scholarly journals Markers for Host-Induced Gene Expression in Trichophyton Dermatophytosis

2005 ◽  
Vol 73 (10) ◽  
pp. 6584-6590 ◽  
Author(s):  
Gil Kaufman ◽  
Israela Berdicevsky ◽  
Judith A. Woodfolk ◽  
Benjamin A. Horwitz
Keyword(s):  
Gene Expression ◽  
Virulence Factors ◽  
Proteolytic Enzymes ◽  
Ex Vivo ◽  
Trichophyton Mentagrophytes ◽  
Skin Tests ◽  
Delayed Type Hypersensitivity ◽  
Protein Substrates ◽  
Genes Encoding ◽  
Encoding Genes

ABSTRACT Dermatophytes are adapted to infect keratinized tissues by their ability to utilize keratin as a nutrient source. Although there have been numerous reports that dermatophytes like Trichophyton sp. secrete proteolytic enzymes, virtually nothing is known about the patterns of gene expression in the host or even when the organisms are cultured on protein substrates in the absence of a host. We characterized the expression of an aminopeptidase gene, the Trichophyton mentagrophytes homolog of the Trichophyton rubrum Tri r 4 gene. The T. rubrum gene was originally isolated based on the ability of the protein encoded by it to induce immediate and delayed-type hypersensitivity in skin tests. T. mentagrophytes Tri m 4 is closely related to Tri r 4 (almost 94% identity at the protein level). Tri m 4 resembles other protease-encoding genes thought to be virulence factors (for example, DPP V of Aspergillus fumigatus). The Tri m 4 protein was detected immunochemically both in fungal extracts and in the culture medium. Expression of the Tri m 4 gene was induced severalfold when T. mentagrophytes was grown on keratin and elastin. Ex vivo, strong induction was observed after culture on blood plasma, but the use of homogenized skin did not result in a significant increase in Tri m 4 transcript levels. In order to identify additional genes encoding putative virulence factors, differential cDNA screening was performed. By this method, a fungal thioredoxin and a cellulase homolog were identified, and both genes were found to be strongly induced by skin extracellular matrix proteins. Induction by superficial (keratin) and deep (elastin) skin elements suggests that the products of these genes may be important in both superficial and deep dermatophytosis, and models for their function are proposed. Upregulation of several newly identified T. mentagrophytes genes on protein substrates suggests that these genes encode proteins which are relevant to the dermatophyte-skin interaction.

scholarly journals The purine biosynthesis regulator PurR moonlights as a virulence regulator in Staphylococcus aureus

2019 ◽  
Vol 116 (27) ◽  
pp. 13563-13572 ◽  
Author(s):  
William E. Sause ◽  
Divya Balasubramanian ◽  
Irnov Irnov ◽  
Richard Copin ◽  
Mitchell J. Sullivan ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Ex Vivo ◽  
Purine Biosynthesis ◽  
In Vivo Studies ◽  
Human Neutrophils ◽  
Infection Models ◽  
Genes Encoding ◽  
Virulence Regulator

The pathogen Staphylococcus aureus colonizes and infects a variety of different sites within the human body. To adapt to these different environments, S. aureus relies on a complex and finely tuned regulatory network. While some of these networks have been well-elucidated, the functions of more than 50% of the transcriptional regulators in S. aureus remain unexplored. Here, we assess the contribution of the LacI family of metabolic regulators to staphylococcal virulence. We found that inactivating the purine biosynthesis regulator purR resulted in a strain that was acutely virulent in bloodstream infection models in mice and in ex vivo models using primary human neutrophils. Remarkably, these enhanced pathogenic traits are independent of purine biosynthesis, as the purR mutant was still highly virulent in the presence of mutations that disrupt PurR’s canonical role. Through the use of transcriptomics coupled with proteomics, we revealed that a number of virulence factors are differentially regulated in the absence of purR. Indeed, we demonstrate that PurR directly binds to the promoters of genes encoding virulence factors and to master regulators of virulence. These results guided us into further ex vivo and in vivo studies, where we discovered that S. aureus toxins drive the death of human phagocytes and mice, whereas the surface adhesin FnbA contributes to the increased bacterial burden observed in the purR mutant. Thus, S. aureus repurposes a metabolic regulator to directly control the expression of virulence factors, and by doing so, tempers its pathogenesis.

