cas9 (dCas9): a new tool for genetic engineering in Leptospira. Sci Rep 2019; 9:1839. [PMID: 30755626 PMCID: PMC6372684 DOI: 10.1038/s41598-018-37949-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 12/10/2018] [Indexed: 12/15/2022] Open
Abstract
Leptospirosis is a worldwide zoonosis caused by pathogenic bacteria of the genus Leptospira, which also includes free-living saprophyte strains. Many aspects of leptospiral basic biology and virulence mechanisms remain unexplored mainly due to the lack of effective genetic tools available for these bacteria. Recently, the type II CRISPR/Cas system from Streptococcus pyogenes has been widely used as an efficient genome engineering tool in bacteria by inducing double-strand breaks (DSBs) in the desired genomic targets caused by an RNA-guided DNA endonuclease called Cas9, and the DSB repair associated machinery. In the present work, plasmids expressing heterologous S. pyogenes Cas9 in L. biflexa cells were generated, and the enzyme could be expressed with no apparent toxicity to leptospiral cells. However, L. biflexa cells were unable to repair RNA-guided Cas9-induced DSBs. Thus, we used a catalytically dead Cas9 (dCas9) to obtain gene silencing rather than disruption, in a strategy called CRISPR interference (CRISPRi). We demonstrated complete gene silencing in L. biflexa cells when both dCas9 and single-guide RNA (sgRNA) targeting the coding strand of the β-galactosidase gene were expressed simultaneously. Furthermore, when the system was applied for silencing the dnaK gene, no colonies were recovered, indicating that DnaK protein is essential in Leptospira. In addition, flagellar motor switch FliG gene silencing resulted in reduced bacterial motility. To the best of our knowledge, this is the first work applying the CRISPRi system in Leptospira and spirochetes in general, expanding the tools available for understanding leptospiral biology.
Collapse
Affiliation(s)
- L G V Fernandes
- Laboratório Especial de Desenvolvimento de Vacinas, Instituto Butantan, Avenida Vital Brasil, 1500, 05503-900, Sao Paulo, SP, Brazil.
| | - L P Guaman
- Universidad Tecnológica Equinoccial, Centro de Investigación Biomédica, Facultad de Ciencias de la Salud Eugenio Espejo, Avenida Mariscal Sucre y Mariana de Jesús. Campus Occidental, 170105, Quito, Ecuador
| | - S A Vasconcellos
- Laboratório de Zoonoses Bacterianas do VPS, Faculdade de Medicina Veterinária e Zootecnia, USP, Avenida Prof. Dr. Orlando Marques de Paiva, 87, 05508-270, Sao Paulo, SP, Brazil
| | - Marcos B Heinemann
- Laboratório de Zoonoses Bacterianas do VPS, Faculdade de Medicina Veterinária e Zootecnia, USP, Avenida Prof. Dr. Orlando Marques de Paiva, 87, 05508-270, Sao Paulo, SP, Brazil
| | - M Picardeau
- Institut Pasteur, Biology of Spirochetes Unit, 25 rue du Dr Roux, 75723, Paris, France
| | - A L T O Nascimento
- Laboratório Especial de Desenvolvimento de Vacinas, Instituto Butantan, Avenida Vital Brasil, 1500, 05503-900, Sao Paulo, SP, Brazil.
| |
Collapse
|
7
|
Jackson KM, Schwartz C, Wachter J, Rosa PA, Stewart PE. A widely conserved bacterial cytoskeletal component influences unique helical shape and motility of the spirochete Leptospira biflexa. Mol Microbiol 2018; 108:77-89. [PMID: 29363884 DOI: 10.1111/mmi.13917] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 12/27/2017] [Accepted: 01/22/2018] [Indexed: 12/16/2022]
Abstract
Leptospires and other members of the evolutionarily ancient phylum of Spirochaetes are bacteria often characterized by long, highly motile spiral- or wave-shaped cells. Morphology and motility are critical factors in spirochete physiology, contributing to the ability of these bacteria to successfully colonize diverse environments. However, the mechanisms conferring the helical structure of Leptospira spp. have yet to be fully elucidated. We have identified five Leptospira biflexa bactofilin proteins, a recently characterized protein family with cytoskeletal properties. These five bactofilins are conserved in all species of the Leptospiraceae, indicating that these proteins arose early in the evolution of this family. One member of this protein family, LbbD, confers the optimal pitch distance in the helical structure of L. biflexa. Mutants lacking lbbD display a unique compressed helical morphology, a reduced motility and a decreased ability to tolerate cell wall stressors. The change in the helical spacing, combined with the motility and cell wall integrity defects, showcases the intimate relationship and coevolution between shape and motility in these spirochetes.
