Extracellular proteinase formation in carbon starving Aspergillus nidulans cultures – physiological function and regulation

Szilágyi, Melinda; Kwon, Nak‐Jung; Bakti, Fruzsina; M-Hamvas, Márta; Jámbrik, Katalin; Park, Heesoo; Pócsi, István; Yu, Jae Hyuk; Emri, Tamás

doi:10.1002/jobm.201100068

Cited by 19 publications

(19 citation statements)

References 45 publications

(48 reference statements)

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“…In particular, NagA have been suggested to mediate the breakdown of chito-oligomers [45,53]. PrtA role was inferred since deletion of the encoding gene has significantly decreased proteolysis during autolysis [51]. Additional proteases were found in the cork secretome (AN2366, AN2903 and AN3918), similar to that reported in the secretome of A. nidulans grown on sorghum stover or on leaf litter [46,47].…”

Section: Fungal Cell Wall Remodelling Enzymesmentioning

confidence: 58%

“…The coordinated expression of these hydrolases and of ChiB has been reported before in A. nidulans [43,50]. They are thought to be associated with the degradation of empty hyphae supporting fungal growth under carbon starvation conditions [51,52]. In particular, NagA have been suggested to mediate the breakdown of chito-oligomers [45,53].…”

Section: Fungal Cell Wall Remodelling Enzymesmentioning

confidence: 63%

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Investigating Aspergillus nidulans secretome during colonisation of cork cell walls

Martins

Garcia

Varela

et al. 2014

Journal of Proteomics

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Cork, the outer bark of Quercus suber, shows a unique compositional structure, a set of remarkable properties, including high recalcitrance. Cork colonisation by Ascomycota remains largely overlooked. Herein, Aspergillus nidulans secretome on cork was analysed (2DE).Proteomic data were further complemented by microscopic (SEM) and spectroscopic (ATR-FTIR) evaluation of the colonised substrate and by targeted analysis of lignin degradation compounds (UPLC-HRMS). Data showed that the fungus formed an intricate network of hyphae around the cork cell walls, which enabled polysaccharides and lignin superficial degradation, but probably not of suberin. The degradation of polysaccharides was suggested by the identification of few polysaccharide degrading enzymes (β-glucosidases and endo-1,5--L-arabinosidase).Lignin degradation, which likely evolved throughout a Fenton-like mechanism relying on the activity of alcohol oxidases, was supported by the identification of small aromatic compounds (e.g. cinnamic acid and veratrylaldehyde) and of several putative high molecular weight lignin degradation products. In addition, cork recalcitrance was corroborated by the identification of several protein species which are associated with autolysis. Finally, stringent comparative proteomics revealed that A. nidulans colonisation of cork and wood share a common set of enzymatic mechanisms. However the higher polysaccharide accessibility in cork might explain the increase of β-glucosidase in cork secretome.

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Section: Fungal Cell Wall Remodelling Enzymesmentioning

confidence: 58%

Section: Fungal Cell Wall Remodelling Enzymesmentioning

confidence: 63%

Investigating Aspergillus nidulans secretome during colonisation of cork cell walls

Martins

Garcia

Varela

et al. 2014

Journal of Proteomics

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“…Major up-regulation of pepJ (AN7962, Table 1) and up-regulation of prtA (AN5558) resulted in accumulation of the encoded proteins in the secretome (Table 2). Both proteases play a role in the degradation of empty hyphae during starvation [42, 43]. Out of the 25 protein species identified in the secretome, ten are involved in cell wall remodelling events typical of autolysis and show, in general, high consistency with the transcriptome data (Table 2).…”

