DksA-dependent regulation of RpoS contributes to Borrelia burgdorferi tick-borne transmission and mammalian infectivity

Boyle, William K.; Richards, Crystal L.; Dulebohn, Daniel P.; Zalud, Amanda K.; Shaw, Jeff A.; Lovas, Sándor; Gherardini, Frank C.; Bourret, Travis J.

doi:10.1371/journal.ppat.1009072

Cited by 7 publications

(6 citation statements)

References 80 publications

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“…During acquisition, transcription of rpoS by the Rrp2/BosR/RpoN complex is quickly shut OFF in the midgut in response to unknown signals [16,20]. Conceivably, to expedite the switch from an RpoS-ON to -OFF, liganded-PlzA also could interfere with transcription by residual RNAP-RpoS holoenzyme allosterically, while BBD18, which is RpoSrepressed and c-di-GMP-induced [36,42], would target free RpoS for proteolytic degradation [91][92][93][94]. During transmission, partial restriction of RNAP-RpoS holoenzyme by liganded-PlzA could enable spirochetes to sustain expression of RpoS-repressed tick phase genes (i.e., ospA, glps) while at the same time allowing reduced expression of RpoS-upregulated genes required for transmission (i.e., bba64) or early infection (i.e., ospC, dbpBA) [36,82,95].…”

Section: Plos Pathogensmentioning

confidence: 99%

PlzA is a bifunctional c-di-GMP biosensor that promotes tick and mammalian host-adaptation of Borrelia burgdorferi

et al. 2021

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In this study, we examined the relationship between c-di-GMP and its only known effector protein, PlzA, in Borrelia burgdorferi during the arthropod and mammalian phases of the enzootic cycle. Using a B. burgdorferi strain expressing a plzA point mutant (plzA-R145D) unable to bind c-di-GMP, we confirmed that the protective function of PlzA in ticks is c-di-GMP-dependent. Unlike ΔplzA spirochetes, which are severely attenuated in mice, the plzA-R145D strain was fully infectious, firmly establishing that PlzA serves a c-di-GMP-independent function in mammals. Contrary to prior reports, loss of PlzA did not affect expression of RpoS or RpoS-dependent genes, which are essential for transmission, mammalian host-adaptation and murine infection. To ascertain the nature of PlzA’s c-di-GMP-independent function(s), we employed infection models using (i) host-adapted mutant spirochetes for needle inoculation of immunocompetent mice and (ii) infection of scid mice with in vitro-grown organisms. Both approaches substantially restored ΔplzA infectivity, suggesting that PlzA enables B. burgdorferi to overcome an early bottleneck to infection. Furthermore, using a Borrelia strain expressing a heterologous, constitutively active diguanylate cyclase, we demonstrate that ‘ectopic’ production of c-di-GMP in mammals abrogates spirochete virulence and interferes with RpoS function at the post-translational level in a PlzA-dependent manner. Structural modeling and SAXS analysis of liganded- and unliganded-PlzA revealed marked conformational changes that underlie its biphasic functionality. This structural plasticity likely enables PlzA to serve as a c-di-GMP biosensor that in its respective liganded and unliganded states promote vector- and host-adaptation by the Lyme disease spirochete.

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Section: Plos Pathogensmentioning

confidence: 99%

PlzA is a bifunctional c-di-GMP biosensor that promotes tick and mammalian host-adaptation of Borrelia burgdorferi

et al. 2021

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“…In some bacteria like E . coli and Borrelia burgdorferi , a dksA mutant exhibited undetectable RpoS level under various conditions, even in the presence of high (p)ppGpp levels [ 6 , 22 ]. In Vibrio cholerae DksA was found to regulate RpoS expression at the transcriptional and translational level [ 8 ].…”

Section: Discussionmentioning

confidence: 99%

“…In A. vinelandii, the sigma factor RpoS has been shown to activate transcription of phbR and the PHB biosynthetic operon phbBAC [10,11]. In some bacteria like E. coli and Borrelia burgdorferi, a dksA mutant exhibited undetectable RpoS level under various conditions, even in the presence of high (p)ppGpp levels [6,22]. In Vibrio cholerae DksA was found to regulate RpoS expression at the transcriptional and translational level [8].…”

Section: Plos Onementioning

confidence: 99%

The stringent response regulates the poly-β-hydroxybutyrate (PHB) synthesis in Azotobacter vinelandii

