scholarly journals Role for sagA and siaA in Quorum Sensing and Iron Regulation in Streptococcus pyogenes

2007 ◽  
Vol 75 (10) ◽  
pp. 5011-5017 ◽  
Author(s):  
Kowthar Y. Salim ◽  
Joyce C. de Azavedo ◽  
Darrin J. Bast ◽  
Dennis G. Cvitkovitch
Keyword(s):  
Quorum Sensing ◽  
Streptococcus Pyogenes ◽  
Iron Acquisition ◽  
Virulence Gene ◽  
Wild Type ◽  
Virulence Gene Expression ◽  
Streptolysin S ◽  
Wide Range ◽  
Cell Densities ◽  
The Many

ABSTRACT Streptococcus pyogenes is a ubiquitous and versatile pathogen that causes a variety of infections with a wide range of severity. The versatility of this organism is due in part to its capacity to regulate virulence gene expression in response to the many environments that it encounters during an infection. We analyzed the expression of two potential virulence factors, sagA and siaA (also referred to as pel and htsA, respectively), in response to conditions of varying cell densities and iron concentrations. The sagA gene was up-regulated in conditioned medium from a wild-type strain but not from sagA-deficient mutants, and the gene was also up-regulated in the presence of streptolysin S (SLS), the gene product of sagA, thus indicating that this gene or its product is involved in density-dependent regulation of S. pyogenes. By comparison, siaA responded in a manner consistent with a role in iron acquisition since it was up-regulated under iron-restricted conditions. Although siaA expression was also up-regulated in the presence of SLS and in conditioned media from both wild-type and sagA-deficient mutants, this up-regulation was not growth phase dependent. We conclude that sagA encodes a quorum-sensing signaling molecule, likely SLS, and further support the notion that siaA is likely involved in iron acquisition.

scholarly journals Molecular Characteristics of Streptococcus pyogenes Isolated From Chinese Children With Different Diseases

2021 ◽  
Vol 12 ◽  
Author(s):  
Dingle Yu ◽  
Yunmei Liang ◽  
Qinghua Lu ◽  
Qing Meng ◽  
Wenjian Wang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Antibiotic Resistance ◽  
Streptococcus Pyogenes ◽  
Wide Spectrum ◽  
Expression Patterns ◽  
Virulence Gene ◽  
High Rate ◽  
Molecular Characteristics ◽  
Virulence Gene Expression ◽  
Obstructive Sleep

Streptococcus pyogenes is a bacterial pathogen that causes a wide spectrum of clinical diseases exclusively in humans. The distribution of emm type, antibiotic resistance and virulence gene expression for S. pyogenes varies temporally and geographically, resulting in distinct disease spectra. In this study, we analyzed antibiotic resistance and resistance gene expression patterns among S. pyogenes isolates from pediatric patients in China and investigated the relationship between virulence gene expression, emm type, and disease categories. Forty-two representative emm1.0 and emm12.0 strains (n = 20 and n = 22, respectively) isolated from patients with scarlet fever or obstructive sleep apnea-hypopnea syndrome were subjected to whole-genome sequencing and phylogenetic analysis. These strains were further analyzed for susceptibility to vancomycin. We found a high rate and degree of resistance to macrolides and tetracycline in these strains, which mainly expressed ermB and tetM. The disease category correlated with emm type but not superantigens. The distribution of vanuG and virulence genes were associated with emm type. Previously reported important prophages, such as φHKU16.vir, φHKU488.vir, Φ5005.1, Φ5005.2, and Φ5005.3 encoding streptococcal toxin, and integrative conjugative elements (ICEs) such as ICE-emm12 and ICE-HKU397 encoding macrolide and tetracycline resistance were found present amongst emm1 or emm12 clones from Shenzhen, China.

scholarly journals Photo sensing and quorum sensing are integrated to control bacterial group behaviors

2019 ◽  
Author(s):  
Sampriti Mukherjee ◽  
Matthew Jemielita ◽  
Vasiliki Stergioula ◽  
Mikhail Tikhonov ◽  
Bonnie L. Bassler
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Response Regulator ◽  
Sensory Information ◽  
Virulence Gene ◽  
Component System ◽  
Virulence Gene Expression ◽  
Bacterial Phyla ◽  
Expression Of Genes ◽  
Genes Encoding