Section: Resultsmentioning

confidence: 99%

Elucidating how the saprophytic fungus Aspergillus nidulans uses the plant polyester suberin as carbon source

et al. 2014

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BackgroundLipid polymers in plant cell walls, such as cutin and suberin, build recalcitrant hydrophobic protective barriers. Their degradation is of foremost importance for both plant pathogenic and saprophytic fungi. Regardless of numerous reports on fungal degradation of emulsified fatty acids or cutin, and on fungi–plant interactions, the pathways involved in the degradation and utilisation of suberin remain largely overlooked. As a structural component of the plant cell wall, suberin isolation, in general, uses harsh depolymerisation methods that destroy its macromolecular structure. We recently overcame this limitation isolating suberin macromolecules in a near-native state.ResultsSuberin macromolecules were used here to analyse the pathways involved in suberin degradation and utilisation by Aspergillus nidulans. Whole-genome profiling data revealed the complex degrading enzymatic machinery used by this saprophytic fungus. Initial suberin modification involved ester hydrolysis and ω-hydroxy fatty acid oxidation that released long chain fatty acids. These fatty acids were processed through peroxisomal β-oxidation, leading to up-regulation of genes encoding the major enzymes of these pathways (e.g. faaB and aoxA). The obtained transcriptome data was further complemented by secretome, microscopic and spectroscopic analyses.ConclusionsData support that during fungal growth on suberin, cutinase 1 and some lipases (e.g. AN8046) acted as the major suberin degrading enzymes (regulated by FarA and possibly by some unknown regulatory elements). Suberin also induced the onset of sexual development and the boost of secondary metabolism.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-613) contains supplementary material, which is available to authorized users.

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“…Determination of Protease Activity 0.1 mL of fermentation broth samples were incubated (60 min, 37 ° C) in 0.2 mol/L -1 Na 2 HPO 4 /0.1 mol/L -1 citric acid buffer (pH 8) with azocasein substrate (final concentration 12.5 mg/mL -1 ) as described elsewhere [Szilágyi et al, 2011]. One unit (U) of protease activity was defined as an amount of enzyme resulting in 1 OD increase in the absorbance at 440 nm.…”

Section: Detection Of Antibiotic Productionmentioning

confidence: 99%

Mutation in afsR Leads to A-Factor Deficiency in Streptomyces griseus B2682

et al. 2018

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Background/Aims: A-factor, a γ-butyrolactone autoregulator, in Streptomyces griseus is involved in the regulation of differentiation and antibiotic production. Here we studied the S. griseus B2682-AFN (A-factor negative) bald mutant that harbors a nonsense mutation in the afsR gene encoding a pleiotropic regulator. Our aim was to prove that this mutation is the cause of the A-factor deficiency in AFN. We also studied whether AfsR regulates A-factor production by AfsA, which is supposed to be the only specific key enzyme in A-factor biosynthesis. Methods: Wild afsR was cloned to the pHJL401 shuttle vector and was transformed to the S. griseus AFN and B2682 strains. During phenotypic characterization, sporulation, antibiotic, protease, A-factor, and AfsA protein production were studied. Results: Transformation of AFN by a wild afsR restored its phenotype including sporulation, antibiotic, extracellular protease, and A-factor production. Introduction of afsR to the B2682 wild-type strain resulted in antibiotic and extracellular protease overproduction that was accompanied with an elevated A-factor level. AfsA was detected both in AFN and B2682. Conclusions: AfsR has an effect on the regulation of A-factor production in S. griseus. The presence of AfsA is not sufficient for normal A-factor production. AfsR regulates A-factor biosynthesis independently of AfsA.

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Extracellular proteinase formation in carbon starving Aspergillus nidulans cultures – physiological function and regulation

Cited by 19 publications

References 45 publications

Investigating Aspergillus nidulans secretome during colonisation of cork cell walls

Investigating Aspergillus nidulans secretome during colonisation of cork cell walls

Elucidating how the saprophytic fungus Aspergillus nidulans uses the plant polyester suberin as carbon source

Mutation in <b><i>afsR</i></b> Leads to A-Factor Deficiency in <b><i>Streptomyces griseus</i></b> B2682

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