Variation in the Group B Streptococcus CsrRS Regulon and Effects on Pathogenicity

ABSTRACT CsrRS (or CovRS) is a two-component regulatory system that controls expression of multiple virulence factors in the important human pathogen group B Streptococcus (GBS). We now report global gene expression studies in GBS strains 2603V/R and 515 and their isogenic csrR and csrS mutants. Together with data reported previously for strain NEM316, the results reveal a conserved 39-gene CsrRS regulon. In vitro phosphorylation-dependent binding of recombinant CsrR to promoter regions of both positively and negatively regulated genes suggests that direct binding of CsrR can mediate activation as well as repression of target gene expression. Distinct patterns of gene regulation in csrR versus csrS mutants in strain 2603V/R compared to 515 were associated with different hierarchies of relative virulence of wild-type, csrR, and csrS mutants in murine models of systemic infection and septic arthritis. We conclude that CsrRS regulates a core group of genes including important virulence factors in diverse strains of GBS but also displays marked variability in the repertoire of regulated genes and in the relative effects of CsrS signaling on CsrR-mediated gene regulation. Such variation is likely to play an important role in strain-specific adaptation of GBS to particular host environments and pathogenic potential in susceptible hosts.

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Cellular Management of Zinc in Group B Streptococcus Supports Bacterial Resistance against Metal Intoxication and Promotes Disseminated Infection

mSphere ◽

10.1128/msphere.00105-21 ◽

2021 ◽

Vol 6 (3) ◽

Author(s):

Matthew J. Sullivan ◽

Kelvin G. K. Goh ◽

Glen C. Ulett

Keyword(s):

Streptococcus Agalactiae ◽

Bacterial Resistance ◽

Group B Streptococcus ◽

Systemic Infection ◽

Metal Stress ◽

Mechanisms Of Resistance ◽

Content Type ◽

Group B ◽

Zn Stress

ABSTRACT Zinc is an essential trace element for normal bacterial physiology but, divergently, can intoxicate bacteria at high concentrations. Here, we define the molecular systems for Zn detoxification in Streptococcus agalactiae, also known as group B streptococcus, and examine the effects of resistance to Zn stress on virulence. We compared the growth of wild-type bacteria and mutants deleted for the Zn exporter, czcD, and the response regulator, sczA, using Zn-stress conditions in vitro. Macrophage antibiotic protection assays and a mouse model of disseminated infection were used to assess virulence. Global bacterial transcriptional responses to Zn stress were defined by RNA sequencing and quantitative reverse transcription-PCR. czcD and sczA enabled S. agalactiae to survive Zn stress, with the putative CzcD efflux system activated by SczA. Additional genes activated in response to Zn stress encompassed divalent cation transporters that contribute to regulation of Mn and Fe homeostasis. In vivo, the czcD-sczA Zn management axis supported virulence in the blood, heart, liver, and bladder. Additionally, several genes not previously linked to Zn stress in any bacterium, including, most notably, arcA for arginine deamination, also mediated resistance to Zn stress, representing a novel molecular mechanism of bacterial resistance to metal intoxication. Taken together, these findings show that S. agalactiae responds to Zn stress by sczA regulation of czcD, with additional novel mechanisms of resistance supported by arcA, encoding arginine deaminase. Cellular management of Zn stress in S. agalactiae supports virulence by facilitating bacterial survival in the host during systemic infection. IMPORTANCE Streptococcus agalactiae, also known as group B streptococcus, is an opportunistic pathogen that causes various diseases in humans and animals. This bacterium has genetic systems that enable zinc detoxification in environments of metal stress, but these systems remain largely undefined. Using a combination of genomic, genetic, and cellular assays, we show that this pathogen controls Zn export through CzcD to manage Zn stress and utilizes a system of arginine deamination never previously linked to metal stress responses in bacteria to survive metal intoxication. We show that these systems are crucial for survival of S. agalactiae in vitro during Zn stress and also enhance virulence during systemic infection in mice. These discoveries establish new molecular mechanisms of resistance to metal intoxication in bacteria; we suggest these mechanisms operate in other bacteria as a way to sustain microbial survival under conditions of metal stress, including in host environments.

