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Maimoni Campanella JE, Ramos Junior SL, Rodrigues Kiraly VT, Severo Gomes AA, de Barros AC, Mateos PA, Freitas FZ, de Mattos Fontes MR, Borges JC, Bertolini MC. Biochemical and biophysical characterization of the RVB-1/RVB-2 protein complex, the RuvBL/RVB homologues in Neurospora crassa. Biochimie 2021; 191:11-26. [PMID: 34375717 DOI: 10.1016/j.biochi.2021.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/08/2021] [Accepted: 08/04/2021] [Indexed: 11/20/2022]
Abstract
The RVB proteins, composed of the conservative paralogs, RVB1 and RVB2, belong to the AAA+ (ATPases Associated with various cellular Activities) protein superfamily and are present in archaea and eukaryotes. The most distinct structural features are their ability to interact with each other forming the RVB1/2 complex and their participation in several macromolecular protein complexes leading them to be involved in many biological processes. We report here the biochemical and biophysical characterization of the Neurospora crassa RVB-1/RVB-2 complex. Chromatographic analyses revealed that the complex (APO) predominantly exists as a dimer in solution although hexamers were also observed. Nucleotides influence the oligomerization state, while ATP favors hexamers formation, ADP favors the formation of multimeric states, likely dodecamers, and the Molecular Dynamics (MD) simulations revealed the contribution of certain amino acid residues in the nucleotide stabilization. The complex binds to dsDNA fragments and exhibits ATPase activity, which is strongly enhanced in the presence of DNA. In addition, both GFP-fused proteins are predominantly nuclear, and their nuclear localization signals (NLS) interact with importin-α (NcIMPα). Our findings show that some properties are specific of the fungus proteins despite of their high identity to orthologous proteins. They are essential proteins in N. crassa, and the phenotypic defects exhibited by the heterokaryotic strains, mainly related to growth and development, indicate N. crassa as a promising organism to investigate additional biological and structural aspects of these proteins.
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Affiliation(s)
- Jonatas Erick Maimoni Campanella
- Departamento de Bioquímica e Química Orgânica, Instituto de Química, Universidade Estadual Paulista, UNESP, 14.800-060, Araraquara, SP, Brazil
| | - Sergio Luiz Ramos Junior
- Departamento de Química e Física Molecular, Instituto de Química de São Carlos, Universidade de São Paulo, USP, 13.560-970, São Carlos, SP, Brazil
| | - Vanessa Thomaz Rodrigues Kiraly
- Departamento de Química e Física Molecular, Instituto de Química de São Carlos, Universidade de São Paulo, USP, 13.560-970, São Carlos, SP, Brazil
| | - Antoniel Augusto Severo Gomes
- Departamento de Biofísica e Farmacologia, Instituto de Biociências, Universidade Estadual Paulista, UNESP, 18.618-689, Botucatu, SP, Brazil
| | - Andrea Coelho de Barros
- Departamento de Biofísica e Farmacologia, Instituto de Biociências, Universidade Estadual Paulista, UNESP, 18.618-689, Botucatu, SP, Brazil
| | - Pablo Acera Mateos
- Departamento de Bioquímica e Química Orgânica, Instituto de Química, Universidade Estadual Paulista, UNESP, 14.800-060, Araraquara, SP, Brazil
| | - Fernanda Zanolli Freitas
- Departamento de Bioquímica e Química Orgânica, Instituto de Química, Universidade Estadual Paulista, UNESP, 14.800-060, Araraquara, SP, Brazil
| | - Marcos Roberto de Mattos Fontes
- Departamento de Biofísica e Farmacologia, Instituto de Biociências, Universidade Estadual Paulista, UNESP, 18.618-689, Botucatu, SP, Brazil
| | - Júlio Cesar Borges
- Departamento de Química e Física Molecular, Instituto de Química de São Carlos, Universidade de São Paulo, USP, 13.560-970, São Carlos, SP, Brazil
| | - Maria Célia Bertolini
- Departamento de Bioquímica e Química Orgânica, Instituto de Química, Universidade Estadual Paulista, UNESP, 14.800-060, Araraquara, SP, Brazil.
