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Pandit SS, Zheng J, Yin Y, Lorber S, Puel O, Dhingra S, Espeso EA, Calvo AM. Homeobox transcription factor HbxA influences expression of over one thousand genes in the model fungus Aspergillus nidulans. PLoS One 2023; 18:e0286271. [PMID: 37478074 PMCID: PMC10361519 DOI: 10.1371/journal.pone.0286271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 05/11/2023] [Indexed: 07/23/2023] Open
Abstract
In fungi, conserved homeobox-domain proteins are transcriptional regulators governing development. In Aspergillus species, several homeobox-domain transcription factor genes have been identified, among them, hbxA/hbx1. For instance, in the opportunistic human pathogen Aspergillus fumigatus, hbxA is involved in conidial production and germination, as well as virulence and secondary metabolism, including production of fumigaclavines, fumiquinazolines, and chaetominine. In the agriculturally important fungus Aspergillus flavus, disruption of hbx1 results in fluffy aconidial colonies unable to produce sclerotia. hbx1 also regulates production of aflatoxins, cyclopiazonic acid and aflatrem. Furthermore, transcriptome studies revealed that hbx1 has a broad effect on the A. flavus genome, including numerous genes involved in secondary metabolism. These studies underline the importance of the HbxA/Hbx1 regulator, not only in developmental processes but also in the biosynthesis of a broad number of fungal natural products, including potential medical drugs and mycotoxins. To gain further insight into the regulatory scope of HbxA in Aspergilli, we studied its role in the model fungus Aspergillus nidulans. Our present study of the A. nidulans hbxA-dependent transcriptome revealed that more than one thousand genes are differentially expressed when this regulator was not transcribed at wild-type levels, among them numerous transcription factors, including those involved in development as well as in secondary metabolism regulation. Furthermore, our metabolomics analyses revealed that production of several secondary metabolites, some of them associated with A. nidulans hbxA-dependent gene clusters, was also altered in deletion and overexpression hbxA strains compared to the wild type, including synthesis of nidulanins A, B and D, versicolorin A, sterigmatocystin, austinol, dehydroaustinol, and three unknown novel compounds.
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Affiliation(s)
- Sandesh S. Pandit
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
| | - Jinfang Zheng
- Nebraska Food for Health Center, Department of Food Science and Technology, University of Nebraska, Lincoln, Nebraska, United States of America
| | - Yanbin Yin
- Nebraska Food for Health Center, Department of Food Science and Technology, University of Nebraska, Lincoln, Nebraska, United States of America
| | - Sophie Lorber
- Toxalim (Research Centre in Food Toxicology), Université de Toulouse, INRAE, ENVT, INP-Purpan, UPS, Toulouse, France
| | - Olivier Puel
- Toxalim (Research Centre in Food Toxicology), Université de Toulouse, INRAE, ENVT, INP-Purpan, UPS, Toulouse, France
| | - Sourabh Dhingra
- Department of Biological Sciences and Eukaryotic Pathogen Innovation Center, Clemson University, Clemson, South Carolina, United States of America
| | - Eduardo A. Espeso
- Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain
| | - Ana M. Calvo
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, United States of America
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Son YE, Yu JH, Park HS. Regulators of the Asexual Life Cycle of Aspergillus nidulans. Cells 2023; 12:1544. [PMID: 37296664 PMCID: PMC10253035 DOI: 10.3390/cells12111544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 06/01/2023] [Accepted: 06/02/2023] [Indexed: 06/12/2023] Open
Abstract
The genus Aspergillus, one of the most abundant airborne fungi, is classified into hundreds of species that affect humans, animals, and plants. Among these, Aspergillus nidulans, as a key model organism, has been extensively studied to understand the mechanisms governing growth and development, physiology, and gene regulation in fungi. A. nidulans primarily reproduces by forming millions of asexual spores known as conidia. The asexual life cycle of A. nidulans can be simply divided into growth and asexual development (conidiation). After a certain period of vegetative growth, some vegetative cells (hyphae) develop into specialized asexual structures called conidiophores. Each A. nidulans conidiophore is composed of a foot cell, stalk, vesicle, metulae, phialides, and 12,000 conidia. This vegetative-to-developmental transition requires the activity of various regulators including FLB proteins, BrlA, and AbaA. Asymmetric repetitive mitotic cell division of phialides results in the formation of immature conidia. Subsequent conidial maturation requires multiple regulators such as WetA, VosA, and VelB. Matured conidia maintain cellular integrity and long-term viability against various stresses and desiccation. Under appropriate conditions, the resting conidia germinate and form new colonies, and this process is governed by a myriad of regulators, such as CreA and SocA. To date, a plethora of regulators for each asexual developmental stage have been identified and investigated. This review summarizes our current understanding of the regulators of conidial formation, maturation, dormancy, and germination in A. nidulans.
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Affiliation(s)
- Ye-Eun Son
- Major in Food Biomaterials, School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, Republic of Korea;
| | - Jae-Hyuk Yu
- Department of Bacteriology, Food Research Institute, University of Wisconsin-Madison, Madison, WI 53706, USA;
| | - Hee-Soo Park
- Major in Food Biomaterials, School of Food Science and Biotechnology, Kyungpook National University, Daegu 41566, Republic of Korea;
- Department of Integrative Biology, Kyungpook National University, Daegu 41566, Republic of Korea
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Clemente I, Aznar M, Nerín C. Effect of an active label based on benzyl isothiocyanate on the morphology and ochratoxins production of Aspergillus ochraceus. Food Res Int 2017; 101:61-72. [DOI: 10.1016/j.foodres.2017.08.060] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 07/31/2017] [Accepted: 08/27/2017] [Indexed: 11/24/2022]
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Extreme Diversity in the Regulation of Ndt80-Like Transcription Factors in Fungi. G3-GENES GENOMES GENETICS 2015; 5:2783-92. [PMID: 26497142 PMCID: PMC4683649 DOI: 10.1534/g3.115.021378] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The Saccharomyces cerevisiaeNdt80 protein is the founding member of a class of p53-like transcription factors that is known as the NDT80/PhoG-like DNA-binding family. The number of NDT80-like genes in different fungi is highly variable and their roles, which have been examined in only a few species, include regulation of meiosis, sexual development, biofilm formation, drug resistance, virulence, the response to nutrient stress and programmed cell death. The protein kinase Ime2 regulates the single NDT80 gene present in S. cerevisiae. In this study we used a genetic approach to investigate whether the Aspergillus nidulansIme2 homolog, ImeB, and/or protein kinases MpkC, PhoA and PhoB regulate the two NDT80-like genes (xprG and ndtA) in A. nidulans. Disruption of imeB, but not mpkC, phoA or phoB, led to increased extracellular protease activity and a defect in mycotoxin production similar to the xprG1 gain-of-function mutation. Quantitative RT-PCR showed that ImeB is a negative regulator of xprG expression and XprG is a negative regulator of xprG and ndtA expression. Thus, in contrast to Ime2, which is a positive regulator of NDT80 in S. cerevisiae, ImeB is a negative regulator as in Neurospora crassa. However, the ability of Ndt80 to autoregulate NDT80 is conserved in A. nidulans though the autoregulatory effect is negative rather than positive. Unlike N. crassa, a null mutation in imeB does not circumvent the requirement for XprG or NdtA. These results show that the regulatory activities of Ime2 and Ndt80-like proteins display an extraordinarily level of evolutionary flexibility.
