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Artykuły w czasopismach na temat "AgrC-AgrA"
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Lade, Harshad, Sung Hee Chung, Yeonhee Lee, Bajarang Vasant Kumbhar, Hwang-Soo Joo, Yun-Gon Kim, Yung-Hun Yang i Jae-Seok Kim. "Thymol Reduces agr-Mediated Virulence Factor Phenol-Soluble Modulin Production in Staphylococcus aureus". BioMed Research International 2022 (9.05.2022): 1–14. http://dx.doi.org/10.1155/2022/8221622.
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Staphylococcus aureus is a major human bacterial pathogen that carries a large number of virulence factors. Many virulence factors of S. aureus are regulated by the accessory gene regulator (agr) quorum-sensing system. Phenol-soluble modulins (PSMs) are one of the agr-mediated virulence determinants known to play a significant role in S. aureus pathogenesis. In the present study, the efficacy of thymol to inhibit PSM production including δ-toxin in S. aureus was explored. We employed liquid chromatography–mass spectrometry (LC–MS) to quantify the PSMsα1–PSMα4, PSMβ1 and PSMβ2, and δ-toxin production from culture supernatants. We found that thymol at 0.5 MIC (128 μg/mL) significantly reduced the PSMα and δ-toxin production in S. aureus WKZ-1, WKZ-2, LAC USA300, and ATCC29213. Downregulation in transcription by quantitative real-time (qRT) PCR analysis of response regulator agrA and receptor histidine kinase agrC upon 0.5 MIC thymol treatment affirmed the results of LC–MS quantification of PSMs. In silico molecular docking analysis demonstrated the binding affinity of thymol with receptors AgrA and AgrC. Transmission electron microscopy images revealed no ultrastructural alterations (cell wall and membrane) in thymol-treated WKZ-1 and WKZ-2 S. aureus strains. Here, we demonstrated that thymol reduces various PSM production in S. aureus clinical isolates and reference strains with mass spectrometry.
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Rieu, Aurélie, Stéphanie Weidmann, Dominique Garmyn, Pascal Piveteau i Jean Guzzo. "agr System of Listeria monocytogenes EGD-e: Role in Adherence and Differential Expression Pattern". Applied and Environmental Microbiology 73, nr 19 (3.08.2007): 6125–33. http://dx.doi.org/10.1128/aem.00608-07.
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ABSTRACT In this study, we investigated the agrBDCA operon in the pathogenic bacterium Listeria monocytogenes EGD-e. In-frame deletion of agrA and agrD resulted in an altered adherence and biofilm formation on abiotic surfaces, suggesting the involvement of the agr system of L. monocytogenes during the early stages of biofilm formation. Real-time PCR experiments indicated that the transcript levels of agrBDCA depended on the stage of biofilm development, since the levels were lower after the initial attachment period than during biofilm growth, whereas transcription during planktonic growth was not growth phase dependent. The mRNA quantification data also suggested that the agr system was autoregulated and pointed to a differential expression of the agr genes during sessile and planktonic growth. Although the reverse transcription-PCR experiments revealed that the four genes were transcribed as a single messenger, chemical half-life and 5′ RACE (rapid amplification of cDNA ends) experiments indicated that the full size transcript underwent cleavage followed by degradation of the agrC and agrA transcripts, which suggests a complex regulation of agr transcription.
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Srivastava, S. K., K. Rajasree, A. Fasim, G. Arakere i B. Gopal. "Influence of the AgrC-AgrA Complex on the Response Time of Staphylococcus aureus Quorum Sensing". Journal of Bacteriology 196, nr 15 (23.05.2014): 2876–88. http://dx.doi.org/10.1128/jb.01530-14.
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Zhang, Linsheng, i Guangyong Ji. "Identification of a Staphylococcal AgrB Segment(s) Responsible for Group-Specific Processing of AgrD by Gene Swapping". Journal of Bacteriology 186, nr 20 (15.10.2004): 6706–13. http://dx.doi.org/10.1128/jb.186.20.6706-6713.2004.