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Alder-Rangel A, Bailão AM, da Cunha AF, Soares CMA, Wang C, Bonatto D, Dadachova E, Hakalehto E, Eleutherio ECA, Fernandes ÉKK, Gadd GM, Braus GH, Braga GUL, Goldman GH, Malavazi I, Hallsworth JE, Takemoto JY, Fuller KK, Selbmann L, Corrochano LM, von Zeska Kress MR, Bertolini MC, Schmoll M, Pedrini N, Loera O, Finlay RD, Peralta RM, Rangel DEN. The second International Symposium on Fungal Stress: ISFUS. Fungal Biol 2017; 122:386-399. [PMID: 29801782 DOI: 10.1016/j.funbio.2017.10.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 10/24/2017] [Indexed: 12/23/2022]
Abstract
The topic of 'fungal stress' is central to many important disciplines, including medical mycology, chronobiology, plant and insect pathology, industrial microbiology, material sciences, and astrobiology. The International Symposium on Fungal Stress (ISFUS) brought together researchers, who study fungal stress in a variety of fields. The second ISFUS was held in May 8-11 2017 in Goiania, Goiás, Brazil and hosted by the Instituto de Patologia Tropical e Saúde Pública at the Universidade Federal de Goiás. It was supported by grants from CAPES and FAPEG. Twenty-seven speakers from 15 countries presented their research related to fungal stress biology. The Symposium was divided into seven topics: 1. Fungal biology in extreme environments; 2. Stress mechanisms and responses in fungi: molecular biology, biochemistry, biophysics, and cellular biology; 3. Fungal photobiology in the context of stress; 4. Role of stress in fungal pathogenesis; 5. Fungal stress and bioremediation; 6. Fungal stress in agriculture and forestry; and 7. Fungal stress in industrial applications. This article provides an overview of the science presented and discussed at ISFUS-2017.
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Affiliation(s)
| | - Alexandre M Bailão
- Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, 74690-900, GO, Brazil
| | - Anderson F da Cunha
- Laboratório de Bioquímica e Genética Aplicada, Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, 90040-060, SP, Brazil
| | - Célia M A Soares
- Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, 74690-900, GO, Brazil
| | - Chengshu Wang
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Diego Bonatto
- Center for Biotechnology, Department of Molecular Biology and Biotechnology, Federal University of Rio Grande do Sul, Porto Alegre, 13565-905, RS, Brazil
| | - Ekaterina Dadachova
- College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5E5, Canada
| | - Elias Hakalehto
- Department of Agricultural Sciences, P.O.B. 27, FI-00014, University of Helsinki, Finland
| | - Elis C A Eleutherio
- Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro, 21941-901, RJ, Brazil
| | - Éverton K K Fernandes
- Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, GO 74605-050, Brazil
| | - Geoffrey M Gadd
- Geomicrobiology Group, School of Life Sciences, University of Dundee, Dundee, DD15EH, Scotland, UK
| | - Gerhard H Braus
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences, University of Göttingen, Göttingen, D-37077, Germany
| | - Gilberto U L Braga
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, 14040-903, SP, Brazil
| | - Gustavo H Goldman
- Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, 14040-903, SP, Brazil
| | - Iran Malavazi
- Centro de Ciências Biológicas e da Saúde, Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, 13565-905, SP, Brazil
| | - John E Hallsworth
- Institute for Global Food Security, School of Biological Sciences, MBC, Queen's University Belfast, Belfast, BT9 7BL, Northern Ireland, UK
| | - Jon Y Takemoto
- Department of Biology, Utah State University, Logan, UT 84322, USA
| | - Kevin K Fuller
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Laura Selbmann
- Department of Ecological and Biological Sciences (DEB), University of Tuscia, Largo dell'Università snc, 01100 Viterbo, Italy
| | - Luis M Corrochano
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Sevilla, Spain
| | - Marcia R von Zeska Kress
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, 14040-903, SP, Brazil
| | - Maria Célia Bertolini
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista, 14800-060, Araraquara, SP, Brazil
| | - Monika Schmoll
- AIT Austrian Institute of Technology GmbH, Center for Health and Bioresources, Konrad-Lorenz Straße 24, 3430 Tulln, Austria
| | - Nicolás Pedrini
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CCT La Plata Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional de La Plata (UNLP), calles 60 y 120, 1900 La Plata, Argentina
| | - Octavio Loera
- Department of Biotechnology, Universidad Autónoma Metropolitana-Iztapalapa, C.P. 09340, Mexico City, Mexico
| | - Roger D Finlay
- Uppsala Biocenter, Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, 750 07 Uppsala, Sweden
| | - Rosane M Peralta
- Department of Biochemistry, Universidade Estadual de Maringá, 87020-900, Maringá, PR, Brazil
| | - Drauzio E N Rangel
- Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, GO 74605-050, Brazil.