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Toh-e A, Ohkusu M, Li HM, Shimizu K, Takahashi-Nakaguchi A, Gonoi T, Kawamoto S, Kanesaki Y, Yoshikawa H, Nishizawa M. Identification of genes involved in the phosphate metabolism in Cryptococcus neoformans. Fungal Genet Biol 2015; 80:19-30. [DOI: 10.1016/j.fgb.2015.04.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 04/21/2015] [Accepted: 04/23/2015] [Indexed: 11/29/2022]
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Jiang H, Liu F, Zhang S, Lu L. Putative PmrA and PmcA are important for normal growth, morphogenesis and cell wall integrity, but not for viability in Aspergillus nidulans. MICROBIOLOGY-SGM 2014; 160:2387-2395. [PMID: 25118249 DOI: 10.1099/mic.0.080119-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
P-type Ca(2+)-transporting ATPases are Ca(2+) pumps, extruding cytosolic Ca(2+) to the extracellular environment or the intracellular Ca(2+) store lumens. In budding yeast, Pmr1 (plasma membrane ATPase related), and Pmc1 (plasma membrane calcium-ATPase) cannot be deleted simultaneously for it to survive in standard medium. Here, we deleted two putative Ca(2+) pumps, designated AnPmrA and AnPmcA, from Aspergillus nidulans, and obtained the mutants ΔanpmrA and ΔanpmcA, respectively. Then, using ΔanpmrA as the starting strain, the promoter of its anpmcA was replaced with the alcA promoter to secure the mutant ΔanpmrAalcApmcA or its anpmcA was deleted completely to produce the mutant ΔanpmrAΔpmcA. Different from the case in Saccharomyces cerevisiae, double deletion of anpmrA and anpmcA was not lethal in A. nidulans. In addition, deletion of anpmrA and/or anpmcA had produced growth defects, although overexpression of AnPmc1 in ΔanpmrAalcApmcA could not restore the growth defects that resulted from the loss of AnPmrA. Moreover, we found AnPmrA was indispensable for maintenance of normal morphogenesis, especially in low-Ca(2+)/Mn(2+) environments. Thus, our findings suggest AnPmrA and AnPmcA might play important roles in growth, morphogenesis and cell wall integrity in A. nidulans in a different way from that in yeasts.
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Affiliation(s)
- Hechun Jiang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology; College of Life Sciences, Nanjing Normal University, Nanjing 210023, PR China
| | - Feifei Liu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology; College of Life Sciences, Nanjing Normal University, Nanjing 210023, PR China
| | - Shizhu Zhang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology; College of Life Sciences, Nanjing Normal University, Nanjing 210023, PR China
| | - Ling Lu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology; College of Life Sciences, Nanjing Normal University, Nanjing 210023, PR China
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Christmann M, Schmaler T, Gordon C, Huang X, Bayram Ö, Schinke J, Stumpf S, Dubiel W, Braus GH. Control of multicellular development by the physically interacting deneddylases DEN1/DenA and COP9 signalosome. PLoS Genet 2013; 9:e1003275. [PMID: 23408908 PMCID: PMC3567183 DOI: 10.1371/journal.pgen.1003275] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 12/11/2012] [Indexed: 11/18/2022] Open
Abstract
Deneddylases remove the ubiquitin-like protein Nedd8 from modified proteins. An increased deneddylase activity has been associated with various human cancers. In contrast, we show here that a mutant strain of the model fungus Aspergillus nidulans deficient in two deneddylases is viable but can only grow as a filament and is highly impaired for multicellular development. The DEN1/DenA and the COP9 signalosome (CSN) deneddylases physically interact in A. nidulans as well as in human cells, and CSN targets DEN1/DenA for protein degradation. Fungal development responds to light and requires both deneddylases for an appropriate light reaction. In contrast to CSN, which is necessary for sexual development, DEN1/DenA is required for asexual development. The CSN-DEN1/DenA interaction that affects DEN1/DenA protein levels presumably balances cellular deneddylase activity. A deneddylase disequilibrium impairs multicellular development and suggests that control of deneddylase activity is important for multicellular development. The family of small ubiquitin-like (Ubl) proteins plays a major role in the control of stability, activity, or localization of modified target proteins in a eukaryotic cell. Lysine side chains are modified by covalent Ubl attachment, and this process can be reversed by specific proteases. Nedd8 is the closest relative to ubiquitin in the Ubl family. We describe here a novel, conserved interplay between two physically interacting deneddylases that are specific for Nedd8. Increased deneddylase activity had been shown to be associated with human cancers. We convey here specific distinct developmental functions of the two deneddylases in multicellular differentiation of the filamentous fungus Aspergillus nidulans. The physical interaction between both proteins affects protein stability and therefore cellular deneddylase activity. The equilibrium between the two deneddylases and their physical interaction are conserved from fungi to human and seem to be important for normal development of a multicellular organism. These findings open a different angle for future studies of tumor formation in humans.
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Affiliation(s)
- Martin Christmann
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Tilo Schmaler
- Department of General, Visceral, Vascular and Thoracic Surgery, Division of Molecular Biology, Charité–Universitätsmedizin Berlin, Berlin, Germany
| | - Colin Gordon
- Medical Research Council, Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom
| | - Xiaohua Huang
- Department of General, Visceral, Vascular and Thoracic Surgery, Division of Molecular Biology, Charité–Universitätsmedizin Berlin, Berlin, Germany
| | - Özgür Bayram
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Josua Schinke
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Sina Stumpf
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Wolfgang Dubiel
- Department of General, Visceral, Vascular and Thoracic Surgery, Division of Molecular Biology, Charité–Universitätsmedizin Berlin, Berlin, Germany
- * E-mail: (WD); (GHB)
| | - Gerhard H. Braus
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Göttingen, Germany
- * E-mail: (WD); (GHB)
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8
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Bongiorno VA, Ferreira da Cruz A, Nunis da Silva A, Corrêa LC. Phosphate limitation induces sporulation in the chytridiomycete Blastocladiella emersonii. Can J Microbiol 2012; 58:1104-11. [PMID: 22913304 DOI: 10.1139/w2012-090] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The cell cycle is controlled by numerous mechanisms that ensure correct cell division. If growth is not possible, cells may eventually promote autophagy, differentiation, or apoptosis. Microorganisms interrupt their growth and differentiate under general nutrient limitation. We analyzed the effects of phosphate limitation on growth and sporulation in the chytridiomycete Blastocladiella emersonii using kinetic data, phase-contrast, and laser confocal microscopy. Under phosphate limitation, zoospores germinated and subsequently formed 2-4 spores, regardless of the nutritional content of the medium. The removal of phosphate at any time during growth induced sporulation of vegetative cells. If phosphate was later added to the same cultures, growth was restored if the cells were not yet committed to sporulation. The cycles of addition and withdrawal of phosphate from growth medium resulted in cycles of germination-growth, germination-sporulation, or germination-growth-sporulation. These results show that phosphate limitation is sufficient to interrupt cell growth and to induce complete sporulation in B. emersonii. We concluded that the determination of growth or sporulation in this microorganism is linked to phosphate availability when other nutrients are not limiting. This result provides a new tool for the dissection of nutrient-energy and signal pathways in cell growth and differentiation.
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Sarkar A, Funk AN, Scherlach K, Horn F, Schroeckh V, Chankhamjon P, Westermann M, Roth M, Brakhage AA, Hertweck C, Horn U. Differential expression of silent polyketide biosynthesis gene clusters in chemostat cultures of Aspergillus nidulans. J Biotechnol 2012; 160:64-71. [DOI: 10.1016/j.jbiotec.2012.01.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 01/09/2012] [Accepted: 01/17/2012] [Indexed: 01/11/2023]
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10
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Shapiro RS, Cowen LE. Uncovering cellular circuitry controlling temperature-dependent fungal morphogenesis. Virulence 2012; 3:400-4. [PMID: 22722238 DOI: 10.4161/viru.20979] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Temperature change is a ubiquitous environmental signal, which exerts powerful control over the development and virulence of microbial pathogens. For Candida albicans, the leading fungal pathogen of humans, temperature influences mating, phenotypic switching, resistance to antifungal drugs and the morphogenetic transition from yeast to filamentous growth. C. albicans morphogenesis is profoundly influenced by temperature, and most filament-inducing cues depend on a concurrent increase in temperature to 37°C before morphogenesis can occur, although the molecular mechanisms underpinning this temperature-dependent developmental transition remain largely unknown. We established that the thermally responsive molecular chaperone Hsp90 orchestrates temperature-dependent morphogenesis, via previously uncharacterized cellular circuitry, comprised of the cyclin-dependent kinase Pho85, the cyclin Pcl1 and the transcriptional regulator Hms1. Here we elaborate on Hsp90's pleiotropic effects on temperature-dependent morphogenetic circuitry, and highlight how changes in protein form and function in response to stress complements the diverse repertoire of mechanisms of microbial temperature sensing.
