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Rajput M, Kumar M, Pareek N. Myco-chitinases as versatile biocatalysts for translation of coastal residual resources to eco-competent chito-bioactives. FUNGAL BIOL REV 2022. [DOI: 10.1016/j.fbr.2022.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Aron O, Wang M, Mabeche AW, Wajjiha B, Li M, Yang S, You H, Cai Y, Zhang T, Li Y, Wang B, Zhang D, Wang Z, Tang W. MoCpa1-mediated arginine biosynthesis is crucial for fungal growth, conidiation, and plant infection of Magnaporthe oryzae. Appl Microbiol Biotechnol 2021; 105:5915-5929. [PMID: 34292355 DOI: 10.1007/s00253-021-11437-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 06/16/2021] [Accepted: 06/19/2021] [Indexed: 12/01/2022]
Abstract
Arginine is an important amino acid involved in processes such as cell signal transduction, protein synthesis, and sexual reproduction. To understand the biological roles of arginine biosynthesis in pathogenic fungi, we used Cpa1, the carbamoyl phosphate synthase arginine-specific small chain subunit in Saccharomyces cerevisiae as a query to identify its ortholog in the Magnaporthe oryzae genome and named it MoCpa1. MoCpa1 is a 471-amino acid protein containing a CPSase_sm_chain domain and a GATase domain. MoCpa1 transcripts were highly expressed at the conidiation, early-infection, and late-infection stages of the fungus. Targeted deletion of the MoCPA1 gene resulted in a ΔMocpa1 mutant exhibiting arginine auxotrophy on minimum culture medium (MM), confirming its role in de novo arginine biosynthesis. The ΔMocpa1 mutant presented significantly decreased sporulation with some of its conidia being defective in morphology. Furthermore, the ΔMocpa1 mutant was nonpathogenic on rice and barley leaves, which was a result of defects in appressorium-mediated penetration and restricted invasive hyphal growth within host cells. Addition of exogenous arginine partially rescued conidiation and pathogenicity defects on the barley and rice leaves, while introduction of the MoCPA1 gene into the ΔMocpa1 mutant fully complemented the lost phenotype. Further confocal microscopy examination revealed that MoCpa1 is localized in the mitochondria. In summary, our results demonstrate that MoCpa1-mediated arginine biosynthesis is crucial for fungal development, conidiation, appressorium formation, and infection-related morphogenesis in M. oryzae, thus serving as an attractive target for mitigating obstinate fungal plant pathogens. KEY POINTS: • MoCpa1 is important for aerial hyphal growth and arginine biosynthesis. • MoCpa1 is pivotal for conidial morphogenesis and appressorium formation. • MoCpa1 is crucial for full virulence in M. oryzae.
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Affiliation(s)
- Osakina Aron
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Min Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Anjago Wilfred Mabeche
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Batool Wajjiha
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Meiqin Li
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Shuai Yang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Haixia You
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Yan Cai
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Tian Zhang
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Yunxi Li
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Baohua Wang
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Dongmei Zhang
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Zonghua Wang
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China. .,State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China. .,Marine and Agricultural Biotechnology Laboratory, Institute of Oceanography, Minjiang University, Fuzhou, 350108, China.
| | - Wei Tang
- Fujian Universities Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
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Emri T, Vékony V, Gila B, Nagy F, Forgács K, Pócsi I. Autolytic hydrolases affect sexual and asexual development of Aspergillus nidulans. Folia Microbiol (Praha) 2018; 63:619-626. [PMID: 29603054 DOI: 10.1007/s12223-018-0601-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 03/21/2018] [Indexed: 11/24/2022]
Abstract
Radial growth, asexual sporulation, and cleistothecia formation as well as extracellular chitinase and proteinase formation of Aspergillus nidulans were monitored in surface cultures in order to study the physiological role of extracellular hydrolase production in carbon-stressed cultures. We set up carbon-stressed and carbon-overfed experimental conditions by varying the starting glucose concentration within the range of 2.5 and 40 g/L. Glucose starvation induced radial growth and hydrolase production and enhanced the maturation of cleistothecia; meanwhile, glucose-rich conditions enhanced mycelial biomass, conidia, and cleistothecia production. Double deletion of chiB and engA (encoding an extracellular endochitinase and a β-1,3-endoglucanase, respectively) decreased conidia production under carbon-stressed conditions, suggesting that these autolytic hydrolases can support conidia formation by releasing nutrients from the cell wall polysaccharides of dead hyphae. Double deletion of prtA and pepJ (both genes encode extracellular proteases) reduced the number of cleistothecia even under carbon-rich conditions except in the presence of casamino acids, which supports the view that sexual development and amino acid metabolism are tightly connected to each other in this fungus.
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Affiliation(s)
- Tamás Emri
- Department of Biotechnology and Microbiology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen, 4032, Hungary. .,Department of Biotechnology and Microbiology, Faculty of Science and Technology, University of Debrecen, P.O. Box 63, Debrecen, 4010, Hungary.
