scholarly journals The tail domain of the Aspergillus fumigatus class V myosin MyoE orchestrates septal localization and hyphal growth

2017 ◽  
Vol 131 (3) ◽  
pp. jcs205955 ◽  
Author(s):  
Hilary Renshaw ◽  
José M. Vargas-Muñiz ◽  
Praveen R. Juvvadi ◽  
Amber D. Richards ◽  
Greg Waitt ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Hyphal Growth ◽  
Tail Domain ◽  
Class V ◽  
Septal Localization

scholarly journals Distinct Roles of Myosins in Aspergillus fumigatus Hyphal Growth and Pathogenesis

2016 ◽  
Vol 84 (5) ◽  
pp. 1556-1564 ◽  
Author(s):  
Hilary Renshaw ◽  
José M. Vargas-Muñiz ◽  
Amber D. Richards ◽  
Yohannes G. Asfaw ◽  
Praveen R. Juvvadi ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Galleria Mellonella ◽  
Fungal Growth ◽  
Hyphal Growth ◽  
Lavage Fluid ◽  
Class Ii ◽  
Necrosis Factor Alpha ◽  
Class V ◽  
Content Type ◽  
Conidial Viability

Myosins are a family of actin-based motor proteins found in many organisms and are categorized into classes based on their structures. Class II and V myosins are known to be important for critical cellular processes, including cytokinesis, endocytosis, exocytosis, and organelle trafficking, in the model fungiSaccharomyces cerevisiaeandAspergillus nidulans. However, the roles of myosins in the growth and virulence of the pathogenAspergillus fumigatusare unknown. We constructed single- and double-deletion strains of the class II and class V myosins inA. fumigatusand found that while the class II myosin (myoB) is dispensable for growth, the class V myosin (myoE) is required for proper hyphal extension; deletion ofmyoEresulted in hyperbranching and loss of hyphal polarity. BothmyoBandmyoEare necessary for proper septation, conidiation, and conidial germination, but onlymyoBis required for conidial viability. Infection with the ΔmyoEstrain in the invertebrateGalleria mellonellamodel and also in a persistently immunosuppressed murine model of invasive aspergillosis resulted in hypovirulence, while analysis of bronchoalveolar lavage fluid revealed that tumor necrosis factor alpha (TNF-α) release and cellular infiltration were similar compared to those of the wild-type strain. The ΔmyoEstrain showed fungal growth in the murine lung, while the ΔmyoBstrain exhibited little fungal burden, most likely due to the reduced conidial viability. These results show, for the first time, the important role these cytoskeletal components play in the growth of and disease caused by a known pathogen, prompting future studies to understand their regulation and potential targeting for novel antifungal therapies.

scholarly journals Characterization of the mbsA Gene Encoding a Putative APSES Transcription Factor in Aspergillus fumigatus

2021 ◽  
Vol 22 (7) ◽  
pp. 3777
Author(s):  
Yong-Ho Choi ◽  
Sang-Cheol Jun ◽  
Min-Woo Lee ◽  
Jae-Hyuk Yu ◽  
Kwang-Soo Shin
Keyword(s):  
Aspergillus Fumigatus ◽  
Pathogenic Fungus ◽  
Hyphal Growth ◽  
Spore Wall ◽  
Mrna Levels ◽  
Chitin Synthesis ◽  
Helix Loop Helix ◽  
Growth Development ◽  
Opportunistic Pathogenic

The APSES family proteins are transcription factors (TFs) with a basic helix-loop-helix domain, known to regulate growth, development, secondary metabolism, and other biological processes in Aspergillus species. In the genome of the human opportunistic pathogenic fungus Aspergillus fumigatus, five genes predicted to encode APSES TFs are present. Here, we report the characterization of one of these genes, called mbsA (Afu7g05620). The deletion (Δ) of mbsA resulted in significantly decreased hyphal growth and asexual sporulation (conidiation), and lowered mRNA levels of the key conidiation genes abaA, brlA, and wetA. Moreover, ΔmbsA resulted in reduced spore germination rates, elevated sensitivity toward Nikkomycin Z, and significantly lowered transcripts levels of genes associated with chitin synthesis. The mbsA deletion also resulted in significantly reduced levels of proteins and transcripts of genes associated with the SakA MAP kinase pathway. Importantly, the cell wall hydrophobicity and architecture of the ΔmbsA asexual spores (conidia) were altered, notably lacking the rodlet layer on the surface of the ΔmbsA conidium. Comparative transcriptomic analyses revealed that the ΔmbsA mutant showed higher mRNA levels of gliotoxin (GT) biosynthetic genes, which was corroborated by elevated levels of GT production in the mutant. While the ΔmbsA mutant produced higher amount of GT, ΔmbsA strains showed reduced virulence in the murine model, likely due to the defective spore integrity. In summary, the putative APSES TF MbsA plays a multiple role in governing growth, development, spore wall architecture, GT production, and virulence, which may be associated with the attenuated SakA signaling pathway.