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Affiliation(s)
- Rebecca S Shapiro
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
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11
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Singh S, Braus-Stromeyer SA, Timpner C, Valerius O, von Tiedemann A, Karlovsky P, Druebert C, Polle A, Braus GH. The plant host Brassica napus induces in the pathogen Verticillium longisporum the expression of functional catalase peroxidase which is required for the late phase of disease. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:569-81. [PMID: 22112218 DOI: 10.1094/mpmi-08-11-0217] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The devastating soilborne fungal pathogen Verticillium longisporum is host specific to members of the family Brassicaceae, including oilseed rape (Brassica napus) as the economically most important crop. The fungus infects through the roots and causes stunting and early senescence of susceptible host plants and a marked decrease in crop yield. We show here that V. longisporum reacts to the presence of B. napus xylem sap with the production of six distinct upregulated and eight downregulated proteins visualized by two-dimensional gel electrophoresis. Identification of 10 proteins by mass spectrometry revealed that all upregulated proteins are involved in oxidative stress response. The V. longisporum catalase peroxidase (VlCPEA) was the most upregulated protein and is encoded by two isogenes, VlcpeA-1 and VlcpeA-2. Both genes are 98% identical, corroborating the diploid or "amphihaploid" status of the fungus. Knock downs of both VlcpeA genes reduced protein expression by 80% and resulted in sensitivity against reactive oxygen species. Whereas saprophytic growth and the initial phase of the plant infection were phenotypically unaffected, the mutants were not able to perform the late phases of disease. We propose that the catalase peroxidase plays a role in protecting the fungus from the oxidative stress generated by the host plant at an advanced phase of the disease.
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Affiliation(s)
- Seema Singh
- Institut für Mikrobiologie und Genetik, Georg-August Universität, 37077 Göttingen, Germany.
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12
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Dyer PS, O'Gorman CM. Sexual development and cryptic sexuality in fungi: insights from Aspergillus species. FEMS Microbiol Rev 2011; 36:165-92. [PMID: 22091779 DOI: 10.1111/j.1574-6976.2011.00308.x] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 09/04/2011] [Indexed: 11/30/2022] Open
Abstract
Major insights into sexual development and cryptic sexuality within filamentous fungi have been gained from investigations using Aspergillus species. Here, an overview is first given into sexual morphogenesis in the aspergilli, describing the different types of sexual structures formed and how their production is influenced by a variety of environmental and nutritional factors. It is argued that the formation of cleistothecia and accessory tissues, such as Hülle cells and sclerotia, should be viewed as two independent but co-ordinated developmental pathways. Next, a comprehensive survey of over 75 genes associated with sexual reproduction in the aspergilli is presented, including genes relating to mating and the development of cleistothecia, sclerotia and ascospores. Most of these genes have been identified from studies involving the homothallic Aspergillus nidulans, but an increasing number of studies have now in addition characterized 'sex-related' genes from the heterothallic species Aspergillus fumigatus and Aspergillus flavus. A schematic developmental genetic network is proposed showing the inter-relatedness between these genes. Finally, the discovery of sexual reproduction in certain Aspergillus species that were formerly considered to be strictly asexual is reviewed, and the importance of these findings for cryptic sexuality in the aspergilli as a whole is discussed.
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Affiliation(s)
- Paul S Dyer
- School of Biology, University of Nottingham, Nottingham, UK.
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13
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Toh-e A, Shimizu K, Li HM, Nishizawa M, Kawamoto S. [Phosphate regulation in Cryptococcus neoformans]. Med Mycol J 2011; 52:19-23. [PMID: 21441709 DOI: 10.3314/jjmm.52.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Affiliation(s)
- Akio Toh-e
- Medical Mycology Research Center, Chiba University
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14
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Helmstaedt K, Schwier EU, Christmann M, Nahlik K, Westermann M, Harting R, Grond S, Busch S, Braus GH. Recruitment of the inhibitor Cand1 to the cullin substrate adaptor site mediates interaction to the neddylation site. Mol Biol Cell 2010; 22:153-64. [PMID: 21119001 PMCID: PMC3016973 DOI: 10.1091/mbc.e10-08-0732] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Cand1 inhibits cullin RING ubiquitin ligases by binding unneddylated cullins. The Cand1 N-terminus blocks the cullin neddylation site, whereas the C-terminus inhibits cullin adaptor interaction. These Cand1 binding sites can be separated into two functional polypeptides which bind sequentially. C-terminal Cand1 can directly bind to unneddylated cullins in the nucleus without blocking the neddylation site. The smaller N-terminal Cand1 cannot bind to the cullin neddylation region without C-terminal Cand1. The separation of a single cand1 into two independent genes represents the in vivo situation of the fungus Aspergillus nidulans, where C-terminal Cand1 recruits smaller N-terminal Cand1 in the cytoplasm. Either deletion results in an identical developmental and secondary metabolism phenotype in fungi, which resembles csn mutants deficient in the COP9 signalosome (CSN) deneddylase. We propose a two-step Cand1 binding to unneddylated cullins which initiates at the adaptor binding site and subsequently blocks the neddylation site after CSN has left.
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Affiliation(s)
- Kerstin Helmstaedt
- Institute of Microbiology and Genetics, Georg-August-Universität, D-37077 Göttingen, Germany
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15
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Functional characterization of a new member of the Cdk9 family in Aspergillus nidulans. EUKARYOTIC CELL 2010; 9:1901-12. [PMID: 20952582 DOI: 10.1128/ec.00384-09] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cdk9-like kinases in complex with T-type cyclins are essential components of the eukaryotic transcription elongation machinery. The full spectrum of Cdk9/cyclin T targets, as well as the specific consequences of phosphorylations, is still largely undefined. We identify and characterize here a Cdk9 kinase (PtkA) in the filamentous ascomycete Aspergillus nidulans. Deletion of ptkA had a lethal effect in later stages of vegetative growth and completely impeded asexual development. Overexpression of ptkA affected directionality of polarized growth and the initiation of new branching sites. A green fluorescent protein-tagged PtkA version localized inside the nucleus during interphase, supporting a role of PtkA in transcription elongation, as observed in other organisms. We also identified a putative cyclin T homolog, PchA, in the A. nidulans genome and confirmed its interaction with PtkA in vivo. Surprisingly, the Pcl-like cyclin PclA, previously described to be involved in asexual development, was also found to interact with PtkA, indicating a possible role of PtkA in linking transcriptional activity with development and/or morphogenesis in A. nidulans. This is the first report of a Cdk9 kinase interacting with a Pcl-like cyclin, revealing interesting new aspects about the involvement of this Cdk-subfamily in differential gene expression.
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16
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Gras DE, Silveira HC, Peres NT, Sanches PR, Martinez-Rossi NM, Rossi A. Transcriptional changes in the nuc-2A mutant strain of Neurospora crassa cultivated under conditions of phosphate shortage. Microbiol Res 2009; 164:658-64. [DOI: 10.1016/j.micres.2008.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2008] [Revised: 12/21/2008] [Accepted: 12/30/2008] [Indexed: 10/21/2022]
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17
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Silva EM, Freitas JS, Gras DE, Squina FM, Leal J, Silveira HCS, Martinez-Rossi NM, Rossi A. Identification of genes differentially expressed in a strain of the mold Aspergillus nidulans carrying a loss-of-function mutation in the palA gene. Can J Microbiol 2009; 54:803-11. [PMID: 18923548 DOI: 10.1139/w08-072] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To identify genes differentially expressed in a strain of the mold Aspergillus nidulans carrying a loss-of-function mutation in palA, a gene in the pH-responsive signal transduction pathway, suppression subtractive hybridization was performed between RNA isolated from the biA1 and biA1 palA1 strains grown under limiting inorganic phosphate at pH 5.0. We have identified several genes upregulated in the biA1 palA1 mutant strain that play important roles in mitotic fidelity, stress responses, enzyme secretion, signal transduction mechanisms, development, genome stability, phosphate sensing, and transcriptional regulation among others. The upregulation of eight of these transcripts was also validated by Northern blot. Moreover, we show that a loss of function mutation in the palA gene drastically reduced the neutral sugar content of the acid phosphatase PacA secreted by the fungus A. nidulans grown at pH 5.0 compared with a control strain.