| | - Viktória Vékony
- Department of Biotechnology and Microbiology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen, 4032, Hungary
| | - Barnabás Gila
- Department of Biotechnology and Microbiology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen, 4032, Hungary
| | - Flóra Nagy
- Department of Biotechnology and Microbiology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen, 4032, Hungary
| | - Katalin Forgács
- Department of Biotechnology and Microbiology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen, 4032, Hungary
| | - István Pócsi
- Department of Biotechnology and Microbiology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen, 4032, Hungary
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MrSkn7 controls sporulation, cell wall integrity, autolysis, and virulence in Metarhizium robertsii. EUKARYOTIC CELL 2015; 14:396-405. [PMID: 25710964 DOI: 10.1128/ec.00266-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 02/16/2015] [Indexed: 01/06/2023]
Abstract
Two-component signaling pathways generally include sensor histidine kinases and response regulators. We identified an ortholog of the response regulator protein Skn7 in the insect-pathogenic fungus Metarhizium robertsii, which we named MrSkn7. Gene deletion assays and functional characterizations indicated that MrSkn7 functions as a transcription factor. The MrSkn7 null mutant of M. robertsii lost the ability to sporulate and had defects in cell wall biosynthesis but was not sensitive to oxidative and osmotic stresses compared to the wild type. However, the mutant was able to produce spores under salt stress. Insect bioassays using these spores showed that the virulence of the mutant was significantly impaired compared to that of the wild type due to the failures to form the infection structure appressorium and evade host immunity. In particular, deletion of MrSkn7 triggered cell autolysis with typical features such as cell vacuolization, downregulation of repressor genes, and upregulation of autolysis-related genes such as extracellular chitinases and proteases. Promoter binding assays confirmed that MrSkn7 could directly or indirectly control different putative target genes. Taken together, the results of this study help us understand the functional divergence of Skn7 orthologs as well as the mechanisms underlying the development and control of virulence in insect-pathogenic fungi.
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Spitzmüller Z, Kwon NJ, Szilágyi M, Keserű J, Tóth V, Yu JH, Pócsi I, Emri T. γ-Glutamyl transpeptidase (GgtA) of Aspergillus nidulans is not necessary for bulk degradation of glutathione. Arch Microbiol 2014; 197:285-97. [PMID: 25519188 DOI: 10.1007/s00203-014-1057-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 10/27/2014] [Accepted: 10/28/2014] [Indexed: 12/31/2022]
Abstract
Aspergillus nidulans exhibited high γ-glutamyl transpeptidase (γGT) activity in both carbon-starved and carbon-limited cultures. Glucose repressed, but casein peptone increased γGT production. Null mutation of creA did not influence γGT formation, but the functional meaB was necessary for the γGT induction. Deletion of the AN10444 gene (ggtA) completely eliminated the γGT activity, and the mRNA levels of ggtA showed strong correlation with the observed γGT activities. While ggtA does not contain a canonical signal sequence, the γGT activity was detectable both in the fermentation broth and in the hyphae. Deletion of the ggtA gene did not prevent the depletion of glutathione observed in carbon-starved and carbon-limited cultures. Addition of casein peptone to carbon-starved cultures lowered the formation of reactive species (RS). Deletion of ggtA could hinder this decrease and resulted in elevated RS formation. This effect of γGT on redox homeostasis may explain the reduced cleistothecia formation of ΔggtA strains in surface cultures.
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Affiliation(s)
- Zsolt Spitzmüller
- Department of Biotechnology and Microbiology, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, Debrecen, H4032, Hungary
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Budak SO, Zhou M, Brouwer C, Wiebenga A, Benoit I, Di Falco M, Tsang A, de Vries RP. A genomic survey of proteases in Aspergilli. BMC Genomics 2014; 15:523. [PMID: 24965873 PMCID: PMC4102723 DOI: 10.1186/1471-2164-15-523] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 06/18/2014] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Proteases can hydrolyze peptides in aqueous environments. This property has made proteases the most important industrial enzymes by taking up about 60% of the total enzyme market. Microorganisms are the main sources for industrial protease production due to their high yield and a wide range of biochemical properties. Several Aspergilli have the ability to produce a variety of proteases, but no comprehensive comparative study has been carried out on protease productivity in this genus so far. RESULTS We have performed a combined analysis of comparative genomics, proteomics and enzymology tests on seven Aspergillus species grown on wheat bran and sugar beet pulp. Putative proteases were identified by homology search and Pfam domains. These genes were then clusters based on orthology and extracellular proteases were identified by protein subcellular localization prediction. Proteomics was used to identify the secreted enzymes in the cultures, while protease essays with and without inhibitors were performed to determine the overall protease activity per protease class. All this data was then integrated to compare the protease productivities in Aspergilli. CONCLUSIONS Genomes of Aspergillus species contain a similar proportion of protease encoding genes. According to comparative genomics, proteomics and enzymatic experiments serine proteases make up the largest group in the protease spectrum across the species. In general wheat bran gives higher induction of proteases than sugar beet pulp. Interesting differences of protease activity, extracellular enzyme spectrum composition, protein occurrence and abundance were identified for species. By combining in silico and wet-lab experiments, we present the intriguing variety of protease productivity in Aspergilli.
