The FUR-like regulators PerRA and PerRB integrate a complex regulatory network that promotes mammalian host-adaptation and virulence of Leptospira interrogans

Grassmann, André Alex; Zavala-Alvarado, Crispín; Bettin, Everton Burlamarque; Picardeau, Mathieu; Benaroudj, Nadia; Caimano, Melissa J.

doi:10.1371/journal.ppat.1009078

Cited by 7 publications

(8 citation statements)

References 203 publications

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“…Polyclonal antisera against FlaB ( 97 ), OspC ( 11 ), DbpA ( 98 ), GlpD ( 99 ), RpoS ( 100 ), and OspA ( 11 ) were previously described. Antisera against BBK32 C1/C1r domain ( 33 ) and VlsE C6 peptide ( 101 ) were generated by immunizing Sprague-Dawley rats (Envigo RMS Inc.) with the corresponding purified, recombinant His-tagged protein, as previously described ( 102 ).…”

Section: Methodsmentioning

confidence: 99%

BosR and PlzA reciprocally regulate RpoS function to sustain Borrelia burgdorferi in ticks and mammals

Grassmann¹,

Tokarz²,

Golino³

et al. 2023

Journal of Clinical Investigation

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The alternative sigma factor RpoS in Borrelia burgdorferi (Bb), the Lyme disease pathogen, is responsible for programmatic positive and negative gene regulation essential for the spirochete's dual-host enzootic cycle. RpoS is expressed during tick-to-mammal transmission and throughout mammalian infection.Although the mammalian-phase RpoS regulon is well described, its counterpart during the transmission blood meal is unknown. Here, we used Bb-specific transcript enrichment by TBDCapSeq to compare the transcriptomes of wild-type and ΔrpoS Bb in engorged nymphs and following mammalian host-adaptation within dialysis membrane chambers. TBDCapSeq revealed dramatic changes in the contours of the RpoS regulon within ticks and mammals and further confirmed that RpoS-mediated repression is specific to the mammalian-phase of Bb's enzootic cycle. We also provide evidence that RpoS-dependent gene regulation, including repression of tick-phase genes, is required for persistence in mice. Comparative transcriptomics of engineered Bb strains revealed that BosR, a non-canonical Fur family regulator, and the c-di-GMP effector PlzA reciprocally regulate the function of RNA polymerase complexed with RpoS. BosR is required for RpoS-mediated transcription activation and repression in addition to its well-defined role promoting RpoN-dependent transcription of rpoS. During transmission, liganded-PlzA antagonizes RpoSmediated repression, presumably acting through BosR.

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Section: Methodsmentioning

confidence: 99%

BosR and PlzA reciprocally regulate RpoS function to sustain Borrelia burgdorferi in ticks and mammals

Grassmann¹,

Tokarz²,

Golino³

et al. 2023

Journal of Clinical Investigation

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“…Importantly, there is an abundance of commercially available reagents for the characterisation of the immune response. In addition, there are mouse mutants e.g., the C3H/HeJ TLR4 mutant, SCID and Rag1 KO mice, which are susceptible to leptospiral infection (Bandeira et al, 2011;Shetty et al, 2021;Grassmann et al, 2021;Kundu et al, 2022). The use of a mouse model would allow the study of both lethal and sublethal forms of leptospirosis, potentially allowing the discovery of immune correlates that can be used to screen vaccine candidates (Pereira et al, 1998;Santos et al, 2010;Gomes-Solecki et al, 2017;Felix et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

Challenges for the development of a universal vaccine against leptospirosis revealed by the evaluation of 22 vaccine candidates

Maia

Bettin

Barbosa

et al. 2022

Front. Cell. Infect. Microbiol.

