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Cheah HL, Ahmed SA, Tang TH. Transcription start site mapping and small RNA profiling of Leptospira biflexa serovar Patoc. World J Microbiol Biotechnol 2023; 39:104. [PMID: 36808011 DOI: 10.1007/s11274-023-03540-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 02/03/2023] [Indexed: 02/23/2023]
Abstract
Leptospirosis is an emerging zoonotic disease caused by bacterial species of the genus Leptospira. However, the regulatory mechanisms and pathways underlying the adaptation of pathogenic and non-pathogenic Leptospira spp. in different environmental conditions remain elusive. Leptospira biflexa is a non-pathogenic species of Leptospira that lives exclusively in a natural environment. It is an ideal model not only for exploring molecular mechanisms underlying the environmental survival of Leptospira species but also for identifying virulence factors unique to Leptospira's pathogenic species. In this study, we aim to establish the transcription start site (TSS) landscape and the small RNA (sRNA) profile of L. biflexa serovar Patoc grown to exponential and stationary phases via differential RNA-seq (dRNA-seq) and small RNA-seq (sRNA-seq) analyses, respectively. Our dRNA-seq analysis uncovered a total of 2726 TSSs, which are also used to identify other elements, e.g., promoter and untranslated regions (UTRs). Besides, our sRNA-seq analysis revealed a total of 603 sRNA candidates, comprising 16 promoter-associated sRNAs, 184 5'UTR-derived sRNAs, 230 true intergenic sRNAs, 136 5'UTR-antisense sRNAs, and 130 open reading frame (ORF)-antisense sRNAs. In summary, these findings reflect the transcriptional complexity of L. biflexa serovar Patoc under different growth conditions and help to facilitate our understanding of regulatory networks in L. biflexa. To the best of our knowledge, this is the first study reporting the TSS landscape of L. biflexa. The TSS and sRNA landscapes of L. biflexa can also be compared with its pathogenic counterparts, e.g., L. borgpetersenii and L. interrogans, to identify features contributing to their environmental survival and virulence.
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Affiliation(s)
- Hong-Leong Cheah
- Advanced Medical & Dental Institute (AMDI), Universiti Sains Malaysia, Bertam, 13200, Kepala Batas, Penang, Malaysia
| | - Siti Aminah Ahmed
- Advanced Medical & Dental Institute (AMDI), Universiti Sains Malaysia, Bertam, 13200, Kepala Batas, Penang, Malaysia
| | - Thean-Hock Tang
- Advanced Medical & Dental Institute (AMDI), Universiti Sains Malaysia, Bertam, 13200, Kepala Batas, Penang, Malaysia.
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Prakash A, Kumar M. Characterizing the transcripts of Leptospira CRISPR I-B array and its processing with endoribonuclease LinCas6. Int J Biol Macromol 2021; 182:785-795. [PMID: 33862076 DOI: 10.1016/j.ijbiomac.2021.04.066] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/08/2021] [Accepted: 04/10/2021] [Indexed: 12/26/2022]
Abstract
In Leptospira interrogans serovar Copenhageni, the CRISPR-Cas I-B locus possesses a CRISPR array between the two independent cas-operons. Using the reverse transcription-PCR and the in vitro endoribonuclease assay with Cas6 of Leptospira (LinCas6), we account that the CRISPR is transcriptionally active and is conventionally processed. The LinCas6 specifically excises at one site within the synthetic cognate repeat RNA or the repeats of precursor-CRISPR RNA (pre-crRNA) in the sense direction. In contrast, the antisense repeat RNA is cleaved at multiple sites. LinCas6 functions as a single turnover endoribonuclease on its repeat RNA substrate, where substitution of one of predicted active site residues (His38) resulted in reduced activity. This study highlights the comprehensive understanding of the Leptospira CRISPR array transcription and its processing by LinCas6 that is central to RNA-mediated CRISPR-Cas I-B adaptive immunity.
