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 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.

scholarly journals The Multifunctional β-Oxidation Enzyme Is Required for Full Symptom Development by the Biotrophic Maize Pathogen Ustilago maydis

2006 ◽  
Vol 5 (12) ◽  
pp. 2047-2061 ◽  
Author(s):  
Jana Klose ◽  
James W. Kronstad
Keyword(s):  
Fatty Acids ◽  
Ustilago Maydis ◽  
Long Chain Fatty Acids ◽  
In Planta ◽  
Gene Encoding ◽  
Metabolic Role ◽  
Fungal Phytopathogen ◽  
Long Chain ◽  
Chain Fatty Acids

ABSTRACT The transition from yeast-like to filamentous growth in the biotrophic fungal phytopathogen Ustilago maydis is a crucial event for pathogenesis. Previously, we showed that fatty acids induce filamentation in U. maydis and that the resulting hyphal cells resemble the infectious filaments observed in planta. To explore the potential metabolic role of lipids in the morphological transition and in pathogenic development in host tissue, we deleted the mfe2 gene encoding the multifunctional enzyme that catalyzes the second and third reactions in β-oxidation of fatty acids in peroxisomes. The growth of the strains defective in mfe2 was attenuated on long-chain fatty acids and abolished on very-long-chain fatty acids. The mfe2 gene was not generally required for the production of filaments during mating in vitro, but loss of the gene blocked extensive proliferation of fungal filaments in planta. Consistent with this observation, mfe2 mutants exhibited significantly reduced virulence in that only 27% of infected seedlings produced tumors compared to 88% tumor production upon infection by wild-type strains. Similarly, a defect in virulence was observed in developing ears upon infection of mature maize plants. Specifically, the absence of the mfe2 gene delayed the development of teliospores within mature tumor tissue. Overall, these results indicate that the ability to utilize host lipids contributes to the pathogenic development of U. maydis.

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 Xylan Utilization Regulon in Xanthomonas citri pv. citri Strain 306: Gene Expression and Utilization of Oligoxylosides

2015 ◽  
Vol 81 (6) ◽  
pp. 2163-2172 ◽  
Author(s):  
V. Chow ◽  
D. Shantharaj ◽  
Y. Guo ◽  
G. Nong ◽  
G. V. Minsavage ◽  
...  
Keyword(s):  
Cell Wall ◽  
Citrus Canker ◽  
Glycoside Hydrolase Family ◽  
In Planta ◽  
Xanthomonas Citri ◽  
Plant Host ◽  
Gene Encoding ◽  
Content Type ◽  
Expression Of Genes ◽  
Genes Encoding

ABSTRACTXanthomonas citripv. citri strain 306 (Xcc306), a causative agent of citrus canker, produces endoxylanases that catalyze the depolymerization of cell wall-associated xylans. In the sequenced genomes of all plant-pathogenic xanthomonads, genes encoding xylanolytic enzymes are clustered in three adjacent operons. InXcc306, these consecutive operons contain genes encoding the glycoside hydrolase family 10 (GH10) endoxylanases Xyn10A and Xyn10C, theagu67gene, encoding a GH67 α-glucuronidase (Agu67), thexyn43Egene, encoding a putative GH43 α-l-arabinofuranosidase, and thexyn43Fgene, encoding a putative β-xylosidase. Recombinant Xyn10A and Xyn10C convert polymeric 4-O-methylglucuronoxylan (MeGXn) to oligoxylosides methylglucuronoxylotriose (MeGX3), xylotriose (X3), and xylobiose (X2).Xcc306 completely utilizes MeGXnpredigested with Xyn10A or Xyn10C but shows little utilization of MeGXn.Xcc306 with a deletion in the gene encoding α-glucuronidase (Xcc306 Δagu67) will not utilize MeGX3for growth, demonstrating the role of Agu67 in the complete utilization of GH10-digested MeGXn. Preferential growth on oligoxylosides compared to growth on polymeric MeGXnindicates that GH10 xylanases, either secreted byXcc306in plantaor produced by the plant host, generate oligoxylosides that are processed by Xyn10 xylanases and Agu67 residing in the periplasm. Coordinate induction by oligoxylosides ofxyn10,agu67,cirA, thetonBreceptor, and other genes within these three operons indicates that they constitute a regulon that is responsive to the oligoxylosides generated by the action ofXcc306 GH10 xylanases on MeGXn. The combined expression of genes in this regulon may allow scavenging of oligoxylosides derived from cell wall deconstruction, thereby contributing to the tissue colonization and/or survival ofXcc306 and, ultimately, to plant disease.