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Affiliation(s)
- Sebnem Ozturkoglu Budak
- />CBS-KNAW Fungal Biodiversity Center, Uppsalalaan 8, Utrecht, 3584 CT The Netherlands
- />Faculty of Agriculture, Department of Dairy Technology, University of Ankara, Ankara, Turkey
- />Fungal Molecular Physiology, Utrecht University, Utrecht, The Netherlands
| | - Miaomiao Zhou
- />CBS-KNAW Fungal Biodiversity Center, Uppsalalaan 8, Utrecht, 3584 CT The Netherlands
- />Fungal Molecular Physiology, Utrecht University, Utrecht, The Netherlands
| | - Carlo Brouwer
- />CBS-KNAW Fungal Biodiversity Center, Uppsalalaan 8, Utrecht, 3584 CT The Netherlands
| | - Ad Wiebenga
- />CBS-KNAW Fungal Biodiversity Center, Uppsalalaan 8, Utrecht, 3584 CT The Netherlands
- />Fungal Molecular Physiology, Utrecht University, Utrecht, The Netherlands
| | - Isabelle Benoit
- />CBS-KNAW Fungal Biodiversity Center, Uppsalalaan 8, Utrecht, 3584 CT The Netherlands
- />Fungal Molecular Physiology, Utrecht University, Utrecht, The Netherlands
| | - Marcos Di Falco
- />Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke Street West, Montreal, QC H4B 1R6 Canada
| | - Adrian Tsang
- />Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke Street West, Montreal, QC H4B 1R6 Canada
| | - Ronald P de Vries
- />CBS-KNAW Fungal Biodiversity Center, Uppsalalaan 8, Utrecht, 3584 CT The Netherlands
- />Fungal Molecular Physiology, Utrecht University, Utrecht, The Netherlands
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Pusztahelyi T, Pócsi I. Chitinase but N-acetyl-β-D-glucosaminidase production correlates to the biomass decline in Penicillium and Aspergillus species. Acta Microbiol Immunol Hung 2014; 61:131-43. [PMID: 24939682 DOI: 10.1556/amicr.61.2014.2.4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Hydrolytic enzyme production is typical of the autolysis in filamentous fungi; however, less attention has been given to the physiological role of the enzymes. Here, the aim was to investigate the possible relation of the chitinolytic enzymes to the changes in the biomass in some filamentous fungi of high importance for pharmaceutical or food industry. In Penicillium and Aspergillus filamentous fungi, which showed different characteristics in submerged cultures, the growth and biomass decline rates were calculated and correlated to the chitinase and N-acetyl-β-D-glucosaminidase enzyme productions. Correlation was found between the biomass decrease rate and the chitinase level at the stationary growth phase; while chitinase production covariates negatively with N-acetyl-β-D-glucosaminidase activities. The chitinase production and the intensive autolysis hindered the production of N-acetyl-β-D-glucosaminidase and, therefore, could hinder the cell death in the cultures.
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Affiliation(s)
- Tünde Pusztahelyi
- 1 University of Debrecen Central Laboratory, Faculty of Agricultural and Food Sciences and Environmental Management, Centre for Agricultural Sciences Böaszöarményi út 138 H-4032 Debrecen Hungary
| | - István Pócsi
- 2 University of Debrecen Department of Microbial Biotechnology and Cell Biology, Faculty of Science and Technology Egyetem tér 1 H-4032 Debrecen Hungary
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Turgeman T, Kakongi N, Schneider A, Vinokur Y, Teper-Bamnolker P, Carmeli S, Levy M, Skory CD, Lichter A, Eshel D. Induction of Rhizopus oryzae germination under starvation using host metabolites increases spore susceptibility to heat stress. PHYTOPATHOLOGY 2014; 104:240-247. [PMID: 24093921 DOI: 10.1094/phyto-08-13-0245-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Sweetpotato is a nutritional source worldwide. Soft rot caused by Rhizopus spp. is a major limiting factor in the storage of produce, rendering it potentially unsafe for human consumption. In this study, Rhizopus oryzae was used to develop a concept of postharvest disease control by weakening the pathogen through induction of spore germination under starvation conditions. We isolated the sweetpotato active fractions (SPAFs) that induce spore germination and used them at a low dose to enhance spore weakening caused by starvation. Germination in SPAF at 1 mg/ml weakened the pathogen spores by delaying their ability to form colonies on rich media and by increasing their sensitivity to heat stress. The weakening effect was also supported by reduced metabolic activity, as detected by Alarmar Blue fluorescent dye assays. Spores incubated with SPAF at 1 mg/ml showed DNA fragmentation in some of their nuclei, as observed by TUNEL assay. In addition, these spores exhibited changes in ultrastructural morphology (i.e., shrinkage of germ tubes, nucleus deformation, and vacuole formation) which are hallmarks of programmed cell death. We suggest that induction of spore germination under starvation conditions increases their susceptibility to stress and, therefore, might be considered a new strategy for pathogen control.
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Kang JY, Chun J, Jun SC, Han DM, Chae KS, Jahng KY. The MpkB MAP kinase plays a role in autolysis and conidiation of Aspergillus nidulans. Fungal Genet Biol 2013; 61:42-9. [DOI: 10.1016/j.fgb.2013.09.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 09/23/2013] [Accepted: 09/26/2013] [Indexed: 12/23/2022]
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Nitsche BM, Burggraaf-van Welzen AM, Lamers G, Meyer V, Ram AFJ. Autophagy promotes survival in aging submerged cultures of the filamentous fungus Aspergillus niger. Appl Microbiol Biotechnol 2013; 97:8205-18. [DOI: 10.1007/s00253-013-4971-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 04/25/2013] [Accepted: 04/29/2013] [Indexed: 11/29/2022]
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Kovács Z, Szarka M, Kovács S, Boczonádi I, Emri T, Abe K, Pócsi I, Pusztahelyi T. Effect of cell wall integrity stress and RlmA transcription factor on asexual development and autolysis in Aspergillus nidulans. Fungal Genet Biol 2013; 54:1-14. [PMID: 23485399 DOI: 10.1016/j.fgb.2013.02.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Revised: 02/13/2013] [Accepted: 02/14/2013] [Indexed: 11/24/2022]
Abstract
The cell wall integrity (CWI) signaling pathway is responsible for cell wall remodeling and reinforcement upon cell wall stress, which is proposed to be universal in fungal cultures. In Aspergillus nidulans, both the deletion of rlmA encoding the RlmA transcription factor in CWI signaling and low concentrations of the cell wall polymer intercalating agent Congo Red caused significant physiological changes. The gene deletion mutant ΔrlmA strain showed decreased CWI and oxidative stress resistances, which indicated the connection between the CWI pathway and the oxidative stress response system. The Congo Red stress resulted in alterations in the cell wall polymer composition in submerged cultures due to the induction of the biosynthesis of the alkali soluble fraction as well as the hydrolysis of cell wall biopolymers. Both RlmA and RlmA-independent factors induced by Congo Red stress regulated the expression of glucanase (ANID_00245, engA) and chitinase (chiB, chiA) genes, which promoted the autolysis of the cultures and also modulated the pellet sizes. CWI stress and rlmA deletion affected the expression of brlA encoding the early conidiophore development regulator transcription factor BrlA and, as a consequence, the formation of conidiophores was significantly changed in submerged cultures. Interestingly, the number of conidiospores increased in surface cultures of the ΔrlmA strain. The in silico analysis of genes putatively regulated by RlmA and the CWI transcription factors AnSwi4/AnSwi6 in the SBF complex revealed only a few jointly regulated genes, including ugmA and srrA coding for UgmA UDP-galactopyranose mutase and SrrA stress response regulator, respectively.