scholarly journals Identification and Characterization of Hemolysin-Like Proteins Similar to RTX Toxin in Pasteurella pneumotropica

2009 ◽  
Vol 191 (11) ◽  
pp. 3698-3705 ◽  
Author(s):  
Hiraku Sasaki ◽  
Eiichi Kawamoto ◽  
Yoshikazu Tanaka ◽  
Takuo Sawada ◽  
Satoshi Kunita ◽  
...  
Keyword(s):  
Virulence Factors ◽  
Opportunistic Pathogen ◽  
Pcr Analysis ◽  
Type I ◽  
Secretion Systems ◽  
Rtx Toxin ◽  
Rtx Toxins ◽  
Genes Encoding ◽  
Encoding Genes

ABSTRACT Pasteurella pneumotropica is an opportunistic pathogen that causes lethal pneumonia in immunodeficient rodents. The virulence factors of this bacterium remain unknown. In this study, we identified the genes encoding two RTX toxins, designated as pnxI and pnxII, from the genomic DNA of P. pneumotropica ATCC 35149 and characterized with respect to hemolysis. The pnxI operon was organized according to the manner in which the genes encoded the structural RTX toxin (pnxIA), the type I secretion systems (pnxIB and pnxID), and the unknown orf. The pnxII gene was involved only with the pnxIIA that coded for a structural RTX toxin. Both the structural RTX toxins of deduced PnxIA and PnxIIA were involved in seven of the RTX repeat and repeat-like sequences. By quantitative PCR analysis of the structural RTX toxin-encoding genes in P. pneumotropica ATCC 35149, the gene expression of pnxIA was found to have increased from the early log phase, while that of pnxIIA increased from the late log to the early stationary phase. As expressed in Escherichia coli, both the recombinant proteins of PnxIA and PnxIIA showed weak hemolytic activity in both sheep and murine erythrocytes. On the basis of the results of the Southern blotting analysis, the pnxIA gene was detected in 82% of the isolates, while the pnxIIA gene was detected in 39%. These results indicate that the products of both pnxIA and pnxIIA were putative associations of virulence factors in the rodent pathogen P. pneumotropica.

Establishment of tolerance to commensal bacteria requires a complex microbiota and is accompanied by decreased intestinal chemokine expression

2012 ◽  
Vol 302 (1) ◽  
pp. G55-G65 ◽  
Author(s):  
L. N. Fink ◽  
S. B. Metzdorff ◽  
L. H. Zeuthen ◽  
C. Nellemann ◽  
M. B. Kristensen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Lymph Nodes ◽  
Ex Vivo ◽  
Gene Expression Pattern ◽  
Mesenteric Lymph Nodes ◽  
Microbial Detection ◽  
E Coli ◽  
Germ Free ◽  
Expression Of Genes ◽  
Genes Encoding

Intricate regulation of tolerance to the intestinal commensal microbiota acquired at birth is critical. We hypothesized that epithelial cell tolerance toward early gram-positive and gram-negative colonizing bacteria is established immediately after birth, as has previously been shown for endotoxin. Gene expression in the intestine of mouse pups born to dams that were either colonized with a conventional microbiota or monocolonized ( Lactobacillus acidophilus or Eschericia coli ) or germ free was examined on day 1 and day 6 after birth. Intestinal epithelial cells from all groups of pups were stimulated ex vivo with L. acidophilus and E. coli to assess tolerance establishment. Intestine from pups exposed to a conventional microbiota displayed lower expression of Ccl2, Ccl3, Cxcl1, Cxcl2, and Tslp than germ-free mice, whereas genes encoding proteins in Toll-like receptor signaling pathways and cytokines were upregulated. When comparing pups on day 1 and day 6 after birth, a specific change in gene expression pattern was evident in all groups of mice. Tolerance to ex vivo stimulation with E. coli was only established in conventional animals. Colonization of the intestine was reflected in the spleen displaying downregulation of Cxcl2 compared with germ-free animals on day 1 after birth. Colonization reduced the expression of genes involved in antigen presentation in the intestine-draining mesenteric lymph nodes, but not in the popliteal lymph nodes, as evidenced by gene expression on day 23 after birth. We propose that microbial detection systems in the intestine are upregulated by colonization with a diverse microbiota, whereas expression of proinflammatory chemokines is reduced to avoid excess recruitment of immune cells to the maturing intestine.

