Aspergillus nidulans DigA, a potential homolog of Saccharomyces cerevisiae Pep3 (Vps18), is required for nuclear migration, mitochondrial morphology and polarized growth

Geissenhöner, Antje; Sievers, Nicole; Brock, Matthias; Fischer, Reinhard

doi:10.1007/s00438-001-0589-6

Cited by 25 publications

(15 citation statements)

References 36 publications

(45 reference statements)

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“…dscE was selected for preliminary analysis in A. fumigatus since it has not been previously studied in the filamentous fungi. One strain contained a deletion in a gene encoding a homolog of Aspergillus nidulans DigA, which is involved in nuclear migration, mitochondrial morphology, and polarized growth (25). However, it is an essential gene in N. crassa that can survive only as a heterokaryon, and we were unable to generate digA deletion strains in A. fumigatus (data not shown).…”

Section: Identification Of Novel Hypoxia-sensitive Mutants In N Crassamentioning

confidence: 96%

Identification and Characterization of a Novel Aspergillus fumigatus Rhomboid Family Putative Protease, RbdA, Involved in Hypoxia Sensing and Virulence

et al. 2016

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dAspergillus fumigatus is the most common pathogenic mold infecting humans and a significant cause of morbidity and mortality in immunocompromised patients. In invasive pulmonary aspergillosis, A. fumigatus spores are inhaled into the lungs, undergoing germination and invasive hyphal growth. The fungus occludes and disrupts the blood vessels, leading to hypoxia and eventual tissue necrosis. The ability of this mold to adapt to hypoxia is regulated in part by the sterol regulatory element binding protein (SREBP) SrbA and the DscA to DscD Golgi E3 ligase complex critical for SREBP activation by proteolytic cleavage. Loss of the genes encoding these proteins results in avirulence. To identify novel regulators of hypoxia sensing, we screened the Neurospora crassa gene deletion library under hypoxia and identified a novel rhomboid family protease essential for hypoxic growth. Deletion of the A. fumigatus rhomboid homolog rbdA resulted in an inability to grow under hypoxia, hypersensitivity to CoCl 2 , nikkomycin Z, fluconazole, and ferrozine, abnormal swollen tip morphology, and transcriptional dysregulation-accurately phenocopying deletion of srbA. In vivo, rbdA deletion resulted in increased sensitivity to phagocytic killing, a reduced inflammatory Th1 and Th17 response, and strongly attenuated virulence. Phenotypic rescue of the ⌬rbdA mutant was achieved by expression and nuclear localization of the N terminus of SrbA, including its HLH domain, further indicating that RbdA and SrbA act in the same signaling pathway. In summary, we have identified RbdA, a novel putative rhomboid family protease in A. fumigatus that mediates hypoxia adaptation and fungal virulence and that is likely linked to SrbA cleavage and activation.T he filamentous fungus Aspergillus fumigatus grows as an environmental saprophyte but can infect humans and animals through its dispersed asexual conidia. Upon inhalation by an immunocompromised host, conidia can germinate to form hyphae which infiltrate the surrounding lung tissue, causing often fatal invasive aspergillosis (IA). It is estimated that worldwide, more than 200,000 individuals suffer from life-threatening IA, with mortality rates ranging between 30 to 95% (1). These alarming statistics are a result of the generally poor health status of the patients, limited diagnostic and therapeutic options, and the arsenal of virulence-promoting properties of this ubiquitous mold (2, 3). Besides the abilities of the fungus to produce potent mycotoxins and to escape from the host innate immune cells, thermophilic growth and versatile nutrient acquisition are further general physiological attributes which favor growth on decaying matter as well as in the human host (4, 5). Adaptation to O 2 concentrations below normal atmospheric levels of 21% is an additional challenge that A. fumigatus must cope with during colonization. O 2 levels can drop to 2 to 4% on the surface of healthy alveolar tissue and be further diminished to less than 1% upon inflammation (6). Such levels of hypoxia are normally no th...

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Section: Identification Of Novel Hypoxia-sensitive Mutants In N Crassamentioning

confidence: 96%

Identification and Characterization of a Novel Aspergillus fumigatus Rhomboid Family Putative Protease, RbdA, Involved in Hypoxia Sensing and Virulence

et al. 2016

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“…Therefore, at least some VPS proteins are presumed to be involved in hyphal morphogenesis in A. oryzae. In A. nidulans, a mutation in digA, a potential homolog of S. cerevisiae VPS18/ PEP3, results in dichotomous and subapical branches (8), which also suggests a correlation between vacuolar protein sorting and hyphal morphogenesis. The properties of multicellularity and cell polarity specific to filamentous fungi may provide an opportunity to characterize morphological abnormalities that cannot occur in unicellular microorganisms such as S. cerevisiae.…”

