The CasKR Two-Component System Is Required for the Growth of Mesophilic and Psychrotolerant Bacillus cereus Strains at Low Temperatures

ABSTRACTThe different strains ofBacillus cereuscan grow at temperatures covering a very diverse range. SomeB. cereusstrains can grow in chilled food and consequently cause food poisoning. We have identified a new sensor/regulator mechanism involved in low-temperatureB. cereusgrowth. Construction of a mutant of this two-component system enabled us to show that this system, called CasKR, is required for growth at the minimal temperature (Tmin). CasKR was also involved in optimal cold growth aboveTminand in cell survival belowTmin. Microscopic observation showed that CasKR plays a key role in cell shape during cold growth. Introducing thecasKRgenes in a ΔcasKRmutant restored its ability to grow atTmin. Although it was first identified in the ATCC 14579 model strain, this mechanism has been conserved in most strains of theB. cereusgroup. We show that the role of CasKR in cold growth is similar in otherB. cereus sensu latostrains with different growth temperature ranges, including psychrotolerant strains.

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The Staphylococcus aureus KdpDE Two-Component System Couples Extracellular K+Sensing and Agr Signaling to Infection Programming

Infection and Immunity ◽

10.1128/iai.01180-10 ◽

2011 ◽

Vol 79 (6) ◽

pp. 2154-2167 ◽

Cited By ~ 56

Author(s):

Ting Xue ◽

Yibo You ◽

De Hong ◽

Haipeng Sun ◽

Baolin Sun

Keyword(s):

Staphylococcus Aureus ◽

Uptake System ◽

Main Function ◽

Two Component System ◽

Component System ◽

Content Type ◽

Two Component ◽

Virulence Regulator ◽

External K

ABSTRACTThe Kdp system is widely distributed among bacteria. InEscherichia coli, the Kdp-ATPase is a high-affinity K+uptake system and its expression is activated by the KdpDE two-component system in response to K+limitation or salt stress. However, information about the role of this system in many bacteria still remains obscure. Here we demonstrate that KdpFABC inStaphylococcus aureusis not a major K+transporter and that the main function of KdpDE is not associated with K+transport but that instead it regulates transcription for a series of virulence factors through sensing external K+concentrations, indicating that this bacterium might modulate its infectious status through sensing specific external K+stimuli in different environments. Our results further reveal thatS. aureusKdpDE is upregulated by the Agr/RNAIII system, which suggests that KdpDE may be an important virulence regulator coordinating the external K+sensing and Agr signaling during pathogenesis in this bacterium.

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Involvement of Two-Component System CBO0366/CBO0365 in the Cold Shock Response and Growth of Group I (Proteolytic) Clostridium botulinum ATCC 3502 at Low Temperatures

Applied and Environmental Microbiology ◽

10.1128/aem.00555-12 ◽

2012 ◽

Vol 78 (15) ◽

pp. 5466-5470 ◽

Cited By ~ 19

Author(s):

Miia Lindström ◽

Elias Dahlsten ◽

Henna Söderholm ◽

Katja Selby ◽

Panu Somervuo ◽

...

Keyword(s):

Clostridium Botulinum ◽

Cold Shock ◽

Two Component System ◽

Component System ◽

Content Type ◽

Cold Shock Response ◽

Group I ◽

Two Component ◽

Shock Response

ABSTRACTThe role of the two-component system (TCS) CBO0366/CBO0365 in the cold shock response and growth of the mesophilicClostridium botulinumATCC 3502 at 15°C was demonstrated by induced expression of the TCS genes upon cold shock and impaired growth of the TCS mutants at 15°C.

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The role of PhoP/PhoQ two component system in regulating stress adaptation in Cronobacter sakazakii

Food Microbiology ◽

10.1016/j.fm.2021.103851 ◽

2021 ◽

pp. 103851

Author(s):

Yan Ma ◽

Yingying Zhang ◽

Ke Chen ◽

Lingzhu Zhang ◽

Yibei Zhang ◽

...

Keyword(s):

Stress Adaptation ◽

Cronobacter Sakazakii ◽

Two Component System ◽

Component System ◽

Two Component

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Nutritional Regulation of the Sae Two-Component System by CodY inStaphylococcus aureus

Journal of Bacteriology ◽

10.1128/jb.00012-18 ◽

2018 ◽

Vol 200 (8) ◽

Cited By ~ 14

Author(s):

Kevin D. Mlynek ◽

William E. Sause ◽

Derek E. Moormeier ◽

Marat R. Sadykov ◽

Kurt R. Hill ◽

...