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Affiliation(s)
- Aman Prakash
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Manish Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
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Fernandes LGV, Hornsby RL, Nascimento ALTO, Nally JE. Genetic manipulation of pathogenic Leptospira: CRISPR interference (CRISPRi)-mediated gene silencing and rapid mutant recovery at 37 °C. Sci Rep 2021; 11:1768. [PMID: 33469138 PMCID: PMC7815788 DOI: 10.1038/s41598-021-81400-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 01/04/2021] [Indexed: 02/07/2023] Open
Abstract
Leptospirosis is a neglected, widespread zoonosis caused by pathogenic species of the genus Leptospira, and is responsible for 60,000 deaths per year. Pathogenic mechanisms of leptospirosis remain poorly understood mainly because targeted mutations or gene silencing in pathogenic Leptospira continues to be inherently inefficient, laborious, costly and difficult to implement. In addition, pathogenic leptospires are highly fastidious and the selection of mutants on solid agar media can take up to 6 weeks. The catalytically inactive Cas9 (dCas9) is an RNA-guided DNA-binding protein from the Streptococcus pyogenes CRISPR/Cas system and can be used for gene silencing, in a strategy termed CRISPR interference (CRISPRi). Here, this technique was employed to silence genes encoding major outer membrane proteins of pathogenic L. interrogans. Conjugation protocols were optimized using the newly described HAN media modified for rapid mutant recovery at 37 °C in 3% CO2 within 8 days. Complete silencing of LipL32 and concomitant and complete silencing of both LigA and LigB outer membrane proteins were achieved, revealing for the first time that Lig proteins are involved in pathogenic Leptospira serum resistance. Gene silencing in pathogenic leptospires and rapid mutant recovery will facilitate novel studies to further evaluate and understand pathogenic mechanisms of leptospirosis.
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Affiliation(s)
- L G V Fernandes
- Infectious Bacterial Diseases Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, IA, USA.
- Laboratório de Desenvolvimento de Vacinas, Instituto Butantan, São Paulo, 05503-900, Brazil.
| | - R L Hornsby
- Infectious Bacterial Diseases Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, IA, USA
| | - A L T O Nascimento
- Laboratório de Desenvolvimento de Vacinas, Instituto Butantan, São Paulo, 05503-900, Brazil
| | - J E Nally
- Infectious Bacterial Diseases Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, IA, USA
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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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Abstract
This chapter covers the progress made in the Leptospira field since the application of mutagenesis techniques and how they have allowed the study of virulence factors and, more generally, the biology of Leptospira. The last decade has seen advances in our ability to perform molecular genetic analysis of Leptospira. Major achievements include the generation of large collections of mutant strains and the construction of replicative plasmids, enabling complementation of mutations. However, there are still no practical tools for routine genetic manipulation of pathogenic Leptospira strains, slowing down advances in pathogenesis research. This review summarizes the status of the molecular genetic toolbox for Leptospira species and highlights new challenges in the nascent field of Leptospira genetics.
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Affiliation(s)
- Mathieu Picardeau
- Biology of Spirochetes Unit, Institut Pasteur, 28 Rue Du Docteur Roux, 75724, Paris Cedex 15, France.
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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.
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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.
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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.
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Affiliation(s)
- Ciamak Ghazaei
- Department of Microbiology, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil, Iran
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Pappas CJ, Picardeau M. Control of Gene Expression in Leptospira spp. by Transcription Activator-Like Effectors Demonstrates a Potential Role for LigA and LigB in Leptospira interrogans Virulence. Appl Environ Microbiol 2015; 81:7888-92. [PMID: 26341206 PMCID: PMC4616954 DOI: 10.1128/aem.02202-15] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 09/01/2015] [Indexed: 12/16/2022] Open
Abstract
Leptospirosis is a zoonotic disease that affects ∼1 million people annually, with a mortality rate of >10%. Currently, there is an absence of effective genetic manipulation tools for targeted mutagenesis in pathogenic leptospires. Transcription activator-like effectors (TALEs) are a recently described group of repressors that modify transcriptional activity in prokaryotic and eukaryotic cells by directly binding to a targeted sequence within the host genome. To determine the applicability of TALEs within Leptospira spp., two TALE constructs were designed. First, a constitutively expressed TALE gene specific for the lacO-like region upstream of bgaL was trans inserted in the saprophyte Leptospira biflexa (the TALEβgal strain). Reverse transcriptase PCR (RT-PCR) analysis and enzymatic assays demonstrated that BgaL was not expressed in the TALEβgal strain. Second, to study the role of LigA and LigB in pathogenesis, a constitutively expressed TALE gene with specificity for the homologous promoter regions of ligA and ligB was cis inserted into the pathogen Leptospira interrogans (TALElig). LigA and LigB expression was studied by using three independent clones: TALElig1, TALElig2, and TALElig3. Immunoblot analysis of osmotically induced TALElig clones demonstrated 2- to 9-fold reductions in the expression levels of LigA and LigB, with the highest reductions being noted for TALElig1 and TALElig2, which were avirulent in vivo and nonrecoverable from animal tissues. This study reconfirms galactosidase activity in the saprophyte and suggests a role for LigA and LigB in pathogenesis. Collectively, this study demonstrates that TALEs are effective at reducing the expression of targeted genes within saprophytic and pathogenic strains of Leptospira spp., providing an additional genetic manipulation tool for this genus.
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Affiliation(s)
- Christopher J Pappas
- Institut Pasteur, Unité de Biologie des Spirochètes, Paris, France Manhattanville College, Department of Biology, Purchase, New York, USA
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