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Affiliation(s)
- Emiliana M Silva
- Departamento de Bioquimica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av Bandeirantes 3900, Ribeirão Preto 14049-900, Brazil
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18
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de Gouvêa PF, Soriani FM, Malavazi I, Savoldi M, Goldman MHDS, Loss O, Bignell E, da Silva Ferreira ME, Goldman GH. Functional characterization of the Aspergillus fumigatus PHO80 homologue. Fungal Genet Biol 2008; 45:1135-46. [DOI: 10.1016/j.fgb.2008.04.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 04/01/2008] [Accepted: 04/02/2008] [Indexed: 10/22/2022]
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19
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Leal J, Squina FM, Martinez-Rossi NM, Rossi A. The transcription of the gene for iso-orotate decarboxylase (IDCase), an enzyme of the thymidine salvage pathway, is downregulated in the pregc mutant strain of Neurospora crassa grown under phosphate starvation. Can J Microbiol 2008; 53:1011-5. [PMID: 17898858 DOI: 10.1139/w07-064] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The preg gene encodes a cyclin-like protein that is implicated in the derepression of nucleases and phosphatases that scavenge phosphate from the environment. To better understand the regulatory role of the preg gene product, the differential display reverse transcriptase - polymerase chain reaction was used to isolate transcripts differentially expressed in the pregc mutant strain of the mold Neurospora crassa grown under phosphate starvation, at pH 7.8. Two transcripts, whose differential expressions were confirmed by Northern blotting, were downregulated in a strain of N. crassa carrying a loss-of-function mutation in the preg gene (preg(c) allele). These transcripts revealed genes coding for enzymes involved in the thymidine salvage pathway (iso-orotate decarboxylase) and in the biosynthesis of coenzyme Q (ubiquinone C-methyltransferase), which may be relevant to a further understanding of the molecular events involved in the phosphorus sensing in N. crassa.
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Affiliation(s)
- Juliana Leal
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av Bandeirantes 3900, 14049-900, Ribeirão Preto, SP, Brazil
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20
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Meyer V. A small protein that fights fungi: AFP as a new promising antifungal agent of biotechnological value. Appl Microbiol Biotechnol 2007; 78:17-28. [PMID: 18066545 DOI: 10.1007/s00253-007-1291-3] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Revised: 11/14/2007] [Accepted: 11/15/2007] [Indexed: 11/28/2022]
Abstract
As fungal infections are becoming more prevalent in the medical or agricultural fields, novel and more efficient antifungal agents are badly needed. Within the scope of developing new strategies for the management of fungal infections, antifungal compounds that target essential fungal cell wall components are highly preferable. Ideally, newly developed antimycotics should also combine major aspects such as sustainability, high efficacy, limited toxicity and low costs of production. A naturally derived molecule that possesses all the desired characteristics is the antifungal protein (AFP) secreted by the filamentous ascomycete Aspergillus giganteus. AFP is a small, basic and cysteine-rich peptide that exerts extremely potent antifungal activity against human- and plant-pathogenic fungi without affecting the viability of bacteria, yeast, plant and mammalian cells. This review summarises the current knowledge of the structure, mode of action and expression of AFP, and highlights similarities and differences concerning these issues between AFP and its related proteins from other Ascomycetes. Furthermore, the potential use of AFP in the combat against fungal contaminations and infections will be discussed.
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Affiliation(s)
- Vera Meyer
- TU Berlin, Institut für Biotechnologie, Fachgebiet Mikrobiologie und Genetik, Gustav-Meyer-Allee 25, 13355, Berlin, Germany.
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21
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Establishment of the ambient pH signaling complex in Aspergillus nidulans: PalI assists plasma membrane localization of PalH. EUKARYOTIC CELL 2007; 6:2365-75. [PMID: 17951518 PMCID: PMC2168248 DOI: 10.1128/ec.00275-07] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The Aspergillus nidulans ambient pH signaling pathway involves two transmembrane domain (TMD)-containing proteins, PalH and PalI. We provide in silico and mutational evidence suggesting that PalI is a three TMD (3-TMD) protein with an N-terminal signal peptide, and we show that PalI localizes to the plasma membrane. PalI is not essential for the proteolytic conversion of the PacC translation product into the processed 27-kDa form, but its absence markedly reduces the accumulation of the 53-kDa intermediate after cells are shifted to an alkaline pH. PalI and its homologues contain a predicted luminal, conserved Gly-Cys-containing motif that distantly resembles a Gly-rich dimerization domain. The Gly44Arg and Gly47Asp substitutions within this motif lead to loss of function. The Gly47Asp substitution prevents plasma membrane localization of PalI-green fluorescent protein (GFP) and leads to its missorting into the multivesicular body pathway. Overexpression of the likely ambient alkaline pH receptor, the 7-TMD protein PalH, partially suppresses the null palI32 mutation. Although some PalH-GFP localizes to the plasma membrane, it predominates in internal membranes. However, the coexpression of PalI to stoichiometrically similar levels results in the strong predominance of PalH-GFP in the plasma membrane. Thus, one role for PalI, but possibly not the only role, is to assist with plasma membrane localization of PalH. These data, considered along with previous reports for both Saccharomyces cerevisiae and A. nidulans, strongly support the prevailing model of pH signaling involving two spatially segregated complexes: a plasma membrane complex containing PalH, PalI, and the arrestin-like protein PalF and an endosomal membrane complex containing PalA and PalB, to which PacC is recruited for its proteolytic activation.
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22
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Castillo-Lluva S, Alvarez-Tabarés I, Weber I, Steinberg G, Pérez-Martín J. Sustained cell polarity and virulence in the phytopathogenic fungus Ustilago maydis depends on an essential cyclin-dependent kinase from the Cdk5/Pho85 family. J Cell Sci 2007; 120:1584-95. [PMID: 17405809 DOI: 10.1242/jcs.005314] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cyclin-dependent kinases from the Cdk5/Pho85 family are thought to play important roles in morphogenesis in organisms as diverse as yeast and humans. Here we used the corn smut fungus Ustilago maydis to address the role of Cdk5/Pho85 kinases in the morphogenesis and virulence of dimorphic phytopathogens. We found that Cdk5 is essential for growth in U. maydis. A temperature-sensitive cdk5 mutant caused cell wall and morphology defects at the restrictive temperature. Actin patches labeled with a fimbrin-GFP fusion protein were delocalized and a GFP-Myo5 fusion was directed towards the growing cell pole and rapidly dissociated from the tip. These defects were found to be due to an impairment in the maintenance of cell polarity. Our results indicated that Cdk5 is required for the activity of Rac1, probably at the level of the localization of its GEF, Cdc24. Cdk5 was required for full virulence, probably because mutant cells are unable to sustain the dramatic polar growth required for the formation of the infective structures. These results support a major role for morphogenesis in the virulence program of dimorphic fungi.