Keyword(s):

Gene Expression ◽

Virulence Factors ◽

Virulence Gene ◽

Nutrient Depletion ◽

Global Regulator ◽

Two Component System ◽

Component System ◽

Content Type ◽

Virulence Gene Expression ◽

Two Component

ABSTRACTStaphylococcus aureussubverts innate defenses during infection in part by killing host immune cells to exacerbate disease. This human pathogen intercepts host cues and activates a transcriptional response via theS. aureusexoprotein expression (SaeR/SaeS [SaeR/S]) two-component system to secrete virulence factors critical for pathogenesis. We recently showed that the transcriptional repressor CodY adjusts nuclease (nuc) gene expression via SaeR/S, but the mechanism remained unknown. Here, we identified two CodY binding motifs upstream of thesaeP1 promoter, which suggested direct regulation by this global regulator. We show that CodY shares a binding site with the positive activator SaeR and that alleviating direct CodY repression at this site is sufficient to abrogate stochastic expression, suggesting that CodY repressessaeexpression by blocking SaeR binding. Epistasis experiments support a model that CodY also controlssaeindirectly through Agr and Rot-mediated repression of thesaeP1 promoter. We also demonstrate that CodY repression ofsaerestrains production of secreted cytotoxins that kill human neutrophils. We conclude that CodY plays a previously unrecognized role in controlling virulence gene expression via SaeR/S and suggest a mechanism by which CodY acts as a master regulator of pathogenesis by tying nutrient availability to virulence gene expression.IMPORTANCEBacterial mechanisms that mediate the switch from a commensal to pathogenic lifestyle are among the biggest unanswered questions in infectious disease research. Since the expression of most virulence genes is often correlated with nutrient depletion, this implies that virulence is a response to the lack of nourishment in host tissues and that pathogens likeS. aureusproduce virulence factors in order to gain access to nutrients in the host. Here, we show that specific nutrient depletion signals appear to be funneled to the SaeR/S system through the global regulator CodY. Our findings reveal a strategy by whichS. aureusdelays the production of immune evasion and immune-cell-killing proteins until key nutrients are depleted.

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Regulatory Role of the MisR/S Two-Component System in Hemoglobin Utilization in Neisseria meningitidis

Infection and Immunity ◽

10.1128/iai.00363-09 ◽

2009 ◽

Vol 78 (3) ◽

pp. 1109-1122 ◽

Cited By ~ 12

Author(s):

Shuming Zhao ◽

Grisselle E. Montanez ◽

Pradeep Kumar ◽

Soma Sannigrahi ◽

Yih-Ling Tzeng

Keyword(s):

Posttranscriptional Regulation ◽

Regulatory Mechanisms ◽

Two Component System ◽

Gene Encoding ◽

Positive Role ◽

Upstream Gene ◽

Component System ◽

Two Component ◽

Major Surface

ABSTRACT Outer membrane iron receptors are some of the major surface entities that are critical for meningococcal pathogenesis. The gene encoding the meningococcal hemoglobin receptor, HmbR, is both independently transcribed and transcriptionally linked to the upstream gene hemO, which encodes a heme oxygenase. The MisR/S two-component system was previously determined to regulate hmbR transcription, and its hemO and hmbR regulatory mechanisms were characterized further here. The expression of hemO and hmbR was downregulated in misR/S mutants under both iron-replete and iron-restricted conditions, and the downregulation could be reversed by complementation. No significant changes in expression of other iron receptors were detected, suggesting that the MisR/S system specifically regulates hmbR. When hemoglobin was the sole iron source, growth defects were detected in the mutants. Primer extension analysis identified a promoter upstream of the hemO-associated Correia element (CE) and another promoter at the proximal end of CE, and processed transcripts previously identified for other cotranscribed CEs were also detected, suggesting that there may be posttranscriptional regulation. MisR directly interacts with sequences upstream of the CE and upstream of the hmbR Fur binding site and thus independently regulates hemO and hmbR. Analysis of transcriptional reporters of hemO and hmbR further demonstrated the positive role of the MisR/S system and showed that the transcription of hmbR initiated from hemO was significantly reduced. A comparison of the effects of the misS mutation under iron-replete and iron-depleted conditions suggested that activation by the MisR/S system and iron-mediated repression by Fur act independently. Thus, the expression of hemO and hmbR is coordinately controlled by multiple independent regulatory mechanisms, including the MisR/S two-component system.

