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Traynor AM, Sheridan KJ, Jones GW, Calera JA, Doyle S. Involvement of Sulfur in the Biosynthesis of Essential Metabolites in Pathogenic Fungi of Animals, Particularly Aspergillus spp.: Molecular and Therapeutic Implications. Front Microbiol 2019; 10:2859. [PMID: 31921039 PMCID: PMC6923255 DOI: 10.3389/fmicb.2019.02859] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 11/25/2019] [Indexed: 12/13/2022] Open
Abstract
Fungal sulfur uptake is required for incorporation into the sidechains of the amino acids cysteine and methionine, and is also essential for the biosynthesis of the antioxidant glutathione (GSH), S-adenosylmethionine (SAM), the key source of methyl groups in cellular transmethylation reactions, and S-adenosylhomocysteine (SAH). Biosynthesis of redox-active gliotoxin in the opportunistic fungal pathogen Aspergillus fumigatus has been elucidated over the past 10 years. Some fungi which produce gliotoxin-like molecular species have undergone unexpected molecular rewiring to accommodate this high-risk biosynthetic process. Specific disruption of gliotoxin biosynthesis, via deletion of gliK, which encodes a γ-glutamyl cyclotransferase, leads to elevated intracellular antioxidant, ergothioneine (EGT), levels, and confirms crosstalk between the biosynthesis of both sulfur-containing moieties. Gliotoxin is ultimately formed by gliotoxin oxidoreductase GliT-mediated oxidation of dithiol gliotoxin (DTG). In fact, DTG is a substrate for both GliT and a bis-thiomethyltransferase, GtmA. GtmA converts DTG to bisdethiobis(methylthio)gliotoxin (BmGT), using 2 mol SAM and resultant SAH must be re-converted to SAM via the action of the Methyl/Met cycle. In the absence of GliT, DTG fluxes via GtmA to BmGT, which results in both SAM depletion and SAH overproduction. Thus, the negative regulation of gliotoxin biosynthesis via GtmA must be counter-balanced by GliT activity to avoid Methyl/Met cycle dysregulation, SAM depletion and trans consequences on global cellular biochemistry in A. fumigatus. DTG also possesses potent Zn2+ chelation properties which positions this sulfur-containing metabolite as a putative component of the Zn2+ homeostasis system within fungi. EGT plays an essential role in high-level redox homeostasis and its presence requires significant consideration in future oxidative stress studies in pathogenic filamentous fungi. In certain filamentous fungi, sulfur is additionally indirectly required for the formation of EGT and the disulfide-bridge containing non-ribosomal peptide, gliotoxin, and related epipolythiodioxopiperazines. Ultimately, interference with emerging sulfur metabolite functionality may represent a new strategy for antifungal drug development.
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Affiliation(s)
- Aimee M Traynor
- Department of Biology, Maynooth University, Maynooth, Ireland
| | | | - Gary W Jones
- Centre for Biomedical Science Research, School of Clinical and Applied Sciences, Leeds Beckett University, Leeds, United Kingdom
| | - José A Calera
- Instituto de Biología Funcional y Genómica (IBFG-CSIC), Universidad de Salamanca, Salamanca, Spain.,Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain
| | - Sean Doyle
- Department of Biology, Maynooth University, Maynooth, Ireland
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Snyman C, Theron LW, Divol B. Understanding the regulation of extracellular protease gene expression in fungi: a key step towards their biotechnological applications. Appl Microbiol Biotechnol 2019; 103:5517-5532. [PMID: 31129742 DOI: 10.1007/s00253-019-09902-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 05/07/2019] [Accepted: 05/07/2019] [Indexed: 12/20/2022]
Abstract
The secretion of proteases by certain species of yeast and filamentous fungi is of importance not only for their biological function and survival, but also for their biotechnological application to various processes in the food, beverage, and bioprocessing industries. A key step towards understanding the role that these organisms play in their environment, and how their protease-secreting ability may be optimally utilised through industrial applications, involves an evaluation of those factors which influence protease production. The objective of this review is to provide an overview of the findings from investigations directed at elucidating the regulatory mechanisms underlying extracellular protease secretion in yeast and filamentous fungi, and the environmental stimuli that elicit these responses. The influence of nitrogen-, carbon-, and sulphur-containing compounds, as well as proteins, temperature, and pH, on extracellular protease regulation, which is frequently exerted at the transcriptional level, is discussed in particular depth. Protease-secreting organisms of biotechnological interest are also presented in this context, in an effort to explore the areas of industrial significance that could possibly benefit from such knowledge. In this way, the establishment of a platform of existing knowledge regarding fungal protease regulation is attempted, with the particular goal of aiding in the practical application of these organisms to processes that require secretion of this enzyme.
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Affiliation(s)
- C Snyman
- Department of Viticulture and Oenology, Institute for Wine Biotechnology, Private Bag X1, Matieland, 7602, South Africa
| | - L W Theron
- Department of Viticulture and Oenology, Institute for Wine Biotechnology, Private Bag X1, Matieland, 7602, South Africa
| | - B Divol
- Department of Viticulture and Oenology, Institute for Wine Biotechnology, Private Bag X1, Matieland, 7602, South Africa.
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El-Sayed ASA, Yassin MA, Ali GS. Transcriptional and Proteomic Profiling of Aspergillus flavipes in Response to Sulfur Starvation. PLoS One 2015; 10:e0144304. [PMID: 26633307 PMCID: PMC4669086 DOI: 10.1371/journal.pone.0144304] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 11/15/2015] [Indexed: 12/19/2022] Open
Abstract
Aspergillus flavipes has received considerable interest due to its potential to produce therapeutic enzymes involved in sulfur amino acid metabolism. In natural habitats, A. flavipes survives under sulfur limitations by mobilizing endogenous and exogenous sulfur to operate diverse cellular processes. Sulfur limitation affects virulence and pathogenicity, and modulates proteome of sulfur assimilating enzymes of several fungi. However, there are no previous reports aimed at exploring effects of sulfur limitation on the regulation of A. flavipes sulfur metabolism enzymes at the transcriptional, post-transcriptional and proteomic levels. In this report, we show that sulfur limitation affects morphological and physiological responses of A. flavipes. Transcription and enzymatic activities of several key sulfur metabolism genes, ATP-sulfurylase, sulfite reductase, methionine permease, cysteine synthase, cystathionine β- and γ-lyase, glutathione reductase and glutathione peroxidase were increased under sulfur starvation conditions. A 50 kDa protein band was strongly induced by sulfur starvation, and the proteomic analyses of this protein band using LC-MS/MS revealed similarity to many proteins involved in the sulfur metabolism pathway.