scholarly journals Short-Chain Fatty Acids Alter Metabolic and Virulence Attributes ofBorrelia burgdorferi

2018 ◽  
Vol 86 (9) ◽  
Author(s):  
Ying-Han Lin ◽  
Yue Chen ◽  
Trever C. Smith ◽  
S. L. Rajasekhar Karna ◽  
J. Seshu
Keyword(s):  
Growth Rates ◽  
Rna Binding ◽  
Protein Profile ◽  
Surface Protein ◽  
Short Chain Fatty Acids ◽  
Immunoblot Analysis ◽  
Short Chain ◽  
Mammalian Host ◽  
Content Type ◽  
C Terminus

ABSTRACTBorrelia burgdorferiresponds to a variety of host-derived factors and appropriately alters its gene expression for adaptation under different host-specific conditions. We previously showed that various levels of acetate, a short-chain fatty acid (SCFA), altered the protein profile ofB. burgdorferi. In this study, we determined the effects of other physiologically relevant SCFAs in the regulation of metabolic/virulence-associated proteins using mutant borrelial strains. No apparent increase in the synthesis of outer surface protein C (OspC) was noted when a carbon storage regulator A (csrAofB. burgdorferi, orcsrABb) mutant (mt) was propagated within dialysis membrane chambers implanted within rat peritoneal cavity, while the parental wild type (wt; B31-A3 strain) andcsrABbcis-complemented strain (ct) had increased OspC with a reciprocal reduction in OspA levels. Growth rates of wt, mt, ct, 7D (csrABbmutant lacking 7 amino acids at the C terminus), and 8S (csrABbwith site-specific changes altering its RNA-binding properties) borrelial strains were similar in the presence of acetate. Increased levels of propionate and butyrate reduced the growth rates of all strains tested, with mt and 8S exhibiting profound growth deficits at higher concentrations of propionate. Transcriptional levels ofrpoSandospCwere elevated on supplementation of SCFAs compared to those of untreated spirochetes. Immunoblot analysis revealed elevated levels of RpoS, OspC, and DbpA with increased levels of SCFAs. Physiological levels of SCFAs prevalent in select human and rodent fluids were synergistic with mammalian host temperature and pH to increase the levels of aforementioned proteins, which could impact the colonization ofB. burgdorferiduring the mammalian phase of infection.

scholarly journals Chitinases Are Essential for Cell Separation in Ustilago maydis

2015 ◽  
Vol 14 (9) ◽  
pp. 846-857 ◽  
Author(s):  
Thorsten Langner ◽  
Merve Öztürk ◽  
Sarah Hartmann ◽  
Stefan Cord-Landwehr ◽  
Bruno Moerschbacher ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Separation ◽  
Morphological Changes ◽  
Ustilago Maydis ◽  
Yeast Cells ◽  
In Planta ◽  
Fungal Cell ◽  
Content Type ◽  
Chitinolytic Enzymes ◽  
Complete Life Cycle

ABSTRACTChitin is an essential component of the fungal cell wall, providing rigidity and stability. Its degradation is mediated by chitinases and supposedly ensures the dynamic plasticity of the cell wall during growth and morphogenesis. Hence, chitinases should be particularly important for fungi with dramatic morphological changes, such asUstilago maydis. This smut fungus switches from yeast to filamentous growth for plant infection, proliferates as a myceliumin planta, and forms teliospores for spreading. Here, we investigate the contribution of its four chitinolytic enzymes to the different morphological changes during the complete life cycle in a comprehensive study of deletion strains combined with biochemical and cell biological approaches. Interestingly, two chitinases act redundantly in cell separation during yeast growth. They mediate the degradation of remnant chitin in the fragmentation zone between mother and daughter cell. In contrast, even the complete lack of chitinolytic activity does not affect formation of the infectious filament, infection, biotrophic growth, or teliospore germination. Thus, unexpectedly we can exclude a major role for chitinolytic enzymes in morphogenesis or pathogenicity ofU. maydis. Nevertheless, redundant activity of even two chitinases is essential for cell separation during saprophytic growth, possibly to improve nutrient access or spreading of yeast cells by wind or rain.

scholarly journals Biological Role of Pigment Production for the Bacterial Phytopathogen Pantoea stewartii subsp. stewartii