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ABSTRACT The four gene products of the accessory gene regulator (agr) P2 operon of Staphylococcus aureus assemble a quorum-sensing system: AgrA and AgrC resemble a two-component signal transduction system, and AgrB and AgrD are required to produce an autoinducing peptide. Upon activation, this quorum-sensing system positively regulates the transcription of the P2 operon as well as the P3 operon, whose transcript, RNAIII, regulates the expression of virulence genes. Four groups of S. aureus have been identified based on the agr sequences and the group-specific interaction between the autoinducing peptide and AgrC. AgrB is a transmembrane protein involved in the processing of AgrD propeptide, and its interaction with AgrD is also group specific. In this study, a series of chimeric AgrBs were constructed by swapping between group I and group II AgrBs, and these mutants were used to analyze the group-specific segment(s) in AgrB that was responsible for AgrD processing. Our results revealed that the first transmembrane α-helix and the extracellular loop 1 of group I AgrB were decisive in the specific processing of group I AgrD. In contrast, two hydrophilic segments of group II AgrB played a crucial role in the group-specific processing of group II AgrD. We also found that several chimeric AgrBs were capable of processing AgrD from both groups, suggesting that all AgrB homologues may utilize the same or a similar mechanism in the processing of AgrDs.
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Somerville, Greg A., Stephen B. Beres, J. Ross Fitzgerald, Frank R. DeLeo, Robert L. Cole, Jessica S. Hoff i James M. Musser. "In Vitro Serial Passage of Staphylococcus aureus: Changes in Physiology, Virulence Factor Production, and agr Nucleotide Sequence". Journal of Bacteriology 184, nr 5 (1.03.2002): 1430–37. http://dx.doi.org/10.1128/jb.184.5.1430-1437.2002.
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ABSTRACT Recently, we observed that Staphylococcus aureus strains newly isolated from patients had twofold-higher aconitase activity than a strain passaged extensively in vitro, leading us to hypothesize that aconitase specific activity decreases over time during in vitro passage. To test this hypothesis, a strain recovered from a patient with toxic shock syndrome was serially passaged for 6 weeks, and the aconitase activity was measured. Aconitase specific activity decreased 38% (P < 0.001) by the sixth week in culture. During serial passage, S. aureus existed as a heterogeneous population with two colony types that had pronounced (wild type) or negligible zones of beta-hemolytic activity. The cell density-sensing accessory gene regulatory (agr) system regulates beta-hemolytic activity. Surprisingly, the percentage of colonies with a wild-type beta-hemolytic phenotype correlated strongly with aconitase specific activity (ρ = 0.96), suggesting a common cause of the decreased aconitase specific activity and the variation in percentage of beta-hemolytic colonies. The loss of the beta-hemolytic phenotype also coincided with the occurrence of mutations in the agrC coding region or the intergenic region between agrC and agrA in the derivative strains. Our results demonstrate that in vitro growth is sufficient to result in mutations within the agr operon. Additionally, our results demonstrate that S. aureus undergoes significant phenotypic and genotypic changes during serial passage and suggest that vigilance should be used when extrapolating data obtained from the study of high-passage strains.
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Wang, Li, Lin Qiao, Aike Li, Lixian Chen, Beibei He, Gang Liu, Weiwei Wang i Jun Fang. "Integrative Multiomics Analysis of the Heat Stress Response of Enterococcus faecium". Biomolecules 13, nr 3 (25.02.2023): 437. http://dx.doi.org/10.3390/biom13030437.
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A continuous heat-adaptation test was conducted for one Enterococcus faecium (E. faecium) strain wild-type (WT) RS047 to obtain a high-temperature-resistant strain. After domestication, the strain was screened with a significantly higher ability of heat resistance. which is named RS047-wl. Then a multi-omics analysis of transcriptomics and metabolomics was used to analyze the mechanism of the heat resistance of the mutant. A total of 98 differentially expressed genes (DEGs) and 115 differential metabolites covering multiple metabolic processes were detected in the mutant, which indicated that the tolerance of heat resistance was regulated by multiple mechanisms. The changes in AgrB, AgrC, and AgrA gene expressions were involved in quorum-sensing (QS) system pathways, which regulate biofilm formation. Second, highly soluble osmotic substances such as putrescine, spermidine, glycine betaine (GB), and trehalose-6P were accumulated for the membrane transport system. Third, organic acids metabolism and purine metabolism were down-regulated. The findings can provide target genes for subsequent genetic modification of E. faecium, and provide indications for screening heat-resistant bacteria, so as to improve the heat-resistant ability of E. faecium for production.