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The SEB-1 Transcription Factor Binds to the STRE Motif in Neurospora crassa and Regulates a Variety of Cellular Processes Including the Stress Response and Reserve Carbohydrate Metabolism. G3-GENES GENOMES GENETICS 2016; 6:1327-43. [PMID: 26994287 PMCID: PMC4856084 DOI: 10.1534/g3.116.028506] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
When exposed to stress conditions, all cells induce mechanisms resulting in an attempt to adapt to stress that involve proteins which, once activated, trigger cell responses by modulating specific signaling pathways. In this work, using a combination of pulldown assays and mass spectrometry analyses, we identified the Neurospora crassa SEB-1 transcription factor that binds to the Stress Response Element (STRE) under heat stress. Orthologs of SEB-1 have been functionally characterized in a few filamentous fungi as being involved in stress responses; however, the molecular mechanisms mediated by this transcription factor may not be conserved. Here, we provide evidences for the involvement of N. crassa SEB-1 in multiple cellular processes, including response to heat, as well as osmotic and oxidative stress. The Δseb-1 strain displayed reduced growth under these conditions, and genes encoding stress-responsive proteins were differentially regulated in the Δseb-1 strain grown under the same conditions. In addition, the SEB-1-GFP protein translocated from the cytosol to the nucleus under heat, osmotic, and oxidative stress conditions. SEB-1 also regulates the metabolism of the reserve carbohydrates glycogen and trehalose under heat stress, suggesting an interconnection between metabolism control and this environmental condition. We demonstrated that SEB-1 binds in vivo to the promoters of genes encoding glycogen metabolism enzymes and regulates their expression. A genome-wide transcriptional profile of the Δseb-1 strain under heat stress was determined by RNA-seq, and a broad range of cellular processes was identified that suggests a role for SEB-1 as a protein interconnecting these mechanisms.
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Bernardes NE, Takeda AAS, Dreyer TR, Freitas FZ, Bertolini MC, Fontes MRM. Structure of Importin-α from a Filamentous Fungus in Complex with a Classical Nuclear Localization Signal. PLoS One 2015; 10:e0128687. [PMID: 26091498 PMCID: PMC4474859 DOI: 10.1371/journal.pone.0128687] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 04/29/2015] [Indexed: 01/07/2023] Open
Abstract
Neurospora crassa is a filamentous fungus that has been extensively studied as a model organism for eukaryotic biology, providing fundamental insights into cellular processes such as cell signaling, growth and differentiation. To advance in the study of this multicellular organism, an understanding of the specific mechanisms for protein transport into the cell nucleus is essential. Importin-α (Imp-α) is the receptor for cargo proteins that contain specific nuclear localization signals (NLSs) that play a key role in the classical nuclear import pathway. Structures of Imp-α from different organisms (yeast, rice, mouse, and human) have been determined, revealing that this receptor possesses a conserved structural scaffold. However, recent studies have demonstrated that the Impα mechanism of action may vary significantly for different organisms or for different isoforms from the same organism. Therefore, structural, functional, and biophysical characterization of different Impα proteins is necessary to understand the selectivity of nuclear transport. Here, we determined the first crystal structure of an Impα from a filamentous fungus which is also the highest resolution Impα structure already solved to date (1.75 Å). In addition, we performed calorimetric analysis to determine the affinity and thermodynamic parameters of the interaction between Imp-α and the classical SV40 NLS peptide. The comparison of these data with previous studies on Impα proteins led us to demonstrate that N. crassa Imp-α possess specific features that are distinct from mammalian Imp-α but exhibit important similarities to rice Imp-α, particularly at the minor NLS binding site.