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Affiliation(s)
- Zsuzsanna Kovács
- Department of Microbial Biotechnology and Cell Biology, Faculty of Science and Technology, University of Debrecen, H-4010 Debrecen, Hungary
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Nitsche BM, Jørgensen TR, Akeroyd M, Meyer V, Ram AFJ. The carbon starvation response of Aspergillus niger during submerged cultivation: insights from the transcriptome and secretome. BMC Genomics 2012; 13:380. [PMID: 22873931 PMCID: PMC3527191 DOI: 10.1186/1471-2164-13-380] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 07/26/2012] [Indexed: 01/13/2023] Open
Abstract
Background Filamentous fungi are confronted with changes and limitations of their carbon source during growth in their natural habitats and during industrial applications. To survive life-threatening starvation conditions, carbon from endogenous resources becomes mobilized to fuel maintenance and self-propagation. Key to understand the underlying cellular processes is the system-wide analysis of fungal starvation responses in a temporal and spatial resolution. The knowledge deduced is important for the development of optimized industrial production processes. Results This study describes the physiological, morphological and genome-wide transcriptional changes caused by prolonged carbon starvation during submerged batch cultivation of the filamentous fungus Aspergillus niger. Bioreactor cultivation supported highly reproducible growth conditions and monitoring of physiological parameters. Changes in hyphal growth and morphology were analyzed at distinct cultivation phases using automated image analysis. The Affymetrix GeneChip platform was used to establish genome-wide transcriptional profiles for three selected time points during prolonged carbon starvation. Compared to the exponential growth transcriptome, about 50% (7,292) of all genes displayed differential gene expression during at least one of the starvation time points. Enrichment analysis of Gene Ontology, Pfam domain and KEGG pathway annotations uncovered autophagy and asexual reproduction as major global transcriptional trends. Induced transcription of genes encoding hydrolytic enzymes was accompanied by increased secretion of hydrolases including chitinases, glucanases, proteases and phospholipases as identified by mass spectrometry. Conclusions This study is the first system-wide analysis of the carbon starvation response in a filamentous fungus. Morphological, transcriptomic and secretomic analyses identified key events important for fungal survival and their chronology. The dataset obtained forms a comprehensive framework for further elucidation of the interrelation and interplay of the individual cellular events involved.
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Affiliation(s)
- Benjamin M Nitsche
- Institute of Biology Leiden, Molecular Microbiology and Biotechnology, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands.
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Szilágyi M, Kwon NJ, Bakti F, M-Hamvas M, Jámbrik K, Park H, Pócsi I, Yu JH, Emri T. Extracellular proteinase formation in carbon starving Aspergillus nidulans cultures--physiological function and regulation. J Basic Microbiol 2011; 51:625-34. [PMID: 21953444 DOI: 10.1002/jobm.201100068] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Accepted: 05/24/2011] [Indexed: 11/09/2022]
Abstract
Extracellular proteinase formation in carbon depleted cultures of the model filamentous fungus Aspergillus nidulans was studied to elucidate its regulation and possible physiological function. As demonstrated by gene deletion, culture optimization, microbial physiological and enzymological experiments, the PrtA and PepJ proteinases of A. nidulans did not appear to play a decisive role in the autolytic decomposition of fungal cells under the conditions we tested. However, carbon starvation induced formation of the proteinases observable in autolytic cultures. Similar to other degradative enzymes, production of proteinase was regulated by FluG-BrlA asexual developmental signaling and modulated by PacC-dependent pH-responsive signaling. Under the same carbon starved culture conditions, alterations of CreA, MeaB or heterotrimeric G protein mediated signaling pathways caused less significant changes in the formation of extracellular proteinases. Taken together, these results indicate that while the accumulation of PrtA and PepJ is tightly coupled to the initiation of autolysis, they are not essential for autolytic cell wall degradation in A. nidulans. Thus, as Aspergillus genomes contain a large group of genes encoding proteinases with versatile physiological functions, selective control of proteinase production in fungal cells is needed for the improved industrial use of fungi.
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Affiliation(s)
- Melinda Szilágyi
- Department of Microbial Biotechnology and Cell Biology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
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Alcazar-Fuoli L, Clavaud C, Lamarre C, Aimanianda V, Seidl-Seiboth V, Mellado E, Latgé JP. Functional analysis of the fungal/plant class chitinase family in Aspergillus fumigatus. Fungal Genet Biol 2010; 48:418-29. [PMID: 21184840 DOI: 10.1016/j.fgb.2010.12.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 12/14/2010] [Accepted: 12/17/2010] [Indexed: 11/28/2022]
Abstract
A quintuple mutant was constructed to delete the entire family of the fungal/plant (class III) chitinases of Aspergillus fumigatus. Only a limited reduction in the total chitinolytic activity was seen for the different chitinase mutants including the quintuple mutant. In spite of this reduction in chitinolytic activity, no growth or germination defects were observed in these chitinase mutants. This result demonstrated that the fungal/plant chitinases do not have an essential role in the morphogenesis of A. fumigatus. A slight diminution of the growth during autolysis was seen for the quintuple mutant suggesting that class III chitinases may play only a nutritional role during this phase of the cycle, retarding fungal death.