Section: Discussionmentioning

confidence: 99%

“…For instance, one cycloheximide-sensitive mutant of A. nidulans shows fragmentation of vacuoles (6). Geissenhoner et al (8) showed that mutation of digA, a homolog of the S. cerevisiae VPS18/PEP3 locus, causes fragmented vacuoles and clustered mitochondria and nuclei, suggesting that the protein functions in organellar positioning and cell polarity in A. nidulans. Previously, we isolated the vpsA, avaA, and avaB genes (homologs of S. cerevisiae VPS1, VAM4/YPT7, and VAM6/VPS39, respectively) from A. nidulans and demonstrated that these genes are involved in vacuolar biogenesis (15,17,26).…”

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confidence: 99%

Isolation and Characterization of Aspergillus oryzae Vacuolar Protein Sorting Mutants

Ohneda

Arioka

Kitamoto

2005

Appl Environ Microbiol

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The vacuolar protein sorting (vps) system in the filamentous fungus Aspergillus oryzae, which has unique cell polarity and the ability to secrete large amounts of proteins, was evaluated by using mutants that missort vacuolar proteins into the medium. Vacuolar carboxypeptidase Y (CPY) fused with enhanced green fluorescent protein (EGFP) was used as a vacuolar marker. Twenty dfc (dim EGFP fluorescence in conidia) mutants with reduced intracellular EGFP fluorescence in conidia were isolated by fluorescence-activated cell sorting from approximately 20,000 UV-treated conidia. Similarly, 22 hfm (hyper-EGFP fluorescence released into the medium) mutants with increased extracellular EGFP fluorescence were isolated by using a fluorescence microplate reader from approximately 20,000 UV-treated conidia. The dfc and hfm mutant phenotypes were pH dependent, and missorting of CPY-EGFP could vary by 10-to 40-fold depending on the ambient pH. At pH 5.5, the dfc-14 and hfm-4 mutants had an abnormal hyphal morphology that is consistent with fragmentation of vacuoles and defects in cell polarity. In contrast, the hyphal and vacuolar morphology of the dfc-14 and hfm-4 mutants was normal at pH 8.0, although CPY-EGFP accumulated in perivacuolar dot-like structures similar to the class E compartments in Saccharomyces cerevisiae vps mutants. In hfm-21, CPY-EGFP localized at the Spitzenkörper when the mutant was grown at pH 8.0 but not in vacuoles, suggesting that hfm-21 may transport CPY-EGFP via a novel pathway that involves the Spitzenkörper. Correlations between vacuolar protein sorting, pH response, and cell polarity are reported for the first time for filamentous fungi.

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“…Moreover, deletion of so-called class E VPS genes that are required for late endosome function and transport to vacuoles results in defective vacuole formation and growth in A. oryzae (Tatsumi et al 2006;Tatsumi et al, in preparation), while it does not affect either of them in the budding yeast (Raymond et al 1992). Apparently, vacuole formation is a prerequisite for proper growth and development in filamentous fungi, because mutations affecting vacuolar function result in defective hyphal growth and conidiation (Geißenhöner et al 2001;Palmer et al 2003;Veses et al 2005;Tatsumi et al 2006). The vital roles of vacuoles may make it difficult to obtain mutants which mis-secrete vacuolar proteins in filamentous fungi.…”

Section: Vacuolesmentioning

confidence: 95%

Dissecting cellular components of the secretory pathway in filamentous fungi: insights into their application for protein production

2007

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Studies on protein production using filamentous fungi have mostly focused on improvement of the protein yields by genetic modifications such as overexpression. Recent genome sequencing in several filamentous fungal species now enables more systematic approaches based on reverse genetics and molecular biology of the secretion pathway. In this review, we summarize recent molecular-based advances in our understanding of vesicular trafficking in filamentous fungi, and discuss insights into their high secretion ability and application for protein production.

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Aspergillus nidulans DigA, a potential homolog of Saccharomyces cerevisiae Pep3 (Vps18), is required for nuclear migration, mitochondrial morphology and polarized growth

Cited by 25 publications

References 36 publications

Identification and Characterization of a Novel Aspergillus fumigatus Rhomboid Family Putative Protease, RbdA, Involved in Hypoxia Sensing and Virulence

Identification and Characterization of a Novel Aspergillus fumigatus Rhomboid Family Putative Protease, RbdA, Involved in Hypoxia Sensing and Virulence

Isolation and Characterization of Aspergillus oryzae Vacuolar Protein Sorting Mutants

Dissecting cellular components of the secretory pathway in filamentous fungi: insights into their application for protein production

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