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Microarray and Functional Analysis of Growth Phase-Dependent Gene Regulation in Bordetella bronchiseptica

Infection and Immunity ◽

10.1128/iai.00136-09 ◽

2009 ◽

Vol 77 (10) ◽

pp. 4221-4231 ◽

Cited By ~ 17

Author(s):

Tracy L. Nicholson ◽

Anne M. Buboltz ◽

Eric T. Harvill ◽

Susan L. Brockmeier

Keyword(s):

Gene Expression ◽

Gene Regulation ◽

Microarray Analysis ◽

Growth Phase ◽

Stationary Phases ◽

Regulatory System ◽

Global Gene Expression ◽

Bordetella Bronchiseptica ◽

Qrt Pcr ◽

Genes Encoding

ABSTRACT Growth phase-dependent gene regulation has recently been demonstrated to occur in Bordetella pertussis, with many transcripts, including known virulence factors, significantly decreasing during the transition from logarithmic to stationary-phase growth. Given that B. pertussis is thought to have derived from a Bordetella bronchiseptica-like ancestor, we hypothesized that growth phase-dependent gene regulation would also occur in B. bronchiseptica. Microarray analysis revealed and quantitative real-time PCR (qRT-PCR) confirmed that growth phase-dependent gene regulation occurs in B. bronchiseptica, resulting in prominent temporal shifts in global gene expression. Two virulence phenotypes associated with these gene expression changes were tested. We found that growth-dependent increases in expression of some type III secretion system (TTSS) genes led to a growth phase-dependent increase in a TTSS-dependent function, cytotoxicity. Although the transcription of genes encoding adhesins previously shown to mediate adherence was decreased in late-log and stationary phases, we found that the adherence of B. bronchiseptica did not decrease in these later phases of growth. Microarray analysis revealed and qRT-PCR confirmed that growth phase-dependent gene regulation occurred in both Bvg+ and Bvg− phase-locked mutants, indicating that growth phase-dependent gene regulation in B. bronchiseptica can function independently from the BvgAS regulatory system.

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Cellular management of Zinc in group B Streptococcus supports bacterial resistance against metal intoxication and promotes disseminated infection

10.1101/2021.02.04.429868 ◽

2021 ◽

Author(s):

Matthew J. Sullivan ◽

Kelvin G. K. Goh ◽

Glen C. Ulett

Keyword(s):