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The Redox Regulator Fnr Is Required for Fermentative Growth and Enterotoxin Synthesis in Bacillus cereus F4430/73

Journal of Bacteriology ◽

10.1128/jb.01701-06 ◽

2007 ◽

Vol 189 (7) ◽

pp. 2813-2824 ◽

Cited By ~ 46

Author(s):

Assia Zigha ◽

Eric Rosenfeld ◽

Philippe Schmitt ◽

Catherine Duport

Keyword(s):

Bacillus Cereus ◽

Anaerobic Fermentation ◽

Virulence Gene ◽

Two Component System ◽

Component System ◽

Transcription Profiles ◽

Catabolic Genes ◽

Two Component ◽

Regulatory Impact ◽

Fermentative Growth

ABSTRACT Glucose-grown cells of Bacillus cereus respond to anaerobiosis and low extracellular oxidoreduction potentials (ORP), notably by enhancing enterotoxin production. This response involves the ResDE two-component system. We searched the B. cereus genome for other redox response regulators potentially involved in this adaptive process, and we identified one gene encoding a protein predicted to have an amino acid sequence 58% identical (80% similar) to that of the Bacillus subtilis Fnr redox regulator. The fnr gene of the food-borne pathogen B. cereus F4430/73 has been cloned and partially characterized. We showed that fnr was up-regulated during anaerobic fermentation, especially when fermentation occurred at low ORP (under highly reducing conditions). The expression of fnr was down-regulated in the presence of O2 and nitrate which, unlike fumarate, stimulated the respiratory pathways. The inactivation of B. cereus fnr abolished fermentative growth but only moderately affected aerobic and anaerobic nitrate respiratory growth. Analyses of glucose by-products and the transcription profiles of key catabolic genes confirmed the strong regulatory impact of Fnr on B. cereus fermentative pathways. More importantly, the fnr mutation strongly decreased the expression of PlcR-dependent hbl and nhe genes, leading to the absence of hemolysin BL (Hbl) and nonhemolytic enterotoxin (Nhe) secretion by the mutant. These data indicate that fnr is essential for both fermentation and toxinogenesis. The results also suggest that both Fnr and the ResDE two-component system belong to a redox regulatory pathway that functions at least partially independently of the pleiotropic virulence gene regulator PlcR to regulate enterotoxin gene expression.

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Identification of a Second Two-Component Signal Transduction System That Controls Fosfomycin Tolerance and Glycerol-3-Phosphate Uptake

Journal of Bacteriology ◽

10.1128/jb.02491-14 ◽

2014 ◽

Vol 197 (5) ◽

pp. 861-871 ◽

Cited By ~ 4

Author(s):

Kumiko Kurabayashi ◽

Yuko Hirakawa ◽

Koichi Tanimoto ◽

Haruyoshi Tomita ◽

Hidetada Hirakawa

Keyword(s):

Phosphate Uptake ◽

Response Regulator ◽

Anaerobic Respiration ◽

Regulatory System ◽

Carbon Substrate ◽

Two Component System ◽

Component System ◽

Content Type ◽

Two Component ◽

Biological Cost

Particular interest in fosfomycin has resurfaced because it is a highly beneficial antibiotic for the treatment of refractory infectious diseases caused by pathogens that are resistant to other commonly used antibiotics. The biological cost to cells of resistance to fosfomycin because of chromosomal mutation is high. We previously found that a bacterial two-component system, CpxAR, induces fosfomycin tolerance in enterohemorrhagicEscherichia coli(EHEC) O157:H7. This mechanism does not rely on irreversible genetic modification and allows EHEC to relieve the fitness burden that results from fosfomycin resistance in the absence of fosfomycin. Here we show that another two-component system, TorSRT, which was originally characterized as a regulatory system for anaerobic respiration utilizing trimethylamine-N-oxide (TMAO), also induces fosfomycin tolerance. Activation of the Tor regulatory pathway by overexpression oftorR, which encodes the response regulator, or addition of TMAO increased fosfomycin tolerance in EHEC. We also show that phosphorylated TorR directly represses the expression ofglpT, a gene that encodes a symporter of fosfomycin and glycerol-3-phosphate, and activation of the TorR protein results in the reduced uptake of fosfomycin by cells. However, cells in which the Tor pathway was activated had an impaired growth phenotype when cultured with glycerol-3-phosphate as a carbon substrate. These observations suggest that the TorSRT pathway is the second two-component system to reversibly control fosfomycin tolerance and glycerol-3-phosphate uptake in EHEC, and this may be beneficial for bacteria by alleviating the biological cost. We expect that this mechanism could be a potential target to enhance the utility of fosfomycin as chemotherapy against multidrug-resistant pathogens.

