scholarly journals VibA, a Homologue of a Transcription Factor for Fungal Heterokaryon Incompatibility, Is Involved in Antifungal Compound Production in the Plant-Symbiotic Fungus Epichloë festucae

2014 ◽  
Vol 14 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Jennifer T. Niones ◽  
Daigo Takemoto
Keyword(s):  
Transcription Factor ◽  
Antifungal Activity ◽  
Critical Role ◽  
Antifungal Compound ◽  
Symbiotic Association ◽  
Wild Type ◽  
Exogenous Dna ◽  
Content Type ◽  
Type Isolate ◽  
Epichloë Festucae

ABSTRACT Symbiotic association of epichloae endophytes ( Epichloë/Neotyphodium species) with cool-season grasses of the subfamily Pooideae confers bioprotective benefits to the host plants against abiotic and biotic stresses. While the production of fungal bioprotective metabolites is a well-studied mechanism of host protection from insect herbivory, little is known about the antibiosis mechanism against grass pathogens by the mutualistic endophyte. In this study, an Epichloë festucae mutant defective in antimicrobial substance production was isolated by a mutagenesis approach. In an isolated mutant that had lost antifungal activity, the exogenous DNA fragment was integrated into the promoter region of the vibA gene, encoding a homologue of the transcription factor VIB-1. VIB-1 in Neurospora crassa is a regulator of genes essential in vegetative incompatibility and promotion of cell death. Here we show that deletion of the vibA gene severely affected the antifungal activity of the mutant against the test pathogen Drechslera erythrospila . Further analyses showed that overexpressing vibA enhanced the antifungal activity of the wild-type isolate against test pathogens. Transformants overexpressing vibA showed an inhibitory activity on test pathogens that the wild-type isolate could not. Moreover, overexpressing vibA in a nonantifungal E. festucae wild-type Fl1 isolate enabled the transformant to inhibit the mycelial and spore germination of D. erythrospila . These results demonstrate that enhanced expression of vibA is sufficient for a nonantifungal isolate to obtain antifungal activity, implicating the critical role of VibA in antifungal compound production by epichloae endophytes.

scholarly journals The Burkholderia contaminans MS14ocfCGene Encodes a Xylosyltransferase for Production of the Antifungal Occidiofungin

2013 ◽  
Vol 79 (9) ◽  
pp. 2899-2905 ◽  
Author(s):  
Kuan-Chih Chen ◽  
Akshaya Ravichandran ◽  
Adam Guerrero ◽  
Peng Deng ◽  
Sonya M. Baird ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Gene Cluster ◽  
Mass Spectroscopy ◽  
Type Strain ◽  
Wild Type Strain ◽  
Activity Level ◽  
Antifungal Compound ◽  
Wild Type ◽  
Content Type ◽  
Burkholderia Contaminans

ABSTRACTBurkholderia contaminansstrain MS14 produces the antifungal compound occidiofungin, which is responsible for significant antifungal activities against a broad range of plant and animal fungal pathogens. Occidiofungin is a cyclic glycolipopeptide made up of eight amino acids and one xylose. A 56-kbocfgene cluster was determined to be essential for occidiofungin production. In this study, theocfCgene, which is located downstream ofocfDand upstream of theocfBgene in theocfgene cluster, was examined. Antifungal activity of theocfCgene mutant MS14KC1 was reduced against the indicator fungusGeotrichum candidumcompared with that of the wild-type strain. Furthermore, the analysis of the protein sequence suggests that theocfCgene encodes a glycosyltransferase. Biochemical analyses using nuclear magnetic resonance (NMR) and mass spectroscopy revealed that theocfCmutant produced the occidiofungin without the xylose. The purifiedocfCmutant MS14KC1 product had a level of bioactivity similar to that of the wild-type product. The revertant MS14KC1-R of theocfCmutant produced the same antifungal activity level on plate assays and the same antifungal compound based on high-performance liquid chromatography (HPLC) and mass spectroscopy analysis as wild-type strain MS14. Collectively, the study demonstrates that theocfCgene encodes a glycosyltransferase responsible to add a xylose to the occidiofungin molecule and that the presence of the xylose is not important for antifungal activity againstCandidaspecies. The finding provides a novel variant for future studies aimed at evaluating its use for inhibiting clinical and agricultural fungi, and the finding could also simplify the chemical synthesis of occidiofungin variants.