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Affiliation(s)
- Laura Alcazar-Fuoli
- Servicio de Micologia, Centro Nacional de Microbiologia, Instituto de Salud Carlos III, Carretera Majadahonda-Pozuelo Km2 (28220), Majadahonda, Madrid, Spain
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Papaspyridi LM, Katapodis P, Gonou-Zagou Z, Kapsanaki-Gotsi E, Christakopoulos P. Optimization of biomass production with enhanced glucan and dietary fibres content by Pleurotus ostreatus ATHUM 4438 under submerged culture. Biochem Eng J 2010. [DOI: 10.1016/j.bej.2010.04.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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16
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Szilágyi M, Kwon NJ, Dorogi C, Pócsi I, Yu JH, Emri T. The extracellular β-1,3-endoglucanase EngA is involved in autolysis of Aspergillus nidulans. J Appl Microbiol 2010; 109:1498-508. [PMID: 20602653 DOI: 10.1111/j.1365-2672.2010.04782.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS To elucidate the roles of the β-1,3-endoglucanase EngA in autolysis of the filamentous fungus Aspergillus nidulans and to identify the common regulatory elements of autolytic hydrolases. METHODS AND RESULTS A β-1,3-endoglucanase was purified from carbon-starving cultures of A. nidulans. This enzyme is found to be encoded by the engA gene (locus ID: AN0472.3). Functional and gene-expression studies demonstrated that EngA is involved in the autolytic cell wall degradation resulting from carbon starvation of the fungus. Moreover, regulation of engA is found to be dependent on the FluG/BrlA asexual sporulation signalling pathway in submerged culture. The deletion of either engA or chiB (encoding an endochitinase) caused highly reduced production of hydrolases in general. CONCLUSIONS The β-1,3-endoglucanase EngA plays a pivotal role in fungal autolysis, and activities of both EngA and ChiB are necessary to orchestrate the expression of autolytic hydrolases. The production of cell wall-degrading enzymes was coordinately controlled in a highly sophisticated and complex manner. SIGNIFICANCE AND IMPACT OF THE STUDY No information was available on the autolytic glucanase(s) of the euascomycete A. nidulans. This study demonstrates that EngA is a key element in fungal autolysis, and normal activities of both EngA and ChiB are crucial for balanced production of hydrolases.
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Affiliation(s)
- M Szilágyi
- Department of Microbial Biotechnology and Cell Biology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
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Szilágyi M, Pócsi I, Forgács K, Emri T. MeaB-dependent nutrition sensing regulates autolysis in carbon starved Aspergillus nidulans cultures. Indian J Microbiol 2010; 50:104-8. [PMID: 23100816 PMCID: PMC3450277 DOI: 10.1007/s12088-010-0023-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Accepted: 01/24/2009] [Indexed: 11/30/2022] Open
Abstract
Carbon starvation induced autolysis is an active process of self-digestion and is under complex regulation in Aspergillus nidulans. In this study we investigated how autolysis depends on the composition of the culture medium, especially on the presence of yeast extract. We demonstrated that the rate of autolytic cell wall degradation as well as the extracellular chitinase and proteinase productions significantly decreased in the presence of this nutrient. The effect of yeast extract on carbon starved cultures was independent of loss-of-function mutations in the carbon and nitrogen regulatory genes creA and areA and in the heterotrimeric G protein signalling genes fadA and ganB. In contrast, the nitrogen regulating transcription factor MeaB was involved in the yeast-extract-mediated repression of autolysis. Reverse transcriptase - polymerase chain reaction (RT-PCR) experiments demonstrated that MeaB affects the FluG-BrlA sporulation regulatory pathway by affecting transcription of brlA, a gene also initiating the autolytic cell wall degradation in this fungus.
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Affiliation(s)
- Melinda Szilágyi
- Department of Microbial Biotechnology and Cell Biology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - István Pócsi
- Department of Microbial Biotechnology and Cell Biology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Katalin Forgács
- Department of Microbial Biotechnology and Cell Biology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Tamás Emri
- Department of Microbial Biotechnology and Cell Biology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
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AtfA bZIP-type transcription factor regulates oxidative and osmotic stress responses in Aspergillus nidulans. Mol Genet Genomics 2010; 283:289-303. [PMID: 20131067 DOI: 10.1007/s00438-010-0513-z] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Accepted: 01/18/2010] [Indexed: 12/18/2022]
Abstract
The aim of the study was to demonstrate that the bZIP-type transcription factor AtfA regulates different types of stress responses in Aspergillus nidulans similarly to Atf1, the orthologous 'all-purpose' transcription factor of Schizosaccharomyces pombe. Heterologous expression of atfA in a S. pombe Deltaatf1 mutant restored the osmotic stress tolerance of fission yeast in surface cultures to the same level as recorded in complementation studies with the atf1 gene, and a partial complementation of the osmotic and oxidative-stress-sensitive phenotypes was also achieved in submerged cultures. AtfA is therefore a true functional ortholog of fission yeast's Atf1. As demonstrated by RT-PCR experiments, elements of both oxidative (e.g. catalase B) and osmotic (e.g. glycerol-3-phosphate dehydrogenase B) stress defense systems were transcriptionally regulated by AtfA in a stress-type-specific manner. Deletion of atfA resulted in oxidative-stress-sensitive phenotypes while the high-osmolarity stress sensitivity of the fungus was not affected significantly. In A. nidulans, the glutathione/glutathione disulfide redox status of the cells as well as apoptotic cell death and autolysis seemed to be controlled by regulatory elements other than AtfA. In conclusion, the orchestrations of stress responses in the aspergilli and in fission yeast share several common features, but further studies are needed to answer the important question of whether a fission yeast-like core environmental stress response also operates in the euascomycete genus Aspergillus.