Streptococcus Agalactiae ◽

Bacterial Resistance ◽

Group B Streptococcus ◽

Systemic Infection ◽

Metal Stress ◽

Mechanisms Of Resistance ◽

Disseminated Infection ◽

Group B ◽

Zn Stress

AbstractZinc (Zn) is an essential trace element for normal bacterial physiology but divergently, can intoxicate bacteria at high concentrations. Here, we define the molecular systems for Zn detoxification in Streptococcus agalactiae, also known as group B Streptococcus, and examine the effects of resistance to Zn stress on virulence. We compared the growth of wild-type bacteria and mutants deleted for the Zn exporter, czcD, and the response regulator, sczA, using Zn-stress conditions in vitro. Macrophage antibiotic protection assays and a mouse model of disseminated infection were used to assess virulence. Global bacterial transcriptional responses to Zn stress were defined by RNA-sequencing and qRTPCR. czcD and sczA enabled S. agalactiae to survive Zn stress, with the putative CzcD efflux system activated by SczA. Additional genes activated in response to Zn stress encompassed divalent cation transporters that contribute to regulation of Mn and Fe homeostasis. In vivo, the czcD-sczA Zn-management axis supported virulence in the blood, heart, liver and bladder. Additionally, several genes not previously linked to Zn stress in any bacterium, including most notably, arcA for arginine deamination also mediated resistance to Zn stress; representing a novel molecular mechanism of bacterial resistance to metal intoxication. Taken together, these findings show that S. agalactiae responds to Zn stress by sczA regulation of czcD, with additional novel mechanisms of resistance supported by arcA, encoding arginine deaminase. Cellular management of Zn stress in S. agalactiae supports virulence by facilitating bacterial survival in the host during systemic infection.Importance StatementStreptococcus agalactiae, also known as group B streptococcus, is an opportunistic pathogen that causes various diseases in humans and animals. This bacterium has genetic systems that enable Zinc (Zn) detoxification in environments of metal stress, but these systems remain largely undefined. Using a combination of genomic, genetic and cellular assays we show that this pathogen controls Zn export through CzcD to manage Zn stress, and utilizes a system of arginine deamination never previously linked to metal stress responses in bacteria to survive metal intoxication. We show that these systems are crucial for survival of S. agalactiae in vitro during Zn stress and also enhance virulence during systemic infection in mice. These discoveries establish new molecular mechanisms of resistance to metal intoxication in bacteria; we suggest these mechanisms are likely to operate in other bacteria as a way to sustain microbial survival in conditions of metal stress, including in host environments.

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Identification of an Unusual Pattern of Global Gene Expression in Group B Streptococcus Grown in Human Blood

PLoS ONE ◽

10.1371/journal.pone.0007145 ◽

2009 ◽

Vol 4 (9) ◽

pp. e7145 ◽

Cited By ~ 5

Author(s):

Laurent Mereghetti ◽

Izabela Sitkiewicz ◽

Nicole M. Green ◽

James M. Musser

Keyword(s):

Gene Expression ◽

Human Blood ◽

Group B Streptococcus ◽

Global Gene Expression ◽

Unusual Pattern ◽

Group B

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Virulence gene regulation inside and outside

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2000.0606 ◽

2000 ◽

Vol 355 (1397) ◽

pp. 657-665 ◽

Cited By ~ 14

Author(s):

Victor J. DiRita ◽

N. Cary Engleberg ◽

Andrew Heath ◽

Alita Miller ◽

J. Adam Crawford ◽

...

Keyword(s):

Gene Expression ◽

Gene Regulation ◽

Regulatory System ◽

Virulence Gene ◽

Virulence Gene Expression ◽

Regulatory Cascade ◽

Transcription Activators ◽

Regulated Gene Expression

Much knowledge about microbial gene regulation and virulence is derived from genetic and biochemical studies done outside of hosts. The aim of this review is to correlate observations made in vitro and in vivo with two different bacterial pathogens in which the nature of regulated gene expression leading to virulence is quite different. The first is Vibrio cholerae , in which the concerted action of a complicated regulatory cascade involving several transcription activators leads ultimately to expression of cholera toxin and the toxin–coregulated pilus. The regulatory cascade is active in vivo and is also required for maintenance of V . cholerae in the intestinal tract during experimental infection. Nevertheless, specific signals predicted to be generated in vivo , such as bile and a temperature of 37°C, have a severe downmodulating effect on activation of toxin and pilus expression. Another unusual aspect of gene regulation in this system is the role played by inner membrane proteins that activate transcription. Although the topology of these proteins suggests an appealing model for signal transduction leading to virulence gene expression, experimental evidence suggests that such a model may be simplistic. In Streptococcus pyogenes , capsule production is critical for virulence in an animal model of necrotizing skin infection. Yet capsule is apparently produced to high levels only from mutation in a two–component regulatory system, CsrR and CsrS. Thus it seems that in V . cholerae a complex regulatory pathway has evolved to control virulence by induction of gene expression in vivo , whereas in S. pyogenes at least one mode of pathogenicity is potentiated by the absence of regulation.

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Proteomic and Transcriptomic Analyses Provide Novel Insights into the Crucial Roles of Host-Induced Carbohydrate Metabolism Enzymes in Xanthomonas oryzae pv. oryzae Virulence and Rice-Xoo Interaction

Rice ◽

10.1186/s12284-021-00503-x ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Guichun Wu ◽

Yuqiang Zhang ◽

Bo Wang ◽

Kaihuai Li ◽

Yuanlai Lou ◽

...