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Affiliation(s)
- Ashraf S. A. El-Sayed
- Botany and Microbiology Department, Faculty of Science, Zagazig University, 44519, Zagazig, Egypt
- Mid-Florida Research and Education Center, Department of Plant Pathology, University of Florida, Apopka, Florida 32703, United States of America
- * E-mail: (GSA); (AES)
| | - Marwa A. Yassin
- Botany and Microbiology Department, Faculty of Science, Zagazig University, 44519, Zagazig, Egypt
| | - Gul Shad Ali
- Mid-Florida Research and Education Center, Department of Plant Pathology, University of Florida, Apopka, Florida 32703, United States of America
- * E-mail: (GSA); (AES)
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Bischof RH, Horejs J, Metz B, Gamauf C, Kubicek CP, Seiboth B. L-Methionine repressible promoters for tuneable gene expression in Trichoderma reesei. Microb Cell Fact 2015; 14:120. [PMID: 26271614 PMCID: PMC4536894 DOI: 10.1186/s12934-015-0308-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 07/30/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Trichoderma reesei is the main producer of lignocellulolytic enzymes that are required for plant biomass hydrolysis in the biorefinery industry. Although the molecular toolbox for T. reesei is already well developed, repressible promoters for strain engineering and functional genomics studies are still lacking. One such promoter that is widely employed for yeasts is that of the L-methionine repressible MET3 gene, encoding ATP sulphurylase. RESULTS We show that the MET3 system can only be applied for T. reesei when the cellulase inducing carbon source lactose is used but not when wheat straw, a relevant lignocellulosic substrate for enzyme production, is employed. We therefore performed a transcriptomic screen for genes that are L-methionine repressible in a wheat straw culture. This analysis retrieved 50 differentially regulated genes of which 33 were downregulated. Among these, genes encoding transport proteins as well as iron containing DszA like monooxygenases and TauD like dioxygenases were strongly overrepresented. We show that the promoter region of one of these dioxygenases can be used for the strongly repressible expression of the Aspergillus niger sucA encoded extracellular invertase in T. reesei wheat straw cultures. This system is also portable to other carbon sources including D-glucose and glycerol as demonstrated by the repressible expression of the Escherichia coli lacZ encoded ß-galactosidase in T. reesei. CONCLUSION We describe a novel, versatile set of promoters for T. reesei that can be used to drive recombinant gene expression in wheat straw cultures at different expression strengths and in an L-methionine repressible manner. The dioxygenase promoter that we studied in detail is furthermore compatible with different carbon sources and therefore applicable for manipulating protein production as well as functional genomics with T. reesei.
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Affiliation(s)
- Robert H Bischof
- Austrian Centre of Industrial Biotechnology (ACIB) GmbH c/o Institute of Chemical Engineering, Technische Universität Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria.
| | - Jennifer Horejs
- Austrian Centre of Industrial Biotechnology (ACIB) GmbH c/o Institute of Chemical Engineering, Technische Universität Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria. .,Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, Technische Universität Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria.
| | - Benjamin Metz
- Austrian Centre of Industrial Biotechnology (ACIB) GmbH c/o Institute of Chemical Engineering, Technische Universität Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria. .,Vogelbusch Biocommodities GmbH, Blechturmgasse 11, 1051, Vienna, Austria.
| | - Christian Gamauf
- Biotech and Renewables Center, Clariant GmbH, 81477, Munich, Germany.
| | - Christian P Kubicek
- Austrian Centre of Industrial Biotechnology (ACIB) GmbH c/o Institute of Chemical Engineering, Technische Universität Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria. .,Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, Technische Universität Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria.
| | - Bernhard Seiboth
- Austrian Centre of Industrial Biotechnology (ACIB) GmbH c/o Institute of Chemical Engineering, Technische Universität Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria. .,Research Division Biotechnology and Microbiology, Institute of Chemical Engineering, Technische Universität Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria.
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Regulatory mutations affecting sulfur metabolism induce environmental stress response in Aspergillus nidulans. Fungal Genet Biol 2014; 65:37-47. [PMID: 24513272 DOI: 10.1016/j.fgb.2014.02.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 01/30/2014] [Accepted: 02/01/2014] [Indexed: 10/25/2022]
Abstract
Mutations in the cysB, sconB and sconC genes affect sulfur metabolism in Aspergillus nidulans in different ways. The cysB mutation blocks synthesis of cysteine by the main pathway and leads to a shortage of this amino acid. The sconB and sconC mutations affect subunits of the SCF ubiquitin ligase complex, which inactivates the MetR transcription factor in the presence of an excess of cysteine. In effect, both cysB and scon mutations lead to permanent derepression of MetR-dependent genes. We compared transcriptomes of these three mutants with that of a wild type strain finding altered expression of a few hundred genes belonging to various functional categories. Besides those involved in sulfur metabolism, many up-regulated genes are related to stress responses including heat shock and osmotic stress. However, only the scon strains are more resistant to exogenous stress agents than the wild type strain while cysB is more sensitive. The two-component signal transduction system is a functional category, which is most enriched among genes up-regulated in the cysB, sconB and sconC mutants. A large group of up-regulated genes are involved in carbohydrate and energy metabolism, including genes coding for enzymes of trehalose and glycerol synthesis. The altered expression of these genes is accompanied by changes in sugar and polyol accumulation in conidia of the mutants. Genes encoding enzymes of the glyoxylate bypass and the GABA shunt are also up-regulated along with genes coding for enzymes of alcohol fermentation. Among the down-regulated genes the most numerous are those encoding membrane proteins and enzymes involved in secondary metabolism, including the penicillin biosynthesis cluster.
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Menino JF, Saraiva M, Gomes-Rezende J, Sturme M, Pedrosa J, Castro AG, Ludovico P, Goldman GH, Rodrigues F. P. brasiliensis virulence is affected by SconC, the negative regulator of inorganic sulfur assimilation. PLoS One 2013; 8:e74725. [PMID: 24066151 PMCID: PMC3774720 DOI: 10.1371/journal.pone.0074725] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 08/05/2013] [Indexed: 11/21/2022] Open
Abstract
Conidia/mycelium-to-yeast transition of Paracoccidioidesbrasiliensis is a critical step for the establishment of paracoccidioidomycosis, a systemic mycosis endemic in Latin America. Thus, knowledge of the factors that mediate this transition is of major importance for the design of intervention strategies. So far, the only known pre-requisites for the accomplishment of the morphological transition are the temperature shift to 37°C and the availability of organic sulfur compounds. In this study, we investigated the auxotrophic nature to organic sulfur of the yeast phase of Paracoccidioides, with special attention to P. brasiliensis species. For this, we addressed the role of SconCp, the negative regulator of the inorganic sulfur assimilation pathway, in the dimorphism and virulence of this pathogen. We show that down-regulation of SCONC allows initial steps of mycelium-to-yeast transition in the absence of organic sulfur compounds, contrarily to the wild-type fungus that cannot undergo mycelium-to-yeast transition under such conditions. However, SCONC down-regulated transformants were unable to sustain yeast growth using inorganic sulfur compounds only. Moreover, pulses with inorganic sulfur in SCONC down-regulated transformants triggered an increase of the inorganic sulfur metabolism, which culminated in a drastic reduction of the ATP and NADPH cellular levels and in higher oxidative stress. Importantly, the down-regulation of SCONC resulted in a decreased virulence of P. brasiliensis, as validated in an in vivo model of infection. Overall, our findings shed light on the inability of P. brasiliensis yeast to rely on inorganic sulfur compounds, correlating its metabolism with cellular energy and redox imbalances. Furthermore, the data herein presented reveal SconCp as a novel virulence determinant of P. brasiliensis.
