scholarly journals The Ustilago maydis Nit2 Homolog Regulates Nitrogen Utilization and Is Required for Efficient Induction of Filamentous Growth

2012 ◽  
Vol 11 (3) ◽  
pp. 368-380 ◽  
Author(s):  
Robin J. Horst ◽  
Christine Zeh ◽  
Alexandra Saur ◽  
Sophia Sonnewald ◽  
Uwe Sonnewald ◽  
...  
Keyword(s):  
Nitrogen Sources ◽  
Ustilago Maydis ◽  
Filamentous Growth ◽  
Phytopathogenic Fungi ◽  
Nitrogen Utilization ◽  
Content Type ◽  
Regulatory Strategy ◽  
Delayed Initiation ◽  
Efficient Induction ◽  
Positive Regulators

ABSTRACTNitrogen catabolite repression (NCR) is a regulatory strategy found in microorganisms that restricts the utilization of complex and unfavored nitrogen sources in the presence of favored nitrogen sources. In fungi, this concept has been best studied in yeasts and filamentous ascomycetes, where the GATA transcription factors Gln3p and Gat1p (in yeasts) and Nit2/AreA (in ascomycetes) constitute the main positive regulators of NCR. The reason why functional Nit2 homologs of some phytopathogenic fungi are required for full virulence in their hosts has remained elusive. We have identified the Nit2 homolog in the basidiomycetous phytopathogenUstilago maydisand show that it is a major, but not the exclusive, positive regulator of nitrogen utilization. By transcriptome analysis of sporidia grown on artificial media devoid of favored nitrogen sources, we show that only a subset of nitrogen-responsive genes are regulated by Nit2, including the Gal4-like transcription factor Ton1 (a target of Nit2). Ustilagic acid biosynthesis is not under the control of Nit2, while nitrogen starvation-induced filamentous growth is largely dependent on functional Nit2.nit2deletion mutants show the delayed initiation of filamentous growth on maize leaves and exhibit strongly compromised virulence, demonstrating that Nit2 is required to efficiently initiate the pathogenicity program ofU. maydis.

scholarly journals Defects in Mitochondrial and Peroxisomal β-Oxidation Influence Virulence in the Maize Pathogen Ustilago maydis

2012 ◽  
Vol 11 (8) ◽  
pp. 1055-1066 ◽  
Author(s):  
Matthias Kretschmer ◽  
Jana Klose ◽  
James W. Kronstad
Keyword(s):  
Ustilago Maydis ◽  
Short Chain Fatty Acids ◽  
Phytopathogenic Fungi ◽  
Metabolic Adaptation ◽  
In Planta ◽  
Gene Encoding ◽  
Disease Symptoms ◽  
Content Type ◽  
C Terminus ◽  
Fungal Phytopathogens

ABSTRACTAn understanding of metabolic adaptation during the colonization of plants by phytopathogenic fungi is critical for developing strategies to protect crops. Lipids are abundant in plant tissues, and fungal phytopathogens in the phylum basidiomycota possess both peroxisomal and mitochondrial β-oxidation pathways to utilize this potential carbon source. Previously, we demonstrated a role for the peroxisomal β-oxidation enzyme Mfe2 in the filamentous growth, virulence, and sporulation of the maize pathogenUstilago maydis. However,mfe2mutants still caused disease symptoms, thus prompting a more detailed investigation of β-oxidation. We now demonstrate that a defect in thehad1gene encoding hydroxyacyl coenzyme A dehydrogenase for mitochondrial β-oxidation also influences virulence, although its paralog,had2, makes only a minor contribution. Additionally, we identified a gene encoding a polypeptide with similarity to the C terminus of Mfe2 and designated it Mfe2b; this gene makes a contribution to virulence only in the background of anmfe2Δ mutant. We also show that short-chain fatty acids induce cell death inU. maydisand that a block in β-oxidation leads to toxicity, likely because of the accumulation of toxic intermediates. Overall, this study reveals that β-oxidation has a complex influence on the formation of disease symptoms byU. maydisthat includes potential metabolic contributions to proliferationin plantaand an effect on virulence-related morphogenesis.

scholarly journals Diverse Nitrogen Sources in Seminal Fluid Act in Synergy To Induce Filamentous Growth of Candida albicans

