Protein kinase A signaling and calcium ions are major players in PAF mediated toxicity against Aspergillus niger.
Ontology highlight
ABSTRACT:
SUBMITTER: Binder U
PROVIDER: S-EPMC4424949 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Two different enzymes exhibiting 6-phosphofructo-1-kinase (PFK1) activity were isolated from the mycelium of Aspergillus niger: the native enzyme with a molecular mass of 85 kDa, which corresponded to the calculated molecular mass of the deduced amino acid sequence of the A. niger pfkA gene, and a shorter protein of approximately 49 kDa. A fragment of identical size also was obtained in vitro by the proteolytic digestion of the partially purified native PFK1 with proteinase K. When PFK1 activity was measured during the proteolytic degradation of the native protein, it was found to be lost after 1 h of incubation, but it was reestablished after induction of phosphorylation by adding the catalytic subunit of cyclic AMP-dependent protein kinase to the system. By determining kinetic parameters, different ratios of activities measured at ATP concentrations of 0.1 and 1 mM were detected with fragmented PFK1, as with the native enzyme. Fructose-2,6-biphosphate significantly increased the Vmax of the fragmented protein, while it had virtually no effect on the native protein. The native enzyme could be purified only from the early stages of growth on a minimal medium, while the 49-kDa fragment appeared later and was activated at the time of a sudden change in the growth rate. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of sequential purifications of PFK1 enzymes by affinity chromatography during the early stages of the fungal development suggested spontaneous posttranslational modification of the native PFK1 in A. niger cells, while from the kinetic parameters determined for both isolated forms it could be concluded that the fragmented enzyme might be more efficient under physiological conditions.
| S-EPMC1065176 | biostudies-literature
Project description:A novel gene, eglC, encoding an endoglucanase, was cloned from Aspergillus niger. Transcription of eglC is regulated by XlnR, a transcriptional activator that controls the degradation of polysaccharides in plant cell walls. EglC is an 858-amino-acid protein and contains a conserved C-terminal cellulose-binding domain. EglC can be classified in glycoside hydrolase family 74. No homology to any of the endoglucanases from Trichoderma reesei was found. In the plant cell wall xyloglucan is closely linked to cellulose fibrils. We hypothesize that the EglC cellulose-binding domain anchors the enzyme to the cellulose chains while it is cleaving the xyloglucan backbone. By this action it may contribute to the degradation of the plant cell wall structure together with other enzymes, including hemicellulases and cellulases. EglC is most active towards xyloglucan and therefore is functionally different from the other two endoglucanases from A. niger, EglA and EglB, which exhibit the greatest activity towards beta-glucan. Although the mode of action of EglC is not known, this enzyme represents a new enzyme function involved in plant cell wall polysaccharide degradation by A. niger.
| S-EPMC123852 | biostudies-literature
Project description:Glucoamylase has a wide range of applications in the production of glucose, antibiotics, amino acids, and other fermentation industries. Fungal glucoamylase, in particular, has attracted much attention because of its wide application in different industries, among which Aspergillus niger is the most popular strain producing glucoamylase. The low availability of NADPH was found to be one of the limiting factors for the overproduction of glucoamylase. In this study, 3 NADH kinases (AN03, AN14, and AN17) and malic enzyme (maeA) were overexpressed in aconidial A. niger by CRISPR/Cas9 technology, significantly increasing the size of the NADPH pool, resulting in the activity of glucoamylase was improved by about 70%, 50%, 90%, and 70%, respectively; the total secreted protein was increased by about 25%, 22%, 52%, and 26%, respectively. Furthermore, the combination of the mitochondrial NADH kinase (AN17) and the malic enzyme (maeA) increased glucoamylase activity by a further 19%. This study provided an effective strategy for enhancing glucoamylase production of A. niger.