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Affiliation(s)
- João Filipe Menino
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/B’s - PT Government Associate Laboratory, University of Minho, Braga/Guimarães, Portugal
| | - Margarida Saraiva
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/B’s - PT Government Associate Laboratory, University of Minho, Braga/Guimarães, Portugal
| | - Jéssica Gomes-Rezende
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/B’s - PT Government Associate Laboratory, University of Minho, Braga/Guimarães, Portugal
| | - Mark Sturme
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/B’s - PT Government Associate Laboratory, University of Minho, Braga/Guimarães, Portugal
| | - Jorge Pedrosa
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/B’s - PT Government Associate Laboratory, University of Minho, Braga/Guimarães, Portugal
| | - António Gil Castro
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/B’s - PT Government Associate Laboratory, University of Minho, Braga/Guimarães, Portugal
| | - Paula Ludovico
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/B’s - PT Government Associate Laboratory, University of Minho, Braga/Guimarães, Portugal
| | - Gustavo H. Goldman
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol, CTBE, Campinas, São Paulo, Brasil
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brasil
| | - Fernando Rodrigues
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/B’s - PT Government Associate Laboratory, University of Minho, Braga/Guimarães, Portugal
- * E-mail:
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Regulation of sulphur assimilation is essential for virulence and affects iron homeostasis of the human-pathogenic mould Aspergillus fumigatus. PLoS Pathog 2013; 9:e1003573. [PMID: 24009505 PMCID: PMC3757043 DOI: 10.1371/journal.ppat.1003573] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 07/08/2013] [Indexed: 11/19/2022] Open
Abstract
Sulphur is an essential element that all pathogens have to absorb from their surroundings in order to grow inside their infected host. Despite its importance, the relevance of sulphur assimilation in fungal virulence is largely unexplored. Here we report a role of the bZIP transcription factor MetR in sulphur assimilation and virulence of the human pathogen Aspergillus fumigatus. The MetR regulator is essential for growth on a variety of sulphur sources; remarkably, it is fundamental for assimilation of inorganic S-sources but dispensable for utilization of methionine. Accordingly, it strongly supports expression of genes directly related to inorganic sulphur assimilation but not of genes connected to methionine metabolism. On a broader scale, MetR orchestrates the comprehensive transcriptional adaptation to sulphur-starving conditions as demonstrated by digital gene expression analysis. Surprisingly, A. fumigatus is able to utilize volatile sulphur compounds produced by its methionine catabolism, a process that has not been described before and that is MetR-dependent. The A. fumigatus MetR transcriptional activator is important for virulence in both leukopenic mice and an alternative mini-host model of aspergillosis, as it was essential for the development of pulmonary aspergillosis and supported the systemic dissemination of the fungus. MetR action under sulphur-starving conditions is further required for proper iron regulation, which links regulation of sulphur metabolism to iron homeostasis and demonstrates an unprecedented regulatory crosstalk. Taken together, this study provides evidence that regulation of sulphur assimilation is not only crucial for A. fumigatus virulence but also affects the balance of iron in this prime opportunistic pathogen.
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Sulfur-regulated control of the met-2⁺ gene of Neurospora crassa encoding cystathionine β-lyase. BMC Res Notes 2013; 6:259. [PMID: 23835025 PMCID: PMC3716945 DOI: 10.1186/1756-0500-6-259] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 07/03/2013] [Indexed: 11/21/2022] Open
Abstract
Background Cystathionine β-lyase performs an essential role in the transsulfuration pathway by its primary reaction of forming homocysteine from cystathionine. Understanding how the Neurospora crassa met-2+ gene, which encodes cystathionine β-lyase, is regulated is important in determining the basis of the cellular control of transsulfuration. The aim of this study was to determine the nature of a potential regulatory connection of met-2+ to the Neurospora sulfur regulatory network. Findings The cystathionine β-lyase (met-2+) gene was cloned by the identification of a cosmid genomic clone capable of transforming a met-2 mutant to methionine prototrophy and subsequently characterized. The gene contains a single intron and encodes a protein of 457 amino acids with conserved residues predicted to be important for catalysis and pyridoxal-5′-phosphate co-factor binding. The expression of met-2+ in wild-type N. crassa increased 3.1-fold under sulfur-limiting growth conditions as compared to the transcript levels seen under high sulfur growth conditions (i.e., repressing conditions). In a Δcys-3 strain, met-2+ transcript levels were substantially reduced under either low- or high-sulfur growth conditions. In addition, the presence of CYS3 activator binding sites on the met-2+ promoter was demonstrated by gel mobility shift assays. Conclusions In this report, we demonstrate the sulfur-regulated expression of the met-2+ gene and confirm its connection to the N. crassa sulfur regulatory circuit by the reduced expression observed in a Δcys-3 mutant and the in vitro detection of CYS3 binding sites in the met-2+ promoter. The data further adds to our understanding of the regulatory dynamics of transsulfuration.
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Novel mutations reveal two important regions in Aspergillus nidulans transcriptional activator MetR. Fungal Genet Biol 2010; 48:104-12. [PMID: 20955810 DOI: 10.1016/j.fgb.2010.10.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 10/01/2010] [Accepted: 10/06/2010] [Indexed: 11/23/2022]
Abstract
Expression of the sulfur assimilation pathway in Aspergillus nidulans is under control of sulfur metabolite repression, which is composed of scon genes encoding subunits of ubiquitin ligase and the metR gene coding for a transcriptional activator. In this paper we report three dominant suppressors of methionine requirement isolated from a metB3 diploid strain. All three mutations lead to the substitution of phenylalanine 48 by serine or leucine in the conserved N-terminal region of the MetR protein. Strains carrying the dominant suppressor mutations exhibit increased activities of homocysteine synthase and sulfur assimilation enzymes as well as elevated levels of the corresponding transcripts. These changes are observed even under conditions of methionine repression, which suggests that the mutated MetR protein may be resistant to inactivation or degradation mediated by sulfur metabolite repression. We also found that a mutant impaired in sulfite reductase activity, known until now as sG8, has a frameshift which changes 41 C-terminal amino acids. Therefore, it is now designated metR18. This mutant has elevated levels of MetR-regulated transcripts and of activities of sulfur assimilation enzymes (except sulfite reductase), which can be repressed to the wild type level by exogenous methionine. Thus, metR18 and the three dominant suppressors represent new types of mutations affecting different parts of the A. nidulans MetR protein.
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Sieńko M, Natorff R, Owczarek S, Olewiecki I, Paszewski A. Aspergillus nidulans genes encoding reverse transsulfuration enzymes belong to homocysteine regulon. Curr Genet 2009; 55:561-70. [PMID: 19685245 DOI: 10.1007/s00294-009-0269-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Revised: 07/29/2009] [Accepted: 07/31/2009] [Indexed: 11/26/2022]
Abstract
Homocysteine is an intermediate in methionine synthesis in Aspergillus nidulans, but it can also be converted to cysteine by the reverse transsulfuration pathway involving cystathionine beta-synthase (CBS) and cystathionine gamma-lyase (CGL). Because homocysteine is toxic to the cell at high concentrations, this pathway also functions as a means of removal of its excess. We found that the transcription of the mecA and mecB genes encoding CBS and CGL was upregulated by excess of homocysteine as well as by shortage of cysteine. Homocysteine induced transcription of both genes when added to the growth medium or overproduced in a regulatory mutant. The derepressing effect of cysteine shortage was observed in some mutants and in the wild-type strain during sulfur starvation. An increase in the level of mecA or mecB transcript roughly parallel with the elevation of the respective enzyme activity. On the basis of the mode of mecA and mecB regulation by homocysteine, these genes may be classified in a group of genes upregulated directly or indirectly by this amino acid. We call this group of genes the "homocysteine regulon".
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Affiliation(s)
- Marzena Sieńko
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawińskiego Str, 02-106, Warsaw, Poland.