2015 ◽  
Vol 81 (8) ◽  
pp. 2770-2780 ◽  
Author(s):  
Francisco J. Alvarez ◽  
Kicki Ryman ◽  
Cornelis Hooijmaijers ◽  
Vincent Bulone ◽  
Per O. Ljungdahl
Keyword(s):  
Candida Albicans ◽  
Seminal Fluid ◽  
Pathogenic Fungus ◽  
Nitrogen Sources ◽  
Filamentous Growth ◽  
Vaginal Fluid ◽  
Content Type ◽  
Intermittent Contact ◽  
Induced Changes

ABSTRACTThe pathogenic fungusCandida albicansis the leading cause of vulvovaginal candidiasis (VVC). VVC represents a major quality-of-life issue for women during their reproductive years, a stage of life where the vaginal epithelium is subject to periodic hormonally induced changes associated with menstruation and concomitant exposure to serum as well as potential intermittent contact with seminal fluid. Seminal fluid potently triggersCandida albicansto switch from yeastlike to filamentous modes of growth, a developmental response tightly linked to virulence. Conversely, vaginal fluid inhibits filamentation. Here, we used artificial formulations of seminal and vaginal fluids that faithfully mimic genuine fluids to assess the contribution of individual components within these fluids to filamentation. The high levels of albumin, amino acids, andN-acetylglucosamine in seminal fluid act synergistically as potent inducers of filamentous growth, even at atmospheric levels of CO2and reduced temperatures (30°C). Using a simplifiedin vitromodel that mimics the natural introduction of seminal fluid into the vulvovaginal environment, a pulse of artificial seminal fluid (ASF) was found to exert an enduring potential to overcome the inhibitory efficacy of artificial vaginal fluid (AVF) on filamentation. These findings suggest that a transient but substantial change in the nutrient levels within the vulvovaginal environment during unprotected coitus can induce residentC. albicanscells to engage developmental programs associated with virulent growth.

scholarly journals Lipid-induced filamentous growth in Ustilago maydis

2004 ◽  
Vol 52 (3) ◽  
pp. 823-835 ◽  
Author(s):  
Jana Klose ◽  
Mário Moniz De Sá ◽  
James W. Kronstad
Keyword(s):  
Ustilago Maydis ◽  
Filamentous Growth

scholarly journals A Mannose Family Phosphotransferase System Permease and Associated Enzymes Are Required for Utilization of Fructoselysine and Glucoselysine in Salmonella enterica Serovar Typhimurium

2015 ◽  
Vol 197 (17) ◽  
pp. 2831-2839 ◽  
Author(s):  
Katherine A. Miller ◽  
Robert S. Phillips ◽  
Paul B. Kilgore ◽  
Grady L. Smith ◽  
Timothy R. Hoover
Keyword(s):  
Nitrogen Source ◽  
Nitrogen Sources ◽  
Maillard Reaction Products ◽  
Reaction Products ◽  
Phosphotransferase System ◽  
Carbon And Nitrogen Sources ◽  
Content Type ◽  
Carbon And Nitrogen ◽  
Serovar Typhimurium ◽  
Food Borne Illness

ABSTRACTSalmonella entericserovar Typhimurium, a major cause of food-borne illness, is capable of using a variety of carbon and nitrogen sources. Fructoselysine and glucoselysine are Maillard reaction products formed by the reaction of glucose or fructose, respectively, with the ε-amine group of lysine. We report here thatS. Typhimurium utilizes fructoselysine and glucoselysine as carbon and nitrogen sources via a mannose family phosphotransferase (PTS) encoded bygfrABCD(glucoselysine/fructoselysine PTS components EIIA, EIIB, EIIC, and EIID; locus numbers STM14_5449 to STM14_5454 inS. Typhimurium 14028s). Genes coding for two predicted deglycases within thegfroperon,gfrEandgfrF, were required for growth with glucoselysine and fructoselysine, respectively. GfrF demonstrated fructoselysine-6-phosphate deglycase activity in a coupled enzyme assay. The biochemical and genetic analyses were consistent with a pathway in which fructoselysine and glucoselysine are phosphorylated at the C-6 position of the sugar by the GfrABCD PTS as they are transported across the membrane. The resulting fructoselysine-6-phosphate and glucoselysine-6-phosphate subsequently are cleaved by GfrF and GfrE to form lysine and glucose-6-phosphate or fructose-6-phosphate. Interestingly, althoughS. Typhimurium can use lysine derived from fructoselysine or glucoselysine as a sole nitrogen source, it cannot use exogenous lysine as a nitrogen source to support growth. Expression ofgfrABCDEFwas dependent on the alternative sigma factor RpoN (σ54) and an RpoN-dependent LevR-like activator, which we designated GfrR.IMPORTANCESalmonellaphysiology has been studied intensively, but there is much we do not know regarding the repertoire of nutrients these bacteria are able to use for growth. This study shows that a previously uncharacterized PTS and associated enzymes function together to transport and catabolize fructoselysine and glucoselysine. Knowledge of the range of nutrients thatSalmonellautilizes is important, as it could lead to the development of new strategies for reducing the load ofSalmonellain food animals, thereby mitigating its entry into the human food supply.