scholarly journals Transcriptomics Analysis ofCandida albicansTreated with Huanglian Jiedu Decoction Using RNA-seq

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Qianqian Yang ◽  
Lei Gao ◽  
Maocan Tao ◽  
Zhe Chen ◽  
Xiaohong Yang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Antifungal Agents ◽  
Enrichment Analysis ◽  
Trichophyton Mentagrophytes ◽  
Inhibition Mechanism ◽  
Pathway Enrichment Analysis ◽  
Rna Seq ◽  
Genes Encoding ◽  
Life Threatening ◽  
Systemic Infections

Candida albicansis the major invasive fungal pathogen of humans, causing diseases ranging from superficial mucosal infections to disseminated, systemic infections that are often life-threatening. Resistance ofC. albicansto antifungal agents and limited antifungal agents has potentially serious implications for management of infections. As a famous multiherb prescription in China, Huanglian Jiedu Decoction (HLJJD,Orengedokutoin Japan) is efficient againstTrichophyton mentagrophytesandC. albicans. But the antifungal mechanism of HLJDD remains unclear. In this study, by using RNA-seq technique, we performed a transcriptomics analysis of gene expression changes forC. albicansunder the treatment of HLJDD. A total of 6057 predicted protein-encoding genes were identified. By gene expression analysis, we obtained a total of 735 differentially expressed genes (DEGs), including 700 upregulated genes and 35 downregulated genes. Genes encoding multidrug transporters such as ABC transporter and MFS transporter were identified to be significantly upregulated. Meanwhile, by pathway enrichment analysis, we identified 26 significant pathways, in which pathways of DNA replication and transporter activity were mainly involved. These results might provide insights for the inhibition mechanism of HLJDD againstC. albicans.

scholarly journals Altered Expression of Selectable Marker URA3 in Gene-Disrupted Candida albicans Strains Complicates Interpretation of Virulence Studies

1998 ◽  
Vol 66 (11) ◽  
pp. 5301-5306 ◽  
Author(s):  
Jennifer Lay ◽  
L. Keith Henry ◽  
Julie Clifford ◽  
Yigal Koltin ◽  
Christine E. Bulawa ◽  
...  
Keyword(s):  
Gene Expression ◽  
Candida Albicans ◽  
Virulence Factors ◽  
Virulence Factor ◽  
Fungal Pathogen ◽  
Selectable Marker ◽  
Activity Levels ◽  
Wild Type ◽  
Altered Expression ◽  
Genes Encoding

ABSTRACT The ura-blaster technique for the disruption of Candida albicans genes has been employed in a number of studies to identify possible genes encoding virulence factors of this fungal pathogen. In this study, the URA3-encoded orotidine 5′-monophosphate (OMP) decarboxylase enzyme activities of C. albicans strains with ura-blaster-mediated genetic disruptions were measured. All strains harboring genetic lesions via the ura-blaster construct showed reduced OMP decarboxylase activities compared to that of the wild type when assayed. The activity levels in different gene disruptions varied, suggesting a positional effect on the level of gene expression. Because the URA3 gene ofC. albicans has previously been identified as a virulence factor for this microorganism, our results suggest that decreased virulence observed in strains constructed with the ura-blaster cassette cannot accurately be attributed, in all cases, to the targeted genetic disruption. Although revised methods for validating aURA3-disrupted gene as a target for antifungal drug development could be devised, it is clearly desirable to replaceURA3 with a different selectable marker that does not influence virulence.

scholarly journals Identification of Three Genes Encoding PII-Like Proteins in Gluconacetobacter diazotrophicus: Studies of Their Role(s) in the Control of Nitrogen Fixation