Keyword(s):

Gene Expression ◽

Signal Transduction ◽

Amino Acids ◽

Secondary Metabolites ◽

Carbohydrate Metabolism ◽

Virulence Factors ◽

Global Gene Expression ◽

Xanthomonas Oryzae ◽

Oxidation Reduction ◽

Phenylpropanoid Biosynthesis

Abstract Background Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight, a devastating rice disease. The Xoo-rice interaction, wherein wide ranging host- and pathogen-derived proteins and genes wage molecular arms race, is a research hotspot. Hence, the identification of novel rice-induced Xoo virulence factors and characterization of their roles affecting rice global gene expression profiles will provide an integrated and better understanding of Xoo-rice interactions from the molecular perspective. Results Using comparative proteomics and an in vitro interaction system, we revealed that 5 protein spots from Xoo exhibited significantly different expression patterns (|fold change| > 1.5) at 3, 6, 12 h after susceptible rice leaf extract (RLX) treatment. MALDI-TOF MS analysis and pathogenicity tests showed that 4 host-induced proteins, including phosphohexose mutase, inositol monophosphatase, arginase and septum site-determining protein, affected Xoo virulence. Among them, mutants of two host-induced carbohydrate metabolism enzyme-encoding genes, ΔxanA and Δimp, elicited enhanced defense responses and nearly abolished Xoo virulence in rice. To decipher rice differentially expressed genes (DEGs) associated with xanA and imp, transcriptomic responses of ΔxanA-treated and Δimp-treated susceptible rice were compared to those in rice treated with PXO99A at 1 and 3 dpi. A total of 1521 and 227 DEGs were identified for PXO99A vs Δimp at 1 and 3 dpi, while for PXO99A vs ΔxanA, there were 131 and 106 DEGs, respectively. GO, KEGG and MapMan analyses revealed that the DEGs for PXO99A vs Δimp were mainly involved in photosynthesis, signal transduction, transcription, oxidation-reduction, hydrogen peroxide catabolism, ion transport, phenylpropanoid biosynthesis and metabolism of carbohydrates, lipids, amino acids, secondary metabolites, hormones, and nucleotides, while the DEGs from PXO99A vs ΔxanA were predominantly associated with photosynthesis, signal transduction, oxidation-reduction, phenylpropanoid biosynthesis, cytochrome P450 and metabolism of carbohydrates, lipids, amino acids, secondary metabolites and hormones. Although most pathways were associated with both the Δimp and ΔxanA treatments, the underlying genes were not the same. Conclusion Our study identified two novel host-induced virulence factors XanA and Imp in Xoo, and revealed their roles in global gene expression in susceptible rice. These results provide valuable insights into the molecular mechanisms of pathogen infection strategies and plant immunity.

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Antimicrobial Photodynamic Inactivation Inhibits Candida albicans Virulence Factors and ReducesIn VivoPathogenicity

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01451-12 ◽

2012 ◽

Vol 57 (1) ◽

pp. 445-451 ◽

Cited By ~ 41

Author(s):

Ilka Tiemy Kato ◽

Renato Araujo Prates ◽

Caetano Padial Sabino ◽

Beth Burgwyn Fuchs ◽

George P. Tegos ◽

...