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Dmitrenko, Olga, Andrey Chaplin, Anna Balbutskaya, Tamara Pkhakadze i Sergey Alkhovsky. "In Silico Genome-Scale Analysis of Molecular Mechanisms Contributing to the Development of a Persistent Infection with Methicillin-Resistant Staphylococcus aureus (MRSA) ST239". International Journal of Molecular Sciences 23, nr 24 (16.12.2022): 16086. http://dx.doi.org/10.3390/ijms232416086.
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The increasing frequency of isolation of methicillin-resistant Staphylococcus aureus (MRSA) limits the chances for the effective antibacterial therapy of staphylococcal diseases and results in the development of persistent infection such as bacteremia and osteomyelitis. The aim of this study was to identify features of the MRSAST239 0943-1505-2016 (SA943) genome that contribute to the formation of both acute and chronic musculoskeletal infections. The analysis was performed using comparative genomics data of the dominant epidemic S. aureus lineages, namely ST1, ST8, ST30, ST36, and ST239. The SA943 genome encodes proteins that provide resistance to the host’s immune system, suppress immunological memory, and form biofilms. The molecular mechanisms of adaptation responsible for the development of persistent infection were as follows: amino acid substitution in PBP2 and PBP2a, providing resistance to ceftaroline; loss of a large part of prophage DNA and restoration of the nucleotide sequence of beta-hemolysin, that greatly facilitates the escape of phagocytosed bacteria from the phagosome and formation of biofilms; dysfunction of the AgrA system due to the presence of psm-mec and several amino acid substitutions in the AgrC; partial deletion of the nucleotide sequence in genomic island vSAβ resulting in the loss of two proteases of Spl—operon; and deletion of SD repeats in the SdrE amino acid sequence.
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Steiner, Elisabeth, Jamie Scott, Nigel P. Minton i Klaus Winzer. "AnagrQuorum Sensing System That Regulates Granulose Formation and Sporulation in Clostridium acetobutylicum". Applied and Environmental Microbiology 78, nr 4 (16.12.2011): 1113–22. http://dx.doi.org/10.1128/aem.06376-11.
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ABSTRACTThe Gram-positive, anaerobic, endospore-forming bacteriumClostridium acetobutylicumhas considerable biotechnological potential due to its ability to produce solvents as fermentation products, in particular the biofuel butanol. Its genome contains a putativeagrlocus,agrBDCA, known in staphylococci to constitute a cyclic peptide-based quorum sensing system. In staphylococci,agrBDis required for the generation of a peptide signal that, upon extracellular accumulation, is sensed by anagrCA-encoded two-component system. Using ClosTron technology,agrB,agrC, andagrAmutants ofC. acetobutylicumATCC 824 were generated and phenotypically characterized. Mutants and wild type displayed similar growth kinetics and no apparent differences in solvent formation under the conditions tested. However, the number of heat-resistant endospores formed by the mutants in liquid culture was reduced by about one order of magnitude. On agar-solidified medium, spore formation was more strongly affected, particularly inagrAandagrCmutants. Similarly, accumulation of the starch-like storage compound granulose was almost undetectable in colonies ofagrB,agrA, andagrCmutants. Importantly, these defects could be genetically complemented, demonstrating that they were directly linked toagrinactivation. A diffusible factor produced byagrBD-expressing strains was found to restore granulose and spore formation in theagrBmutant. Furthermore, a synthetic cyclic peptide, designed on the basis of theC. acetobutylicumAgrD sequence, was also capable of complementing the defects of theagrBmutant when added exogenously to the culture. Together, these findings support the hypothesis thatagr-dependent quorum sensing is involved in the regulation of sporulation and granulose formation inC. acetobutylicum.
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Sung, Julia M. L., Peter D. Chantler i David H. Lloyd. "Accessory Gene Regulator Locus of Staphylococcus intermedius". Infection and Immunity 74, nr 5 (maj 2006): 2947–56. http://dx.doi.org/10.1128/iai.74.5.2947-2956.2006.