Collapse
Affiliation(s)
- Katrina M Jackson
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Cindi Schwartz
- Research Technologies Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Jenny Wachter
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Patricia A Rosa
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Philip E Stewart
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| |
Collapse
|
8
|
Ghazaei C. Pathogenic Leptospira: Advances in understanding the molecular pathogenesis and virulence. Open Vet J 2018; 8:13-24. [PMID: 29445617 PMCID: PMC5806663 DOI: 10.4314/ovj.v8i1.4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 01/08/2018] [Indexed: 12/16/2022] Open
Abstract
Leptospirosis is a common zoonotic disease has emerged as a major public health problem, with developing countries bearing disproportionate burdens. Although the diverse range of clinical manifestations of the leptospirosis in humans is widely documented, the mechanisms through which the pathogen causes disease remain undetermined. In addition, leptospirosis is a much-neglected life-threatening disease although it is one of the most important zoonoses occurring in a diverse range of epidemiological distribution. Recent advances in molecular profiling of pathogenic species of the genus Leptospira have improved our understanding of the evolutionary factors that determine virulence and mechanisms that the bacteria employ to survive. However, a major impediment to the formulation of intervention strategies has been the limited understanding of the disease determinants. Consequently, the association of the biological mechanisms to the pathogenesis of Leptospira, as well as the functions of numerous essential virulence factors still remain implicit. This review examines recent advances in genetic screening technologies, the underlying microbiological processes, the virulence factors and associated molecular mechanisms driving pathogenesis of Leptospira species.
Collapse
Affiliation(s)
- Ciamak Ghazaei
- Department of Microbiology, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil, Iran
| |
Collapse
|
9
|
Screening of a Leptospira biflexa mutant library to identify genes involved in ethidium bromide tolerance. Appl Environ Microbiol 2014; 80:6091-103. [PMID: 25063661 DOI: 10.1128/aem.01619-14] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Leptospira spp. are spirochete bacteria comprising both pathogenic and free-living species. The saprophyte L. biflexa is a model bacterium for studying leptospiral biology due to relative ease of culturing and genetic manipulation. In this study, we constructed a library of 4,996 random transposon mutants in L. biflexa. We screened the library for increased susceptibility to the DNA intercalating agent, ethidium bromide (EtBr), in order to identify genetic determinants that reduce L. biflexa susceptibility to antimicrobial agents. By phenotypic screening, using subinhibitory EtBr concentrations, we identified 29 genes that, when disrupted via transposon insertion, led to increased sensitivity of the bacteria to EtBr. At the functional level, these genes could be categorized by function as follows: regulation and signaling (n=11), transport (n=6), membrane structure (n=5), stress response (n=2), DNA damage repair (n=1), and other processes (n=3), while 1 gene had no predicted function. Genes involved in transport (including efflux pumps) and regulation (two-component systems, anti-sigma factor antagonists, etc.) were overrepresented, demonstrating that these genes are major contributors to EtBr tolerance. This finding suggests that transport genes which would prevent EtBr to enter the cell cytoplasm are critical for EtBr resistance. We identified genes required for the growth of L. biflexa in the presence of sublethal EtBr concentration and characterized their potential as antibiotic resistance determinants. This study will help to delineate mechanisms of adaptation to toxic compounds, as well as potential mechanisms of antibiotic resistance development in pathogenic L. interrogans.
Collapse
|
10
|
Characterization of the Bat proteins in the oxidative stress response of Leptospira biflexa. BMC Microbiol 2012; 12:290. [PMID: 23234440 PMCID: PMC3557215 DOI: 10.1186/1471-2180-12-290] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 12/10/2012] [Indexed: 11/23/2022] Open
Abstract
Background Leptospires lack many of the homologs for oxidative defense present in other bacteria, but do encode homologs of the Bacteriodes aerotolerance (Bat) proteins, which have been proposed to fulfill this function. Bat homologs have been identified in all families of the phylum Spirochaetes, yet a specific function for these proteins has not been experimentally demonstrated. Results We investigated the contribution of the Bat proteins in the model organism Leptospira biflexa for their potential contributions to growth rate, morphology and protection against oxidative challenges. A genetically engineered mutant strain in which all bat ORFs were deleted did not exhibit altered growth rate or morphology, relative to the wild-type strain. Nor could we demonstrate a protective role for the Bat proteins in coping with various oxidative stresses. Further, pre-exposing L. biflexa to sublethal levels of reactive oxygen species did not appear to induce a general oxidative stress response, in contrast to what has been shown in other bacterial species. Differential proteomic analysis of the wild-type and mutant strains detected changes in the abundance of a single protein only – HtpG, which is encoded by the gene immediately downstream of the bat loci. Conclusion The data presented here do not support a protective role for the Leptospira Bat proteins in directly coping with oxidative stress as previously proposed. L. biflexa is relatively sensitive to reactive oxygen species such as superoxide and H2O2, suggesting that this spirochete lacks a strong, protective defense against oxidative damage despite being a strict aerobe.