ABSTRACTPseudomonas aeruginosa transitions between the free-swimming state and the sessile biofilm mode during its pathogenic lifestyle. We show that quorum sensing represses P. aeruginosa biofilm formation and virulence by activating expression of genes encoding the KinB-AlgB two-component system. Phospho-AlgB represses biofilm and virulence genes, while KinB dephosphorylates, and thereby, inactivates AlgB. We discover that the photoreceptor BphP is the kinase that, in response to light, phosphorylates and activates AlgB. Indeed, exposing P. aeruginosa to light represses biofilm formation and virulence gene expression. To our knowledge, P. aeruginosa was not previously known to detect light. The KinB-AlgB-BphP module is present in all Pseudomonads, and we demonstrate that AlgB is the cognate response regulator for BphP in diverse bacterial phyla. We propose that KinB-AlgB-BphP constitutes a “three-component” system and AlgB is the node at which varied sensory information is integrated. This study sets the stage for light-mediated control of P. aeruginosa infectivity.

scholarly journals Investigation of Iron uptake and virulence gene factors (fur, tonB, exbD, exbB, hgbA, hgbB1, hgbB2 and tbpA) among isolates of Pasteurella multocida from Iran

2019 ◽  
Author(s):  
Motahare Feizabadi Farahani ◽  
Majid Esmaelizad ◽  
Ahmad Reza Jabbari
Keyword(s):  
Virulence Factors ◽  
Iron Uptake ◽  
Pasteurella Multocida ◽  
Iron Acquisition ◽  
Virulence Gene ◽  
Basic Information ◽  
Iron Supply ◽  
Wide Range ◽  
Pcr Method ◽  
First Time

Background and Objectives: Iron is an essential compound in metabolic pathway of wide range of organisms. Because of limited free iron supply in mammalian and avian hosts, bacteria have applied various ways to acquire iron. Materials and Methods: In this study, the frequency of 8 iron acquisition factors was examined among 63 avian and ovine Pasteurella multocida field isolates and their vaccine strains using PCR method. Results: Five candidate genes (fur, tonB, exbD, exbB and hgbA) were identified among all isolates. For the first time, 2 loci (hgbB1 and hgbB2) of the hgbB gene were identified, which were previously reported as 1 gene. Also, it was found that 5 ovine and 1 avian isolates possessed all the virulence factors, which could also be considered for evaluating the frequency of other virulence factors. Conclusion: More studies need to be conducted on the frequency of all other virulence factors among these isolates, which can provide basic information for improvement or substitution of current vaccinal strains. Overall, as the new designed sets of primers showed more potential in detecting the corresponded genes, researchers can consider them in further studies.

scholarly journals The RofA Binding Site in Streptococcus pyogenes Is Utilized in Multiple Transcriptional Pathways

2000 ◽  
Vol 182 (6) ◽  
pp. 1529-1540 ◽  
Author(s):  
Alexander B. Granok ◽  
Derek Parsonage ◽  
R. Paul Ross ◽  
Michael G. Caparon
Keyword(s):  
Binding Site ◽  
Streptococcus Pyogenes ◽  
Virulence Gene ◽  
Local Environment ◽  
Recognition Sequence ◽  
Direct Role ◽  
Virulence Gene Expression ◽  
Protein F ◽  
Adhesin Protein ◽  
Target Promoters

ABSTRACT Understanding the regulation of adhesins defines a pathogenic bacterium's interaction with the local environment within the host. In certain strains of Streptococcus pyogenes, transcription ofprtF, the gene which encodes the fibronectin-binding adhesin protein F, is activated by RofA under anaerobic conditions. RofA binds specifically to DNA in its target promoters and autoregulates its own expression. In this study, we have used DNase I protection assays to further investigate the interaction of RofA with its target promoters. In the region between rofA and the gene which encodes protein F (prtF), RofA binds to two distinct sites: a smaller site (17 bp) adjacent to the rofApromoter, and a larger site (40 bp) adjacent to the prtFpromoter. Analysis of fusions to a novel reporter gene whose product consists of the fusion of the N-terminal secretion domain of protein F with the C-terminal enzymatic domain of the enterococcal alkaline phosphatase (PhoZ) revealed that the small RofA binding site had no direct role in control of prtF transcription but contributed to regulation of rofA. Comparison in several strains representing different patterns of prtF expression indicated that the larger site was required for activation ofrofA and of prtF in all strains by both RofA-dependent and -independent pathways. Thus, it would appear that a common recognition sequence provides separate entries to a final common pathway in S. pyogenes virulence gene expression. The identification of multiple RofA-like proteins and promoters with RofA binding sites implies the existence of a widespread interacting regulatory network.