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19
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Pócsi I, Leiter E, Kwon NJ, Shin KS, Kwon GS, Pusztahelyi T, Emri T, Abuknesha RA, Price RG, Yu JH. Asexual sporulation signalling regulates autolysis of Aspergillus nidulans via modulating the chitinase ChiB production. J Appl Microbiol 2009; 107:514-23. [PMID: 19486415 DOI: 10.1111/j.1365-2672.2009.04237.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIMS Elucidation of the regulation of ChiB production in Aspergillus nidulans. METHODS AND RESULTS Mutational inactivation of the A. nidulans chiB gene resulted in a nonautolytic phenotype. To better understand the mechanisms controlling both developmental progression and fungal autolysis, we examined a range of autolysis-associated parameters in A. nidulans developmental and/or autolytic mutants. Investigation of disorganization of mycelial pellets, loss of biomass, extra-/intracellular chitinase activities, ChiB production and chiB mRNA levels in various cultures revealed that, in submerged cultures, initialization of autolysis and stationary phase-induced ChiB production are intimately coupled, and that both processes are controlled by the FluG-BrlA asexual sporulation regulatory pathway. ChiB production does not affect the progression of apoptotic cell death in the aging A. nidulans cultures. CONCLUSIONS The endochitinase ChiB plays an important role in autolysis of A. nidulans, and its production is initiated by FluG-BrlA signalling. Despite the fact that apoptosis is an inseparable part of fungal autolysis, its regulation is independent to FluG-initiated sporulation signalling. SIGNIFICANCE AND IMPACT OF THE STUDY Deletion of chiB and fluG homologues in industrial filamentous fungal strains may stabilize the hyphal structures in the autolytic phase of growth and limit the release of autolytic hydrolases into the culture medium.
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Affiliation(s)
- I Pócsi
- Department of Microbial Biotechnology and Cell Biology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary.
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20
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Differential roles of the ChiB chitinase in autolysis and cell death of Aspergillus nidulans. EUKARYOTIC CELL 2009; 8:738-46. [PMID: 19286987 DOI: 10.1128/ec.00368-08] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Autolysis is a natural event that occurs in most filamentous fungi. Such self-degradation of fungal cells becomes a predominant phenomenon in the absence of the regulator of G protein signaling FlbA in Aspergillus nidulans. Among a number of potential hydrolytic enzymes in the A. nidulans genome, the secreted endochitinase ChiB was shown to play a major role in autolysis. In this report, we investigate the roles of ChiB in fungal autolysis and cell death processes through genetic, biochemical, and cellular analyses using a set of critical mutants. Determination of mycelial mass revealed that, while the flbA deletion (DeltaflbA) mutant autolyzed completely after a 3-day incubation, the DeltaflbA DeltachiB double mutant escaped from hyphal disintegration. These results indicate that ChiB is necessary for the DeltaflbA-induced autolysis. However, importantly, both DeltaflbA and DeltaflbA DeltachiB strains displayed dramatically reduced cell viability compared to the wild type. These imply that ChiB is dispensable for cell death and that autolysis and cell death are separate processes. Liquid chromatography-tandem mass spectrometry analyses of the proteins that accumulate at high levels in the DeltaflbA and DeltaflbA DeltachiB mutants identify chitinase (ChiB), dipeptidyl peptidase V (DppV), O-glycosyl compound hydrolase, beta-N-acetylhexosaminidase (NagA), and myo-inositol-1-phosphate synthase (InoB). Functional characterization of these four genes reveals that the deletion of nagA results in reduced cell death. A working model bridging G protein signaling and players in autolysis/cell death is proposed.
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21
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Rékangalt D, Pépin R, Verner MC, Debaud JC, Marmeisse R, Fraissinet-Tachet L. Expression of the nitrate transporter nrt2 gene from the symbiotic basidiomycete Hebeloma cylindrosporum is affected by host plant and carbon sources. MYCORRHIZA 2009; 19:143-148. [PMID: 19125303 DOI: 10.1007/s00572-008-0221-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Accepted: 12/10/2008] [Indexed: 05/27/2023]
Abstract
Although the function of the extramatrical mycelium of ectomycorrhizal fungi is considered essential for the acquisition of nitrogen by forest trees, gene regulation in this fungal compartment is poorly characterized. In this study, the expression of the nitrate transporter gene nrt2 from the ectomycorrhizal basidiomycete Hebeloma cylindrosporum was shown to be regulated by plant host and carbon sources. In the presence of a low fructose concentration, nrt2 expression could not be detected in the free-living mycelium but was high in the extramatrical symbiotic mycelium associated to the host plant Pinus pinaster. In the absence of nitrogen or in the presence of nitrate, high sugar concentrations in the medium were able to enhance nrt2 expression. Nevertheless, in the presence of high fructose concentration, high ammonium concentration still completely repressed nrt2 expression indicating that the nitrogen repression overrides sugar stimulation. This is the first report revealing an effect of host plant and of carbon sources on the expression of a fungal nitrate transporter-encoding gene.