Collapse
|
11
|
Leptospiral outer membrane protein microarray, a novel approach to identification of host ligand-binding proteins. J Bacteriol 2012; 194:6074-87. [PMID: 22961849 DOI: 10.1128/jb.01119-12] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Leptospirosis is a zoonosis with worldwide distribution caused by pathogenic spirochetes belonging to the genus Leptospira. The leptospiral life cycle involves transmission via freshwater and colonization of the renal tubules of their reservoir hosts. Infection requires adherence to cell surfaces and extracellular matrix components of host tissues. These host-pathogen interactions involve outer membrane proteins (OMPs) expressed on the bacterial surface. In this study, we developed an Leptospira interrogans serovar Copenhageni strain Fiocruz L1-130 OMP microarray containing all predicted lipoproteins and transmembrane OMPs. A total of 401 leptospiral genes or their fragments were transcribed and translated in vitro and printed on nitrocellulose-coated glass slides. We investigated the potential of this protein microarray to screen for interactions between leptospiral OMPs and fibronectin (Fn). This approach resulted in the identification of the recently described fibronectin-binding protein, LIC10258 (MFn8, Lsa66), and 14 novel Fn-binding proteins, denoted Microarray Fn-binding proteins (MFns). We confirmed Fn binding of purified recombinant LIC11612 (MFn1), LIC10714 (MFn2), LIC11051 (MFn6), LIC11436 (MFn7), LIC10258 (MFn8, Lsa66), and LIC10537 (MFn9) by far-Western blot assays. Moreover, we obtained specific antibodies to MFn1, MFn7, MFn8 (Lsa66), and MFn9 and demonstrated that MFn1, MFn7, and MFn9 are expressed and surface exposed under in vitro growth conditions. Further, we demonstrated that MFn1, MFn4 (LIC12631, Sph2), and MFn7 enable leptospires to bind fibronectin when expressed in the saprophyte, Leptospira biflexa. Protein microarrays are valuable tools for high-throughput identification of novel host ligand-binding proteins that have the potential to play key roles in the virulence mechanisms of pathogens.
Collapse
|
12
|
Truong KN, Coburn J. The emergence of severe pulmonary hemorrhagic leptospirosis: questions to consider. Front Cell Infect Microbiol 2012; 1:24. [PMID: 22919589 PMCID: PMC3417368 DOI: 10.3389/fcimb.2011.00024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Accepted: 12/19/2011] [Indexed: 12/14/2022] Open
Abstract
Since the 1980s, the incidence of severe pulmonary hemorrhage caused by Leptospira spp. infection has increased. The mild, non-specific symptoms or the more classical form of severe disease with hepatorenal manifestations, Weil's syndrome, predominate world-wide. However, several regions of the world have seen increases in numbers of patients with pulmonary hemorrhage attributed to leptospirosis. The reasons behind the emergence of this syndrome, which carries a high mortality rate, are not known. Several avenues for future research may shed light on the mechanisms involved in development of pulmonary hemorrhage, and inform targeted therapeutics to improve outcomes. Possibilities to consider include: (1) emergence of new bacterial strains, (2) acquisition of virulence traits by strains in the endemic regions, (3) changes in underlying health of the affected human populations, and (4) increased recognition of the syndrome and better record keeping by the medical and veterinary communities. Determining the causes of emerging clinical manifestations presents challenges and opportunities for potentially life-saving research into the pathogenesis of a number of infectious diseases, including leptospirosis.