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The PedS2/PedR2 Two-Component System Is Crucial for the Rare Earth Element Switch inPseudomonas putidaKT2440

mSphere ◽

10.1128/msphere.00376-18 ◽

2018 ◽

Vol 3 (4) ◽

Cited By ~ 12

Author(s):

Matthias Wehrmann ◽

Charlotte Berthelot ◽

Patrick Billard ◽

Janosch Klebensberger

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Response Regulator ◽

Regulatory Function ◽

Methylotrophic Bacteria ◽

Two Component System ◽

Component System ◽

Content Type ◽

Two Component ◽

Type Response

ABSTRACTInPseudomonas putidaKT2440, two pyrroloquinoline quinone-dependent ethanol dehydrogenases (PQQ-EDHs) are responsible for the periplasmic oxidation of a broad variety of volatile organic compounds (VOCs). Depending on the availability of rare earth elements (REEs) of the lanthanide series (Ln3+), we have recently reported that the transcription of the genes encoding the Ca2+-utilizing enzyme PedE and the Ln3+-utilizing enzyme PedH are inversely regulated. With adaptive evolution experiments, site-specific mutations, transcriptional reporter fusions, and complementation approaches, we now demonstrate that the PedS2/PedR2 (PP_2671/PP_2672) two-component system (TCS) plays a central role in the observed REE-mediated switch of PQQ-EDHs inP. putida. We provide evidence that in the absence of lanthanum (La3+), the sensor histidine kinase PedS2 phosphorylates its cognate LuxR-type response regulator PedR2, which in turn not only activatespedEgene transcription but is also involved in repression ofpedH. Our data further suggest that the presence of La3+lowers kinase activity of PedS2, either by the direct binding of the metal ions to the periplasmic region of PedS2 or by an uncharacterized indirect interaction, leading to reduced levels of phosphorylated PedR2. Consequently, the decreasingpedEexpression and concomitant alleviation ofpedHrepression causes—in conjunction with the transcriptional activation of thepedHgene by a yet unknown regulatory module—the Ln3+-dependent transition from PedE- to PedH-catalyzed oxidation of alcoholic VOCs.IMPORTANCEThe function of lanthanides for methanotrophic and methylotrophic bacteria is gaining increasing attention, while knowledge about the role of rare earth elements (REEs) in nonmethylotrophic bacteria is still limited. The present study investigates the recently described differential expression of the two PQQ-EDHs ofP. putidain response to lanthanides. We demonstrate that a specific TCS is crucial for their inverse regulation and provide evidence for a dual regulatory function of the LuxR-type response regulator involved. Thus, our study represents the first detailed characterization of the molecular mechanism underlying the REE switch of PQQ-EDHs in a nonmethylotrophic bacterium and stimulates subsequent investigations for the identification of additional genes or phenotypic traits that might be coregulated during REE-dependent niche adaptation.

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The CtrA Regulon of Rhodobacter sphaeroides Favors Adaptation to a Particular Lifestyle

Journal of Bacteriology ◽

10.1128/jb.00678-19 ◽

2020 ◽

Vol 202 (7) ◽

Author(s):

José Hernández-Valle ◽

Alejandro Sanchez-Flores ◽

Sebastian Poggio ◽

Georges Dreyfus ◽

Laura Camarena

Keyword(s):