2003 ◽  
Vol 185 (19) ◽  
pp. 5854-5861 ◽  
Author(s):  
Olena Perlova ◽  
Alejandro Ureta ◽  
Stefan Nordlund ◽  
Dietmar Meletzus
Keyword(s):  
Gene Expression ◽  
Nitrogen Fixation ◽  
Gluconacetobacter Diazotrophicus ◽  
Triple Mutant ◽  
Gene Encoding ◽  
Protein Encoding ◽  
Genes Encoding ◽  
Encoding Gene ◽  
Encoding Genes ◽  
Expression And Activity

ABSTRACT In our studies on the regulation of nitrogen metabolism in Gluconacetobacter diazotrophicus, an endophytic diazotroph of sugarcane, three glnB-like genes were identified and their role(s) in the control of nitrogen fixation was studied. Sequence analysis revealed that one PII protein-encoding gene, glnB, was adjacent to a glnA gene (encoding glutamine synthetase) and that two other PII protein-encoding genes, identified as glnK1 and glnK2, were located upstream of amtB1 and amtB2, respectively, genes which in other organisms encode ammonium (or methylammonium) transporters. Single and double mutants and a triple mutant with respect to the three PII protein-encoding genes were constructed, and the effects of the mutations on nitrogenase expression and activity in the presence of either ammonium starvation or ammonium sufficiency were studied. Based on the results presented here, it is suggested that none of the three PII homologs is required for nif gene expression, that the GlnK2 protein acts primarily as an inhibitor of nif gene expression, and that GlnB and GlnK1 control the expression of nif genes in response to ammonium availability, both directly and by relieving the inhibition by GlnK2. This model includes novel regulatory features of PII proteins.

scholarly journals IDENTIFICATION TARGETED ON toxR GENE AND DETECTION OF VIRULENT FACTOR ENCODING GENES ON Vibrio parahaemolyticus ISOLATED FROM RAW CHICKEN MEAT

2011 ◽  
Vol 2 (1) ◽  
pp. 7-11
Author(s):  
Eka Fitrianda
Keyword(s):  
Virulence Factors ◽  
Chicken Meat ◽  
Specific Gene ◽  
Gene Encoding ◽  
Genes Encoding ◽  
Thermostable Direct Hemolysin ◽  
Pcr Method ◽  
Toxr Gene ◽  
Meat Samples ◽  
Encoding Genes

A number of V. parahaemolyticus isolates has been isolated from raw chicken meat samples collected in Pasar raya Padang. Isolation was done using ChromagarTM Vibrio media. Identification of toxR gene was then done to these isolates. toxR is a very specific gene in V. parahaemolyticus species. Detection for the presence of genes encoding virulence factors, in this case were the gene encoding thermostable direct hemolysin (tdh) and TDH related hemolysin (trh) was performed on toxR positive V. parahaemolyticus isolates. Identification of toxR gene and detection of tdh and trh genes were done trough amplification using polymerase chain reaction PCR (method). The results showed that all of the tested V. parahaemolyticus isolates (22 isolates) had toxR gene, but none of isolates has gene encoding the production of virulence factors both tdh and trh.

scholarly journals Transcriptional Silencing by TsrA in the Evolution of Pathogenic Vibrio cholerae Biotypes

mBio ◽  
2020 ◽  
Vol 11 (6) ◽  
Author(s):  
Florence Caro ◽  
José A. Caro ◽  
Nicole M. Place ◽  
John J. Mekalanos
Keyword(s):  
Gene Expression ◽  
Vibrio Cholerae ◽  
Virulence Factors ◽  
Virulence Genes ◽  
Secretion System ◽  
Type Vi Secretion System ◽  
Content Type ◽  
Type Vi Secretion ◽  
Genes Encoding ◽  
El Tor