scholarly journals Use of a Phosphorylation Site Mutant To Identify Distinct Modes of Gene Repression by the Control of Virulence Regulator (CovR) in Streptococcus pyogenes

2017 ◽  
Vol 199 (18) ◽  
Author(s):  
Nicola Horstmann ◽  
Pranoti Sahasrabhojane ◽  
Hui Yao ◽  
Xiaoping Su ◽  
Samuel A. Shelburne
Keyword(s):  
Gene Expression ◽  
Streptococcus Pyogenes ◽  
Response Regulator ◽  
Phosphorylation Site ◽  
Virulence Gene ◽  
Content Type ◽  
Virulence Gene Expression ◽  
Superficial Skin ◽  
Virulence Regulator ◽  
The Impact

ABSTRACT Control of the virulence regulator/sensor kinase (CovRS) two-component system (TCS) serves as a model for investigating the impact of signaling pathways on the pathogenesis of Gram-positive bacteria. However, the molecular mechanisms by which CovR, an OmpR/PhoB family response regulator, controls virulence gene expression are poorly defined, partly due to the labile nature of its aspartate phosphorylation site. To better understand the regulatory effect of phosphorylated CovR, we generated the phosphorylation site mutant strain 10870-CovR-D53E, which we predicted to have a constitutive CovR phosphorylation phenotype. Interestingly, this strain showed CovR activity only for a subset of the CovR regulon, which allowed for classification of CovR-influenced genes into D53E-regulated and D53E-nonregulated groups. Inspection of the promoter sequences of genes belonging to each group revealed distinct promoter architectures with respect to the location and number of putative CovR-binding sites. Electrophoretic mobility shift analysis demonstrated that recombinant CovR-D53E protein retains its ability to bind promoter DNA from both CovR-D53E-regulated and -nonregulated groups, implying that factors other than mere DNA binding are crucial for gene regulation. In fact, we found that CovR-D53E is incapable of dimerization, a process thought to be critical to OmpR/PhoB family regulator function. Thus, our global analysis of CovR-D53E indicates dimerization-dependent and dimerization-independent modes of CovR-mediated repression, thereby establishing distinct mechanisms by which this critical regulator coordinates virulence gene expression. IMPORTANCE Streptococcus pyogenes causes a wide variety of diseases, ranging from superficial skin and throat infections to life-threatening invasive infections. To establish these various disease manifestations, Streptococcus pyogenes requires tightly coordinated production of its virulence factor repertoire. Here, the response regulator CovR plays a crucial role. As an OmpR/PhoB family member, CovR is activated by phosphorylation on a conserved aspartate residue, leading to protein dimerization and subsequent binding to operator sites. Our transcriptome analysis using the monomeric phosphorylation mimic mutant CovR-D53E broadens this general notion by revealing dimerization-independent repression of a subset of CovR-regulated genes. Combined with promoter analyses, these data suggest distinct mechanisms of CovR transcriptional control, which allow for differential expression of virulence genes in response to environmental cues.

scholarly journals The SloR/Dlg Metalloregulator Modulates Streptococcus mutans Virulence Gene Expression

2006 ◽  
Vol 188 (14) ◽  
pp. 5033-5044 ◽  
Author(s):  
Elizabeth Rolerson ◽  
Adam Swick ◽  
Lindsay Newlon ◽  
Cameron Palmer ◽  
Yong Pan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Streptococcus Mutans ◽  
Metal Ion ◽  
Ion Homeostasis ◽  
Virulence Gene ◽  
Wild Type ◽  
Genetic Competence ◽  
Virulence Gene Expression ◽  
Metal Ion Homeostasis