scholarly journals Redox Regulation of an AP-1-Like Transcription Factor, YapA, in the Fungal Symbiont Epichloë festucae

2013 ◽  
Vol 12 (10) ◽  
pp. 1335-1348 ◽  
Author(s):  
Gemma M. Cartwright ◽  
Barry Scott
Keyword(s):  
Oxidative Stress ◽  
Transcription Factor ◽  
Redox Regulation ◽  
Bzip Transcription Factor ◽  
Wild Type ◽  
In Planta ◽  
Content Type ◽  
Epichloë Festucae ◽  
Whole Plant ◽  
Cellular Phenotypes

ABSTRACTOne of the central regulators of oxidative stress inSaccharomyces cerevisiaeis Yap1, a bZIP transcription factor of the AP-1 family. In unstressed cells, Yap1 is reduced and cytoplasmic, but in response to oxidative stress, it becomes oxidized and accumulates in the nucleus. To date, there have been no reports on the role of AP-1-like transcription factors in symbiotic fungi. An ortholog of Yap1, named YapA, was identified in the genome of the grass symbiontEpichloë festucaeand shown to complement anS. cerevisiaeΔyap1mutant. Hyphae of theE. festucaeΔyapAstrain were sensitive to menadione and diamide but resistant to H2O2, KO2, andtert-butyl hydroperoxide (t-BOOH). In contrast, conidia of the ΔyapAstrain were very sensitive to H2O2and failed to germinate. Using a PcatA-eGFPdegron-tagged reporter, YapA was shown to be required for expression of a spore-specific catalase gene,catA. Although YapA-EGFP localized to the nucleus in response to host reactive oxygen species during seedling infection, there was no difference in whole-plant and cellular phenotypes of plants infected with the ΔyapAstrain compared to the wild-type strain. Homologs of theS. cerevisiaeandSchizosaccharomyces pomberedox-sensing proteins (Gpx3 and Tpx1, respectively) did not act as redox sensors for YapA inE. festucae. In response to oxidative stress, YapA-EGFP localized to the nuclei ofE. festucaeΔgpxC, ΔtpxA, and ΔgpxCΔtpxAcells to the same degree as that in wild-type cells. These results show thatE. festucaehas a robust system for countering oxidative stress in culture andin plantabut that Gpx3- or Tpx1-like thiol peroxidases are dispensable for activation of YapA.

scholarly journals Phagocytes from Mice Lacking the Sts Phosphatases Have an Enhanced Antifungal Response to Candida albicans

mBio ◽  
2018 ◽  
Vol 9 (4) ◽  
Author(s):  
David Frank ◽  
Shamoon Naseem ◽  
Gian Luigi Russo ◽  
Cindy Li ◽  
Kaustubh Parashar ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Immune Response ◽  
Candida Albicans ◽  
Tyrosine Kinase ◽  
Critical Role ◽  
Inflammasome Activation ◽  
Wild Type ◽  
Content Type ◽  
Enhanced Production ◽  
Immunological Mechanisms