Keyword(s):

Candida Albicans ◽

Virulence Factors ◽

Sodium Dodecyl ◽

Systemic Infection ◽

Tube Formation ◽

Photodynamic Inactivation ◽

Content Type ◽

Daughter Cells

ABSTRACTThe objective of this study was to evaluate whetherCandida albicansexhibits altered pathogenicity characteristics following sublethal antimicrobial photodynamic inactivation (APDI) and if such alterations are maintained in the daughter cells.C. albicanswas exposed to sublethal APDI by using methylene blue (MB) as a photosensitizer (0.05 mM) combined with a GaAlAs diode laser (λ 660 nm, 75 mW/cm2, 9 to 27 J/cm2).In vitro, we evaluated APDI effects onC. albicansgrowth, germ tube formation, sensitivity to oxidative and osmotic stress, cell wall integrity, and fluconazole susceptibility.In vivo, we evaluatedC. albicanspathogenicity with a mouse model of systemic infection. Animal survival was evaluated daily. Sublethal MB-mediated APDI reduced the growth rate and the ability ofC. albicansto form germ tubes compared to untreated cells (P< 0.05). Survival of mice systemically infected withC. albicanspretreated with APDI was significantly increased compared to mice infected with untreated yeast (P< 0.05). APDI increasedC. albicanssensitivity to sodium dodecyl sulfate, caffeine, and hydrogen peroxide. The MIC for fluconazole forC. albicanswas also reduced following sublethal MB-mediated APDI. However, none of those pathogenic parameters was altered in daughter cells ofC. albicanssubmitted to APDI. These data suggest that APDI may inhibit virulence factors and reducein vivopathogenicity ofC. albicans. The absence of alterations in daughter cells indicates that APDI effects are transitory. The MIC reduction for fluconazole following APDI suggests that this antifungal could be combined with APDI to treatC. albicansinfections.

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Genomic and phenotypic characterisation of invasive neonatal and colonising group B Streptococcus isolates from Slovenia, 2001–2018

BMC Infectious Diseases ◽

10.1186/s12879-020-05599-y ◽

2020 ◽

Vol 20 (1) ◽

Author(s):

Tina Perme ◽

Daniel Golparian ◽

Maja Bombek Ihan ◽

Andrej Rojnik ◽

Miha Lučovnik ◽

...

Keyword(s):

Pregnant Women ◽

Virulence Factors ◽

Late Onset ◽

Group B Streptococcus ◽

Genomic Diversity ◽

Neonatal Disease ◽

Phenotypic Characterisation ◽

High Prevalence ◽

Group B ◽

The Impact

Abstract Background Group B Streptococcus (GBS) is the leading cause of invasive neonatal disease in the industrialized world. We aimed to genomically and phenotypically characterise invasive GBS isolates in Slovenia from 2001 to 2018 and contemporary colonising GBS isolates from screening cultures in 2018. Methods GBS isolates from 101 patients (invasive isolates) and 70 pregnant women (colonising isolates) were analysed. Basic clinical characteristics of the patients were collected from medical records. Antimicrobial susceptibility and phenotypic capsular serotype were determined. Whole-genome sequencing was performed to assign multilocus sequence types (STs), clonal complexes (CCs), pathogenicity/virulence factors, including capsular genotypes, and genome-based phylogeny. Results Among invasive neonatal disease patients, 42.6% (n = 43) were females, 41.5% (n = 39/94) were from preterm deliveries (< 37 weeks gestation), and 41.6% (n = 42) had early-onset disease (EOD). All isolates were susceptible to benzylpenicillin with low minimum inhibitory concentrations (MICs; ≤0.125 mg/L). Overall, 7 serotypes were identified (Ia, Ib, II-V and VIII); serotype III being the most prevalent (59.6%). Twenty-eight MLST STs were detected that clustered into 6 CCs. CC-17 was the most common CC overall (53.2%), as well as among invasive (67.3%) and non-invasive (32.9%) isolates (p < 0.001). CC-17 was more common among patients with late-onset disease (LOD) (81.4%) compared to EOD (47.6%) (p < 0.001). The prevalence of other CCs was 12.9% (CC-23), 11.1% (CC-12), 10.5% (CC-1), 8.2% (CC-19), and 1.8% (CC-498). Of all isolates, 2.3% were singletons. Conclusions A high prevalence of hypervirulent CC-17 isolates, with low genomic diversity and characteristic profile of pathogenicity/virulence factors, was detected among invasive neonatal and colonising GBS isolates from pregnant women in Slovenia. This is the first genomic characterisation of GBS isolates in Slovenia and provides valuable microbiological and genomic baseline data regarding the invasive and colonising GBS population nationally. Continuous genomic surveillance of GBS infections is crucial to analyse the impact of IND prevention strategies on the population structure of GBS locally, nationally, and internationally.

