Autolytic hydrolases affect sexual and asexual development of Aspergillus nidulans

Emri, Tamás; Vékony, Viktória; Gila, Barnabás Cs.; Nagy, Fruzsina; Forgács, Katalin; Pócsi, István

doi:10.1007/s12223-018-0601-8

Cited by 8 publications

(4 citation statements)

References 50 publications

(68 reference statements)

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“…With this activity, AnAFP thus contributes to the survival of A. niger . This hypothesis is supported by publications from others who demonstrated that asexual sporulation of A. nidulans is accompanied by autolytic and apoptotic processes [ 53 , 54 , 55 , 56 ]. It is also in agreement with the observation that there is a considerable delay between induction of anafp gene expression and detection of AnAFP in the culture supernatant of A. niger [ 44 , 57 ].…”

Section: Gene Regulation Of Afp-encoding Genes: From the General Tsupporting

confidence: 59%

Antifungal Peptides of the AFP Family Revisited: Are These Cannibal Toxins?

Meyer

Jung

2018

Microorganisms

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The emergence and spread of pathogenic fungi resistant to currently used antifungal drugs represents a serious challenge for medicine and agriculture. The use of smart antimicrobials, so-called “dirty drugs” which affect multiple cellular targets, is one strategy to prevent resistance. Of special interest is the exploitation of the AFP family of antimicrobial peptides, which include its founding member AFP from Aspergillus giganteus. This latter is a highly potent inhibitor of chitin synthesis and affects plasma membrane integrity in many human and plant pathogenic fungi. A transcriptomic meta-analysis of the afp-encoding genes in A. giganteus and A. niger predicts a role for these proteins during asexual sporulation, autophagy, and nutrient recycling, suggesting that AFPs are molecules important for the survival of A. niger and A. giganteus under nutrient limitation. In this review, we discuss parallels which exist between AFPs and bacterial cannibal toxins and provide arguments that the primary function of AFPs could be to kill genetically identical siblings. We hope that this review inspires computational and experimental biologists studying alternative explanations for the nature and function of antimicrobial peptides beyond the general assumption that they are mere defense molecules to fight competitors.

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Section: Gene Regulation Of Afp-encoding Genes: From the General Tsupporting

confidence: 59%

Antifungal Peptides of the AFP Family Revisited: Are These Cannibal Toxins?

Meyer

Jung

2018

Microorganisms

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“…We propose that young hyphae of A. niger mainly work as nutrient scavengers, having a highly active and compact cytoplasm, whereas old hyphae are important in setting the biofilm's three-dimensional structure, where only the cell wall is needed and thus the cytoplasm appears empty. Mature fungal colonies have been reported to be composed of both metabolic active, metabolic inactive as well as dead hyphae, the latter of which develop through autophagy (Boswell and Hopkins, 2008;Krijgsheld et al, 2013, Emri et al, 2018Kaur and Punekar, 2019;Khalid et al, 2019;Lingo et al, 2021). Our study supports these observations and further highlights that young hyphae at the edge of the colony are not significantly covered by an extracellular matrix.…”

Section: Discussionsupporting

confidence: 87%

Colony growth and biofilm formation of Aspergillus niger under simulated microgravity

et al. 2022

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The biotechnology- and medicine-relevant fungus Aspergillus niger is a common colonizer of indoor habitats such as the International Space Station (ISS). Being able to colonize and biodegrade a wide range of surfaces, A. niger can ultimately impact human health and habitat safety. Surface contamination relies on two key-features of the fungal colony: the fungal spores, and the vegetative mycelium, also known as biofilm. Aboard the ISS, microorganisms and astronauts are shielded from extreme temperatures and radiation, but are inevitably affected by spaceflight microgravity. Knowing how microgravity affects A. niger colony growth, in particular regarding the vegetative mycelium (biofilm) and spore production, will help prevent and control fungal contaminations in indoor habitats on Earth and in space. Because fungal colonies grown on agar can be considered analogs for surface contamination, we investigated A. niger colony growth on agar in normal gravity (Ground) and simulated microgravity (SMG) conditions by fast-clinorotation. Three strains were included: a wild-type strain, a pigmentation mutant (ΔfwnA), and a hyperbranching mutant (ΔracA). Our study presents never before seen scanning electron microscopy (SEM) images of A. niger colonies that reveal a complex ultrastructure and biofilm architecture, and provide insights into fungal colony development, both on ground and in simulated microgravity. Results show that simulated microgravity affects colony growth in a strain-dependent manner, leading to thicker biofilms (vegetative mycelium) and increased spore production. We suggest that the Rho GTPase RacA might play a role in A. niger’s adaptation to simulated microgravity, as deletion of ΔracA leads to changes in biofilm thickness, spore production and total biomass. We also propose that FwnA-mediated melanin production plays a role in A. niger’s microgravity response, as ΔfwnA mutant colonies grown under SMG conditions showed increased colony area and spore production. Taken together, our study shows that simulated microgravity does not inhibit A. niger growth, but rather indicates a potential increase in surface-colonization. Further studies addressing fungal growth and surface contaminations in spaceflight should be conducted, not only to reduce the risk of negatively impacting human health and spacecraft material safety, but also to positively utilize fungal-based biotechnology to acquire needed resources in situ.