ABSTRACT Mice lacking expression of the homologous phosphatases Sts-1 and Sts-2 (Sts−/− mice) are resistant to disseminated candidiasis caused by the fungal pathogen Candida albicans. To better understand the immunological mechanisms underlying the enhanced resistance of Sts−/− mice, we examined the kinetics of fungal clearance at early time points. In contrast to the rapid C. albicans growth seen in normal kidneys during the first 24 h postinfection, we observed a reduction in kidney fungal CFU within Sts−/− mice beginning at 12 to 18 h postinfection. This corresponds to the time period when large numbers of innate leukocytes enter the renal environment to counter the infection. Because phagocytes of the innate immune system are important for host protection against pathogenic fungi, we evaluated responses of bone marrow leukocytes. Relative to wild-type cells, Sts−/− marrow monocytes and bone marrow-derived dendritic cells (BMDCs) displayed a heightened ability to inhibit C. albicans growth ex vivo. This correlated with significantly enhanced production of reactive oxygen species (ROS) by Sts−/− BMDCs downstream of Dectin-1, a C-type lectin receptor that plays a critical role in stimulating host responses to fungi. We observed no visible differences in the responses of other antifungal effector pathways, including cytokine production and inflammasome activation, despite enhanced activation of the Syk tyrosine kinase downstream of Dectin-1 in Sts−/− cells. Our results highlight a novel mechanism regulating the immune response to fungal infections. Further understanding of this regulatory pathway could aid the development of therapeutic approaches to enhance protection against invasive candidiasis. IMPORTANCE Systemic candidiasis caused by fungal Candida species is becoming an increasingly serious medical problem for which current treatment is inadequate. Recently, the Sts phosphatases were established as key regulators of the host antifungal immune response. In particular, genetic inactivation of Sts significantly enhanced survival of mice infected intravenously with Candida albicans. The Sts−/− in vivo resistance phenotype is associated with reduced fungal burden and an absence of inflammatory lesions. To understand the underlying mechanisms, we studied phagocyte responses. Here, we demonstrate that Sts−/− phagocytes have heightened responsiveness to C. albicans challenge relative to wild-type cells. Our data indicate the Sts proteins negatively regulate phagocyte activation via regulating selective elements of the Dectin-1–Syk tyrosine kinase signaling axis. These results suggest that phagocytes lacking Sts respond to fungal challenge more effectively and that this enhanced responsiveness partially underlies the profound resistance of Sts−/− mice to systemic fungal challenge.

scholarly journals MicroRNA-29a Suppresses CD36 to Ameliorate High Fat Diet-Induced Steatohepatitis and Liver Fibrosis in Mice

Cells ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1298 ◽  
Author(s):  
Hung-Yu Lin ◽  
Feng-Sheng Wang ◽  
Ya-Ling Yang ◽  
Ying-Hsien Huang
Keyword(s):  
Transcription Factor ◽  
Liver Fibrosis ◽  
High Fat Diet ◽  
Critical Role ◽  
Luciferase Reporter ◽  
Hepatic Tissue ◽  
Wild Type ◽  
High Fat ◽  
Alcoholic Fatty Liver ◽  
Mesenchymal Transition

MicroRNA-29 (miR-29) has been shown to play a critical role in reducing inflammation and fibrosis following liver injury. Non-alcoholic fatty liver disease (NAFLD) occurs when fat is deposited (steatosis) in the liver due to causes other than excessive alcohol use and is associated with liver fibrosis. In this study, we asked whether miR-29a could reduce experimental high fat diet (HFD)-induced obesity and liver fibrosis in mice. We performed systematical expression analyses of miR-29a transgenic mice (miR-29aTg mice) and wild-type littermates subjected to HFD-induced NAFLD. The results demonstrated that increased miR-29a not only alleviated HFD-induced body weight gain but also subcutaneous, visceral, and intestinal fat accumulation and hepatocellular steatosis in mice. Furthermore, hepatic tissue in the miR-29aTg mice displayed a weak fibrotic matrix concomitant with low fibrotic collagen1α1 expression within the affected tissues compared to the wild-type (WT) mice fed the HFD diet. Increased miR-29a signaling also resulted in the downregulation of expression of the epithelial mesenchymal transition-executing transcription factor snail, mesenchymal markers vimentin, and such pro-inflammation markers as il6 and mcp1 within the liver tissue. Meanwhile, miR-29aTg-HFD mice exhibited significantly lower levels of peroxisome proliferator-activated receptor γ (PPARγ), mitochondrial transcription factor A TFAM, and mitochondria DNA content in the liver than the WT-HFD mice. An in vitro luciferase reporter assay further confirmed that miR-29a mimic transfection reduced fatty acid translocase CD36 expression in HepG2 cells. Conclusion: Our data provide new insights that miR-29a can improve HDF-induced obesity, hepatocellular steatosis, and fibrosis, as well as highlight the role of miR-29a in regulation of NAFLD.