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ABSTRACT The accessory gene regulator (agr) locus, a candidate system for the regulation of the production of virulence factors in Staphylococcus intermedius, has been characterized. Using PCR-based genome walking, we have obtained the first complete sequence (3,436 bp) of the accessory gene regulator (agr) gene in this organism. Sequence analysis of the agr gene has identified five open reading frames (ORFs), agrB, agrD, agrC, agrA, and hld. The translated ORF contained amino acid motifs characteristic of the response regulator and histidine protein kinase signal transducer of the classic two-component regulatory system. Sequencing of the agrD PCR products amplified from DNA from 20 different isolates has facilitated detection of genetic variation in the putative autoinducing peptide (AIP) within the agr gene of S. intermedius, revealing the presence of at least three agr specificity groups within this species. Classification of the agr gene from S. intermedius was supported by phylogenetic analysis. Real-time PCR also revealed that the effector molecule of the agr system, RNAIII, was regulated in an autocrine manner in S. intermedius and demonstrated positive correlation with the temporal gene expression patterns of luk and entC. Transcription of RNAIII was also dependent on self secreted cues. Cyclic self and nonself peptides were synthesized on the basis of the novel AIPs produced by S. intermedius, which lack the cysteine necessary to form the thiolactone ring in analogous peptides from Staphylococcus aureus and Staphylococcus epidermidis. Experiments with these synthetic cyclic peptides indicated that self peptides led to up-regulation of RNAIII—findings in support of the assumption that activation of the agr gene is initiated by growth- and species-specific factors generated during bacterial growth.
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Qin, Xiang, Kavindra V. Singh, George M. Weinstock i Barbara E. Murray. "Effects of Enterococcus faecalis fsrGenes on Production of Gelatinase and a Serine Protease and Virulence". Infection and Immunity 68, nr 5 (1.05.2000): 2579–86. http://dx.doi.org/10.1128/iai.68.5.2579-2586.2000.
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ABSTRACT Three agr-like genes (fsrA,fsrB, and fsrC, for Enterococcus faecalis regulator) were found upstream of the previously reported gelatinase gene (gelE) and a downstream putative serine protease gene (sprE; accession number Z12296 ) ofEnterococcus faecalis OG1RF. The deduced amino acid sequence of fsrA shows 26% identity and 38% similarity toStaphylococcus aureus AgrA (the response regulator of the accessory gene regulator system in the agr locus), FsrB shows 23% identity and 41% similarity to S. aureus AgrB, and FsrC shows 23% identity and 36% similarity to S. aureus AgrC (the sensor transducer of Agr system). Northern blot analysis suggested that gelE and sprE are cotranscribed and that fsrB and fsrC are also cotranscribed in OG1RF. Northern blot analysis of fsrA,fsrB, fsrC, gelE, andsprE insertion mutants showed that fsrB,fsrC, gelE, and sprE are not expressed in fsrA, fsrB, and fsrCmutants, while insertion in an open reading frame further upstream offsrA did not effect the expression of these genes, suggesting that agr-like genes may be autoregulated and that they regulate gelE and sprE expression, as further confirmed by complementation of fsr gene mutations with a 6-kb fragment which contains all three fsr genes in the shuttle vector, pAT18. Testing of 95 other isolates of E. faecalis showed that 62% produced gelatinase (Gel+), while 91% (including all Gel+ strains) hybridized to agelE probe; 71% (including all Gel+ strains) hybridized to an fsr probe, corroborating the conclusion that both gelE and fsr are necessary for gelatinase production. Testing of fsrA, fsrB, and sprE mutants in a mouse peritonitis model showed that sprE and agr-like gene mutants resulted in highly significantly prolonged survival compared to the parent strain OG1RF, a finding similar to what we had previously shown for agelE mutant. These results suggest that sprEand agr-like genes contribute to the virulence of E. faecalis OG1RF in this model.
Rozprawy doktorskie na temat "AgrC-AgrA"
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Rajasree, Kalagiri. "Structural Studies on the Intracellular Steps that Govern the Staphylococcus aureus Quorum Sensing System". Thesis, 2015. https://etd.iisc.ac.in/handle/2005/4819.
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Quorum sensing in bacteria has been extensively examined over the past two decades. These studies suggest that the molecular mechanism that governs quorum sensing incorporates niche-specific, environmentally sensitive information in addition to chemosensory information embedded in the signaling molecules- autoinducing peptides (AIPs) or homoserine lactones. One aspect of the quorum sensing mechanism that was examined in the course of this study was the sensitivity and fidelity of the intracellular signal transduction cascade that correlates extracellular information with a cellular response. The Agr quorum-sensing system in Staphylococcus aureus provided a good model system to examine this aspect of the mechanism. As individual components of this mechanism had been characterized by other groups earlier, the tools to probe the intracellular cascade existed at the start of this project. This thesis describes the progress made in the course of studies to examine the role of two important intracellular components- AgrC and AgrA. These proteins were examined using a variety of biophysical, biochemical and structural biology techniques.