Ortiz-Vasco,

Moreno,

Quintero-Navarro

et al. 2024

PLoS ONE

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The stringent response exerted by (p)ppGpp and RNA-polymerase binding protein DksA regulates gene expression in diverse bacterial species. To control gene expression (p)ppGpp, synthesized by enzymes RelA and SpoT, interacts with two sites within the RNA polymerase; site 1, located in the interphase between subunits β’ and ω (rpoZ), and site 2 located in the secondary channel that is dependent on DksA protein. In Escherichia coli, inactivation of dksA results in a reduced sigma factor RpoS expression. In Azotobacter vinelandii the synthesis of polyhydroxybutyrate (PHB) is under RpoS regulation. In this study, we found that the inactivation of relA or dksA, but not rpoZ, resulted in a negative effect on PHB synthesis. We also found that the dksA, but not the relA mutation reduced both rpoS transcription and RpoS protein levels, implying that (p)ppGpp and DksA control PHB synthesis through different mechanisms. Interestingly, despite expressing rpoS from a constitutive promoter in the dksA mutant, PHB synthesis was not restored to wild type levels. A transcriptomic analysis in the dksA mutant, revealed downregulation of genes encoding enzymes needed for the synthesis of acetyl-CoA, the precursor substrate for PHB synthesis. Together, these data indicate that DksA is required for optimal expression of RpoS which in turn activates transcription of genes for PHB synthesis. Additionally, DksA is required for optimal transcription of genes responsible for the synthesis of precursors for PHB synthesis.

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“…Transcription of glpD and the glp operon has been shown to be regulated by a number of different mechanisms. The glycerol utilization system is positively regulated by the Hk1/Rrp1 two component system (Caimano et al, 2015; He et al, 2011; Rogers et al, 2009) as well as DksA or the stringent response under conditions of starvation (Boyle et al, 2021; Bugrysheva et al, 2015; Drecktrah et al, 2015) and negatively regulated by RpoS (Grove et al, 2017) and BosR (Hyde et al, 2006). The cyclic‐di‐GMP effector protein PlzA has been shown to be both a negative and positive regulator of glp expression depending on whether or not the protein is bound to the second messenger (Zhang et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

Riboflavin salvage by Borrelia burgdorferi supports carbon metabolism and is essential for survival in the tick vector

Ramos

Lasseter

Richards

et al. 2022

Molecular Microbiology

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The spirochete Borrelia (Borreliella) burgdorferi is an obligate parasite and is maintained in nature in an enzootic cycle between Ixodes scapularis ticks and a variety of small mammals, birds, and reptiles. Humans are inadvertent hosts and can become infected with B. burgdorferi if bitten by an infected tick leading to Lyme disease (Coburn et al., 2021). B. burgdorferi harbors a fragmented and reduced genome lacking genes required for numerous metabolic and regulatory pathways, including genes that encode proteins for the de novo synthesis of amino acids, nucleotides, and enzyme cofactors (Casjens et al., 2012;Fraser et al., 1997). Therefore, B. burgdorferi must scavenge these critical nutrients from its host environments to survive. One of these nutrients is riboflavin, which is important for humans and bacteria alike (Averianova et al., 2020).Riboflavin is the precursor to flavin adenine mononucleotide (FAD) and flavin mononucleotide (FMN), which are cofactors required for an array of proteins to function. Flavoproteins contribute to a wide range of important biological functions including central metabolism, redox homeostasis, DNA repair, and apoptosis (Massey, 2000). Unlike many bacterial species, B. burgdorferi appears to lack the enzymatic machinery for the de novo synthesis of riboflavin (Casjens et al., 2000;Fraser et al., 1997), suggesting that the spirochete relies on the uptake of riboflavin from its hosts.

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DksA-dependent regulation of RpoS contributes to Borrelia burgdorferi tick-borne transmission and mammalian infectivity

Cited by 7 publications

References 80 publications

PlzA is a bifunctional c-di-GMP biosensor that promotes tick and mammalian host-adaptation of Borrelia burgdorferi

PlzA is a bifunctional c-di-GMP biosensor that promotes tick and mammalian host-adaptation of Borrelia burgdorferi

The stringent response regulates the poly-β-hydroxybutyrate (PHB) synthesis in Azotobacter vinelandii

Riboflavin salvage by Borrelia burgdorferi supports carbon metabolism and is essential for survival in the tick vector

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