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11
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Gremel G, Dorrer M, Schmoll M. Sulphur metabolism and cellulase gene expression are connected processes in the filamentous fungus Hypocrea jecorina (anamorph Trichoderma reesei). BMC Microbiol 2008; 8:174. [PMID: 18842142 PMCID: PMC2584116 DOI: 10.1186/1471-2180-8-174] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Accepted: 10/08/2008] [Indexed: 02/02/2023] Open
Abstract
Background Sulphur compounds like cysteine, methionine and S-adenosylmethionine are essential for the viability of most cells. Thus many organisms have developed a complex regulatory circuit that governs the expression of enzymes involved in sulphur assimilation and metabolism. In the filamentous fungus Hypocrea jecorina (anamorph Trichoderma reesei) little is known about the participants in this circuit. Results Analyses of proteins binding to the cellulase activating element (CAE) within the promotor of the cellobiohydrolase cbh2 gene led to the identification of a putative E3 ubiquitin ligase protein named LIMPET (LIM1), which is an orthologue of the sulphur regulators SCON-2 of Neurospora crassa and Met30p of Saccharomyces cerevisiae. Transcription of lim1 is specifically up-regulated upon sulphur limitation and responds to cellulase inducing conditions. In addition, light dependent stimulation/shut down of cellulase gene transcription by methionine in the presence of sulphate was observed. Further, lim1 transcriptionally reacts to a switch from constant darkness to constant light and is subject to regulation by the light regulatory protein ENVOY. Thus lim1, despite its function in sulphur metabolite repression, responds both to light as well as sulphur- and carbon source. Upon growth on cellulose, the uptake of sulphate is dependent on the light status and essential for growth in light. Unlike other fungi, growth of H. jecorina is not inhibited by selenate under low sulphur conditions, suggesting altered regulation of sulphur metabolism. Phylogenetic analysis of the five sulphate permeases found in the genome of H. jecorina revealed that the predominantly mycelial sulphate permease is lacking, thus supporting this hypothesis. Conclusion Our data indicate that the significance of the sulphate/methionine-related signal with respect to cellulase gene expression is dependent on the light status and reaches beyond detection of sulphur availability.
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Affiliation(s)
- Gabriela Gremel
- Research Area of Gene Technology and Applied Biochemistry, Institute of Chemical Engineering, Vienna University of Technology, Getreidemarkt 9/1665, A-1060 Wien, Austria.
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Wróbel M, Lewandowska I, Bronowicka-Adamska P, Paszewski A. The level of sulfane sulfur in the fungus Aspergillus nidulans wild type and mutant strains. Amino Acids 2008; 37:565-71. [PMID: 18781374 DOI: 10.1007/s00726-008-0175-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Accepted: 08/01/2008] [Indexed: 11/24/2022]
Abstract
The interdependence of the sulfane sulfur metabolism and sulfur amino acid metabolism was studied in the fungus Aspergillus nidulans wild type strain and in mutants impaired in genes encoding enzymes involved in the synthesis of cysteine (a precursor of sulfane sulfur) or in regulatory genes of the sulfur metabolite repression system. It was found that a low concentration of cellular cysteine leads to elevation of two sulfane sulfurtransferases, rhodanase and cystathionine gamma-lyase, while the level of 3-mercaptopyruvate sulfurtransferase remains largely unaffected. In spite of drastic differences in the levels of biosynthetic enzymes and of sulfur amino acids due to mutations or sulfur supplementation of cultures, the level of total sulfane sulfur is fairly stable. This stability confirms the crucial role of sulfane sulfur as a fine-tuning regulator of cellular metabolism.
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Affiliation(s)
- Maria Wróbel
- Chair of Medical Biochemistry, Collegium Medicum, Jagiellonian University, Kopernika 7, 31-034, Cracow, Poland.
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Rolland SG, Bruel CA. Sulphur and nitrogen regulation of the protease-encoding ACP1 gene in the fungus Botrytis cinerea: correlation with a phospholipase D activity. MICROBIOLOGY-SGM 2008; 154:1464-1473. [PMID: 18451055 DOI: 10.1099/mic.0.2007/012005-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Sulphur and nitrogen catabolic repressions are regulations that have long been recognized in fungi, but whose molecular bases remain largely elusive. This paper shows that catabolic repression of a protease-encoding gene correlates with the modulation of a phosphatidylethanolamine (PE)-specific phospholipase D (PLD) activity in the pathogenic fungus Botrytis cinerea. Our results first demonstrate that the ACP1 gene is subject to sulphur catabolic repression, with sulphate and cysteine inhibiting its expression. Sulphate and cysteine also cause a decrease of the total cellular PLD activity and, reciprocally, the two PLD inhibitors AEBSF [4-(2-aminoethyl)benzenesulphonyl fluoride] and curcumin negatively affect ACP1 expression in vivo. Cysteine moreover inhibits the PE-specific PLD activity in cell extracts. ACP1 is regulated by nitrogen, but here we show that this regulation does not rely on the proximal AREA binding site in its promoter, and that glutamine does not play a particular role in the process. A decrease in the total cellular PLD activity is also observed when the cells are fed ammonia, but this effect is smaller than that produced by sulphur. RNA-interference experiments finally suggest that the enzyme responsible for the PE-specific PLD activity is encoded by a gene that does not belong to the known HKD gene family of PLDs.
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Affiliation(s)
- Stéphane G Rolland
- Génomique fonctionnelle des champignons pathogènes des plantes, UMR5240 Microbiologie, Adaptation et Pathogénie, Université Lyon 1, CNRS, Bayer CropScience, Université de Lyon, 14 Rue Pierre Baizet, 69263 Lyon Cedex 9, France
| | - Christophe A Bruel
- Génomique fonctionnelle des champignons pathogènes des plantes, UMR5240 Microbiologie, Adaptation et Pathogénie, Université Lyon 1, CNRS, Bayer CropScience, Université de Lyon, 14 Rue Pierre Baizet, 69263 Lyon Cedex 9, France
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14
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Cary JW, OBrian GR, Nielsen DM, Nierman W, Harris-Coward P, Yu J, Bhatnagar D, Cleveland TE, Payne GA, Calvo AM. Elucidation of veA-dependent genes associated with aflatoxin and sclerotial production in Aspergillus flavus by functional genomics. Appl Microbiol Biotechnol 2007; 76:1107-18. [PMID: 17646985 DOI: 10.1007/s00253-007-1081-y] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Revised: 06/06/2007] [Accepted: 06/10/2007] [Indexed: 02/07/2023]
Abstract
The aflatoxin-producing fungi, Aspergillus flavus and A. parasiticus, form structures called sclerotia that allow for survival under adverse conditions. Deletion of the veA gene in A. flavus and A. parasiticus blocks production of aflatoxin as well as sclerotial formation. We used microarray technology to identify genes differentially expressed in wild-type veA and veA mutant strains that could be involved in aflatoxin production and sclerotial development in A. flavus. The DNA microarray analysis revealed 684 genes whose expression changed significantly over time; 136 of these were differentially expressed between the two strains including 27 genes that demonstrated a significant difference in expression both between strains and over time. A group of 115 genes showed greater expression in the wild-type than in the veA mutant strain. We identified a subgroup of veA-dependent genes that exhibited time-dependent expression profiles similar to those of known aflatoxin biosynthetic genes or that were candidates for involvement in sclerotial production in the wild type.
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Affiliation(s)
- J W Cary
- Southern Regional Research Center,Agricultural Research Service, U.S. Department of Agriculture, New Orleans, LA, USA
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15
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Piłsyk S, Natorff R, Sieńko M, Paszewski A. Sulfate transport in Aspergillus nidulans: a novel gene encoding alternative sulfate transporter. Fungal Genet Biol 2007; 44:715-25. [PMID: 17223367 DOI: 10.1016/j.fgb.2006.11.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Revised: 11/13/2006] [Accepted: 11/14/2006] [Indexed: 10/23/2022]
Abstract
In Aspergillus nidulans sulfate is taken up by sulfate permease encoded by the sB gene. A unique tight auxotrophic mutant with an impaired promoter region of the sulfate permease gene, sB1(pr), was isolated. Three suppressor genes were cloned by complementation of this mutation. One of them, described here, is the astA gene (alternative sulfate transporter) derived from a genomic library of the Japanese A. nidulans IAM 2006 strain. In the reference strain of Glasgow origin the astA gene was found to be a pseudogene having several nucleotide deletions in ORF. The gene encodes a novel type of sulfate transporter which is distinct from other known sulfate permeases forming the SulP family. The putative ASTA protein belongs to an extensive and poorly characterized Dal5 allantoate permease family of fungal organic anion transporters. We have shown that ASTA is a physiological sulfate transporter. We also report cloning and characterization of the sB gene in this work. Both genes, sB and astA, are regulated at the transcriptional level by sulfur metabolite repression (SMR).