scholarly journals Specific Midgut Region Controlling the Symbiont Population in an Insect-Microbe Gut Symbiotic Association

2013 ◽  
Vol 79 (23) ◽  
pp. 7229-7233 ◽  
Author(s):  
Jiyeun Kate Kim ◽  
Na Hyang Kim ◽  
Ho Am Jang ◽  
Yoshitomo Kikuchi ◽  
Chan-Hee Kim ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Molecular Basis ◽  
Critical Role ◽  
Symbiotic Bacteria ◽  
Symbiotic Association ◽  
Control Mechanisms ◽  
Content Type ◽  
Bean Bug ◽  
Gut Symbionts ◽  
Series Of Experiments

ABSTRACTMany insects possess symbiotic bacteria that affect the biology of the host. The level of the symbiont population in the host is a pivotal factor that modulates the biological outcome of the symbiotic association. Hence, the symbiont population should be maintained at a proper level by the host's control mechanisms. Several mechanisms for controlling intracellular symbionts of insects have been reported, while mechanisms for controlling extracellular gut symbionts of insects are poorly understood. The bean bugRiptortus pedestrisharbors a betaproteobacterial extracellular symbiont of the genusBurkholderiain the midgut symbiotic organ designated the M4 region. We found that the M4B region, which is directly connected to the M4 region, also harborsBurkholderiasymbiont cells, but the symbionts therein are mostly dead. A series of experiments demonstrated that the M4B region exhibits antimicrobial activity, and the antimicrobial activity is specifically potent against theBurkholderiasymbiont but not the culturedBurkholderiaand other bacteria. The antimicrobial activity of the M4B region was detected in symbiotic host insects, reaching its highest point at the fifth instar, but not in aposymbiotic host insects, which suggests the possibility of symbiont-mediated induction of the antimicrobial activity. This antimicrobial activity was not associated with upregulation of antimicrobial peptides of the host. Based on these results, we propose that the M4B region is a specialized gut region ofR. pedestristhat plays a critical role in controlling the population of theBurkholderiagut symbiont. The molecular basis of the antimicrobial activity is of great interest and deserves future study.

scholarly journals SAGA/ADA Complex Subunit Ada2 Is Required for Cap1- but Not Mrr1-Mediated Upregulation of the Candida albicans Multidrug Efflux PumpMDR1

2014 ◽  
Vol 58 (9) ◽  
pp. 5102-5110 ◽  
Author(s):  
Bernardo Ramírez-Zavala ◽  
Selene Mogavero ◽  
Eva Schöller ◽  
Christoph Sasse ◽  
P. David Rogers ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Candida Albicans ◽  
Efflux Pump ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Gain Of Function ◽  
Content Type ◽  
Zinc Cluster ◽  
Fluconazole Resistant

ABSTRACTOverexpression of the multidrug efflux pumpMDR1is one mechanism by which the pathogenic yeastCandida albicansdevelops resistance to the antifungal drug fluconazole. The constitutive upregulation ofMDR1in fluconazole-resistant, clinicalC. albicansisolates is caused by gain-of-function mutations in the zinc cluster transcription factor Mrr1. It has been suggested that Mrr1 activatesMDR1transcription by recruiting Ada2, a subunit of the SAGA/ADA coactivator complex. However,MDR1expression is also regulated by the bZIP transcription factor Cap1, which mediates the oxidative stress response inC. albicans. Here, we show that a hyperactive Mrr1 containing a gain-of-function mutation promotesMDR1overexpression independently of Ada2. In contrast, a C-terminally truncated, hyperactive Cap1 causedMDR1overexpression in a wild-type strain but only weakly in mutants lackingADA2. In the presence of benomyl or H2O2, compounds that induceMDR1expression in an Mrr1- and Cap1-dependent fashion,MDR1was upregulated with the same efficiency in wild-type andada2Δ cells. These results indicate that Cap1, but not Mrr1, recruits Ada2 to theMDR1promoter to induce the expression of this multidrug efflux pump and that Ada2 is not required forMDR1overexpression in fluconazole-resistantC. albicansstrains containing gain-of-function mutations in Mrr1.