Collapse
|
13
|
Figueira CP, Croda J, Choy HA, Haake DA, Reis MG, Ko AI, Picardeau M. Heterologous expression of pathogen-specific genes ligA and ligB in the saprophyte Leptospira biflexa confers enhanced adhesion to cultured cells and fibronectin. BMC Microbiol 2011; 11:129. [PMID: 21658265 PMCID: PMC3133549 DOI: 10.1186/1471-2180-11-129] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 06/09/2011] [Indexed: 12/15/2022] Open
Abstract
Background In comparison to other bacterial pathogens, our knowledge of the molecular basis of the pathogenesis of leptospirosis is extremely limited. An improved understanding of leptospiral pathogenetic mechanisms requires reliable tools for functional genetic analysis. Leptospiral immunoglobulin-like (Lig) proteins are surface proteins found in pathogenic Leptospira, but not in saprophytes. Here, we describe a system for heterologous expression of the Leptospira interrogans genes ligA and ligB in the saprophyte Leptospira biflexa serovar Patoc. Results The genes encoding LigA and LigB under the control of a constitutive spirochaetal promoter were inserted into the L. biflexa replicative plasmid. We were able to demonstrate expression and surface localization of LigA and LigB in L. biflexa. We found that the expression of the lig genes significantly enhanced the ability of transformed L. biflexa to adhere in vitro to extracellular matrix components and cultured cells, suggesting the involvement of Lig proteins in cell adhesion. Conclusions This work reports a complete description of the system we have developed for heterologous expression of pathogen-specific proteins in the saprophytic L. biflexa. We show that expression of LigA and LigB proteins from the pathogen confers a virulence-associated phenotype on L. biflexa, namely adhesion to eukaryotic cells and fibronectin in vitro. This study indicates that L. biflexa can serve as a surrogate host to characterize the role of key virulence factors of the causative agent of leptospirosis.
Collapse
|
14
|
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.
Collapse
Affiliation(s)
- Karen V Evangelista
- Department of Microbiology & Molecular Genetics, Medical College of Wisconsin, Milwaukee, USA
| | | |
Collapse
|
15
|
Antibiotic resistance markers for genetic manipulations of Leptospira spp. Appl Environ Microbiol 2010; 76:4882-5. [PMID: 20511419 DOI: 10.1128/aem.00775-10] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We measured the frequency of appearance of spontaneous mutants resistant to gentamicin, kanamycin, streptomycin, and spectinomycin in saprophytic and pathogenic Leptospira strains. The mutations responsible for the spontaneous resistance to streptomycin and spectinomycin were identified in the rpsL and rrs genes, respectively. We also generated a gentamicin resistance cassette that allows the use of a third selectable marker in leptospires. These results may facilitate further advances in gene transfer systems in Leptospira spp.
Collapse
|
16
|
Methodologies to increase the transformation efficiencies and the range of bacteria that can be transformed. Appl Microbiol Biotechnol 2009; 85:1301-13. [DOI: 10.1007/s00253-009-2349-1] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 11/06/2009] [Accepted: 11/07/2009] [Indexed: 10/20/2022]
|
17
|
Ko AI, Goarant C, Picardeau M. Leptospira: the dawn of the molecular genetics era for an emerging zoonotic pathogen. Nat Rev Microbiol 2009; 7:736-47. [PMID: 19756012 PMCID: PMC3384523 DOI: 10.1038/nrmicro2208] [Citation(s) in RCA: 475] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Leptospirosis is a zoonotic disease that has emerged as an important cause of morbidity and mortality among impoverished populations. One hundred years after the discovery of the causative spirochaetal agent, little is understood about Leptospira spp. pathogenesis, which in turn has hampered the development of new intervention strategies to address this neglected disease. However, the recent availability of complete genome sequences for Leptospira spp. and the discovery of genetic tools for their transformation have led to important insights into the biology of these pathogens and their pathogenesis. We discuss the life cycle of the bacterium, the recent advances in our understanding and the implications for the future prevention of leptospirosis.
Collapse
Affiliation(s)
- Albert I. Ko
- Division of Infectious Disease, Weill Medical College of Cornell University, New York, USA
- Gonçalo Moniz Research Centre, Oswaldo Cruz Foundation, Brazilian Ministry of Health, Salvador, Brazil
| | - Cyrille Goarant
- Institut Pasteur de Nouvelle-Calédonie, Laboratoire de Recherche en Bactériologie, Nouméa, New-Caledonia
| | | |
Collapse
|
18
|
Abstract
Leptospira interrogans is the most common cause of leptospirosis in humans and animals. Genetic analysis of L. interrogans has been severely hindered by a lack of tools for genetic manipulation. Recently we developed the mariner-based transposon Himar1 to generate the first defined mutants in L. interrogans. In this study, a total of 929 independent transposon mutants were obtained and the location of insertion determined. Of these mutants, 721 were located in the protein coding regions of 551 different genes. While sequence analysis of transposon insertion sites indicated that transposition occurred in an essentially random fashion in the genome, 25 unique transposon mutants were found to exhibit insertions into genes encoding 16S or 23S rRNAs, suggesting these genes are insertional hot spots in the L. interrogans genome. In contrast, loci containing notionally essential genes involved in lipopolysaccharide and heme biosynthesis showed few transposon insertions. The effect of gene disruption on the virulence of a selected set of defined mutants was investigated using the hamster model of leptospirosis. Two attenuated mutants with disruptions in hypothetical genes were identified, thus validating the use of transposon mutagenesis for the identification of novel virulence factors in L. interrogans. This library provides a valuable resource for the study of gene function in L. interrogans. Combined with the genome sequences of L. interrogans, this provides an opportunity to investigate genes that contribute to pathogenesis and will provide a better understanding of the biology of L. interrogans.