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Affiliation(s)
- Sebastian Piłsyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Department of Genetics, 5A Pawińskiego Str, 02-106 Warszawa, Poland
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16
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Sieńko M, Natorff R, Zieliński Z, Hejduk A, Paszewski A. Two Aspergillus nidulans genes encoding methylenetetrahydrofolate reductases are up-regulated by homocysteine. Fungal Genet Biol 2006; 44:691-700. [PMID: 17257865 DOI: 10.1016/j.fgb.2006.12.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Revised: 12/05/2006] [Accepted: 12/05/2006] [Indexed: 10/23/2022]
Abstract
Methylenetetrahydrofolate reductase (MTHFR) catalyzes the reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, a co-substrate in the synthesis of methionine from homocysteine. We have cloned and characterized two Aspergillus nidulans genes encoding MTHFRs: metA and metF. Mutations in either gene result in methionine requirement; the metA-encoded enzyme is responsible for only 10-15% of total MTHFR activity. These two enzymes belong to different classes of MTHFRs. Mutations in metA but not in the metF gene are suppressed by mutations resulting in enhancement of homocysteine synthesis. The expression of both genes is up-regulated by homocysteine.
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Affiliation(s)
- Marzena Sieńko
- Institute of Biochemistry and Biophysics, PAS, Department of Genetics, 5A Pawińskiego Str, 02-106 Warszawa, Poland.
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17
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Uthman A, Dockal M, Söltz-Szöts J, Tschachler E. Fluconazole upregulates sconC expression and inhibits sulphur metabolism in Microsporum canis. Fungal Genet Biol 2005; 42:719-25. [PMID: 15922636 DOI: 10.1016/j.fgb.2005.04.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2004] [Revised: 04/04/2005] [Accepted: 04/06/2005] [Indexed: 10/25/2022]
Abstract
Azole derivatives such as fluconazole are the mainstay of therapeutic agents for the treatment of fungal infections. Their mode of action involving alteration in the conversion of lanosterol to ergosterol is well established. Here we report the effect of fluconazole on the sulphur metabolism negative regulator gene (sconC) in Microsporum canis. Characterization of the M. canis sconC gene revealed that its ORF is comprised of 495bp interrupted by four introns of 47-70bp. Exposure of M. canis in suspension to fluconazole upregulates sconC mRNA level and protein expression as determined by Northern and Western blot analysis, respectively. Upregulation of sconC was accompanied by inhibition of sulphur metabolism of the fungus resulting in a greatly reduced incorporation of radioactive labelled sulphuric acid into fungal proteins. These data establish that in addition to its action on ergosterol synthesis, fluconazole acts on other biological pathways in fungal cells.
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Affiliation(s)
- Aumaid Uthman
- Ludwig Boltzmann Institute for Studies of Venero-Dermatological Infectious Diseases, Medical University of Vienna, Vienna, Austria
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18
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Jin JK, Adams DO, Ko Y, Yu CW, Lin CH. Aviglycine and propargylglycine inhibit conidial germination and mycelial growth of Fusarium oxysporumf. sp. luffae. Mycopathologia 2004; 158:369-75. [PMID: 15645176 DOI: 10.1007/s11046-004-2225-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2004] [Accepted: 06/07/2004] [Indexed: 10/25/2022]
Abstract
Two inhibitors, aviglycine and propargylglycine, were tested for their ability to suppress methionine synthesis thus inhibit conidial germination and mycelial growth of Czapek-Dox liquid medium grown Fusarium oxysporum f. sp. luffaemuM. The linear inhibition range for mycelial growth was about 7.6-762.9 microM. Although aviglycine did not completely inhibit both conidial germination and mycelial growth, it showed significant inhibitory effect at 1.5 microM. The inhibition range for propargylglycine against conidial germination and mycelial growth were from 0.08 to 8841 microM and from 0.8 to 884.1 microM, respectively. Propargylglycine inhibited conidial germination and mycelial growth at a concentration of 8841 muM. The EC(50) values of aviglycine were 1 microM for conidial growth and 122 microM for mycelial growth, and the EC(50) values of propargylglycine were 47.7 microM for conidial growth and 55.6 muM for mycelial growth. Supplement of methionine released inhibition of aviglycine or propargylglycine to conidial germination. In addition, a mixture of aviglycine (1.5 microM) and propargylglycine (8841 microM) showed additive inhibitive effect than applied alone on 10 isolates. From these results, both aviglycine and propargylglycine exhibited inhibitory activity, and suggest that they can provide potential tools to design novel fungicide against fungal pathogens.
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Affiliation(s)
- Jung-Kang Jin
- Department of Life Science, National Chung Hsing University, Taichung, Taiwan, Republic of China
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19
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Kacprzak MM, Lewandowska I, Matthews RG, Paszewski A. Transcriptional regulation of methionine synthase by homocysteine and choline in Aspergillus nidulans. Biochem J 2003; 376:517-24. [PMID: 12954077 PMCID: PMC1223784 DOI: 10.1042/bj20030747] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2003] [Revised: 08/27/2003] [Accepted: 09/03/2003] [Indexed: 11/17/2022]
Abstract
Roles played by homocysteine and choline in the regulation of MS (methionine synthase) have been examined in fungi. The Aspergillus nidulans metH gene encoding MS was cloned and characterized. Its transcription was not regulated by methionine, but was enhanced by homocysteine and repressed by choline and betaine. MS activity levels were regulated in a similar way. The repression by betaine was due to its metabolic conversion to choline, which was found to be very efficient in A. nidulans. Betaine and choline supplementation stimulated growth of leaky metH mutants apparently by decreasing the demand for methyl groups and thus saving methionine and S -adenosylmethionine. We have also found that homocysteine stimulates transcription of MS-encoding genes in Saccharomyces cerevisiae and Schizosaccharomyces pombe.
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Affiliation(s)
- Magdalena M Kacprzak
- Department of Genetics, Institute of Biochemistry and Biophysics, PAS, Pawinskiego 5a, 02-106 Warsaw, Poland
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20
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Natorff R, Sieńko M, Brzywczy J, Paszewski A. The Aspergillus nidulans metR gene encodes a bZIP protein which activates transcription of sulphur metabolism genes. Mol Microbiol 2003; 49:1081-94. [PMID: 12890030 DOI: 10.1046/j.1365-2958.2003.03617.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The identification, isolation and characterization of a new Aspergillus nidulans positive-acting gene metR, which encodes a transcriptional activator of sulphur metabolism, is reported. metR mutants are tight auxotrophs requiring methionine or homocysteine for growth. Mutations in the metR gene are epistatic to mutations in the negative-acting sulphur regulatory scon genes. The metR coding sequence is interrupted by a single intron of 492 bp which is unusually long for fungi. Aspergillus nidulans METR is a member of bZIP family of DNA-binding proteins. The bZIP domains of METR and the Neurospora crassa CYS3 transcriptional activator of sulphur genes are highly similar. Although Neurospora cys-3 gene does not substitute for the metR function, a chimeric metR gene with a cys-3 bZIP domain is able to transform the DeltametR mutant to methionine prototrophy. This indicates that METR recognizes the same regulatory sequence as CYS3. The metR gene is not essential, as deletion mutants are viable and have similar phenotype as point mutants. In contrast to the Neurospora cys-3, transcription of the metR gene was found to be regulated neither by METR protein nor by sulphur source. Transcription of metR gene is derepressed in the sconB2 mutant. Transcription of genes encoding sulphate permease, homocysteine synthase, cysteine synthase, ATP-sulphurylase, and sulphur controller--sconB is strongly regulated by the metR gene product and depends on the character of the metR mutation and sulphur supplementation.
