• Mycobiology
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• 제38권1호
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• pp.26-32
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• 2010

The cyclic AMP (cAMP) pathway plays a major role in growth, sexual differentiation, and virulence factor synthesis of pathogenic fungi. In Cryptococcus neoformans, perturbation of the cAMP pathway, such as a deletion in the gene encoding adenylyl cyclase (CAC1), causes defects in the production of virulence factors, including capsule and melanin production, as well as mating. Previously, we performed a comparative transcriptome analysis of the Ras- and cAMP- pathway mutants, which revealed 163 potential cAMP-regulated genes (38 genes at a 2-fold cutoff). The present study characterized the role of one of the cAMP pathway-dependent genes (serotype A identification number CNAG_ 06576.2). The expression patterns were confirmed by Northern blot analysis and the gene was designated cAMP-regulated gene 1 (CAR1). Interestingly, deletion of CAR1 did not affect biosynthesis of any virulence factors and the mating process, unlike the cAMP-signaling deficient cac1$\Delta$ mutant. Furthermore, the car1$\Delta$ mutant exhibited wild-type levels of the stress-response phenotype against diverse environmental cues, indicating that Car1, albeit regulated by the cAMP-pathway, is not essential to confer a cAMP-dependent phenotype in C. neoformans.

• 한국미생물·생명공학회지
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• 제50권1호
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• pp.1-14
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• 2022

Bacteria communicate with each other through an intricate communication mechanism known as quorum sensing (QS). QS regulates different behavioral aspects in bacteria, such as biofilm formation, sporulation, virulence gene expression, antibiotic production, and bioluminescence. Several different chemical signals and signal detection systems play vital roles in promoting highly efficient intra- and interspecies communication. Gram-negative bacteria coordinate gene regulation through the production of acyl homoserine lactones (AHLs). Gram-positive bacteria do not code for AHL production, while some gram-negative bacteria have an incomplete AHL-QS system. Despite this fact, these microbes can detect AHLs owing to the presence of LuxR solo receptors. Various studies have reported the role of AHLs in interspecies signaling. Moreover, as bacteria live in a polymicrobial community, the production of extracellular compounds to compete for resources is imperative. Thus, AHL-mediated signaling and inhibition are considered to affect virulence in bacteria. In the current review, we focus on the synthesis and regulation mechanisms of AHLs and highlight their role in interspecies bacterial signaling. Exploring interspecies bacterial signaling will further help us understand host-pathogen interactions, thereby contributing to the development of therapeutic strategies intended to target chronic polymicrobial infections.

• Journal of Microbiology and Biotechnology
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• 제20권12호
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• pp.1624-1629
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• 2010

Bacterial cell-to-cell communication, termed quorum sensing (QS), leads to coordinated group behavior in a cell-density-dependent fashion and controls a variety of physiological processes including virulence gene expression. The repressor of the lsr operon, LsrR, is the only known regulator of LuxS/AI-2-mediated QS in Salmonella. Although lack of lsrR did not result in noticeable differences in Salmonella survival, the down-regulation of QS as a result of lsrR overexpression decreased Salmonella survival within macrophages. We found that impaired growth of Salmonella overexpressing lsrR within macrophages was due largely to its hypersensitivity to NADPH-dependent oxidative stress. This, in turn, was a result of decreased expression of genes involved in the oxidative stress response, such as sodA, sodCI, and sodCII, when lsrR was overexpressed. These results suggest that down-regulation of QS by excess LsrR can lower Salmonella virulence by hampering Salmonella evasion from oxidative killing within macrophages.

• 한국미생물·생명공학회지
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• 제51권4호
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• pp.507-516
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• 2023

Eradication of Helicobacter pylori infection is an essential strategy to decrease the risk of developing gastric cancer. However, the standard triple therapy has negative aspects associated with side effects and the emergence of antibiotic resistance. Therefore, alternative therapies are required to enhance the management of H. pylori infection effectively. In this study we examined the effect of emodin on the amelioration of inflammatory response due to H. pylori infection. Our results indicated that emodin treatment effectively decreased the expression of virulence genes, including sabA, vacA, cagL, cagA, sabA, and suppressed the adhesion ability of H. pylori to AGS cells. Emodin has been shown inhibitory effects on the inflammasome pathway through reductions in VacA translocation, lowering ROS stress, cleaved Caspase-1, NLRP3, and cleaved Gasdermin D levels, thereby lowered pyroptosis in infected cells. In summary, our study demonstrated that emodin has the ability to attenuate inflammation caused by H. pylori by modulating virulence gene expression and decreasing VacA translocation. Further study is required to evaluate the therapeutic efficacy of emodin in treating H. pylori infection and better understand the underlying mechanisms.