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Affiliation(s)
- David Rékangalt
- Université de Lyon, 69622, Lyon, France
- CNRS, UMR5557, INRA, USC 1193, Ecologie Microbienne, Bât. Lwoff, Université Lyon 1, 43 boulevard du 11 novembre 1918, 69622, Villeurbanne Cedex, France
| | - Régis Pépin
- Université de Lyon, 69622, Lyon, France
- CNRS, UMR5557, INRA, USC 1193, Ecologie Microbienne, Bât. Lwoff, Université Lyon 1, 43 boulevard du 11 novembre 1918, 69622, Villeurbanne Cedex, France
| | - Marie-Christine Verner
- Université de Lyon, 69622, Lyon, France
- CNRS, UMR5557, INRA, USC 1193, Ecologie Microbienne, Bât. Lwoff, Université Lyon 1, 43 boulevard du 11 novembre 1918, 69622, Villeurbanne Cedex, France
| | - Jean-Claude Debaud
- Université de Lyon, 69622, Lyon, France
- CNRS, UMR5557, INRA, USC 1193, Ecologie Microbienne, Bât. Lwoff, Université Lyon 1, 43 boulevard du 11 novembre 1918, 69622, Villeurbanne Cedex, France
| | - Roland Marmeisse
- Université de Lyon, 69622, Lyon, France
- CNRS, UMR5557, INRA, USC 1193, Ecologie Microbienne, Bât. Lwoff, Université Lyon 1, 43 boulevard du 11 novembre 1918, 69622, Villeurbanne Cedex, France
| | - Laurence Fraissinet-Tachet
- Université de Lyon, 69622, Lyon, France.
- CNRS, UMR5557, INRA, USC 1193, Ecologie Microbienne, Bât. Lwoff, Université Lyon 1, 43 boulevard du 11 novembre 1918, 69622, Villeurbanne Cedex, France.
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22
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Transcriptional profiling identifies a role for BrlA in the response to nitrogen depletion and for StuA in the regulation of secondary metabolite clusters in Aspergillus fumigatus. EUKARYOTIC CELL 2008; 8:104-15. [PMID: 19028996 DOI: 10.1128/ec.00265-08] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Conidiation (asexual sporulation) is a key developmental process in filamentous fungi. We examined the gene regulatory roles of the Aspergillus fumigatus developmental transcription factors StuAp and BrlAp during conidiation. Conidiation was completely abrogated in an A. fumigatus DeltabrlA mutant and was severely impaired in a DeltastuA mutant. We determined the full genome conidiation transcriptomes of wild-type and DeltabrlA and DeltastuA mutant A. fumigatus and found that BrlAp and StuAp governed overlapping but distinct transcriptional programs. Six secondary metabolite biosynthetic clusters were found to be regulated by StuAp, while only one cluster exhibited BrlAp-dependent expression. The DeltabrlA mutant, but not the DeltastuA mutant, had impaired downregulation of genes encoding ribosomal proteins under nitrogen-limiting, but not carbon-limiting, conditions. Interestingly, inhibition of the target of rapamycin (TOR) pathway also caused downregulation of ribosomal protein genes in both the wild-type strain and the DeltabrlA mutant. Downregulation of these genes by TOR inhibition was associated with conidiation in the wild-type strain but not in the DeltabrlA mutant. Therefore, BrlAp-mediated repression of ribosomal protein gene expression is not downstream of the TOR pathway. Furthermore, inhibition of ribosomal protein gene expression is not sufficient to induce conidiation in the absence of BrlAp.
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23
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Erdei E, Pusztahelyi T, Miskei M, Barna T, Pócsi I. Characterization and heterologous expression of an age-dependent fungal/bacterial type chitinase of Aspergillus nidulans. Acta Microbiol Immunol Hung 2008; 55:351-61. [PMID: 18800599 DOI: 10.1556/amicr.55.2008.3.6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Under carbon starvation, Aspergillus nidulans produced a fungal/bacterial type chitinase, ChiB. The chiB gene was cloned and subcloned into pJC40 expression vector containing a 10XHis fusion tag, and the ChiB protein was expressed heterologously in Escherichia coli. Recombinant and native ChiB enzymes shared the same optimal pH ranges and showed similar substrate specificities with endo-acting cleavage patterns.
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Affiliation(s)
- Eva Erdei
- Department of Microbial Biotechnology and Cell Biology, Faculty of Science and Technology, University of Debrecen, H-4010 Debrecen, Hungary
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24
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Emri T, Szilágyi M, Justyák A, Pócsi I. Heterotrimeric G protein mediated regulation of proteinase production in Aspergillus nidulans. Acta Microbiol Immunol Hung 2008; 55:111-7. [PMID: 18595316 DOI: 10.1556/amicr.55.2008.2.3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Extracellular proteinase production induced by carbon starvation was studied in a series of heterotrimeric G protein signaling pathway mutants of Aspergillus nidulans. All the mutants tested--including deltafadA (Galpha), deltasfaD (Gbeta), deltagpgA (Ggamma) and deltasfgA (regulator of FadA signaling)--showed an elevated proteinase production after glucose depletion. Our results strongly support the view that during growth, FadA/SfaD/GpgA G protein signaling inhibits proteinase production via both Galpha and Gbetagamma subunits, and all conditions, which are not sufficient to support vegetative growth and, hence, inhibit this type of G protein signaling, elevate extracellular proteinase activities.
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Affiliation(s)
- Tamás Emri
- Department of Microbial Biotechnology and Cell Biology, Faculty of Science and Technology, University of Debrecen, P.O. Box 63, H-4010 Debrecen, Hungary.