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Affiliation(s)
- Renata Natorff
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawińskiego Str., 02-106 Warszawa, Poland.
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21
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Brzywczy J, Sieńko M, Kucharska A, Paszewski A. Sulphur amino acid synthesis in Schizosaccharomyces pombe represents a specific variant of sulphur metabolism in fungi. Yeast 2002; 19:29-35. [PMID: 11754480 DOI: 10.1002/yea.798] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Schizosaccharomyces pombe, in contrast to Saccharomyces cerevisiae and Aspergillus nidulans, lacks cystathionine beta-synthase and cystathionine gamma-lyase, two enzymes in the pathway from methionine to cysteine. As a consequence, methionine cannot serve as an efficient sulphur source for the fungus and does not bring about repression of sulphur assimilation, which is under control of the cysteine-mediated sulphur metabolite repression system. This system operates at the transcriptional level, as was shown for the homocysteine synthase encoding gene. Our results corroborate the growing evidence that cysteine is the major low-molecular-weight effector in the regulation of sulphur metabolism in bacteria, fungi and plants.
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Affiliation(s)
- Jerzy Brzywczy
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, ul. Pawińskiego 5A, 02-106 Warszawa, Poland
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22
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Grynberg M, Piotrowska M, Pizzinini E, Turner G, Paszewski A. The Aspergillus nidulans metE gene is regulated by a second system independent from sulphur metabolite repression. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1519:78-84. [PMID: 11406274 DOI: 10.1016/s0167-4781(01)00224-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mutations in the Aspergillus nidulans metE gene lead to requirement for O-acetylhomoserine. The gene was cloned by complementation of the metE31 mutation. The coding sequence was found to be interrupted by two introns of 66 and 50 bp, respectively. metE codes for a peptide of 489 amino acids which belongs to the family of homoserine O-acetyltransferases and a well-defined superfamily of alpha/beta hydrolases. Transcription of the metE gene is strongly up-regulated by a severe limitation of methionine, but not of cysteine. This gene is the first sulphur metabolism gene described in A. nidulans which is not regulated by the sulphur metabolite repression system in which cysteine acts as the low-molecular-weight effector.
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Affiliation(s)
- M Grynberg
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
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23
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Metabolic Regulation in Fungi. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s1874-5334(01)80005-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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24
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van de Kamp M, Schuurs TA, Vos A, van der Lende TR, Konings WN, Driessen AJ. Sulfur regulation of the sulfate transporter genes sutA and sutB in Penicillium chrysogenum. Appl Environ Microbiol 2000; 66:4536-8. [PMID: 11010912 PMCID: PMC92338 DOI: 10.1128/aem.66.10.4536-4538.2000] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Penicillium chrysogenum uses sulfate as a source of sulfur for the biosynthesis of penicillin. Sulfate uptake and the mRNA levels of the sulfate transporter-encoding sutB and sutA genes are all reduced by high sulfate concentrations and are elevated by sulfate starvation. In a high-penicillin-yielding strain, sutB is effectively transcribed even in the presence of excess sulfate. This deregulation may facilitate the efficient incorporation of sulfur into cysteine and penicillin.
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Affiliation(s)
- M van de Kamp
- Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9750 AA Haren, The Netherlands
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25
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Grynberg M, Topczewski J, Godzik A, Paszewski A. The Aspergillus nidulans cysA gene encodes a novel type of serine O-acetyltransferase which is homologous to homoserine O-acetyltransferases. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 10):2695-2703. [PMID: 11021945 DOI: 10.1099/00221287-146-10-2695] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Aspergillus nidulans cysA gene was cloned by functional complementation of the cysA1 mutation that impairs the synthesis of O:-acetylserine. The molecular nature of cysA1 and cysA103 alleles was characterized; a nucleotide substitution and a frame shift were found in the former and a deletion mutation in the latter. The CYSA protein is 525 amino acids long and is encoded by an uninterrupted open reading frame. Expression of the cysA gene appears not to be regulated by sulfur, carbon and nitrogen sources. Protein sequence analysis reveals extensive similarity to homoserine O:-acetyltransferases, particularly the bacterial ones, and no homology with known serine O:-acetyltransferases. The authors propose that the CYSA protein is analogous to serine O:-acetyltransferases, i.e. it catalyses the same reaction but has an independent evolutionary origin.
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Affiliation(s)
- Marcin Grynberg
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawinskiego St, 02-106 Warszawa, Poland1
| | - Jacek Topczewski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawinskiego St, 02-106 Warszawa, Poland1
| | - Adam Godzik
- The Burnham Institute, 10901 N. Torrey Pines Rd, La Jolla, CA 92037, USA2
| | - Andrzej Paszewski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawinskiego St, 02-106 Warszawa, Poland1
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Craig KL, Tyers M. The F-box: a new motif for ubiquitin dependent proteolysis in cell cycle regulation and signal transduction. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1999; 72:299-328. [PMID: 10581972 DOI: 10.1016/s0079-6107(99)00010-3] [Citation(s) in RCA: 198] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The ubiquitin system of intracellular protein degradation controls the abundance of many critical regulatory proteins. Specificity in the ubiquitin system is determined largely at the level of substrate recognition, a step that is mediated by E3 ubiquitin ligases. Analysis of the mechanisms of phosphorylation directed proteolysis in cell cycle regulation has uncovered a new class of E3 ubiquitin ligases called SCF complexes, which are composed of the subunits Skp1, Rbx1, Cdc53 and any one of a large number of different F-box proteins. The substrate specificity of SCF complexes is determined by the interchangeable F-box protein subunit, which recruits a specific set of substrates for ubiquitination to the core complex composed of Skp1, Rbx1, Cdc53 and the E2 enzyme Cdc34. F-box proteins have a bipartite structure--the shared F-box motif links F-box proteins to Skp1 and the core complex, whereas divergent protein-protein interaction motifs selectively bind their cognate substrates. To date all known SCF substrates are recognised in a strictly phosphorylation dependent manner, thus linking intracellular signalling networks to the ubiquitin system. The plethora of different F-box proteins in databases suggests that many pathways will be governed by SCF-dependent proteolysis. Indeed, genetic analysis has uncovered roles for F-box proteins in a variety of signalling pathways, ranging from nutrient sensing in yeast to conserved developmental pathways in plants and animals. Moreover, structural analysis has revealed ancestral relationships between SCF complexes and two other E3 ubiquitin ligases, suggesting that the combinatorial use of substrate specific adaptor proteins has evolved to allow the regulation of many cellular processes. Here, we review the known signalling pathways that are regulated by SCF complexes and highlight current issues in phosphorylation dependent protein degradation.
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Affiliation(s)
- K L Craig
- Programme in Molecular Biology and Cancer, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Canada
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27
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van de Kamp M, Pizzinini E, Vos A, van der Lende TR, Schuurs TA, Newbert RW, Turner G, Konings WN, Driessen AJ. Sulfate transport in Penicillium chrysogenum: cloning and characterization of the sutA and sutB genes. J Bacteriol 1999; 181:7228-34. [PMID: 10572125 PMCID: PMC103684 DOI: 10.1128/jb.181.23.7228-7234.1999] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In industrial fermentations, Penicillium chrysogenum uses sulfate as the source of sulfur for the biosynthesis of penicillin. By a PCR-based approach, two genes, sutA and sutB, whose encoded products belong to the SulP superfamily of sulfate permeases were isolated. Transformation of a sulfate uptake-negative sB3 mutant of Aspergillus nidulans with the sutB gene completely restored sulfate uptake activity. The sutA gene did not complement the A. nidulans sB3 mutation, even when expressed under control of the sutB promoter. Expression of both sutA and sutB in P. chrysogenum is induced by growth under sulfur starvation conditions. However, sutA is expressed to a much lower level than is sutB. Disruption of sutB resulted in a loss of sulfate uptake ability. Overall, the results show that SutB is the major sulfate permease involved in sulfate uptake by P. chrysogenum.