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Affiliation(s)
- Natalia E. Bernardes
- Departamento de Física e Biofísica, Instituto de Biociências, Universidade Estadual Paulista, UNESP, Botucatu, SP, Brazil
| | - Agnes A. S. Takeda
- Departamento de Física e Biofísica, Instituto de Biociências, Universidade Estadual Paulista, UNESP, Botucatu, SP, Brazil
| | - Thiago R. Dreyer
- Departamento de Física e Biofísica, Instituto de Biociências, Universidade Estadual Paulista, UNESP, Botucatu, SP, Brazil
| | - Fernanda Z. Freitas
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista, UNESP, Araraquara, SP, Brazil
| | - Maria Célia Bertolini
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista, UNESP, Araraquara, SP, Brazil
| | - Marcos R. M. Fontes
- Departamento de Física e Biofísica, Instituto de Biociências, Universidade Estadual Paulista, UNESP, Botucatu, SP, Brazil
- * E-mail:
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Cupertino FB, Virgilio S, Freitas FZ, Candido TDS, Bertolini MC. Regulation of glycogen metabolism by the CRE-1, RCO-1 and RCM-1 proteins in Neurospora crassa. The role of CRE-1 as the central transcriptional regulator. Fungal Genet Biol 2015; 77:82-94. [PMID: 25889113 DOI: 10.1016/j.fgb.2015.03.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 03/30/2015] [Accepted: 03/31/2015] [Indexed: 11/17/2022]
Abstract
The transcription factor CreA/Mig1/CRE-1 is a repressor protein that regulates the use of alternative carbon sources via a mechanism known as Carbon Catabolite Repression (CCR). In Saccharomyces cerevisiae, Mig1 recruits the complex Ssn6-Tup1, the Neurospora crassa RCM-1 and RCO-1 orthologous proteins, respectively, to bind to promoters of glucose-repressible genes. We have been studying the regulation of glycogen metabolism in N. crassa and the identification of the RCO-1 corepressor as a regulator led us to investigate the regulatory role of CRE-1 in this process. Glycogen content is misregulated in the rco-1(KO), rcm-1(RIP) and cre-1(KO) strains, and the glycogen synthase phosphorylation is decreased in all strains, showing that CRE-1, RCO-1 and RCM-1 proteins are involved in glycogen accumulation and in the regulation of GSN activity by phosphorylation. We also confirmed the regulatory role of CRE-1 in CCR and its nuclear localization under repressing condition in N. crassa. The expression of all glycogenic genes is misregulated in the cre-1(KO) strain, suggesting that CRE-1 also controls glycogen metabolism by regulating gene expression. The existence of a high number of the Aspergillus nidulans CreA motif (5'-SYGGRG-3') in the glycogenic gene promoters led us to analyze the binding of CRE-1 to some DNA motifs both in vitro by DNA gel shift and in vivo by ChIP-qPCR analysis. CRE-1 bound in vivo to all motifs analyzed demonstrating that it down-regulates glycogen metabolism by controlling gene expression and GSN phosphorylation.
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Affiliation(s)
- Fernanda Barbosa Cupertino
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista, UNESP, 14800-060 Araraquara, SP, Brazil
| | - Stela Virgilio
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista, UNESP, 14800-060 Araraquara, SP, Brazil
| | - Fernanda Zanolli Freitas
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista, UNESP, 14800-060 Araraquara, SP, Brazil
| | - Thiago de Souza Candido
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista, UNESP, 14800-060 Araraquara, SP, Brazil
| | - Maria Célia Bertolini
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista, UNESP, 14800-060 Araraquara, SP, Brazil.