| S-EPMC9338884 | biostudies-literature
Project description:The transcriptome of conidia of Aspergillus niger was analysed during the first 8 h of germination. Dormant conidia started to grow isotropically two h after inoculation in liquid medium. Isotropic growth changed to polarised growth after 6 h, which coincided with one round of mitosis. Dormant conidia contained transcripts from 4 626 genes. The number of genes with transcripts decreased to 3 557 after 2 h of germination, after which an increase was observed with 4 780 expressed genes 8 h after inoculation. The RNA composition of dormant conidia was substantially different than all the subsequent stages of germination. The correlation coefficient between the RNA profiles of 0 h and 8 h was 0.46. They were between 0.76-0.93 when profiles of 2, 4 and 6 h were compared with that of 8 h. Dormant conidia were characterised by high levels of transcripts of genes involved in the formation of protecting components such as trehalose, mannitol, protective proteins (e.g. heat shock proteins and catalase). Transcripts belonging to the Functional Gene Categories (FunCat) protein synthesis, cell cycle and DNA processing and respiration were over-represented in the up-regulated genes at 2 h, whereas metabolism and cell cycle and DNA processing were over-represented in the up-regulated genes at 4 h. At 6 h and 8 h no functional gene classes were over- or under-represented in the differentially expressed genes. Taken together, it is concluded that the transcriptome of conidia changes dramatically during the first two h and that initiation of protein synthesis and respiration are important during early stages of germination.
| S-EPMC3563291 | biostudies-literature
Project description:Fungi produce a wide range of enzymes that allow them to grow on diverse plant biomass. Wheat bran is a low-cost substrate with high potential for biotechnological applications. It mainly contains cellulose and (arabino)xylan, as well as starch, proteins, lipids and lignin to a lesser extent. In this study, we dissected the regulatory network governing wheat bran degradation in Aspergillus niger to assess the relative contribution of the regulators to the utilization of this plant biomass substrate. Deletion of genes encoding transcription factors involved in (hemi-)cellulose utilization (XlnR, AraR, ClrA and ClrB) individually and in combination significantly reduced production of polysaccharide-degrading enzymes, but retained substantial growth on wheat bran. Proteomic analysis suggested the ability of A. niger to grow on other carbon components, such as starch, which was confirmed by the additional deletion of the amylolytic regulator AmyR. Growth was further reduced but not impaired, indicating that other minor components provide sufficient energy for residual growth, displaying the flexibility of A. niger, and likely other fungi, in carbon utilization. Better understanding of the complexity and flexibility of fungal regulatory networks will facilitate the generation of more efficient fungal cell factories that use plant biomass as a substrate.
| S-EPMC8313289 | biostudies-literature
Project description:The control of Aspergillus niger (A. niger) is of great significance for the agricultural economy and food safety. In this study, the antifungal effect and mechanism of iturin A from Bacillus amyloliquefaciens (CGMCC No. 8473) against A. niger (ATCC 16404) were investigated using biochemical analyses and proteomics. Changes in a mycelium treated with iturin A were observed using scanning electron microscopy and transmission electron microscopy, including mycelial twisting and collapse, organelle disintegration, and intracellular vacuolization. The cytomembrane integrity of A. niger was affected by iturin A, as detected by propidium iodide staining. In addition, the generation of excess reactive oxygen species, the hyperpolarization of the mitochondrial membrane potential and malondialdehyde accumulation also indicated that iturin A induced apoptosis in A. niger through the oxidative stress pathway. Proteomics results showed that 310 proteins were differentially expressed in the A. niger mycelium exposed to iturin A, including 159 upregulated proteins and 151 downregulated proteins, which were mainly associated with energy metabolism of A. niger. We propose that iturin A might inhibit the growth of A. niger by disrupting cytomembrane integrity, via oxidative stress, and by interfering with glycolysis/gluconeogenesis and the tricarboxylic acid cycle. Overall, iturin A is a promising antifungal agent that provides a rationale for controlling A. niger contamination in food.