scholarly journals Insight into phenotypic and genotypic differences between vaginal Lactobacillus crispatus BC5 and Lactobacillus gasseri BC12 to unravel nutritional and stress factors influencing their metabolic activity

2021 ◽  
Vol 7 (6) ◽  
Author(s):  
Paolo Emidio Costantini ◽  
Andrea Firrincieli ◽  
Stefano Fedi ◽  
Carola Parolin ◽  
Carlo Viti ◽  
...  
Keyword(s):  
Type Species ◽  
Carbon Sources ◽  
Nitrogen Sources ◽  
Stress Factors ◽  
Genotypic Differences ◽  
Phenotype Microarray ◽  
Genetic Traits ◽  
Content Type ◽  
Phenotypic Profile ◽  
Link Type

The vaginal microbiota, normally characterized by lactobacilli presence, is crucial for vaginal health. Members belonging to L. crispatus and L. gasseri species exert crucial protective functions against pathogens, although a total comprehension of factors that influence their dominance in healthy women is still lacking. Here we investigated the complete genome sequence and comprehensive phenotypic profile of L. crispatus strain BC5 and L. gasseri strain BC12, two vaginal strains featured by anti-bacterial and anti-viral activities. Phenotype microarray (PM) results revealed an improved capacity of BC5 to utilize different carbon sources as compared to BC12, although some specific carbon sources that can be associated to the human diet were only metabolized by BC12, i.e. uridine, amygdalin, tagatose. Additionally, the two strains were mostly distinct in the capacity to utilize the nitrogen sources under analysis. On the other hand, BC12 showed tolerance/resistance towards twice the number of stressors (i.e. antibiotics, toxic metals etc.) with respect to BC5. The divergent phenotypes observed in PM were supported by the identification in either BC5 or BC12 of specific genetic determinants that were found to be part of the core genome of each species. The PM results in combination with comparative genome data provide insights into the possible environmental factors and genetic traits supporting the predominance of either L. crispatus BC5 or L. gasseri BC12 in the vaginal niche, giving also indications for metabolic predictions at the species level.

scholarly journals British law on corporate bribery

2015 ◽  
Vol 22 (1) ◽  
pp. 16-27 ◽  
Author(s):  
Jonathan Mukwiri
Keyword(s):  
Criminal Liability ◽  
Company Law ◽  
Content Type ◽  
Secondary Sources ◽  
Regulatory Strategy ◽  
Regulatory Approach ◽  
Corporate Criminal Liability ◽  
Corporate Liability ◽  
A Company

Purpose – This paper aims to assess the effectiveness of the Bribery Act 2010 in curbing corporate bribery. Design/methodology/approach – The paper takes a doctrinal focus in assessing UK bribery law using both primary and secondary sources. Findings – This paper finds that the effectiveness of the Bribery Act 2010 in curbing bribery lies in its approach of changing the basis for corporate criminal liability from focusing on the guilt of personnel within the company to focusing on the quality of the system governing the activities of the company. Companies have to address the risks of bribery or risk facing liability for failure to prevent bribery. With its regulatory approach to corporate liability, coupled with its extraterritorial reach, the Bribery Act is likely to change business cultures that facilitate bribery, thereby proving an effective law to corporate bribes. Originality/value – This paper highlights the deficiency of earlier laws in tackling corporate bribery, examines the crime of bribery from a company law perspective and argues that the regulatory strategy in the Bribery Act is likely to be an effective tool against bribery.

scholarly journals Dal81 Regulates Expression of Arginine Metabolism Genes inCandida parapsilosis

mSphere ◽  
2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Siobhan A. Turner ◽  
Qinxi Ma ◽  
Mihaela Ola ◽  
Kontxi Martinez de San Vicente ◽  
Geraldine Butler
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Pathogenic Fungus ◽  
Nitrogen Sources ◽  
Nitrogen Utilization ◽  
Nitrogen Regulation ◽  
Transcriptional Level ◽  
Pathogenic Yeast ◽  
Secondary Sources ◽  
Expression Of Genes ◽  
Maximal Induction