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Cupertino FB, Freitas FZ, de Paula RM, Bertolini MC. Ambient pH controls glycogen levels by regulating glycogen synthase gene expression in Neurospora crassa. New insights into the pH signaling pathway. PLoS One 2012; 7:e44258. [PMID: 22952943 PMCID: PMC3432076 DOI: 10.1371/journal.pone.0044258] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 07/31/2012] [Indexed: 01/15/2023] Open
Abstract
Glycogen is a polysaccharide widely distributed in microorganisms and animal cells and its metabolism is under intricate regulation. Its accumulation in a specific situation results from the balance between glycogen synthase and glycogen phosphorylase activities that control synthesis and degradation, respectively. These enzymes are highly regulated at transcriptional and post-translational levels. The existence of a DNA motif for the Aspergillus nidulans pH responsive transcription factor PacC in the promoter of the gene encoding glycogen synthase (gsn) in Neurospora crassa prompted us to investigate whether this transcription factor regulates glycogen accumulation. Transcription factors such as PacC in A. nidulans and Rim101p in Saccharomyces cerevisiae play a role in the signaling pathway that mediates adaptation to ambient pH by inducing the expression of alkaline genes and repressing acidic genes. We showed here that at pH 7.8 pacC was over-expressed and gsn was down-regulated in wild-type N. crassa coinciding with low glycogen accumulation. In the pacCKO strain the glycogen levels and gsn expression at alkaline pH were, respectively, similar to and higher than the wild-type strain at normal pH (5.8). These results characterize gsn as an acidic gene and suggest a regulatory role for PACC in gsn expression. The truncated recombinant protein, containing the DNA-binding domain specifically bound to a gsn DNA fragment containing the PacC motif. DNA-protein complexes were observed with extracts from cells grown at normal and alkaline pH and confirmed by ChIP-PCR analysis. The PACC present in these extracts showed equal molecular mass, indicating that the protein is already processed at normal pH, in contrast to A. nidulans. Together, these results show that the pH signaling pathway controls glycogen accumulation by regulating gsn expression and suggest the existence of a different mechanism for PACC activation in N. crassa.
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Affiliation(s)
- Fernanda Barbosa Cupertino
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista, UNESP, Araraquara, São Paulo, Brazil
| | - Fernanda Zanolli Freitas
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista, UNESP, Araraquara, São Paulo, Brazil
| | | | - Maria Célia Bertolini
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, Universidade Estadual Paulista, UNESP, Araraquara, São Paulo, Brazil
- * E-mail:
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Gonçalves RD, Cupertino FB, Freitas FZ, Luchessi AD, Bertolini MC. A genome-wide screen for Neurospora crassa transcription factors regulating glycogen metabolism. Mol Cell Proteomics 2011; 10:M111.007963. [PMID: 21768394 DOI: 10.1074/mcp.m111.007963] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Transcription factors play a key role in transcription regulation as they recognize and directly bind to defined sites in promoter regions of target genes, and thus modulate differential expression. The overall process is extremely dynamic, as they have to move through the nucleus and transiently bind to chromatin in order to regulate gene transcription. To identify transcription factors that affect glycogen accumulation in Neurospora crassa, we performed a systematic screen of a deletion strains set generated by the Neurospora Knockout Project and available at the Fungal Genetics Stock Center. In a wild-type strain of N. crassa, glycogen content reaches a maximal level at the end of the exponential growth phase, but upon heat stress the glycogen content rapidly drops. The gene encoding glycogen synthase (gsn) is transcriptionally down-regulated when the mycelium is exposed to the same stress condition. We identified 17 deleted strains having glycogen accumulation profiles different from that of the wild-type strain under both normal growth and heat stress conditions. Most of the transcription factors identified were annotated as hypothetical protein, however some of them, such as the PacC, XlnR, and NIT2 proteins, were biochemically well-characterized either in N. crassa or in other fungi. The identification of some of the transcription factors was coincident with the presence of DNA-binding motifs specific for the transcription factors in the gsn 5'-flanking region, and some of these DNA-binding motifs were demonstrated to be functional by Electrophoretic Mobility Shift Assay (EMSA) experiments. Strains knocked-out in these transcription factors presented impairment in the regulation of gsn expression, suggesting that the transcription factors regulate glycogen accumulation by directly regulating gsn gene expression. Five selected mutant strains showed defects in cell cycle progression, and two transcription factors were light-regulated. The results indicate that there are connections linking different cellular processes, such as metabolism control, biological clock, and cell cycle progression.