2012 ◽  
Vol 78 (19) ◽  
pp. 6859-6865 ◽  
Author(s):  
Mojtaba Mohammadi ◽  
Lindsey Burbank ◽  
M. Caroline Roper
Keyword(s):  
Sweet Corn ◽  
Insertion Site ◽  
Carotenoid Biosynthesis ◽  
Carotenoid Pigment ◽  
In Planta ◽  
Gene Encoding ◽  
Content Type ◽  
Pantoea Stewartii ◽  
Transposon Insertion ◽  
Stewart's Wilt

ABSTRACTPantoea stewartiisubsp.stewartii, the causal agent of Stewart's wilt of sweet corn, produces a yellow carotenoid pigment. A nonpigmented mutant was selected from a bank of mutants generated by random transposon mutagenesis. The transposon insertion site was mapped to thecrtBgene, encoding a putative phytoene synthase, an enzyme involved in the early steps of carotenoid biosynthesis. We demonstrate here that the carotenoid pigment imparts protection against UV radiation and also contributes to the complete antioxidant pathway ofP. stewartii. Moreover, production of this pigment is regulated by the EsaI/EsaR quorum-sensing system and significantly contributes to the virulence of the pathogenin planta.

scholarly journals The Effect of Fusarium verticillioides Fumonisins on Fatty Acids, Sphingolipids, and Oxylipins in Maize Germlings

2021 ◽  
Vol 22 (5) ◽  
pp. 2435
Author(s):  
Marzia Beccaccioli ◽  
Manuel Salustri ◽  
Valeria Scala ◽  
Matteo Ludovici ◽  
Andrea Cacciotti ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fusarium Verticillioides ◽  
Fungal Growth ◽  
Defense Responses ◽  
Ceramide Synthase ◽  
Ear Rot ◽  
In Planta ◽  
Disease Symptoms ◽  
The Impact

Fusarium verticillioides causes multiple diseases of Zea mays (maize) including ear and seedling rots, contaminates seeds and seed products worldwide with toxic chemicals called fumonisins. The role of fumonisins in disease is unclear because, although they are not required for ear rot, they are required for seedling diseases. Disease symptoms may be due to the ability of fumonisins to inhibit ceramide synthase activity, the expected cause of lipids (fatty acids, oxylipins, and sphingolipids) alteration in infected plants. In this study, we explored the impact of fumonisins on fatty acid, oxylipin, and sphingolipid levels in planta and how these changes affect F. verticillioides growth in maize. The identity and levels of principal fatty acids, oxylipins, and over 50 sphingolipids were evaluated by chromatography followed by mass spectrometry in maize infected with an F. verticillioides fumonisin-producing wild-type strain and a fumonisin-deficient mutant, after different periods of growth. Plant hormones associated with defense responses, i.e., salicylic and jasmonic acid, were also evaluated. We suggest that fumonisins produced by F. verticillioides alter maize lipid metabolism, which help switch fungal growth from a relatively harmless endophyte to a destructive necrotroph.

scholarly journals PacBio Amplicon Sequencing Method To Measure Pilin Antigenic Variation Frequencies of Neisseria gonorrhoeae

mSphere ◽  
2019 ◽  
Vol 4 (5) ◽  
Author(s):  
Egon A. Ozer ◽  
Lauren L. Prister ◽  
Shaohui Yin ◽  
Billy H. Ward ◽  
Stanimir Ivanov ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Antigenic Variation ◽  
Amplicon Sequencing ◽  
Common Mechanism ◽  
Macrophage Infection ◽  
Gene Encoding ◽  
Transmitted Infection ◽  
Variable Regions ◽  
Content Type ◽  
Strain Fa1090

ABSTRACT Gene diversification is a common mechanism pathogens use to alter surface structures to aid in immune avoidance. Neisseria gonorrhoeae uses a gene conversion-based diversification system to alter the primary sequence of the gene encoding the major subunit of the pilus, pilE. Antigenic variation occurs when one of the nonexpressed 19 silent copies donates part of its DNA sequence to pilE. We have developed a method using Pacific Biosciences (PacBio) amplicon sequencing and custom software to determine pilin antigenic variation frequencies. The program analyzes 37 variable regions across the strain FA1090 1-81-S2 pilE gene and can be modified to determine sequence variation from other starting pilE sequences or other diversity generation systems. Using this method, we measured pilin antigenic variation frequencies for various derivatives of strain FA1090 and showed we can also analyze pilin antigenic variation frequencies during macrophage infection. IMPORTANCE Diversity generation systems are used by many unicellular organism to provide subpopulations of cell with different properties that are available when needed. We have developed a method using the PacBio DNA sequencing technology and a custom computer program to analyze the pilin antigenic variation system of the organism that is the sole cause of the sexually transmitted infection, gonorrhea.

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