scholarly journals SREBP-Dependent Triazole Susceptibility in Aspergillus fumigatus Is Mediated through Direct Transcriptional Regulation oferg11A(cyp51A)

2011 ◽  
Vol 56 (1) ◽  
pp. 248-257 ◽  
Author(s):  
Sara J. Blosser ◽  
Robert A. Cramer
Keyword(s):  
Aspergillus Fumigatus ◽  
Regulatory Element ◽  
Critical Role ◽  
Clinical Importance ◽  
Growth Defect ◽  
Ergosterol Biosynthesis ◽  
Wild Type ◽  
Transcript Levels ◽  
Content Type ◽  
Conditional Expression

ABSTRACTAs triazole antifungal drug resistance during invasiveAspergillus fumigatusinfection has become more prevalent, the need to understand mechanisms of resistance inA. fumigatushas increased. The presence of twoerg11(cyp51) genes inAspergillusspp. is hypothesized to account for the inherent resistance of this mold to the triazole fluconazole (FLC). Recently, anA. fumigatusnull mutant of a transcriptional regulator in the sterol regulatory element binding protein (SREBP) family, the ΔsrbAstrain, was found to have increased susceptibility to FLC and voriconazole (VCZ). In this study, we examined the mechanism engendering the observed increase inA. fumigatustriazole susceptibility in the absence of SrbA. We observed a significant reduction in theerg11Atranscript in the ΔsrbAstrain in response to FLC and VCZ. Transcript levels oferg11Bwere also reduced but not to the extent oferg11A. Interestingly,erg11Atranscript levels increased upon extended VCZ, but not FLC, exposure. Construction of anerg11Aconditional expression strain in the ΔsrbAstrain was able to restoreerg11Atranscript levels and, consequently, wild-type MICs to the triazole FLC. The VCZ MIC was also partially restored upon increasederg11Atranscript levels; however, total ergosterol levels remained significantly reduced compared to those of the wild type. Induction of theerg11Aconditional strain did not restore the hypoxia growth defect of the ΔsrbAstrain. Taken together, our results demonstrate a critical role for SrbA-mediated regulation of ergosterol biosynthesis and triazole drug interactions inA. fumigatusthat may have clinical importance.

scholarly journals ClpP is required for proteolytic regulation of type II toxin–antitoxin systems and persister cell formation in Streptococcus mutans

2019 ◽  
Vol 1 (8) ◽  
Author(s):  
Xiao-Lin Tian ◽  
Miao Li ◽  
Zachariah Scinocca ◽  
Heather Rutherford ◽  
Yung-Hua Li
Keyword(s):  
Streptococcus Mutans ◽  
Type Species ◽  
Critical Role ◽  
Cell Formation ◽  
Type Ii ◽  
Wild Type ◽  
Content Type ◽  
Link Type ◽  
Viability Assay ◽  
Persister Cell