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Group B Streptococcal and Pneumococcal Sepsis in Newborn Infants: The Role of Pneumococcal Antibody

PEDIATRICS ◽

10.1542/peds.62.4.620 ◽

1978 ◽

Vol 62 (4) ◽

pp. 620-621

Author(s):

Gerald W. Fischer ◽

James W. Bass ◽

George H. Lowell ◽

Martin H. Crumrine

Keyword(s):

Streptococcus Pneumoniae ◽

Hydrochloric Acid ◽

Group B Streptococcus ◽

Newborn Infants ◽

Polysaccharide Antigen ◽

Type Iii ◽

Pneumococcal Sepsis ◽

Group B

The article by Bortolussi et al. on pneumococcal septicemia and meningitis in the neonat (Pediatrics 60:352, September 1977) was of great interest to us, since we have been analyzing the effect of antibody directed against Streptococcus pneumoniae on group B Streptococcus type III. We have recently shown (unpublished data) that antibody directed against S. pneumoniae type 14 precipitates the hot hydrochloric acid-extracted polysaccharide antigen of group B Streptococcus type III. Further studies have shown that this antibody is opsonic for group B Streptococcus type III in an in vitro bactericidal assay and protective in a suckling rat model of group B Streptococcus type III sepsis.1

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FlhF and Its GTPase Activity Are Required for Distinct Processes in Flagellar Gene Regulation and Biosynthesis in Campylobacter jejuni

Journal of Bacteriology ◽

10.1128/jb.00884-09 ◽

2009 ◽

Vol 191 (21) ◽

pp. 6602-6611 ◽

Cited By ~ 39

Author(s):

Murat Balaban ◽

Stephanie N. Joslin ◽

David R. Hendrixson

Keyword(s):

Gene Expression ◽

Gene Regulation ◽

Campylobacter Jejuni ◽

Regulatory System ◽

Flagellar Gene ◽

Gtpase Activity ◽

Gtp Hydrolysis ◽

Genetic Analyses ◽

Flagellar Biosynthesis ◽

Two Component

ABSTRACT FlhF proteins are putative GTPases that are often necessary for one or more steps in flagellar organelle development in polarly flagellated bacteria. In Campylobacter jejuni, FlhF is required for σ54-dependent flagellar gene expression and flagellar biosynthesis, but how FlhF influences these processes is unknown. Furthermore, the GTPase activity of any FlhF protein and the requirement of this speculated activity for steps in flagellar biosynthesis remain uncharacterized. We show here that C. jejuni FlhF hydrolyzes GTP, indicating that these proteins are GTPases. C. jejuni mutants producing FlhF proteins with reduced GTPase activity were not severely defective for σ54-dependent flagellar gene expression, unlike a mutant lacking FlhF. Instead, these mutants had a propensity to lack flagella or produce flagella in improper numbers or at nonpolar locations, indicating that GTP hydrolysis by FlhF is required for proper flagellar biosynthesis. Additional studies focused on elucidating a possible role for FlhF in σ54-dependent flagellar gene expression were conducted. These studies revealed that FlhF does not influence production of or signaling between the flagellar export apparatus and the FlgSR two-component regulatory system to activate σ54. Instead, our data suggest that FlhF functions in an independent pathway that converges with or works downstream of the flagellar export apparatus-FlgSR pathway to influence σ54-dependent gene expression. This study provides corroborative biochemical and genetic analyses suggesting that different activities of the C. jejuni FlhF GTPase are required for distinct steps in flagellar gene expression and biosynthesis. Our findings are likely applicable to many polarly flagellated bacteria that utilize FlhF in flagellar biosynthesis processes.

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