ABSTRACT Metal ion availability in the human oral cavity plays a putative role in Streptococcus mutans virulence gene expression and in appropriate formation of the plaque biofilm. In this report, we present evidence that supports such a role for the DtxR-like SloR metalloregulator (called Dlg in our previous publications) in this oral pathogen. Specifically, the results of gel mobility shift assays revealed the sloABC, sloR, comDE, ropA, sod, and spaP promoters as targets of SloR binding. We confirmed differential expression of these genes in a GMS584 SloR-deficient mutant versus the UA159 wild-type progenitor by real-time semiquantitative reverse transcriptase PCR experiments. The results of additional expression studies support a role for SloR in S. mutans control of glucosyltransferases, glucan binding proteins, and genes relevant to antibiotic resistance. Phenotypic analysis of GMS584 revealed that it forms aberrant biofilms on an abiotic surface, is compromised for genetic competence, and demonstrates heightened incorporation of iron and manganese as well as resistance to oxidative stress compared to the wild type. Taken together, these findings support a role for SloR in S. mutans adherence, biofilm formation, genetic competence, metal ion homeostasis, oxidative stress tolerance, and antibiotic gene regulation, all of which contribute to S. mutans-induced disease.

scholarly journals Integration of Cyclic di-GMP and Quorum Sensing in the Control ofvpsTandaphAin Vibrio cholerae

2011 ◽  
Vol 193 (22) ◽  
pp. 6331-6341 ◽  
Author(s):  
Disha Srivastava ◽  
Rebecca C. Harris ◽  
Christopher M. Waters
Keyword(s):  
Quorum Sensing ◽  
Binding Site ◽  
Vibrio Cholerae ◽  
Biofilm Formation ◽  
Virulence Gene ◽  
Transcriptional Activator ◽  
Transcriptional Regulators ◽  
Content Type ◽  
Virulence Gene Expression ◽  
Signaling Systems

Vibrio choleraetransitions between aquatic environmental reservoirs and infection in the gastrointestinal tracts of human hosts. The second-messenger molecule cyclic di-GMP (c-di-GMP) and quorum sensing (QS) are important signaling systems that enableV. choleraeto alternate between these distinct environments by controlling biofilm formation and virulence factor expression. Here we identify a conserved regulatory mechanism inV. choleraethat integrates c-di-GMP and QS to control the expression of two transcriptional regulators:aphA, an activator of virulence gene expression and an important regulator of the quorum-sensing pathway, andvpsT, a transcriptional activator that induces biofilm formation. Surprisingly,aphAexpression was induced by c-di-GMP. Activation of bothaphAandvpsTby c-di-GMP requires the transcriptional activator VpsR, which binds to c-di-GMP. The VpsR binding site at each of these promoters overlaps with the binding site of HapR, the master QS regulator at high cell densities. Our results suggest thatV. choleraecombines information conveyed by QS and c-di-GMP to appropriately respond and adapt to divergent environments by modulating the expression of key transcriptional regulators.

scholarly journals Regulation of streptokinase expression by CovR/S in Streptococcus pyogenes: CovR acts through a single high-affinity binding site

Microbiology ◽  
2009 ◽  
Vol 155 (2) ◽  
pp. 566-575 ◽  
Author(s):  
Gordon Churchward ◽  
Christopher Bates ◽  
Asiya A. Gusa ◽  
Virginia Stringer ◽  
June R. Scott
Keyword(s):  
Streptococcus Pyogenes ◽  
Group A Streptococcus ◽  
Virulence Gene ◽  
Regulation Of Transcription ◽  
Virulence Gene Expression ◽  
Consensus Sequences ◽  
Dna Binding Sites ◽  
High Affinity Binding Site ◽  
Two Component Signal Transduction ◽  
Modes Of Interaction