scholarly journals Proliferation of Intrahyphal Hyphae Caused by Disruption ofcsmA, Which Encodes a Class V Chitin Synthase with a Myosin Motor-Like Domain in Aspergillus nidulans

1999 ◽  
Vol 181 (12) ◽  
pp. 3721-3729 ◽  
Author(s):  
Hiroyuki Horiuchi ◽  
Makoto Fujiwara ◽  
Shuichi Yamashita ◽  
Akinori Ohta ◽  
Masamichi Takagi
Keyword(s):  
Cell Wall ◽  
Aspergillus Nidulans ◽  
Wild Type Strain ◽  
Hyphal Growth ◽  
Chitin Synthase ◽  
Calcofluor White ◽  
Class V ◽  
Myosin Motor ◽  
Fungal Morphogenesis ◽  
Novel Protein

ABSTRACT We have found that the Aspergillus nidulans csmA gene encodes a novel protein which consists of an N-terminal myosin motor-like domain and a C-terminal chitin synthase domain (M. Fujiwara, H. Horiuchi, A. Ohta, and M. Takagi, Biochem. Biophys. Res. Commun. 236:75–78, 1997). To clarify the roles of csmA in fungal morphogenesis, we constructed csmA null mutants. The growth rate of the mutant colonies was almost the same as that of the wild-type strain, but hyphal growth was severely inhibited when a chitin-binding reagent, Calcofluor white or Congo red, was added to the medium. Moreover, morphological abnormalities in tip growth and septum formation were identified microscopically. Proliferation of intracellular new hyphae, called intrahyphal hyphae, which behaved as intrinsic hyphae, was the most striking phenotypic feature among them. These phenotypes were not suppressed when the only chitin synthase domain of csmA was expressed under the control of thealcA promoter, whereas they were suppressed when the intact form of csmA was expressed. Therefore, it was concluded that the product of csmA (CsmA) has important roles in polarized cell wall synthesis and maintenance of cell wall integrity and that the myosin motor-like domain is indispensable for these functions.

scholarly journals Influence of Human Sera on the In Vitro Activity of the Echinocandin Caspofungin (MK-0991) against Aspergillus fumigatus

2000 ◽  
Vol 44 (12) ◽  
pp. 3302-3305 ◽  
Author(s):  
Tom Chiller ◽  
Kouros Farrokhshad ◽  
Elmer Brummer ◽  
David A. Stevens
Keyword(s):  
Aspergillus Fumigatus ◽  
Human Serum ◽  
Hyphal Growth ◽  
Significant Inhibition ◽  
Dependent Inhibition ◽  
Human Sera ◽  
Dose Dependent Inhibition ◽  
Synthase Inhibitor ◽  
Dose Dependent

ABSTRACT There have been several reports that the activity of echinocandin antifungal agents is not affected or decreased in the presence of human sera. It is known that these drugs are bound >80% in animal and human sera. The activity of the echinocandin caspofungin (MK-0991), a 1,3-β-d-glucan synthase inhibitor, againstAspergillus fumigatus with and without human sera was studied. Conidia of A. fumigatus in microtest plate wells formed germlings after overnight culture in RPMI 1640. Caspofungin was then added with or without serum, and the germlings were incubated at 37°C for 24 h. Human serum (5%) in RPMI 1640 alone did not significantly inhibit the growth of A. fumigatus in vitro. Caspofungin in RPMI 1640 exhibited dose-dependent inhibition, with concentrations of 0.1 and 0.05 μg/ml inhibiting 24.9% +/− 10.4% and 11.7% +/− 3.6%, respectively (n = 10;P < 0.01). The addition of 5% human serum to caspofungin at 0.1 or 0.05 μg/ml increased the inhibition to 78.6% +/− 5.8% or 58.3% +/− 19.2%, respectively (n = 10; P < 0.01 versus controls and versus the drug without serum). Lower concentrations of serum also potentiated drug activity. The effect of human sera was further seen when using caspofungin that had lost activity (e.g., by storage) against A. fumigatus at 0.1 μg/ml. Inactive caspofungin alone demonstrated no significant inhibition of hyphal growth, whereas the addition of 5% human serum to the inactive drug showed 83% +/− 16.5% inhibition (n = 5; P < 0.01). The restoration of activity of caspofungin was seen at concentrations as low as 0.05% human serum. In contrast to prior reports, this study suggests that human serum acts synergistically with caspofungin to enhance its inhibitory activity in vitro against A. fumigatus.