ABSTRACT Vibrio cholerae is a globally important pathogen responsible for the severe epidemic diarrheal disease called cholera. The current and ongoing seventh pandemic of cholera is caused by El Tor strains, which have completely replaced the sixth-pandemic classical strains of V. cholerae. To successfully establish infection and disseminate to new victims, V. cholerae relies on key virulence factors encoded on horizontally acquired genetic elements. The expression of these factors relies on the regulatory architecture that coordinates the timely expression of virulence determinants during host infection. Here, we apply transcriptomics and structural modeling to understand how type VI secretion system regulator A (TsrA) affects gene expression in both the classical and El Tor biotypes of V. cholerae. We find that TsrA acts as a negative regulator of V. cholerae virulence genes encoded on horizontally acquired genetic elements. The TsrA regulon comprises genes encoding cholera toxin (CT), the toxin-coregulated pilus (TCP), and the type VI secretion system (T6SS), as well as genes involved in biofilm formation. The majority of the TsrA regulon is carried on horizontally acquired AT-rich genetic islands whose loss or acquisition could be directly ascribed to the differences between the classical and El Tor strains studied. Our modeling predicts that the TsrA protein is a structural homolog of the histone-like nucleoid structuring protein (H-NS) oligomerization domain and is likely capable of forming higher-order superhelical structures, potentially with DNA. These findings describe how TsrA can integrate into the intricate V. cholerae virulence gene expression program, controlling gene expression through transcriptional silencing. IMPORTANCE Pathogenic Vibrio cholerae strains express multiple virulence factors that are encoded by bacteriophage and chromosomal islands. These include cholera toxin and the intestinal colonization pilus called the toxin-coregulated pilus, which are essential for causing severe disease in humans. However, it is presently unclear how the expression of these horizontally acquired accessory virulence genes can be efficiently integrated with preexisting transcriptional programs that are presumably fine-tuned for optimal expression in V. cholerae before its conversion to a human pathogen. Here, we report the role of a transcriptional regulator (TsrA) in silencing horizontally acquired genes encoding important virulence factors. We propose that this factor could be critical to the efficient acquisition of accessory virulence genes by silencing their expression until other signals trigger their transcriptional activation within the host.

scholarly journals WhiB6 regulation of ESX-1 gene expression is controlled by a negative feedback loop inMycobacterium marinum

2017 ◽  
Vol 114 (50) ◽  
pp. E10772-E10781 ◽  
Author(s):  
Rachel E. Bosserman ◽  
Tiffany T. Nguyen ◽  
Kevin G. Sanchez ◽  
Alexandra E. Chirakos ◽  
Micah J. Ferrell ◽  
...  
Keyword(s):  
Gene Expression ◽  
Feedback Control ◽  
Negative Feedback ◽  
Feedback Loop ◽  
Protein Substrates ◽  
Membrane Complex ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Negative Feedback Control ◽  
Membrane Components

ESX (ESAT-6 system) export systems play diverse roles across mycobacterial species. Interestingly, genetic disruption of ESX systems in different species does not result in an accumulation of protein substrates in the mycobacterial cell. However, the mechanisms underlying this observation are elusive. We hypothesized that the levels of ESX substrates were regulated by a feedback-control mechanism, linking the levels of substrates to the secretory status of ESX systems. To test this hypothesis, we used a combination of genetic, transcriptomic, and proteomic approaches to define export-dependent mechanisms regulating the levels of ESX-1 substrates inMycobacterium marinum. WhiB6 is a transcription factor that regulates expression of genes encoding ESX-1 substrates. We found that, in the absence of the genes encoding conserved membrane components of the ESX-1 system, the expression of thewhiB6gene and genes encoding ESX-1 substrates were reduced. Accordingly, the levels of ESX-1 substrates were decreased, and WhiB6 was not detected inM. marinumstrains lacking genes encoding ESX-1 components. We demonstrated that, in the absence of EccCb1, a conserved ESX-1 component, substrate gene expression was restored by constitutive, but not native, expression of thewhiB6gene. Finally, we found that the loss of WhiB6 resulted in a virulentM. marinumstrain with reduced ESX-1 secretion. Together, our findings demonstrate that the levels of ESX-1 substrates inM. marinumare fine-tuned by negative feedback control, linking the expression of thewhiB6gene to the presence, not the functionality, of the ESX-1 membrane complex.

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