The important human pathogen Streptococcus pyogenes (the group A streptococcus or GAS) produces many virulence factors that are regulated by the two-component signal transduction system CovRS (CsrRS). Dissemination of GAS infection originating at the skin has been shown to require production of streptokinase, whose transcription is repressed by CovR. In this work we have studied the interaction of CovR and phosphorylated CovR (CovR-P) with the promoter for streptokinase, Pska. We found that, in contrast to the other CovR-repressed promoters, Pska regulation by CovR occurs through binding at a single ATTARA consensus binding sequence (CB) that overlaps the −10 region of the promoter. Binding of CovR to other nearby consensus sequences occurs upon phosphorylation of the protein, but these other CBs do not contribute to the regulation of Pska by CovR. Thus, binding at a specific site does not necessarily indicate that the site is involved in regulation by CovR. In addition, at Pska, CovR binding to the different sites does not appear to involve cooperative interactions, which simplifies the analysis of CovR binding and gives us insight into the modes of interaction that occur between CovR and its specific DNA-binding sites. Finally, the observation that regulation of transcription from Pska occurs at a very low concentration of phosphorylated CovR may have important implications for the regulation of virulence gene expression during GAS infection.

scholarly journals Sociality in Escherichia coli: Enterochelin Is a Private Good at Low Cell Density and Can Be Shared at High Cell Density

2015 ◽  
Vol 197 (13) ◽  
pp. 2122-2128 ◽  
Author(s):  
Rebecca L. Scholz ◽  
E. Peter Greenberg
Keyword(s):  
Escherichia Coli ◽  
Cell Density ◽  
Iron Acquisition ◽  
Partial Privatization ◽  
High Cell ◽  
Wild Type ◽  
Content Type ◽  
Cell Densities ◽  
The Cost ◽  
Low Cell Density

ABSTRACTMany bacteria produce secreted iron chelators called siderophores, which can be shared among cells with specific siderophore uptake systems regardless of whether the cell produces siderophores. Sharing secreted products allows freeloading, where individuals use resources without bearing the cost of production. Here we show that theEscherichia colisiderophore enterochelin is not evenly shared between producers and nonproducers. Wild-typeEscherichia coligrows well in low-iron minimal medium, and an isogenic enterochelin synthesis mutant (ΔentF) grows very poorly. The enterochelin mutant grows well in low-iron medium supplemented with enterochelin. At high cell densities the ΔentFmutant can compete equally with the wild type in low-iron medium. At low cell densities the ΔentFmutant cannot compete. Furthermore, the growth rate of the wild type is unaffected by cell density. The wild type grows well in low-iron medium even at very low starting densities. Our experiments support a model where at least some enterochelin remains associated with the cells that produce it, and the cell-associated enterochelin enables iron acquisition even at very low cell density. Enterochelin that is not retained by producing cells at low density is lost to dilution. At high cell densities, cell-free enterochelin can accumulate and be shared by all cells in the group. Partial privatization is a solution to the problem of iron acquisition in low-iron, low-cell-density habitats. Cell-free enterochelin allows for iron scavenging at a distance at higher population densities. Our findings shed light on the conditions under which freeloaders might benefit from enterochelin uptake systems.IMPORTANCESociality in microbes has become a topic of great interest. One facet of sociality is the sharing of secreted products, such as the iron-scavenging siderophores. We present evidence that theEscherichia colisiderophore enterochelin is relatively inexpensive to produce and is partially privatized such that it can be efficiently shared only at high producer cell densities. At low cell densities, cell-free enterochelin is scarce and only enterochelin producers are able to grow in low-iron medium. Because freely shared products can be exploited by freeloaders, this partial privatization may help explain how enterochelin production is stabilized inE. coliand may provide insight into when enterochelin is available for freeloaders.

scholarly journals High intracellular c-di-GMP levels antagonize quorum sensing and virulence gene expression in Burkholderia cenocepacia H111

Microbiology ◽  
2017 ◽  
Vol 163 (5) ◽  
pp. 754-764 ◽  
Author(s):  
Nadine Schmid ◽  
Angela Suppiger ◽  
Elisabeth Steiner ◽  
Gabriella Pessi ◽  
Volkhard Kaever ◽  
...  
Keyword(s):  
Gene Expression ◽  
Quorum Sensing ◽  
Virulence Gene ◽  
Burkholderia Cenocepacia ◽  
Virulence Gene Expression
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