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Affiliation(s)
- M van de Kamp
- Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9751 NN Haren, The Netherlands
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28
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Demain AL, Zhang J. Cephalosporin C production by Cephalosporium acremonium: the methionine story. Crit Rev Biotechnol 1999; 18:283-94. [PMID: 9887506 DOI: 10.1080/0738-859891224176] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
More than 40 years ago, it was reported that methionine markedly stimulated production of cephalosporin C by Cephalosporium acremonium. Over the years, many hypotheses were put forth to explain this phenomenon. The accumulating evidence strongly supported the concept that methionine stimulates by inducing enzymes of the biosynthetic pathway such as delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase, isopenicillin N synthase, and deacetoxycephalosporin C synthase. This mechanism has been strengthened by the finding that transcription of the genes encoding the above enzymes is markedly enhanced by growth with methionine. An effect of methionine in the fermentation unrelated to the titer stimulation is its contribution of the sulfur atom to the cephalosporin molecule. Methionine also stimulates mycelial fragmentation; the relationship between this effect on hyphal differentiation and the induction of the cephalosporin synthases remains to be elucidated.
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Affiliation(s)
- A L Demain
- Biology Department, Massachusetts Institute of Technology, Cambridge 02139, USA
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29
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Abstract
The most commonly used beta-lactam antibiotics for the therapy of infectious diseases are penicillin and cephalosporin. Penicillin is produced as an end product by some fungi, most notably by Aspergillus (Emericella) nidulans and Penicillium chrysogenum. Cephalosporins are synthesized by both bacteria and fungi, e.g., by the fungus Acremonium chrysogenum (Cephalosporium acremonium). The biosynthetic pathways leading to both secondary metabolites start from the same three amino acid precursors and have the first two enzymatic reactions in common. Penicillin biosynthesis is catalyzed by three enzymes encoded by acvA (pcbAB), ipnA (pcbC), and aatA (penDE). The genes are organized into a cluster. In A. chrysogenum, in addition to acvA and ipnA, a second cluster contains the genes encoding enzymes that catalyze the reactions of the later steps of the cephalosporin pathway (cefEF and cefG). Within the last few years, several studies have indicated that the fungal beta-lactam biosynthesis genes are controlled by a complex regulatory network, e. g., by the ambient pH, carbon source, and amino acids. A comparison with the regulatory mechanisms (regulatory proteins and DNA elements) involved in the regulation of genes of primary metabolism in lower eukaryotes is thus of great interest. This has already led to the elucidation of new regulatory mechanisms. Furthermore, such investigations have contributed to the elucidation of signals leading to the production of beta-lactams and their physiological meaning for the producing fungi, and they can be expected to have a major impact on rational strain improvement programs. The knowledge of biosynthesis genes has already been used to produce new compounds.
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Affiliation(s)
- A A Brakhage
- Lehrstuhl für Mikrobiologie, Universität München, D-80638 Munich, Germany.
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30
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Patton EE, Willems AR, Sa D, Kuras L, Thomas D, Craig KL, Tyers M. Cdc53 is a scaffold protein for multiple Cdc34/Skp1/F-box proteincomplexes that regulate cell division and methionine biosynthesis in yeast. Genes Dev 1998; 12:692-705. [PMID: 9499404 PMCID: PMC316590 DOI: 10.1101/gad.12.5.692] [Citation(s) in RCA: 230] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In budding yeast, ubiquitination of the cyclin-dependent kinase (Cdk) inhibitor Sic1 is catalyzed by the E2 ubiquitin conjugating enzyme Cdc34 in conjunction with an E3 ubiquitin ligase complex composed of Skp1, Cdc53 and the F-box protein, Cdc4 (the SCFCdc4 complex). Skp1 binds a motif called the F-box and in turn F-box proteins appear to recruit specific substrates for ubiquitination. We find that Skp1 interacts with Cdc53 in vivo, and that Skp1 bridges Cdc53 to three different F-box proteins, Cdc4, Met30, and Grr1. Cdc53 contains independent binding sites for Cdc34 and Skp1 suggesting it functions as a scaffold protein within an E2/E3 core complex. F-box proteins show remarkable functional specificity in vivo: Cdc4 is specific for degradation of Sic1, Grr1 is specific for degradation of the G1 cyclin Cln2, and Met30 is specific for repression of methionine biosynthesis genes. In contrast, the Cdc34-Cdc53-Skp1 E2/E3 core complex is required for all three functions. Combinatorial control of SCF complexes may provide a basis for the regulation of diverse cellular processes.
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Affiliation(s)
- E E Patton
- Programme in Molecular Biology and Cancer, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Canada M5G 1X5
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Hubbard EJ, Wu G, Kitajewski J, Greenwald I. sel-10, a negative regulator of lin-12 activity in Caenorhabditis elegans, encodes a member of the CDC4 family of proteins. Genes Dev 1997; 11:3182-93. [PMID: 9389650 PMCID: PMC316751 DOI: 10.1101/gad.11.23.3182] [Citation(s) in RCA: 196] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Mutations that influence lin-12 activity in Caenorhabditis elegans may identify conserved factors that regulate the activity of lin-12/Notch proteins. We describe genetic evidence indicating that sel-10 is a negative regulator of lin-12/Notch-mediated signaling in C. elegans. Sequence analysis shows that SEL-10 is a member of the CDC4 family of proteins and has a potential human ortholog. Coimmunoprecipitation data indicate that C. elegans SEL-10 complexes with LIN-12 and with murine Notch4. We propose that SEL-10 promotes the ubiquitin-mediated turnover of LIN-12/Notch proteins, and discuss potential roles for the regulation of lin-12/Notch activity by sel-10 in cell fate decisions and tumorigenesis.
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Affiliation(s)
- E J Hubbard
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, New York, New York 10032, USA
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Abstract
The filamentous fungi Aspergillus nidulans and Neurospora crassa and the yeast Saccharomyces cerevisiae each possess a global regulatory circuit that controls the expression of permeases and enzymes that function both in the acquisition of sulfur from the environment and in its assimilation. Control of the structural genes that specify an array of enzymes that catalyze reactions of sulfur metabolism occurs at the transcriptional level and involves both positive-acting and negative-acting regulatory factors. Positive trans-acting regulatory proteins that contain a basic region, leucine zipper-DNA binding domain, are found in Neurospora and yeast. Each of these fungi contain a sulfur regulatory protein of the beta-transducin family that acts in a negative fashion to control gene expression. Sulfur regulation in yeast also involves the general DNA binding protein, centromere binding factor I. Sulfate uptake is a highly regulated step and appears to occur in fungi, plants, and mammals via a family of related transporter proteins. Recent developments have provided new insight into the nature and control of the enzymes ATP sulfurylase and APS kinase, which catalyze the early steps of sulfate assimilation, and of the Aspergillus enzyme, cysteine synthase, which produces cysteine from O-acetylserine.
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Affiliation(s)
- G A Marzluf
- Department of Biochemistry and Program in Molecular, Cellular, and Developmental Biology, The Ohio State University, Columbus 43210, USA.