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“…The production of extracellular autolytic enzymes such as chitinase and glucanase is induced by carbon starvation in A. nidulans (43). Intriguingly, the strain defective in both chiB and engA produced fewer conidia on medium containing low concentrations of glucose (44). This observation indicates that autolysis contributes to the supply of…”

Section: Figmentioning

confidence: 97%

The Cell Wall Integrity Pathway Contributes to the Early Stages of Aspergillus fumigatus Asexual Development

Rocha

Fabri

Simões

et al. 2020

Appl Environ Microbiol

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Aspergillus fumigatus is a major cause of human disease. The survival of this fungus is dependent on the cell wall organization and function of its components. The cell wall integrity pathway (CWIP) is the primary signaling cascade that controls de novo synthesis of the cell wall in fungi. Abundant conidiation is a hallmark in A. fumigatus, and uptake of conidia by a susceptible host is usually the initial event in infection. The formation of conidia is mediated by the development of fungus-specific specialized structures, conidiophores, which are accompanied by cell wall remodeling. The molecular regulation of these changes in cell wall composition required for the rise of conidiophore from the solid surface and to disperse the conidia into the air is currently unknown. Here, we investigated the role of CWIP in conidiation. We show that CWIP pkcAG579R, ΔmpkA, and ΔrlmA mutants displayed reduced conidiation during synchronized asexual differentiation. The transcription factor RlmA directly regulated the expression of regulators of conidiation, including flbB, flbC, brlA, abaA, and rasB, as well as genes involved in cell wall synthesis and remodeling, and this affected the chitin content in aerial hyphae. Phosphorylation of RlmA and MpkA was increased during asexual differentiation. We also observed that MpkA physically associated with the proteins FlbB, FlbC, BrlA, and RasB during this process, suggesting another level of cross talk between the CWIP and asexual development pathways. In summary, our results support the conclusion that one function of the CWIP is the regulation of asexual development in filamentous fungi. IMPORTANCE A remarkable feature of the human pathogen Aspergillus fumigatus is its ability to produce impressive amounts of infectious propagules known as conidia. These particles reach immunocompromised patients and may initiate a life-threatening mycosis. The conidiation process in Aspergillus is governed by a sequence of proteins that coordinate the development of conidiophores. This process requires the remodeling of the cell wall so that the conidiophores can rise and withstand the chains of conidia. The events regulating cell wall remodeling during conidiation are currently unknown. Here, we show that the cell wall integrity pathway (CWIP) components RlmA and MpkA directly contribute to the activation of the conidiation cascade by enabling transcription or phosphorylation of critical proteins involved in asexual development. This study points to an essential role for the CWIP during conidiation and provides further insights into the complex regulation of asexual development in filamentous fungi.

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Autolytic hydrolases affect sexual and asexual development of Aspergillus nidulans

Cited by 8 publications

References 50 publications

Antifungal Peptides of the AFP Family Revisited: Are These Cannibal Toxins?

Antifungal Peptides of the AFP Family Revisited: Are These Cannibal Toxins?

Colony growth and biofilm formation of Aspergillus niger under simulated microgravity

The Cell Wall Integrity Pathway Contributes to the Early Stages of Aspergillus fumigatus Asexual Development

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