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25
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Katz ME, Bernardo SM, Cheetham BF. The interaction of induction, repression and starvation in the regulation of extracellular proteases in Aspergillus nidulans: evidence for a role for CreA in the response to carbon starvation. Curr Genet 2008; 54:47-55. [PMID: 18512059 DOI: 10.1007/s00294-008-0198-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Revised: 05/14/2008] [Accepted: 05/15/2008] [Indexed: 11/26/2022]
Abstract
In Aspergillus nidulans, production of extracellular proteases in response to carbon starvation and to a lesser extent nitrogen starvation is controlled by XprG, a putative transcriptional activator. In this study the role of genes involved in carbon catabolite repression and the role of protein as an inducer of extracellular protease gene expression were examined. The addition of exogenous protein to the growth medium did not increase extracellular protease activity whether or not additional carbon or nitrogen sources were present indicating that induction does not play a major role in the regulation of extracellular proteases. Northern blot analysis confirmed that protein is not an inducer of the major A. nidulans protease, PrtA. Mutations in the creA, creB and creC genes increased extracellular protease levels in medium lacking a carbon source suggesting that they may have a role in the response to carbon starvation as well as carbon catabolite repression. Analysis of glkA4 frA2 and creADelta4 mutants showed that the loss of glucose signalling or the DNA-binding protein which mediates carbon catabolite repression did not abolish glucose repression but did increase extracellular protease activity. This increase was XprG-dependent indicating that the effect of these genes may be through modulation of XprG activity.
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Affiliation(s)
- Margaret E Katz
- Molecular and Cellular Biology, University of New England, Armidale, NSW 2351, Australia.
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26
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Yamazaki H, Tanaka A, Kaneko JI, Ohta A, Horiuchi H. Aspergillus nidulans ChiA is a glycosylphosphatidylinositol (GPI)-anchored chitinase specifically localized at polarized growth sites. Fungal Genet Biol 2008; 45:963-72. [PMID: 18420434 DOI: 10.1016/j.fgb.2008.02.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 02/25/2008] [Accepted: 02/25/2008] [Indexed: 11/26/2022]
Abstract
It is believed that chitinases play important physiological roles in filamentous fungi since chitin is one of the major cell wall components in these organisms. In this paper we investigated a chitinase gene, chiA, of Aspergillus nidulans and found that the gene product of chiA consists of a signal sequence, a region including chitinase consensus motifs, a Ser/Thr/Pro-rich region and a glycosylphosphatidylinositol (GPI)-anchor attachment motif. Phosphatidylinositol-specific phospholipase C treatment of the fusion protein of ChiA and enhanced green fluorescent protein (EGFP)-ChiA-EGFP-caused a change in its hydrophobicity, indicating that ChiA is a GPI-anchored protein. ChiA-EGFP localized at the germ tubes of conidia, at hyphal branching sites and hyphal tips. chiA expression was specifically high during conidia germination and in the marginal growth regions of colonies. These results suggest that ChiA functions as a GPI-anchored chitinase at the sites where cell wall remodeling and/or cell wall maturation actively take place.
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Affiliation(s)
- Harutake Yamazaki
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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27
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Regulation of autolysis in Aspergillus nidulans. Appl Biochem Biotechnol 2008; 151:211-20. [PMID: 18975147 DOI: 10.1007/s12010-008-8174-7] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Accepted: 02/05/2008] [Indexed: 10/22/2022]
Abstract
In terms of cell physiology, autolysis is the centerpiece of carbon-starving fungal cultures. In the filamentous fungus model organism Aspergillus nidulans, the last step of carbon-starvation-triggered autolysis was the degradation of the cell wall of empty hyphae, and this process was independent of concomitantly progressing cell death at the level of regulation. Autolysis-related proteinase and chitinase activities were induced via FluG signaling, which initiates sporulation and inhibits vegetative growth in surface cultures of A. nidulans. Extracellular hydrolase production was also subjected to carbon repression, which was only partly dependent on CreA, the main carbon catabolite repressor in this fungus. These data support the view that one of the main functions of autolysis is supplying nutrients for sporulation, when no other sources of nutrients are available. The divergent regulation of cell death and cell wall degradation provides the fungus with the option to keep dead hyphae intact to help surviving cells to absorb biomaterials from dead neighboring cells before these are released into the extracellular space. The industrial significance of these observations is also discussed in this paper.
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28
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Pócsi I, Molnár Z, Pusztahelyi T, Varecza Z, Emri T. Yeast-like cell formation and glutathione metabolism in autolysing cultures of Penicillium chrysogenum. ACTA BIOLOGICA HUNGARICA 2007; 58:431-40. [PMID: 18277469 DOI: 10.1556/abiol.58.2007.4.10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The bulk formation of yeast-like (arthrospore-like) cells were typical in carbon-depleted submerged cultures of the high beta-lactam producer Penicillium chrysogenum NCAIM 00237 strain independently of the nitrogen-content of the culture medium. This morphogenetic switch was still quite common in carbon-starving cultures of the low-penicillin-producer strain P. chrysogenum ATCC 28089 (Wis 54-1255) when the nitrogen-content of the medium was low but was a very rare event in wild-type P. chrysogenum cultures. The mycelium-->yeast-like cell transition correlated well with a relatively high glutathione concentration and a reductive glutathione/glutathione disulfite (GSH/GSSG) redox balance in autolysing cultures, which was a consequence of industrial strain development. Paradoxically, the development of high beta-lactam productivity resulted in a high intracellular GSH level and, concomitantly, in an increased y-glutamyltranspeptidase (i.e. GSH-decomposing) activity in the autolytic phase of growth of P. chrysogenum NCAIM 00237. The hypothesized causal connection between GSH metabolism and cell morphology, if verified, may help us in future metabolic engineering of industrially important filamentous fungi.
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Affiliation(s)
- I Pócsi
- Department of Microbial Biotechnology and Cell Biology, Faculty of Sciences, University of Debrecen, Debrecen, Hungary
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