Streptomyces halstedii K122 produces the antifungal compounds bafilomycin B1 and C1

2000 ◽  
Vol 46 (8) ◽  
pp. 753-758 ◽  
Author(s):  
Emma Frändberg ◽  
Carl Petersson ◽  
Lennart N Lundgren ◽  
Johan Schnürer
Keyword(s):  
Aspergillus Fumigatus ◽  
Amphotericin B ◽  
Solid Phase ◽  
Hyphal Growth ◽  
Biologically Active ◽  
Antifungal Compounds ◽  
Penicillium Roqueforti ◽  
Mucor Hiemalis ◽  
Nikkomycin Z ◽  
Streptomyces Halstedii

Streptomyces halstedii K122 was previously found to produce antifungal compounds on solid substrates that inhibit radial growth of fungi among Ascomycetes, Basidiomycetes, Deuteromycetes, Oomycetes, and Zygomycetes, and strongly affected hyphal branching and morphology. During growth of S. halstedii K122 in submerged culture, no antifungal activity could be detected. However, cultivation of S. halstedii in thin (1 mm) liquid substrate layers in large surface-area tissue culture flasks caused intense growth and sporulation of S. halstedii K122, and the biologically active compounds could be extracted from the mycelium with methanol. Antifungal compounds were purified using C18 solid phase extraction and silica gel column chromatography, and identified as bafilomycins B1 and C1, using 2D NMR and FAB MS. Production of bafilomycins, which are specific inhibitors of vacuolar ATPases, has not been reported from S. halstedii previously. Minimum inhibitory concentrations (MIC) of bafilomycins B1 and C1, amphotericin B, and nikkomycin Z were determined at pH 5.5 and 7.0 for the target fungi Aspergillus fumigatus, Mucor hiemalis, Penicillium roqueforti, and Paecilomyces variotii. Penicillium roqueforti was the most sensitive species to all the compounds investigated. The MIC values for amphotericin B were 0.5-4 µg·mL-1 for the fungi tested, and pH did not affect the toxicity. The MIC values for nikkomycin Z ranged from <0.5 µg·mL-1 for Mucor hiemalis to >500 µg·mL-1 for Aspergillus fumigatus, and pH had no influence on toxicity. Bafilomycins B1 and C1 were equally active against the fungal species tested, with MIC values in the range of <0.5-64 µg·mL-1. All fungi were more sensitive to both bafilomycin B1 and C1 at pH 7.0 than at pH 5.5.Key words: antifungal, bafilomycin, MIC, hyphal growth, Streptomyces halstedii.

scholarly journals A Fungus-Specific Ras Homolog Contributes to the Hyphal Growth and Virulence of Aspergillus fumigatus

2005 ◽  
Vol 4 (12) ◽  
pp. 1982-1989 ◽  
Author(s):  
Jarrod R. Fortwendel ◽  
Wei Zhao ◽  
Ruchi Bhabhra ◽  
Steven Park ◽  
David S. Perlin ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Growth Control ◽  
Biomass Accumulation ◽  
Hyphal Growth ◽  
Pathogenic Fungi ◽  
Total Biomass ◽  
Gene Encoding ◽  
Directional Growth ◽  
Solid Media ◽  
Hyphal Morphology

ABSTRACT The Ras family of GTPase proteins has been shown to control morphogenesis in many organisms, including several species of pathogenic fungi. In a previous study, we identified a gene encoding a fungus-specific Ras subfamily homolog, rasB, in Aspergillus fumigatus. Here we report that deletion of A. fumigatus rasB caused decreased germination and growth rates on solid media but had no effect on total biomass accumulation after 24 h of growth in liquid culture. The ΔrasB mutant had an irregular hyphal morphology characterized by increased branching. Expression of rasBΔ113-135, a mutant transgene lacking the conserved rasB internal amino acid insertion, did not complement the deletion phenotype of delayed growth and germination rates and abnormal hyphal morphology. Virulence of the rasB deletion strain was diminished; mice infected with this strain exhibited ∼65% survival compared to ∼10% with wild-type and reconstituted strains. These data support the hypothesis that rasB homologs, which are highly conserved among fungi that undergo hyphal growth, control signaling modules important to the directional growth of fungal hyphae.

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