| S-EPMC10970988 | biostudies-literature
Project description:Adaptation to a changing environment is essential for the survival and propagation of sessile organisms, such as plants or fungi. Filamentous fungi commonly respond to a worsening of their growth conditions by differentiation of asexually or sexually produced spores. The formation of these specialized cell types is, however, also triggered as part of the general life cycle by hyphal age or density. Spores typically serve for dispersal and, therefore, translocation but can also act as resting states to endure times of scarcity. Eukaryotic differentiation in response to environmental and self-derived signals is commonly mediated by three-tiered mitogen-activated protein (MAP) kinase signaling cascades. Here, we report that the MAP kinase Fus3 of the black mold Aspergillus niger (AngFus3) and its upstream kinase AngSte7 control vegetative spore formation and secondary metabolism. Mutants lacking these kinases are defective in conidium induction in response to hyphal density but are fully competent in starvation-induced sporulation, indicating that conidiation in A. niger is triggered by various independent signals. In addition, the mutants exhibit an altered profile of volatile metabolites and secrete dark pigments into the growth medium, suggesting a dysregulation of the secondary metabolism. By assigning the AngFus3 MAP kinase pathway to the transduction of a potentially self-derived trigger, this work contributes to the unraveling of the intricate signaling networks controlling fungal differentiation. Moreover, our data further support earlier observations that differentiation and secondary metabolism are tightly linked in filamentous fungi.
| S-EPMC4452566 | biostudies-literature
Project description:Fungal endocarditis/aortitis is an uncommon yet emerging entity accounting for 2% to 4% of all cases of infective endocarditis and continues to be associated with a poor prognosis. We present the first case of polyethylene-terephthalate (PETE) graft aortitis caused by A. niger, a rare fungal agent. Early diagnosis with frequent transoesophageal echocardiography (TEE) and a prompt surgical intervention coupled with optimal antifungal therapy are still the only option to reduce the exceedingly high mortality and morbidity.
| S-EPMC7256640 | biostudies-literature
Project description:Onychomycosis is usually caused by dermatophytes, but some species of nondermatophytic molds and yeasts are also associated with nail invasion. Aspergillus niger is a nondermatophytic mold which exists as an opportunistic filamentous fungus in all environments. Here, we report a case of onychomycosis caused by A. niger in a 66-year-old female. The patient presented with a black discoloration and a milky white base and onycholysis on the proximal portion of the right thumb nail. Direct microscopic examination of scrapings after potassium hydroxide (KOH) preparation revealed dichotomous septate hyphae. Repeated cultures on Sabouraud's dextrose agar (SDA) without cycloheximide produced the same black velvety colonies. No colony growth occurred on SDA with cycloheximide slants. Biseriate phialides covering the entire vesicle with radiate conidial heads were observed on the slide culture. The DNA sequence of the internal transcribed spacer region of the clinical sample was a 100% match to that of A. niger strain ATCC 16888 (GenBank accession number AY373852). A. niger was confirmed by KOH mount, colony identification, light microscopic morphology, and DNA sequence analysis. The patient was treated orally with 250 mg terbinafine daily and topical amorolfine 5% nail lacquer for 3 months. As a result, the patient was completely cured clinically and mycologically.
| S-EPMC3505779 | biostudies-literature
Project description:Aspergillus niger is an important filamentous fungus used for the industrial production of citric acid. One of the most important factors that affect citric acid production is the concentration of manganese(II) ions present in the culture broth. Under manganese(II)-limiting conditions, the fungus develops a pellet-like morphology that is crucial for high citric acid accumulation. The impact of manganese(II) ions on the transcription of the major citrate exporter encoding gene cexA was studied under manganese(II)-deficient and -sufficient conditions. Furthermore, citric acid production was analyzed in overexpression mutant strains of cexA in the presence and absence of manganese(II) ions, and the influence of CexA on fungal morphology was investigated by microscopy. Transcriptional upregulation of cexA in the absence of manganese(II) ions was observed and, by decoupling cexA expression from the native promoter system, it was possible to secrete more citric acid even in the presence of manganese. This effect was shown for both an inducible and a constitutive overexpression of cexA. Furthermore, it was found that the presence of CexA influences fungal morphology and promotes a more branched phenotype. According to this study, manganese(II) ions suppress transcription of the citrate exporter cexA in Aspergillus niger, causing citric acid secretion to decrease.
| S-EPMC10698684 | biostudies-literature