ABSTRACTFungi can use a wide variety of nitrogen sources. In the absence of preferred sources such as ammonium, glutamate, and glutamine, secondary sources, including most other amino acids, are used. Expression of the nitrogen utilization pathways is very strongly controlled at the transcriptional level. Here, we investigated the regulation of nitrogen utilization in the pathogenic yeastCandida parapsilosis. We found that the functions of many regulators are conserved with respect toSaccharomyces cerevisiaeand other fungi. For example, the core GATA activatorsGAT1andGLN3have a conserved role innitrogencataboliterepression (NCR). There is one ortholog ofGZF3andDAL80, which represses expression of genes in preferred nitrogen sources. The regulatorsPUT3andUGA3are required for metabolism of proline and γ-aminobutyric acid (GABA), respectively. However, the role of the Dal81 transcription factor is distinctly different. InS. cerevisiae, Dal81 is a positive regulator of acquisition of nitrogen from GABA, allantoin, urea, and leucine, and it is required for maximal induction of expression of the relevant pathway genes. InC. parapsilosis, induction of GABA genes is independent of Dal81, and deletingDAL81has no effect on acquisition of nitrogen from GABA or allantoin. Instead, Dal81 represses arginine synthesis during growth under preferred nitrogen conditions.IMPORTANCEUtilization of nitrogen by fungi is controlled bynitrogencataboliterepression (NCR). Expression of many genes is switched off during growth on nonpreferred nitrogen sources. Gene expression is regulated through a combination of activation and repression. Nitrogen regulation has been studied best in the model yeastSaccharomyces cerevisiae. We found that although many nitrogen regulators have a conserved function inSaccharomycesspecies, some do not. The Dal81 transcriptional regulator has distinctly different functions inS. cerevisiaeandC. parapsilosis. In the former, it regulates utilization of nitrogen from GABA and allantoin, whereas in the latter, it regulates expression of arginine synthesis genes. Our findings make an important contribution to our understanding of nitrogen regulation in a human-pathogenic fungus.

Streptomyces botrytidirepellens sp. nov., a novel actinomycete with antifungal activity against Botrytis cinerea

2021 ◽  
Vol 71 (9) ◽  
Author(s):  
Mengqi Jiang ◽  
Xi Xu ◽  
Jia Song ◽  
Dongmei Li ◽  
Liyuan Han ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Botrytis Cinerea ◽  
Gene Clusters ◽  
Gray Mold ◽  
Phytopathogenic Fungi ◽  
Antagonistic Effect ◽  
Economic Losses ◽  
Content Type ◽  
Desferrioxamine B ◽  
Cell Free Filtrate

The fungal pathogen Botrytis cinerea is the causal agent of devastating gray mold diseases in many economically important fruits, vegetables, and flowers, leading to serious economic losses worldwide. In this study, a novel actinomycete NEAU-LD23T exhibiting antifungal activity against B. cinerea was isolated, and its taxonomic position was evaluated using a polyphasic approach. Based on the genotypic, phenotypic and chemotaxonomic data, it is concluded that the strain represents a novel species within the genus Streptomyces , for which the name Streptomyces botrytidirepellens sp. nov. is proposed. The type strain is NEAU-LD23T (=CCTCC AA 2019029T=DSM 109824T). In addition, strain NEAU-LD23T showed a strong antagonistic effect against B. cinerea (82.6±2.5%) and varying degrees of inhibition on nine other phytopathogenic fungi. Both cell-free filtrate and methanol extract of mycelia of strain NEAU-LD23T significantly inhibited mycelial growth of B. cinerea. To preliminarily explore the antifungal mechanisms, the genome of strain NEAU-LD23T was sequenced and analyzed. AntiSMASH analysis led to the identification of several gene clusters responsible for the biosynthesis of bioactive secondary metabolites with antifungal activity, including 9-methylstreptimidone, echosides, anisomycin, coelichelin and desferrioxamine B. Overall, this research provided us an excellent strain with considerable potential to use for biological control of tomato gray mold.

scholarly journals Investigation of Malic Acid Production in Aspergillus oryzae under Nitrogen Starvation Conditions

2013 ◽  
Vol 79 (19) ◽  
pp. 6050-6058 ◽  
Author(s):  
Christoph Knuf ◽  
Intawat Nookaew ◽  
Stephen H. Brown ◽  
Michael McCulloch ◽  
Alan Berry ◽  
...  
Keyword(s):  
Malic Acid ◽  
Acid Production ◽  
Large Scale ◽  
High Capacity ◽  
Nitrogen Sources ◽  
Building Blocks ◽  
Close Relative ◽  
Biotechnological Production ◽  
Content Type ◽  
The One