• 한국토양비료학회지
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• 제33권4호
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• pp.253-260
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• 2000

Agrobacterium tumefaciens에 존재하는 Ti 플라스미드의 virulence(vir)유전자들은 상처난 식물세포에서 분비되는 페놀화합물에 의해서 발현이 유도된다. 본 연구에서는 3종류의 A. tumefaciens들을 대상으로 8종의 페놀화합물들 중에서 vir유전자의 발현에 영향을 미치는 페놀 화합물들의 종류와 이들 균주에서 발현되는 vir유전자의 활성을 조사하였다. A. tumefaciens MW102에 존재하는 vir유전자는 4-hydroxyacetophenone, phenol, catechol, resorcinol과 vanillin등 5종류의 페놀화합물들에 의해서 높게 발현된 반면, 다른 A. tumefaciens Mw105와 Mw108의 vir유전자들은 이들 페놀화합물들에 의해서 매우 낮게 발현되거나 또는 발현되지 않았다. 또한 A. tumefaciens Mw102는 A. tumefaciens Mw105와 Mw108의 vir유전자를 매우 높게 발현시키는 acetosyringene에 의해서는 매우 낮게 발현되었다. 따라서 vir유전자의 발현을 유도시키는 능력은 Ti 플라스미드들의 종류와 페놀화합물들의 종류에 따라서 서로 다르다는 결과를 얻었다. 결과적으로 vir유전자 유도능력의 차이는 vir A 유전자에서 발현되는 sensor단백질의 차이 때문일 것으로 사료된다.

• Journal of Periodontal and Implant Science
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• 제38권3호
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• pp.543-550
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• 2008

Purpose: The purpose of this study was to investigate induction of cytokine expression in human gingival fibroblasts (HGFs) by whole cell and the components of T. forsythia. Material and Methods: After HGFs were treated with lipopolysaccharide (LPS), membrane protein isolated from T. forsythia or culture media of T. forsythia, the induction of interleukin (IL)-1, IL-6 and IL-8 was examined with real-time PCR and ELISA. Their induction ability of cytokines was compared with whole bacteria. Result: The expression of IL-6 and IL-8 was significantly induced in HGFs by whole bacteria and membrane protein. The expression of IL-$1{\beta}$ was induced by membrane protein of T. forsythia, not by whole bacteria. LPS and condition media of T. forsythia slightly activated HGFs. Conclusion: The membrane protein of T. forsythia could be one of virulence factors.

• Journal of Microbiology and Biotechnology
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• 제32권2호
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• pp.220-227
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• 2022

The spread of antibiotic-resistant strains of Staphylococcus aureus, a gram-positive opportunistic pathogen, has increased due to the frequent use of antibiotics. Inhibition of the quorum-sensing systems of biofilm-producing strains using plant extracts represents an efficient approach for controlling infections. Torilis japonica is a medicinal herb showing various bioactivities; however, no studies have reported the anti-biofilm effects of T. japonica extracts against drug-resistant S. aureus. In this study, we evaluated the inhibitory effects of T. japonica ethanol extract (TJE) on biofilm production in methicillin-sensitive S. aureus (MSSA) KCTC 1927, methicillin-resistant S. aureus (MRSA) KCCM 40510, and MRSA KCCM 40511. Biofilm assays showed that TJE could inhibit biofilm formation in all strains. Furthermore, the hemolysis of sheep blood was found to be reduced when the strains were treated with TJE. The mRNA expression of agrA, sarA, icaA, hla, and RNAIII was evaluated using reverse transcription-polymerase chain reaction to determine the effect of TJE on the regulation of genes encoding quorum sensing-related virulence factors in MSSA and MRSA. The expression of hla reduced in a concentration-dependent manner upon treatment with TJE. Moreover, the expression levels of other genes were significantly reduced compared to those in the control group. In conclusion, TJE can suppress biofilm formation and virulence factor-related gene expression in MSSA and MRSA strains. The extract may therefore be used to develop treatments for infections caused by antibiotic-resistant S. aureus.

• 생명과학회지
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• 제11권4호
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• pp.316-320
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• 2001

Sonication tremendously improves the efficiency of Agrobacterium infection by introducing small and uniform fissures and channels throughout the targeted tissue. Using shoot tips of cotton as explants, the effect of sonication treatment and virulence genes in Agrobacterium tumefaciens on transformation efficiency was investigated. The pat gene which encodes resistance to the herbicide, glufosinate, was used as a selectable marker. Transformation efficiency was evaluated on th basis of survival rates of cocultivated shoot tips on selection medium containing 2.5 mg/l gulfosinate-ammonium(ppt) adn 25. mg/l Clavamax. Sonication from 5 to 15 second has a positive effect on shoop tip survival. However, whil virE as well as virG or vir GN54D showed an enhancement in transformation efficiency, virE,. virG resulted in the most significant enhancement. Overall, the combination of additional virG/virE gene and sonication treatment resulted in the most significant increase in transformation efficiency.

• 한국응용곤충학회지
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• 제19권1호
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• pp.11-20
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• 1980

특정수도품종에 대한 도열병균의 침입률은 접종전처리온도와 균주의 조합보다는 공시균주나 온도의 단독요인에 의한 영향이컸다. 이병성품종은 그 품종이 어떤 온도조건하에서 자랐던지 또는 병원성이 다른 어떤 균주로 접종이 되었던지 이병성으로 남아 있었으며 접종전에 기주가 다른 온도조건하에서 자랐을 경우, 도열병균의 특정균주 또는 Race의 병원성발현은 다르게 나타나는 것이 관찰되었다.

• Journal of Microbiology
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• 제42권2호
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• pp.143-146
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• 2004

Vancomycin-resistant Enterococcus faecium (VREFM) is becoming a threatening pathogen. We identified a gene called DD1.5K by differential display-PCR, which was preferentially expressed in the bloodstream isolates of VREFM. Due to its amino acid similarity to transfer complex protein, trsE, and tissue-specific expression, this gene may be involved in virulence of VREFM.