Collapse
|
19
|
Ristow P, Bourhy P, Kerneis S, Schmitt C, Prevost MC, Lilenbaum W, Picardeau M. Biofilm formation by saprophytic and pathogenic leptospires. MICROBIOLOGY-SGM 2008; 154:1309-1317. [PMID: 18451039 DOI: 10.1099/mic.0.2007/014746-0] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Leptospires exist as saprophytic organisms that are aquatic or as pathogens that are able to survive in water. Leptospirosis is transmitted to humans through environmental surface waters contaminated by the urine of mammals, usually rodents, which are chronically infected by pathogenic strains. The ecology of Leptospira spp. prompted us to evaluate if these spirochaetes were able to form biofilms. This study investigated the characteristics of biofilm development by both saprophytic and pathogenic Leptospira species using microscopic examinations and a polystyrene plate model. Biofilms were formed preferentially on glass and polystyrene surfaces. Electron microscopic images showed cells embedded in an extracellular matrix. The formation of such a biofilm is consistent with the life of saprophytic strains in water and may help pathogenic strains to survive in environmental habitats and to colonize the host.
Collapse
Affiliation(s)
- Paula Ristow
- Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro, Brazil.,Unité de Biologie des Spirochètes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Pascale Bourhy
- Unité de Biologie des Spirochètes, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Sophie Kerneis
- Plate-Forme de Microscopie Électronique, Institut Pasteur, Paris, France
| | - Christine Schmitt
- Plate-Forme de Microscopie Électronique, Institut Pasteur, Paris, France
| | | | | | - Mathieu Picardeau
- Unité de Biologie des Spirochètes, Institut Pasteur, 75724 Paris Cedex 15, France
| |
Collapse
|
20
|
Ristow P, Bourhy P, McBride FWDC, Figueira CP, Huerre M, Ave P, Girons IS, Ko AI, Picardeau M. The OmpA-like protein Loa22 is essential for leptospiral virulence. PLoS Pathog 2007; 3:e97. [PMID: 17630832 PMCID: PMC1914066 DOI: 10.1371/journal.ppat.0030097] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Accepted: 05/17/2007] [Indexed: 11/28/2022] Open
Abstract
Pathogenic mechanisms of Leptospira interrogans, the causal agent of leptospirosis, remain largely unknown. This is mainly due to the lack of tools for genetic manipulations of pathogenic species. In this study, we characterized a mutant obtained by insertion of the transposon Himar1 into a gene encoding a putative lipoprotein, Loa22, which has a predicted OmpA domain based on sequence identity. The resulting mutant did not express Loa22 and was attenuated in virulence in the guinea pig and hamster models of leptospirosis, whereas the genetically complemented strain was restored in Loa22 expression and virulence. Our results show that Loa22 was expressed during host infection and exposed on the cell surface. Loa22 is therefore necessary for virulence of L. interrogans in the animal model and represents, to our knowledge, the first genetically defined virulence factor in Leptospira species.
Collapse
Affiliation(s)
- Paula Ristow
- Unité de Biologie des Spirochètes, Institut Pasteur, Paris, France
- Instituto de Microbiologia Professor Paulo de Goes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Pascale Bourhy
- Unité de Biologie des Spirochètes, Institut Pasteur, Paris, France
| | | | | | - Michel Huerre
- Unité de Recherche et d'Expertise Histotechnologie et Pathologie, Institut Pasteur, Paris, France
| | - Patrick Ave
- Unité de Recherche et d'Expertise Histotechnologie et Pathologie, Institut Pasteur, Paris, France
| | | | - Albert I Ko
- Instituto de Microbiologia Professor Paulo de Goes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Division of International Medicine and Infectious Disease, Weill Medical College of Cornell University, New York, New York, United States of America
| | | |
Collapse
|