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Affiliation(s)
- Sonia Castillo-Lluva
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología CSIC, 28049 Madrid, Spain
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23
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Takeo K, Virtudazo E, Ohkusu M, Kawamoto S, Ito-Kuwa S, Aoki S. [Cell cycle control and CDC28/Cdc2 homologue and related gene cloning of Cryptococcus neoformans]. ACTA ACUST UNITED AC 2007; 47:257-62. [PMID: 17086156 DOI: 10.3314/jjmm.47.257] [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] [Indexed: 11/05/2022]
Abstract
In Cryptococcus neoformans the DNA content of cells having tiny buds varied rather widely, depending on growth phases and strains used. Typically, buds of C. neoformans emerged soon after initiation of DNA synthesis in the early exponential phase. However, bud emergence was delayed to G2 during transition to the stationary phase, and in the early stationary phase budding scarcely occurred, although roughly half of the cells completed DNA synthesis. The timing of budding in C. neoformans was shifted to later cell cycle points with progression of the growth phase of the culture. Similarly, a deficit in oxygen was demonstrated to delay the timing of budding, prolong the G2 phase and cause accumulation of cells after DNA synthesis, but before commitment to budding. The C. neoformans homologue of the main cell cycle control gene CDC28/Cdc2 was isolated using degenerate RT-PCR. The full-length coding region was then amplified using primers to target the regions around the start and stop codons. The gene was called CnCdk1 and was found to have high homologies to S. cerevisiae CDC28 and S. pombe cdc2. To determine its function, its ability to rescue S. cerevisiae cdc28-temperature sensitive mutants was tested. S. cerevisiae cdc28-4 and cdc28-1N strains transformed with the pYES2-CnCdk1 construct exhibited growth at the restrictive temperature. Results of the sequence analysis and the ability of CnCdk1 to complement the S. cerevisiae cdc28-ts mutations support its assumed role as the CDC28/cdc2 homologue in C. neoformans.
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Affiliation(s)
- Kanji Takeo
- Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Japan
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24
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Osmani AH, Oakley BR, Osmani SA. Identification and analysis of essential Aspergillus nidulans genes using the heterokaryon rescue technique. Nat Protoc 2006; 1:2517-26. [PMID: 17406500 DOI: 10.1038/nprot.2006.406] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the heterokaryon rescue technique, gene deletions are carried out using the pyrG nutritional marker to replace the coding region of target genes via homologous recombination in Aspergillus nidulans. If an essential gene is deleted, the null allele is maintained in spontaneously generated heterokaryons that consist of two genetically distinct types of nuclei. One nuclear type has the essential gene deleted but has a functional pyrG allele (pyrG+). The other has the wild-type allele of the essential gene but lacks a functional pyrG allele (pyrG-). Thus, a simple growth test applied to the uninucleate asexual spores formed from primary transformants can identify deletions of genes that are non-essential from those that are essential and can only be propagated by heterokaryon rescue. The growth tests also enable the phenotype of the null allele to be defined. Diagnostic PCR can be used to confirm deletions at the molecular level. This technique is suitable for large-scale gene-deletion programs and can be completed within 3 weeks.
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Affiliation(s)
- Aysha H Osmani
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210, USA
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25
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Bömeke K, Pries R, Korte V, Scholz E, Herzog B, Schulze F, Braus GH. Yeast Gcn4p stabilization is initiated by the dissociation of the nuclear Pho85p/Pcl5p complex. Mol Biol Cell 2006; 17:2952-62. [PMID: 16611745 PMCID: PMC1483032 DOI: 10.1091/mbc.e05-10-0975] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2005] [Revised: 04/04/2006] [Accepted: 04/05/2006] [Indexed: 11/11/2022] Open
Abstract
Protein stability of the c-jun-like yeast bZIP transcriptional activator Gcn4p is exclusively controlled in the yeast nucleus. Phosphorylation by the nuclear Pho85p cyclin-dependent protein kinase, a functional homolog of mammalian Cdk5, initiates the Gcn4p degradation pathway in complex with the cyclin Pcl5p. We show that the initial step in Gcn4p stabilization is the dissociation of the Pho85p/Pcl5p complex. Pcl7p, another nuclear and constantly present cyclin, is required for Gcn4p stabilization and is able to associate to Pho85p independently of the activity of the Gcn4p degradation pathway. In addition, the nuclear cyclin-dependent Pho85p kinase inhibitor Pho81p is required for Gcn4p stabilization. Pho81p only interacts with Pcl5p when Gcn4p is rapidly degraded but constitutively interacts with Pcl7p. Our data suggest that Pcl7p and Pho81p are antagonists of the Pho85p/Pcl5p complex formation in a yet unknown way, which are specifically required for Gcn4p stabilization. We suggest that dissociation of the Pho85p/Pcl5p complex as initial step in Gcn4p stabilization is a prerequisite for a shift of equilibrium to an increased amount of the Pho85p/Pcl7p complexes and subsequently results in decreased Gcn4p phosphorylation and therefore increased stability of the transcription factor.
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Affiliation(s)
- Katrin Bömeke
- Institute of Microbiology and Genetics, Georg August University, D-37077 Göttingen, Germany
| | - Ralph Pries
- Institute of Microbiology and Genetics, Georg August University, D-37077 Göttingen, Germany
| | - Virginia Korte
- Institute of Microbiology and Genetics, Georg August University, D-37077 Göttingen, Germany
| | - Eva Scholz
- Institute of Microbiology and Genetics, Georg August University, D-37077 Göttingen, Germany
| | - Britta Herzog
- Institute of Microbiology and Genetics, Georg August University, D-37077 Göttingen, Germany
| | - Florian Schulze
- Institute of Microbiology and Genetics, Georg August University, D-37077 Göttingen, Germany
| | - Gerhard H. Braus
- Institute of Microbiology and Genetics, Georg August University, D-37077 Göttingen, Germany
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26
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Fagundes MRVZK, Lima JF, Savoldi M, Malavazi I, Larson RE, Goldman MHS, Goldman GH. The Aspergillus nidulans npkA gene encodes a Cdc2-related kinase that genetically interacts with the UvsBATR kinase. Genetics 2005; 167:1629-41. [PMID: 15342504 PMCID: PMC1470983 DOI: 10.1534/genetics.103.024166] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The DNA damage response is a protective mechanism that ensures the maintenance of genomic integrity. We have used Aspergillus nidulans as a model system to characterize the DNA damage response caused by the antitopoisomerase I drug, camptothecin. We report the molecular characterization of a p34Cdc2-related gene, npkA, from A. nidulans. The npkA gene is transcriptionally induced by camptothecin and other DNA-damaging agents, and its induction in the presence of camptothecin is dependent on the uvsBATR gene. There were no growth defects, changes in developmental patterns, increased sensitivity to DNA-damaging agents, or effects on septation or growth rate in the A. nidulans npkA deletion strain. However, the DeltanpkA mutation can partially suppress HU sensitivity caused by the DeltauvsBATR and uvsD153ATRIP checkpoint mutations. We demonstrated that the A. nidulans uvsBATR gene is involved in DNA replication and the intra-S-phase checkpoints and that the DeltanpkA mutation can suppress its intra-S-phase checkpoint deficiency. There is a defect in both the intra-S-phase and DNA replication checkpoints due to the npkA inactivation when DNA replication is slowed at 6 mm HU. Our results suggest that the npkA gene plays a role in cell cycle progression during S-phase as well as in a DNA damage signal transduction pathway in A. nidulans.
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Affiliation(s)
- Marcia R V Z Kress Fagundes
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, CEP 14040-903, Ribeirão Preto, São Paulo, Brazil
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27
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Kato N, Brooks W, Calvo AM. The expression of sterigmatocystin and penicillin genes in Aspergillus nidulans is controlled by veA, a gene required for sexual development. EUKARYOTIC CELL 2004; 2:1178-86. [PMID: 14665453 PMCID: PMC326641 DOI: 10.1128/ec.2.6.1178-1186.2003] [Citation(s) in RCA: 188] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Secondary metabolism is commonly associated with morphological development in microorganisms, including fungi. We found that veA, a gene previously shown to control the Aspergillus nidulans sexual/asexual developmental ratio in response to light, also controls secondary metabolism. Specifically, veA regulates the expression of genes implicated in the synthesis of the mycotoxin sterigmatocystin and the antibiotic penicillin. veA is necessary for the expression of the transcription factor aflR, which activates the gene cluster that leads to the production of sterigmatocystin. veA is also necessary for penicillin production. Our results indicated that although veA represses the transcription of the isopenicillin synthetase gene ipnA, it is necessary for the expression of acvA, the key gene in the first step of penicillin biosynthesis, encoding the delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase. With respect to the mechanism of veA in directing morphological development, veA has little effect on the expression of the known sexual transcription factors nsdD and steA. However, we found that veA regulates the expression of the asexual transcription factor brlA by modulating the alpha/beta transcript ratio that controls conidiation.
