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A novel hybrid two-component system Lvr mediates virulence and global regulation in pathogenic Leptospira

ABSTRACT: Transmission of leptospirosis requires that the spirochete pathogen adapts rapidly to the mammalian host milieu during infection and the external environment upon shedding from the renal tubules of animal reservoirs. The pathogenic Leptospira genomes encode a notably large number (≥76) of putative two-component system (TCS) proteins, which presumably play a key role in switching the ecological niches. Yet to date, the regulatory networks that govern virulence and environmental adaptation have not been elucidated in Leptospira. We identified seven ORFs encoding putative TCS proteins that are exclusively conserved in all the pathogenic Leptospira species. Two of these ORFs (LMANv2_670020, LMANv2_670019), juxtaposed in an operon, are predicted to encode a cytoplasmic hybrid histidine kinase and response regulator. Corresponding transposon mutants ΔlvrA/B and ΔlvrB demonstrated a loss-of-virulence in a hamster model of leptospirosis and aberrant motility phenotype. RNA sequencing revealed the differential expression of transcripts on a global scale in ΔlvrA/B (8.13%), ΔlvrB (5.06%) and ΔlvrA/B∩ΔlvrB (8.24%). In vitro transcriptomes provided insights into the role of Lvr dyad in regulating virulence, motility, signal transduction and metabolism related genes. Phosphotransfer assays indicated that LvrA interacts with LvrB in a branched signaling pathway. Phylogenetic analyses indicated that Our findings suggest that a novel, hybrid two-component system Lvr plays a key role in governing virulence and mediating global regulation in pathogenic Leptospira.

ORGANISM(S): Leptospira interrogans serovar Manilae

PROVIDER: GSE79107 | GEO | 2018/04/04

REPOSITORIES: GEO

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Project description:The life-threatening pathogen Leptospira interrogans navigates a dual existence: surviving in environmental reservoirs and infecting mammalian hosts. Leptospira biofilm formation is thought to be an important survival strategy in environmental contexts and may also contribute to the persistence of leptospirosis in maintenance hosts. Examining the correlation between biofilm formation and the virulence of pathogenic strains might improve our comprehension of the epidemiology of leptospirosis. To further explore Leptospira’s survival strategy, our study focused on elucidating the biological state of pathogenic Leptospira within biofilms, particularly aiming to uncover the adaptations and regulatory mechanisms that are involved in such complex microenvironments. To determine the transcriptional profile of pathogenic Leptospira in biofilm, we compared the genome-wide transcriptomic profiles in late biofilms (21 days old) with those in exponential planktonic cultures (5 days old), revealing a pronounced transcriptomic shift. While genes linked to motility, energy production, and metabolism were downregulated, those governing the general stress response, defense against metal stress, and redox homeostasis showed a significant upsurge, hinting at a tailored defensive strategy against stress in late biofilms. A standout finding was the increased expression of the csoR, copZ, and copA locus, integral to copper ion stress response in other bacterial genera, suggesting a unique adaptation to metal-induced stress. Further, despite a reduced metabolic state in biofilms, their disruption swiftly restored metabolic activity. Crucially, bacteria either in late biofilms or resulting from biofilm disruption retained virulence in a hamster infection model, defying the notion that biofilm maturation abolishes pathogenicity. In summary, our study highlights Leptospira's adaptive equilibrium in biofilms: minimizing cellular energy expenditure to conserve resources, potentially aiding in withstanding stresses while maintaining its pathogenicity. These insights are important for explaining the survival strategies of Leptospira, revealing that a biofilm lifestyle may confer an advantage in maintaining virulence. This understanding is essential for managing leptospirosis across both environmental reservoirs and mammalian hosts.

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A novel hybrid two-component system Lvr mediates virulence and global regulation in pathogenic Leptospira

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