Rhodobacter Sphaeroides ◽

Stress Responses ◽

Transcriptome Sequencing ◽

Growth Conditions ◽

Fine Tuning ◽

Rna Seq ◽

Two Component System ◽

Component System ◽

Content Type ◽

Two Component

ABSTRACT Activation of the two-component system formed by CckA, ChpT, and CtrA (kinase, phosphotransferase, and response regulator, respectively) in Rhodobacter sphaeroides does not occur under the growth conditions commonly used in the laboratory. However, it is possible to isolate a gain-of-function mutant in CckA that turns the system on. Using massive parallel transcriptome sequencing (RNA-seq), we identified 321 genes that are differentially regulated by CtrA. From these genes, 239 were positively controlled and 82 were negatively regulated. Genes encoding the Fla2 polar flagella and gas vesicle proteins are strongly activated by CtrA. Genes involved in stress responses as well as several transcriptional factors are also positively controlled, whereas the photosynthetic and CO2 fixation genes are repressed. Potential CtrA-binding sites were bioinformatically identified, leading to the proposal that at least 81 genes comprise the direct regulon. Based on our results, we ponder that the transcriptional response orchestrated by CtrA enables a lifestyle in which R. sphaeroides will effectively populate the surface layer of a water body enabled by gas vesicles and will remain responsive to chemotactic stimuli using the chemosensoring system that controls the Fla2 flagellum. Simultaneously, fine-tuning of photosynthesis and stress responses will reduce the damage caused by heat and high light intensity in this water stratum. In summary, in this bacterium CtrA has evolved to control physiological responses that allow its adaptation to a particular lifestyle instead of controlling the cell cycle as occurs in other species. IMPORTANCE Cell motility in Alphaproteobacteria is frequently controlled by the CckA, ChpT, and CtrA two-component system. Under the growth conditions commonly used in the laboratory, ctrA is transcriptionally inactive in Rhodobacter sphaeroides, and motility depends on the Fla1 flagellar system that was acquired by a horizontal transfer event. Likely, the incorporation of this flagellar system released CtrA from the strong selective pressure of being the main motility regulator, allowing this two-component system to specialize and respond to some specific conditions. Identifying the genes that are directly regulated by CtrA could help us understand the conditions in which the products of this regulon are required. Massive parallel transcriptome sequencing (RNA-seq) revealed that CtrA orchestrates an adaptive response that contributes to the colonization of a particular environmental niche.

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A Two-Component System That Modulates Cyclic di-GMP Metabolism PromotesLegionella pneumophilaDifferentiation and Viability in Low-Nutrient Conditions

Journal of Bacteriology ◽

10.1128/jb.00253-19 ◽

2019 ◽

Vol 201 (17) ◽

Cited By ~ 2

Author(s):

Elisa D. Hughes ◽

Brenda G. Byrne ◽

Michele S. Swanson

Keyword(s):

Life Cycle ◽

Lifestyle Changes ◽

Negative Regulator ◽

Broth Culture ◽

Cell Type ◽

Two Component System ◽

Term Survival ◽

Component System ◽

Content Type ◽

Two Component

ABSTRACTDuring its life cycle, the environmental pathogenLegionella pneumophilaalternates between a replicative and transmissive cell type when cultured in broth, macrophages, or amoebae. Within a protozoan host,L. pneumophilafurther differentiates into the hardy cell type known as the mature infectious form (MIF). The second messenger cyclic di-GMP coordinates lifestyle changes in many bacterial species, but its role in theL. pneumophilalife cycle is less understood. Using anin vitrobroth culture model that approximates the intracellular transition from the replicative to the transmissive form, here we investigate the contribution toL. pneumophiladifferentiation of a two-component system (TCS) that regulates cyclic di-GMP metabolism. The TCS is encoded bylpg0278-lpg0277and is cotranscribed withlpg0279, which encodes a protein upregulated in MIF cells. The promoter for this operon is RpoS dependent and induced in nutrient-limiting conditions that do not support replication, as demonstrated using agfpreporter and quantitative PCR (qPCR). The response regulator of the TCS (Lpg0277) is a bifunctional enzyme that both synthesizes and degrades cyclic di-GMP. Using a panel of site-directed point mutants, we show that cyclic di-GMP synthesis mediated by a conserved GGDEF domain promotes growth arrest of replicativeL. pneumophila, accumulation of pigment and poly-3-hydroxybutyrate storage granules, and viability in nutrient-limiting conditions. Genetic epistasis tests predict that the MIF protein Lpg0279 acts as a negative regulator of the TCS. Thus,L. pneumophilais equipped with a regulatory network in which cyclic di-GMP stimulates the switch from a replicative to a resilient state equipped to survive in low-nutrient environments.IMPORTANCEAlthough an intracellular pathogen,L. pneumophilahas developed mechanisms to ensure long-term survival in low-nutrient aqueous conditions. Eradication ofL. pneumophilafrom contaminated water supplies has proven challenging, as outbreaks have been traced to previously remediated systems. Understanding the genetic determinants that supportL. pneumophilapersistence in low-nutrient environments can inform design and assessment of remediation strategies. Here we characterize a genetic locus that encodes a two-component signaling system (lpg0278-lpg0277) and a putative regulator protein (lpg0279) that modulates the production of the messenger molecule cyclic di-GMP. We show that this locus promotes bothL. pneumophilacell differentiation and survival in nutrient-limiting conditions, thus advancing the understanding of the mechanisms that contribute toL. pneumophilaenvironmental resilience.

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