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Affiliation(s)
- Naoki Kato
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois 60115, USA
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28
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Wu D, Dou X, Hashmi SB, Osmani SA. The Pho80-like cyclin of Aspergillus nidulans regulates development independently of its role in phosphate acquisition. J Biol Chem 2004; 279:37693-703. [PMID: 15247298 DOI: 10.1074/jbc.m403853200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In Saccharomyces cerevisiae, phosphate acquisition enzymes are regulated by a cyclin-dependent kinase (Pho85), a cyclin (Pho80), the cyclin-dependent kinase inhibitor Pho81, and the helix-loop-helix transcription factor Pho4 (the PHO system). Previous studies in Aspergillus nidulans indicate that a Pho85-like kinase, PHOA, does not regulate the classic PHO system but regulates development in a phosphate-dependent manner. A Pho80-like cyclin has now been isolated through its interaction with PHOA. Surprisingly, unlike PHOA, An-PHO80 does play a negative role in the PHO system. Similarly, an ortholog of Pho4 previously identified genetically as palcA also regulates the PHO system. However, An-PHO81, a putative cyclin-dependent kinase inhibitor, does not regulate the PHO system. Therefore, there are significant differences between the classic PHO system conserved between S. cerevisiae and Neurospora crassa compared with that which has evolved in A. nidulans. Most interestingly, under low phosphate conditions, the An-PHO80 cyclin also promotes sexual development while having a negative effect on asexual development. These effects are independent of the role An-PHO80 has in the classic PHO system. However, in high phosphate medium, An-PHO80 affects development because of deregulation of the PHO system as loss of palcA(Pho4) function negates the developmental defects caused by lack of An-pho80. Therefore, under low phosphate conditions the An-PHO80 cyclin regulates development independently of the PHO system, whereas in high phosphate it affects development through the PHO system. The data indicate that a single cyclin can control various aspects of growth and development in a multicellular organism.
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Affiliation(s)
- Dongliang Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210, USA
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29
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Takeo K, Ogura Y, Virtudazo E, Raclavsky V, Kawamoto S. Isolation of a CDC28 homologue from Cryptococcus neoformans that is able to complement cdc28 temperature-sensitive mutants of Saccharomyces cerevisiae. FEMS Yeast Res 2004; 4:737-44. [PMID: 15093777 DOI: 10.1016/j.femsyr.2004.01.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2003] [Revised: 01/19/2004] [Accepted: 01/25/2004] [Indexed: 11/30/2022] Open
Abstract
A partial cDNA fragment of the Cryptococcus neoformans homologue of the main cell cycle control gene CDC28/cdc2 was isolated using degenerate primer RT-PCR. A subsequent search in the C. neoformans genome database identified several sequences similar to CDC28/cdc2. A part of the sequence which showed the highest similarity to CDC28/cdc2 turned out to be identical to the partial cyclin-dependent kinase (Cdk) cDNA fragment isolated by degenerate RT-PCR. The full-length coding region of this Cdk homologue was amplified by RT-PCR using primers designed to target regions around start and stop codons, and the gene was named CnCdk1. To determine its function, an analysis of deduced amino acid sequence of the CnCdk1 was performed and its ability to rescue Saccharomyces cerevisiae cdc28-temperature sensitive mutants was tested. S. cerevisiae cdc28-4 and cdc28-1N strains transformed with the pYES2- CnCdk1 construct exhibited growth at 36.5 degrees C in galactose-raffinose medium, but not in glucose medium. Results of the sequence analysis and the fact that CnCdk1 is able to complement the S. cerevisiae cdc28-ts mutation support its assumed role as the CDC28/cdc2 homologue in C. neoformans.
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Affiliation(s)
- Kanji Takeo
- Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8673, Japan.
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30
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Dou X, Wu D, An W, Davies J, Hashmi SB, Ukil L, Osmani SA. The PHOA and PHOB Cyclin-Dependent Kinases Perform an Essential Function in Aspergillus nidulans. Genetics 2003; 165:1105-15. [PMID: 14668368 PMCID: PMC1462817 DOI: 10.1093/genetics/165.3.1105] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Unlike Pho85 of Saccharomyces cerevisiae, the highly related PHOA cyclin-dependent kinase (CDK) of Aspergillus nidulans plays no role in regulation of enzymes involved in phosphorous acquisition but instead modulates differentiation in response to environmental conditions, including limited phosphorous. Like PHO85, Aspergillus phoA is a nonessential gene. However, we find that expression of dominant-negative PHOA inhibits growth, suggesting it may have an essential but redundant function. Supporting this we have identified another cyclin-dependent kinase, PHOB, which is 77% identical to PHOA. Deletion of phoB causes no phenotype, even under phosphorous-limited growth conditions. To investigate the function of phoA/phoB, double mutants were selected from a cross of strains containing null alleles and by generating a temperature-sensitive allele of phoA in a ΔphoB background. Double-deleted ascospores were able to germinate but had a limited capacity for nuclear division, suggesting a cell cycle defect. Longer germination revealed morphological defects. The temperature-sensitive phoA allele caused both nuclear division and polarity defects at restrictive temperature, which could be complemented by expression of mammalian CDK5. Therefore, an essential function exists in A. nidulans for the Pho85-like kinase pair PHOA and PHOB, which may involve cell cycle control and morphogenesis.
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Affiliation(s)
- Xiaowei Dou
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210, USA
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31
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Busch S, Eckert SE, Krappmann S, Braus GH. The COP9 signalosome is an essential regulator of development in the filamentous fungus Aspergillus nidulans. Mol Microbiol 2003; 49:717-30. [PMID: 12864854 DOI: 10.1046/j.1365-2958.2003.03612.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The COP9 signalosome (CSN) is a conserved multiprotein complex involved in regulation of eukaryotic development. The deduced amino acid sequences of two Aspergillus nidulans genes, csnD and csnE, show high identities to the fourth and fifth CSN subunits of higher eukaryotes. The csnD transcript is abundant during vegetative growth as well as development and the corresponding protein accumulates in the nucleus. Strains deleted for either csn gene are viable and show identical mutant phenotypes at conditions that allow development: hyphae appear partly red and contain cells of reduced size. Additionally, light dependence of propagation onset is affected. The Delta csn mutants are capable of initiating the sexual cycle and develop primordia, but maturation to sexual fruit bodies is blocked. This developmental arrest could not be overcome by overexpression of the sexual activator velvet (VEA). We conclude that the COP9 signalosome in A. nidulans is a key regulator of sexual development, and its proposed structural and functional conservation to the CSN of higher eukaryotes enables studies on this regulatory complex in a genetically amenable organism.
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Affiliation(s)
- Silke Busch
- Institut für Mikrobiologie und Genetik, Georg-August-Universität, Grisebachstrasse 8, D-37077 Göttingen, Germany
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32
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Osmani AH, Davies J, Oakley CE, Oakley BR, Osmani SA. TINA interacts with the NIMA kinase in Aspergillus nidulans and negatively regulates astral microtubules during metaphase arrest. Mol Biol Cell 2003; 14:3169-79. [PMID: 12925754 PMCID: PMC181558 DOI: 10.1091/mbc.e02-11-0715] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The tinA gene of Aspergillus nidulans encodes a protein that interacts with the NIMA mitotic protein kinase in a cell cycle-specific manner. Highly similar proteins are encoded in Neurospora crassa and Aspergillus fumigatus. TINA and NIMA preferentially interact in interphase and larger forms of TINA are generated during mitosis. Localization studies indicate that TINA is specifically localized to the spindle pole bodies only during mitosis in a microtubule-dependent manner. Deletion of tinA alone is not lethal but displays synthetic lethality in combination with the anaphase-promoting complex/cyclosome mutation bimE7. At the bimE7 metaphase arrest point, lack of TINA enhanced the nucleation of bundles of cytoplasmic microtubules from the spindle pole bodies. These microtubules interacted to form spindles joined in series via astral microtubules as revealed by live cell imaging. Because TINA is modified and localizes to the spindle pole bodies at mitosis, and lack of TINA causes enhanced production of cytoplasmic microtubules at metaphase arrest, we suggest TINA is involved in negative regulation of the astral microtubule organizing capacity of the spindle pole bodies during metaphase.