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Leptospirosis is a neglected disease of man and animals that affects nearly half a million people annually and causes considerable economic losses. Current human vaccines are inactivated whole-cell preparations (bacterins) of Leptospira spp. that provide strong homologous protection yet fail to induce a cross-protective immune response. Yearly boosters are required, and serious side-effects are frequently reported so the vaccine is licensed for use in humans in only a handful of countries. Novel universal vaccines require identification of conserved surface-exposed epitopes of leptospiral antigens. Outer membrane β-barrel proteins (βb-OMPs) meet these requirements and have been successfully used as vaccines for other diseases. We report the evaluation of 22 constructs containing protein fragments from 33 leptospiral βb-OMPs, previously identified by reverse and structural vaccinology and cell-surface immunoprecipitation. Three-dimensional structures for each leptospiral βb-OMP were predicted by I-TASSER. The surface-exposed epitopes were predicted using NetMHCII 2.2 and BepiPred 2.0. Recombinant constructs containing regions from one or more βb-OMPs were cloned and expressed in Escherichia coli. IMAC-purified recombinant proteins were adsorbed to an aluminium hydroxide adjuvant to produce the vaccine formulations. Hamsters (4-6 weeks old) were vaccinated with 2 doses containing 50 – 125 μg of recombinant protein, with a 14-day interval between doses. Immunoprotection was evaluated in the hamster model of leptospirosis against a homologous challenge (10 – 20× ED50) with L. interrogans serogroup Icterohaemorrhagiae serovar Copenhageni strain Fiocruz L1-130. Of the vaccine formulations, 20/22 were immunogenic and induced significant humoral immune responses (IgG) prior to challenge. Four constructs induced significant protection (100%, P < 0.001) and sterilizing immunity in two independent experiments, however, this was not reproducible in subsequent evaluations (0 – 33.3% protection, P > 0.05). The lack of reproducibility seen in these challenge experiments and in other reports in the literature, together with the lack of immune correlates and commercially available reagents to characterize the immune response, suggest that the hamster may not be the ideal model for evaluation of leptospirosis vaccines and highlight the need for evaluation of alternative models, such as the mouse.

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“…However, PerRA is present in all saprophytes whereas homologs of PerRB cannot be found in non-pathogenic Leptospira species. Conversely, PerRB homologs are found in the P2 clade species where PerRA is generally missing [ 166 , 167 ] ( Figure 4 ).…”

Section: Regulation Of the Oxidative Stress Responsementioning

confidence: 99%

“…PerRA inactivation leads to a higher survival in the presence of H 2 O 2 than the WT [ 165 , 168 ]. Identification of the PerRA regulon indicates that not only PerRA represses the ank-katE operon (LIMLP_10145-10150) and genes encoding AhpC1 (LIMLP_05955) and CCP (LIMLP_02795), but it also activates a gene locus encoding a TonB-dependent transporter and the two-component system VicKR [ 165 , 166 , 167 ]. The main function of PerRA is therefore to control expression of defenses against H 2 O 2 .…”

Section: Regulation Of the Oxidative Stress Responsementioning

confidence: 99%

“…From this phenotype, one can infer that L. interrogans PerRB represses genes involved in superoxide detoxification. RNASeq analyses of a perRB mutant when L. interrogans are cultivated in the EMJH culture medium or in dialysis membrane chamber did not provide an obvious explanation for this phenotype [ 166 , 167 ]. Indeed, the PerRB regulon encompasses either genes with unknown or poorly characterized function, or genes encoding factors involved in regulation (transcriptional regulators, c-di-GMP metabolism, and sigma factors).…”

Section: Regulation Of the Oxidative Stress Responsementioning

confidence: 99%

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The Arsenal of Leptospira Species against Oxidants

Huete

Benaroudj

2023

Antioxidants

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Reactive oxygen species (ROS) are byproducts of oxygen metabolism produced by virtually all organisms living in an oxic environment. ROS are also produced by phagocytic cells in response to microorganism invasion. These highly reactive molecules can damage cellular constituents (proteins, DNA, and lipids) and exhibit antimicrobial activities when present in sufficient amount. Consequently, microorganisms have evolved defense mechanisms to counteract ROS-induced oxidative damage. Leptospira are diderm bacteria form the Spirochaetes phylum. This genus is diverse, encompassing both free-living non-pathogenic bacteria as well as pathogenic species responsible for leptospirosis, a widespread zoonotic disease. All leptospires are exposed to ROS in the environment, but only pathogenic species are well-equipped to sustain the oxidative stress encountered inside their hosts during infection. Importantly, this ability plays a pivotal role in Leptospira virulence. In this review, we describe the ROS encountered by Leptospira in their different ecological niches and outline the repertoire of defense mechanisms identified so far in these bacteria to scavenge deadly ROS. We also review the mechanisms controlling the expression of these antioxidants systems and recent advances in understanding the contribution of Peroxide Stress Regulators in Leptospira adaptation to oxidative stress.

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The FUR-like regulators PerRA and PerRB integrate a complex regulatory network that promotes mammalian host-adaptation and virulence of Leptospira interrogans

Cited by 7 publications

References 203 publications

BosR and PlzA reciprocally regulate RpoS function to sustain Borrelia burgdorferi in ticks and mammals

BosR and PlzA reciprocally regulate RpoS function to sustain Borrelia burgdorferi in ticks and mammals

Challenges for the development of a universal vaccine against leptospirosis revealed by the evaluation of 22 vaccine candidates

The Arsenal of Leptospira Species against Oxidants

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