ABSTRACTMalic acid has great potential for replacing petrochemical building blocks in the future. For this application, high yields, rates, and titers are essential in order to sustain a viable biotechnological production process. Natural high-capacity malic acid producers like the malic acid producerAspergillus flavushave so far been disqualified because of special growth requirements or the production of mycotoxins. AsA. oryzaeis a very close relative or even an ecotype ofA. flavus, it is likely that its high malic acid production capabilities with a generally regarded as safe (GRAS) status may be combined with already existing large-scale fermentation experience. In order to verify the malic acid production potential, two wild-type strains, NRRL3485 and NRRL3488, were compared in shake flasks. As NRRL3488 showed a volumetric production rate twice as high as that of NRRL3485, this strain was selected for further investigation of the influence of two different nitrogen sources on malic acid secretion. The cultivation in lab-scale fermentors resulted in a higher final titer, 30.27 ± 1.05 g liter−1, using peptone than the one of 22.27 ± 0.46 g liter−1obtained when ammonium was used. Through transcriptome analysis, a binding site similar to the one of theSaccharomyces cerevisiaeyeast transcription factor Msn2/4 was identified in the upstream regions of glycolytic genes and the cytosolic malic acid production pathway from pyruvate via oxaloacetate to malate, which suggests that malic acid production is a stress response. Furthermore, the pyruvate carboxylase reaction was identified as a target for metabolic engineering, after it was confirmed to be transcriptionally regulated through the correlation of intracellular fluxes and transcriptional changes.

scholarly journals The Unfolded Protein Response Regulates Pathogenic Development of Ustilago maydis by Rok1-Dependent Inhibition of Mating-Type Signaling

mBio ◽  
2019 ◽  
Vol 10 (6) ◽  
Author(s):  
Lara Schmitz ◽  
Melina Ayaka Schwier ◽  
Kai Heimel
Keyword(s):  
Unfolded Protein Response ◽  
Mating Type ◽  
Ustilago Maydis ◽  
Mitogen Activated Protein Kinase ◽  
In Planta ◽  
Fungal Virulence ◽  
Content Type ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

ABSTRACT Fungal pathogens require the unfolded protein response (UPR) to maintain protein homeostasis of the endoplasmic reticulum (ER) during pathogenic development. In the corn smut fungus Ustilago maydis, pathogenic development is controlled by the a and b mating-type loci. The UPR is specifically activated after plant penetration and required for efficient secretion of effectors and suppression of the plant defense response. The interaction between the UPR regulator Cib1 and the central developmental regulator Clp1 modulates the pathogenic program and triggers fungal colonization of the host plant. By contrast, when activated before plant penetration, the UPR interferes with fungal virulence by reducing expression of bE and bW, the central regulators of pathogenic development encoded by the b mating-type locus. Here, we show that this inhibitory effect results from UPR-mediated suppression of the pheromone response pathway upstream of the b regulatory network. UPR activity prompts dephosphorylation of the pheromone-responsive mitogen-activated protein kinase (MAPK) Kpp2, reducing activity of the pheromone response factor Prf1 that regulates expression of bE and bW. Deletion of the dual specificity phosphatase rok1 fully suppressed UPR-dependent inhibition of Kpp2 phosphorylation, formation of infectious filaments, and fungal virulence. Rok1 determines the activity of mating-type signaling pathways and thus the degree of fungal virulence. We propose that UPR-dependent regulation of Rok1 aligns ER physiology with fungal aggressiveness and effector gene expression during biotrophic growth of U. maydis in the host plant. IMPORTANCE The unfolded protein response (UPR) is crucial for endoplasmic reticulum (ER) homeostasis and disease development in fungal pathogens. In the plant-pathogenic fungus Ustilago maydis, the UPR supports fungal proliferation in planta and effector secretion for plant defense suppression. In this study, we uncovered that UPR activity, which is normally restricted to the biotrophic stage in planta, inhibits mating and the formation of infectious filaments by Rok1-dependent dephosphorylation of the pheromone responsive mitogen-activated protein kinase (MAPK) Kpp2. This observation is relevant for understanding how the fungal virulence program is regulated by cellular physiology. UPR-mediated control of mating-type signaling pathways predicts that effector gene expression and the virulence potential are controlled by ER stress levels.

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