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Affiliation(s)
- Aysha H Osmani
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210, USA.
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33
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Kim H, Han K, Kim K, Han D, Jahng K, Chae K. The veA gene activates sexual development in Aspergillus nidulans. Fungal Genet Biol 2002; 37:72-80. [PMID: 12223191 DOI: 10.1016/s1087-1845(02)00029-4] [Citation(s) in RCA: 208] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The previously isolated gene complementing the veA1 mutation was confirmed to be the veA gene. The determined nucleotide sequence of the gene demonstrated that there is an open reading frame (ORF) of a 573 amino acid polypeptide. The nucleotide sequence matched some clones of which functions were not assigned yet and the amino acid sequence matched that of Neurospora crassa VeA-related protein with 61% similarity. The nucleotide sequence of the veA1 mutant gene differed from that of the wild type gene by only one nucleotide and the nucleotide G in the initiation codon ATG of the VeA ORF was mutated to the nucleotide T. Then, the mutant ORF may use the 37th methionine codon of the wild type one as a new initiation codon. The veA transcript was present in the conidia and in mycelia cultured for up to 14h and expressed almost constitutively at an increased level throughout the asexual and sexual developmental processes, suggesting that it may act from a relatively early developmental stage. Null mutants of the gene never formed sexual structures, even under conditions where sexual development preferentially occurs in wild types. Over-expressors of the gene formed larger numbers of sexual structures with a much reduced number of conidial heads than a control strain (a veA1 mutant), even under conditions where wild type strains form little sexual structure but form conidial heads very well, such as in the presence of a salt at high concentration. Furthermore, over-expressors could form Hülle cells and cleistothecia, even in a liquid culture. These results indicated that the veA gene is a positive regulator in sexual development and simultaneously a negative one in asexual development.
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Affiliation(s)
- Hee Kim
- Basic Science Research Institute, Division of Biological Sciences, Chonbuk National University, Chonju, Chonbuk 561-756, Republic of Korea
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de Jesús-Berríos M, Rodríguez-del Valle N. Expression of a Pho85 cyclin-dependent kinase is repressed during the dimorphic transition in Sporothrix schenckii. Fungal Genet Biol 2002; 37:39-48. [PMID: 12223188 DOI: 10.1016/s1087-1845(02)00031-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Sporothrix schenckii is a pathogenic fungus that undergoes a dimorphic transition from yeast to mycelium in response to environmental conditions such as cell density, temperature, and calcium. We identified a homolog of the Pho85 cyclin-dependent kinase (Cdk) that mediates cellular responses to environmental conditions in other organisms. By Western blot, three proteins containing the PSTAIRE motif, which characterize the cyclin-dependent protein kinases, were identified in S. schenckii. The gene encoding a Pho85 homolog, PhoSs, was identified and sequenced. The phoSs gene consists of 990bp, contains one intron, and encodes a protein of 306 amino acids. The S. schenckii Pho85 homolog shares features with Cdks, including the PSTAIRE motif, an ATP binding domain, and a serine-threonine kinase domain. By quantitative competitive RT-PCR, expression of the phoSs gene was found to decrease 30-fold during the yeast to mycelium transition. The addition of extracellular calcium accelerated the dimorphic transition and restored phoSs expression. These findings suggest PhoSs may participate in the control of the yeast to mycelium transition in S. schenckii.
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Affiliation(s)
- Marisol de Jesús-Berríos
- Department of Microbiology and Medical Zoology, Medical Sciences Campus, University of Puerto Rico, San Juan 00936, USA.
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Han KH, Han KY, Yu JH, Chae KS, Jahng KY, Han DM. The nsdD gene encodes a putative GATA-type transcription factor necessary for sexual development of Aspergillus nidulans. Mol Microbiol 2001; 41:299-309. [PMID: 11489119 DOI: 10.1046/j.1365-2958.2001.02472.x] [Citation(s) in RCA: 153] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ability to reproduce both sexually and asexually is one of the characteristics of the homothalic ascomycete Aspergillus nidulans. Unlike the other Aspergillus species, A. nidulans undergoes sexual development that seems to be regulated by internal and external stimuli. To begin to understand the sexual reproduction of A. nidulans we previously isolated and characterized several NSD (never in sexual development) mutants that failed to produce any sexual reproductive organs, and identified four complementation groups, nsdA, nsdB, nsdC, and nsdD. The nsdD gene has been isolated, and it is predicted to encode a GATA-type transcription factor with the type IVb zinc finger DNA-binding domain. The mRNA of the nsdD gene started to accumulate in the early phase of vegetative growth, and the level increased as sexual development proceeded. However, it decreased during asexual sporulation and no nsdD mRNA was detected in conidia. Deletion of nsdD resulted in no cleistothecia (fruiting bodies) formation, even under the conditions that preferentially promoted sexual development, indicating that nsdD is necessary for sexual development. In contrast, when the nsdD gene was over-expressed, sexual-specific organ (Hülle cell) was formed even in submerged culture, which normally completely blocked sexual development, and the number of cleistothecia was also dramatically increased on solid medium. These results lead us to propose that the nsdD gene functions in activating sexual development of A. nidulans. Multiple copies of the nsdD gene could suppress nsdB5 and veA1, indicating that either nsdD acts downstream of these genes or possibly functions in overlapping pathway(s).
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Affiliation(s)
- K H Han
- Division of Life Sciences, Wonkwang University, Iksan 570-749, South Korea
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Schier N, Liese R, Fischer R. A Pcl-like cyclin of Aspergillus nidulans is transcriptionally activated by developmental regulators and is involved in sporulation. Mol Cell Biol 2001; 21:4075-88. [PMID: 11359914 PMCID: PMC87069 DOI: 10.1128/mcb.21.12.4075-4088.2001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The filamentous fungus Aspergillus nidulans reproduces asexually through the formation of spores on a multicellular aerial structure, called a conidiophore. A key regulator of asexual development is the TFIIIA-type zinc finger containing transcriptional activator Bristle (BRLA). Besides BRLA, the transcription factor ABAA, which is located downstream of BRLA in the developmental regulation cascade, is necessary to direct later gene expression during sporulation. We isolated a new developmental mutant and identified a leaky brlA mutation and the mutated Saccharomyces cerevisiae cyclin homologue pclA, both contributing to the developmental phenotype of the mutant. pclA was found to be 10-fold transcriptionally upregulated during conidiation, and a pclA deletion strain was reduced three- to fivefold in production of conidia. Expression of pclA was strongly induced by ectopic expression of brlA or abaA under conidiation-suppressing conditions, indicating a direct role for brlA and abaA in pclA regulation. PCLA is homologous to yeast Pcl cyclins, which interact with the Pho85 cyclin-dependent kinase. Although interaction with a PSTAIRE kinase was shown in vivo, PCLA function during sporulation was independent of the A. nidulans Pho85 homologue PHOA. Besides the developmental regulation, pclA expression was cell cycle dependent with peak transcript levels in S phase. Our findings suggest a role for PCLA in mediating cell cycle events during late stages of sporulation.