The type II toxin–antitoxin (TA) modules, mazEF and relBE, in Streptococcus mutans have been implicated in stress response, antibiotic tolerance and persister cell formation. However, how S. mutans regulates these systems to prevent unwanted toxin activation and persister cell formation is unclear. In this study, we provide evidence that ClpP is required for the proteolytic regulation of these TA systems and persister cell formation in S. mutans following antibiotic challenge. A persister viability assay showed that S. mutans UA159 (WT) formed a larger quantity of persister cells than its isogenic mutant ΔclpP following antibiotic challenge. However, the lux reporter assay revealed that clpP deletion did not affect the transcriptional levels of mazEF and relBE, since no significant differences (P>0.05) in the reporter activities were detected between the wild-type and ΔclpP background. Instead, all antibiotics tested at a sub-minimum inhibitory concentration (sub-MIC) induced transcriptional levels of mazEF and relBE operons. We then examined the protein profiles of His-tagged MazE and RelB proteins in the UA159 and ΔclpP backgrounds by Western blotting analysis. The results showed that S. mutans strains grown under non-stress conditions expressed very low but detectable levels of MazE and RelB antitoxin proteins. Antibiotics at sub-MICs induced the levels of the MazE and RelB proteins, but the protein levels decreased rapidly in the wild-type background. In contrast, a stable level of MazE and RelB proteins could be detected in the ΔclpP mutant background, suggesting that both proteins accumulated in the ΔclpP mutant. We conclude that ClpP is required for the proteolytic regulation of cellular levels of the MazE and RelB antitoxins in S. mutans , which may play a critical role in modulating the TA activities and persister cell formation of this organism following antibiotic challenge.

scholarly journals Complete Genome Sequence of a Wild-Type Isolate of Caulobacter vibrioides Strain CB1

2018 ◽  
Vol 7 (12) ◽  
Author(s):  
Derrick C. Scott ◽  
Kiesha Wilson ◽  
Keshawn Ross ◽  
Damyen Ingram ◽  
Tajah Lewter ◽  
...  
Keyword(s):  
Genome Sequence ◽  
Dna Sequences ◽  
Complete Genome Sequence ◽  
Complete Genome ◽  
Genome Rearrangement ◽  
Gc Content ◽  
Wild Type ◽  
Content Type ◽  
Type Isolate

The complete genome sequence of Caulobacter vibrioides strain CB1 consists of a chromosome of 4,137,285 bp, with a GC content of 67.2% and 3,990 coding DNA sequences. This strain contains the typical genome rearrangement that is characteristic of the Caulobacter strains that are currently sequenced.

scholarly journals 5-Lipoxygenase Negatively Regulates Th1 Response during Brucella abortus Infection in Mice

2015 ◽  
Vol 83 (3) ◽  
pp. 1210-1216 ◽  
Author(s):  
Júlia Silveira Fahel ◽  
Mariana Bueno de Souza ◽  
Marco Túlio Ribeiro Gomes ◽  
Patricia P. Corsetti ◽  
Natalia B. Carvalho ◽  
...  
Keyword(s):  
Brucella Abortus ◽  
Critical Role ◽  
Lipid Mediators ◽  
Negative Regulator ◽  
Host Responses ◽  
Interleukin 12 ◽  
Dependent Manner ◽  
Wild Type ◽  
Content Type ◽  
Deficient Mice

Brucella abortusis a Gram-negative bacterium that infects humans and cattle, causing a chronic inflammatory disease known as brucellosis. A Th1-mediated immune response plays a critical role in host control of this pathogen. Recent findings indicate contrasting roles for lipid mediators in host responses against infections. 5-Lipoxygenase (5-LO) is an enzyme required for the production of the lipid mediators leukotrienes and lipoxins. To determine the involvement of 5-LO in host responses toB. abortusinfection, we intraperitoneally infected wild-type and 5-LO-deficient mice and evaluated the progression of infection and concomitant expression of immune mediators. Here, we demonstrate thatB. abortusinduced the upregulation of 5-LO mRNA in wild-type mice. Moreover, this pathogen upregulated the production of the lipid mediators leukotriene B4and lipoxin A4in a 5-LO-dependent manner. 5-LO-deficient mice displayed lower bacterial burdens in the spleen and liver and less severe liver pathology, demonstrating an enhanced resistance to infection. Host resistance paralleled an increased expression of the proinflammatory mediators interleukin-12 (IL-12), gamma interferon (IFN-γ), and inducible nitric oxide synthase (iNOS) during the course of infection. Moreover, we demonstrated that 5-LO downregulated the expression of IL-12 in macrophages duringB. abortusinfection. Our results suggest that 5-LO has a major involvement inB. abortusinfection, by functioning as a negative regulator of the protective Th1 immune responses against this pathogen.

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