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Affiliation(s)
- Rodrigo Duarte Gonçalves
- Instituto de Química, UNESP, Departamento de Bioquímica e Tecnologia Química, 14800-900, Araraquara, SP, Brazil
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cAMP signaling pathway controls glycogen metabolism in Neurospora crassa by regulating the glycogen synthase gene expression and phosphorylation. Fungal Genet Biol 2010; 47:43-52. [PMID: 19883780 DOI: 10.1016/j.fgb.2009.10.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Revised: 10/26/2009] [Accepted: 10/26/2009] [Indexed: 11/22/2022]
Abstract
The cAMP-PKA signaling pathway plays an important role in many biological processes including glycogen metabolism. In this work we investigated its role in the Neurospora crassa glycogen metabolism control using mutant strains affected in components of the pathway, the cr-1 strain deficient in adenylyl cyclase activity therefore has the PKA pathway not active, and the mcb strain a temperature-sensitive mutant defective in the regulatory subunit of PKA therefore is a strain with constitutively active PKA. We analyzed the expression of the gene encoding glycogen synthase (gsn), the regulatory enzyme in glycogen synthesis as a potential target of the regulation. The cr-1 strain accumulated, during vegetative growth, glycogen levels much higher than the wild type strain indicating a role of the PKA pathway in the glycogen accumulation. The gsn transcript was not increased in this strain but the GSN protein was less phosphorylated "in vitro", and therefore more active, suggesting that the post-translational modification of GSN is likely the main mechanism controlling glycogen accumulation during vegetative growth. Heat shock down-regulates gsn gene transcription in the two mutant strains, as well as in the wild type strain, suggesting that the PKA pathway may not be the only pathway having a direct role in gsn transcription under heat shock. DNA-protein complexes were formed between the STRE motif in the gsn promoter and nuclear proteins from heat-shocked mycelium. However STRE was not able to induce transcription of a reporter gene in Saccharomyces cerevisiae, suggesting that the motif might be involved in a different way of regulation in the N. crassa gene expression under heat shock. The CRE-like DNA elements present in the gsn promoter were shown to be bound by different proteins from the PKA mutant strains. The DNA-protein complexes were observed with proteins from the strains grown under normal condition and under heat shock indicating the functionality of this DNA element. In this work we presented some evidences that the PKA signaling pathway regulates glycogen metabolism in N. crassa in a different way when compared to the well-characterized model of regulation existent in S. cerevisiae.
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Aspergillus fumigatus calcipressin CbpA is involved in hyphal growth and calcium homeostasis. EUKARYOTIC CELL 2009; 8:511-9. [PMID: 19252123 DOI: 10.1128/ec.00336-08] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Calcineurin is a conserved protein phosphatase that plays a critical role in Ca(2+) signaling and stress responses. Previously, a new class of conserved calcineurin-binding proteins, the calcipressins, was identified. However, the role of these proteins remains controversial, and both inhibitory and stimulatory effects on calcineurin were observed. In this study, we investigate the role of CbpA, the Aspergillus fumigatus member of the calcipressin family, and report that deletion of the cbpA gene resulted in reduced hyphal growth and limited attenuated virulence. Interestingly, under high-calcium-level conditions, the DeltacbpA strain displayed improved Ca(2+) tolerance compared to the wild-type strain and revealed increased expression of vcxA, chsA, and cnaA, which encode the vacuolar Ca(2+)/H(+) exchanger VcxA, chitin synthase A, and the calcineurin catalytic subunit CnaA, respectively. The increased transcript levels of these three genes were reversed in the presence of the calcineurin inhibitor FK506, indicating a calcineurin-dependent mechanism. Overexpression of cbpA resulted in decreased transcription of vcxA, chsA, and cnaA, associated with wild-type sensitivity to Ca(2+). Taken together, our study highlights the importance of CbpA in the regulation of hyphal growth and calcium adaptation of A. fumigatus and provides evidence that CbpA may serve as a feedback inhibitor in some aspects of calcineurin functions.
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