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West CM, Kozarov E, Teng-umnuay P. The cytosolic glycoprotein FP21 of Dictyostelium discoideum is encoded by two genes resulting in a polymorphism at a single amino acid position. Gene X 1997; 200:1-10. [PMID: 9373134 DOI: 10.1016/s0378-1119(97)00194-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
FP21 is a glycoprotein within the cytosolic compartment of Dictyostelium which carries an unusual carbohydrate modification(s) including the sugars fucose, galactose and N-acetylglucosamine. The soluble pool of FP21 from crude extracts resolves chromatographically into two fractions that differ in their glycosylation. Previous gene-mapping studies indicating the existence of two loci suggested that the FP21 fractions might be encoded by different genes. To address this issue, the two genes were cloned and sequenced, leading to the prediction that the protein products would differ by only a single amino acid, Ser or Ala, at codon 39. Protein sequence data on CNBr fragments of purified FP21 showed that both gene products are found in both fractions of the soluble pool. After further purification, the two fractions were no longer chromatographically resolvable, and there was no evidence for charge heterogeneity as determined by 2-D gel electrophoresis of whole cells. Thus, the initial separation of the different soluble subpopulations of this protein appears to be due to distinct molecular complexes, possibly related to differential glycosylation, and is not the result of the genetically-encoded amino acid polymorphism.
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Affiliation(s)
- C M West
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville 32610-0235, USA.
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Lewandowska I, Balińska M, Paszewski A. Identification of new regulatory genes controlling synthesis of folate-dependent enzymes in Aspergillus nidulans. MICROBIOLOGY (READING, ENGLAND) 1997; 143 ( Pt 10):3273-3278. [PMID: 9462964 DOI: 10.1099/00221287-143-10-3273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Prototrophic revertants of a meth2 strain of aspergillus nidulans which is impaired in the regulation of synthesis of folate-dependent enzymes were isolated and six of them analysed. In three of the isolates reversion was the result of an intragenic suppressor mutation in the metH locus. In the remaining strains suppressor mutations occurred in independent genes. These genes, designated folA, folB and folC, are linked and located in chromosome VI. Mutations in these genes render synthesis of some folate enzymes, particularly folylpolyglutamate synthetase, insensitive to methionine-mediated repression.
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Affiliation(s)
- Irmina Lewandowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawińskiego St, 02-106 Warszawa, Poland
| | - Malgorzata Balińska
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St, 02-093 Warszawa, Poland
| | - Andrzej Paszewski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawińskiego St, 02-106 Warszawa, Poland
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35
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Lewandowska I, Balińska M, Natorff R, Paszewski A. Regulation of folate-dependent enzyme levels in Aspergillus nidulans: studies with regulatory mutants. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1290:89-94. [PMID: 8645712 DOI: 10.1016/0304-4165(96)00004-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The synthesis of folate-dependent enzymes in Aspergillus nidulans appears to be regulated by intracellular pools of homocysteine and methionine. The results are consistent with the view that homocysteine acts as an inducer and methionine as a corepressor, but the molecular mechanism of the regulation is still unknown. Methionine-requiring mutants, metH2 and metD10, apparently allelic, show deregulation of folate-dependent enzymes. Most characteristic of the mutants is a repressed level of folylpolyglutamate synthetase. New mutations suppressing the metH2 lesion which render folate enzymes insensitive to methionine-mediated repression have been isolated. These mutations are likely to identify new regulatory genes in folate metabolism.
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Affiliation(s)
- I Lewandowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
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Katz ME, Flynn PK, vanKuyk PA, Cheetham BF. Mutations affecting extracellular protease production in the filamentous fungus Aspergillus nidulans. MOLECULAR & GENERAL GENETICS : MGG 1996; 250:715-24. [PMID: 8628232 DOI: 10.1007/bf02172983] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The extracellular proteases of Aspergillus nidulans are known to be regulated by carbon, nitrogen and sulphur metabolite repression. In this study, a mutant with reduced levels of extracellular protease was isolated by screening for loss of halo production on milk plates. Genetic analysis of the mutant showed that it contains a single, recessive mutation, in a gene which we have designated xprE, located on chromosome VI. The xprE1 mutation affected the production of extracellular proteases in response to carbon, nitrogen and, to a lesser extent, sulphur limitation. Three reversion mutations, xprF1, xprF2 and xprG1, which suppress xprE1, were characterised. Both xprF and xprG map to chromosome VII but the two genes are unlinked. The xprF1, xprF2 and xprG1 mutants showed high levels of milk-clearing activity on medium containing milk as a carbon source but reduced growth on a number of nitrogen sources. Evidence is presented that the xprE1 and xprG1 mutations alter expression of more than one protease and affect levels of alkaline protease gene mRNA.
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Affiliation(s)
- M E Katz
- Department of Molecular and Cellular Biology, University of New England, Armidale, N.S.W., Australia
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Borges-Walmsley MI, Turner G, Bailey AM, Brown J, Lehmbeck J, Clausen IG. Isolation and characterisation of genes for sulphate activation and reduction in Aspergillus nidulans: implications for evolution of an allosteric control region by gene duplication. MOLECULAR & GENERAL GENETICS : MGG 1995; 247:423-9. [PMID: 7770049 DOI: 10.1007/bf00293143] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A region of the Aspergillus nidulans genome carrying the sA and sC genes, encoding PAPS reductase and ATP sulphurylase, respectively, was isolated by transformation of an sA mutant with a cosmid library. The genes were subcloned and their functions confirmed by retransformation and complementation of A. nidulans strains carrying sA and sC mutations. The physical distance of 2 kb between the genes corresponds to a genetic distance of 1 cM. While the deduced amino acid sequence of the sA gene product shows homology with the equivalent MET16 gene product of Saccharomyces cerevisiae, the sC gene product resembles the equivalent MET3 yeast gene product at the N-terminal end, but differs markedly from it at the C-terminal end, showing homology to the APS kinases of several microorganisms. It is proposed that this C-terminal region does not encode a functional APS kinase, but is responsible for allosteric regulation by PAPS of the sulphate assimilation pathway in A. nidulans, and that the ATP sulphurylase encoding-gene (sC) of filamentous ascomycetes may have evolved from a bifunctional gene similar to the nodQ gene of Rhizobium meliloti.
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Affiliation(s)
- M I Borges-Walmsley
- Department of Molecular Biology and Biotechnology, Krebs Institute for Biomolecular Research, University of Sheffield, UK
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Marzluf GA. Genetics and molecular genetics of sulfur assimilation in the fungi. ADVANCES IN GENETICS 1994; 31:187-206. [PMID: 8036994 DOI: 10.1016/s0065-2660(08)60398-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- G A Marzluf
- Department of Biochemistry, Ohio State University, Columbus 43210
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Brzywczy J, Paszewski A. Role of O-acetylhomoserine sulfhydrylase in sulfur amino acid synthesis in various yeasts. Yeast 1993; 9:1335-42. [PMID: 8154184 DOI: 10.1002/yea.320091207] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Mutants defective in O-acetylhomoserine sulfhydrylase (OAH-SHLase) were obtained in five yeast strains representative of different yeast genera: Saccharomyces cerevisiae, Kluyveromyces lactis, Yarrowia lipolytica, Schizosaccharomyces pombe and Trichosporon cutaneum. In vitro, in all five strains, the enzyme also had O-acetylserine (OAS) sulfhydrylase activity so it is a 'bifunctional' OAH/OAS-SHLase (Yamagata, 1989). The enzyme was only found to be essential in S. cerevisiae (OAH SHLase-negative mutants are auxotrophs). Its impairment in K. lactis caused a slower growth rate and a decrease of the sulfur amino acid pool. In T. cutaneum only the pool was affected whereas in Y. lipolytica and S. pombe the lesion caused no change in the growth rate nor in the pool. In all strains where OAH SHLase-negative mutants were prototrophs, a monofunctional OAS sulhydrylase was detected. The results indicate that OAH SHLase may play different physiological roles in various yeasts.
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Affiliation(s)
- J Brzywczy
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warszawa
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