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Affiliation(s)
- N Schier
- Laboratorium für Mikrobiologie, Philipps-Universität Marburg and Max-Planck-Institut für Terrestrische Mikrobiologie, D-35043 Marburg, Germany
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Toh-E A, Nishizawa M. Structure and function of cyclin-dependent Pho85 kinase of Saccharomyces cerevisiae. J GEN APPL MICROBIOL 2001; 47:107-117. [PMID: 12483553 DOI: 10.2323/jgam.47.107] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Yeast Saccharomyces cerevisiae has five cyclin-dependent protein kinases (Cdks), Cdc28, Srb10, Kin28, Ctk1, and Pho85. Any of these Cdks requires a cyclin partner for its kinase activity and a Cdk/cyclin complex, thus produced, phosphorylates a set of specific substrate proteins to exert its function. The cyclin partners of Srb10, Kin28, and Ctk1 are Srb11, Ccl1, and Ctk2, respectively. In contrast to the fact that each of Srb10, Kin28, and Ctk1 has a single cyclin partner, Cdc28 and Pho85 are polygamous; Cdc28 has 9 cyclins and Pho85 has 10 cyclins. Among these Cdks, Kin28 and Cdc28 are essential Cdks and it is well known that Cdc28 kinase plays a major role in regulating cell cycle progression. Pho85 is a non-essential Cdk but its absence causes a broad spectrum of phenotypes such as constitutive expression of PHO5, inability to utilize non-fermentable carbon sources, defects in cell cycle progression, and so on. Pho85 homologues are expanding to higher eukaryotes. Pho85 is most closely related with Cdk5 in terms of the amino acid sequence. The functional analysis of the domains of Pho85 also supports the close relationship between Pho85 and Cdk5, in which it was shown that the method of regulation of these two kinases is similar. Furthermore, forced expression of the mammalian CDK5 gene in a pho85Delta strain canceled a part of the pho85 defects. In this review, we summarize the functions of both Pho85/cyclin kinase and emphasize yeast Pho85 as valuable model systems to elucidate the functions of their homologues in other organisms.
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Affiliation(s)
- Akio Toh-E
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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Shim WB, Woloshuk CP. Regulation of fumonisin B(1) biosynthesis and conidiation in Fusarium verticillioides by a cyclin-like (C-type) gene, FCC1. Appl Environ Microbiol 2001; 67:1607-12. [PMID: 11282612 PMCID: PMC92776 DOI: 10.1128/aem.67.4.1607-1612.2001] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2000] [Accepted: 01/25/2001] [Indexed: 11/20/2022] Open
Abstract
Fumonisins are a group of mycotoxins produced in corn kernels by the plant-pathogenic fungus Fusarium verticillioides. A mutant of the fungus, FT536, carrying a disrupted gene named FCC1 (for Fusarium cyclin C1) resulting in altered fumonisin B(1) biosynthesis was generated. FCC1 contains an open reading frame of 1,018 bp, with one intron, and encodes a putative 319-amino-acid polypeptide. This protein is similar to UME3 (also called SRB11 or SSN8), a cyclin C of Saccharomyces cerevisiae, and contains three conserved motifs: a cyclin box, a PEST-rich region, and a destruction box. Also similar to the case for C-type cyclins, FCC1 was constitutively expressed during growth. When strain FT536 was grown on corn kernels or on defined minimal medium at pH 6, conidiation was reduced and FUM5, the polyketide synthase gene involved in fumonisin B(1) biosynthesis, was not expressed. However, when the mutant was grown on a defined minimal medium at pH 3, conidiation was restored, and the blocks in expression of FUM5 and fumonisin B(1) production were suppressed. Our data suggest that FCC1 plays an important role in signal transduction regulating secondary metabolism (fumonisin biosynthesis) and fungal development (conidiation) in F. verticillioides.
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Affiliation(s)
- W B Shim
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA
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Bussink HJ, Oliver R. Identification of two highly divergent catalase genes in the fungal tomato pathogen, Cladosporium fulvum. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:15-24. [PMID: 11121097 DOI: 10.1046/j.1432-1327.2001.01774.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Catalases of pathogenic micro-organisms have attracted attention as potential virulence factors. Homology-based screens were performed to identify catalase genes in the fungal tomato pathogen Cladosporium fulvum. Two highly divergent genes, Cat1 and Cat2, were isolated and characterized. Cat1 codes for a putative 566-amino-acid catalase subunit and belongs to the gene family that also encodes the mainly peroxisome-localized catalases of animal and yeast species. Cat2 codes for a putative catalase subunit of 745 amino acids and belongs to a different gene family coding for the large-subunit catalases similar to ones found in bacteria and filamentous fungi. Neither catalase had an obvious secretory signal sequence. A search for an extracellular catalase was unproductive. The Cat1 and Cat2 genes showed differential expression, with the Cat1 mRNA preferentially accumulating in spores and the Cat2 mRNA preferentially accumulating in response to external H(2)O(2). With Cat2-deleted strains, activity of the Cat2 gene product (CAT2) was identified among four proteins with catalase activity separated on non-denaturing gels. The CAT2 activity represented a minor fraction of the catalase activity in spores and H(2)O(2)-stressed mycelium, and no phenotype was observed for Cat2-deleted strains, which showed a normal response to H(2)O(2) treatment. These results indicate the existence of a complex catalase system in C. fulvum, with regard to both the structure and regulation of the genes involved. In addition, efficient C. fulvum gene-replacement technology has been established.
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Affiliation(s)
- H J Bussink
- Carlsberg Laboratory, Department of Physiology, Copenhagen Valby, Denmark
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Lengeler KB, Davidson RC, D'souza C, Harashima T, Shen WC, Wang P, Pan X, Waugh M, Heitman J. Signal transduction cascades regulating fungal development and virulence. Microbiol Mol Biol Rev 2000; 64:746-85. [PMID: 11104818 PMCID: PMC99013 DOI: 10.1128/mmbr.64.4.746-785.2000] [Citation(s) in RCA: 652] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cellular differentiation, mating, and filamentous growth are regulated in many fungi by environmental and nutritional signals. For example, in response to nitrogen limitation, diploid cells of the yeast Saccharomyces cerevisiae undergo a dimorphic transition to filamentous growth referred to as pseudohyphal differentiation. Yeast filamentous growth is regulated, in part, by two conserved signal transduction cascades: a mitogen-activated protein kinase cascade and a G-protein regulated cyclic AMP signaling pathway. Related signaling cascades play an analogous role in regulating mating and virulence in the plant fungal pathogen Ustilago maydis and the human fungal pathogens Cryptococcus neoformans and Candida albicans. We review here studies on the signaling cascades that regulate development of these and other fungi. This analysis illustrates both how the model yeast S. cerevisiae can serve as a paradigm for signaling in other organisms and also how studies in other fungi provide insights into conserved signaling pathways that operate in many divergent organisms.
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Affiliation(s)
- K B Lengeler
- Departments of Genetics, Pharmacology and Cancer Biology, Microbiology, and Medicine, Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710, USA
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41
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Lengeler KB, Davidson RC, D'souza C, Harashima T, Shen WC, Wang P, Pan X, Waugh M, Heitman J. Signal transduction cascades regulating fungal development and virulence. Microbiol Mol Biol Rev 2000. [PMID: 11104818 DOI: 10.1023/a:1024123915158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/18/2023] Open
Abstract
Cellular differentiation, mating, and filamentous growth are regulated in many fungi by environmental and nutritional signals. For example, in response to nitrogen limitation, diploid cells of the yeast Saccharomyces cerevisiae undergo a dimorphic transition to filamentous growth referred to as pseudohyphal differentiation. Yeast filamentous growth is regulated, in part, by two conserved signal transduction cascades: a mitogen-activated protein kinase cascade and a G-protein regulated cyclic AMP signaling pathway. Related signaling cascades play an analogous role in regulating mating and virulence in the plant fungal pathogen Ustilago maydis and the human fungal pathogens Cryptococcus neoformans and Candida albicans. We review here studies on the signaling cascades that regulate development of these and other fungi. This analysis illustrates both how the model yeast S. cerevisiae can serve as a paradigm for signaling in other organisms and also how studies in other fungi provide insights into conserved signaling pathways that operate in many divergent organisms.
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Affiliation(s)
- K B Lengeler
- Departments of Genetics, Pharmacology and Cancer Biology, Microbiology, and Medicine, Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710, USA
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Jeong HY, Han DM, Jahng KY, Chae KS. The rpl16a gene for ribosomal protein L16A identified from expressed sequence tags is differentially expressed during sexual development of Aspergillus nidulans. Fungal Genet Biol 2000; 31:69-78. [PMID: 11170736 DOI: 10.1006/fgbi.2000.1233] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We obtained 305 expressed sequence tags (ESTs), which are from the poly(A) site to the most proximal MboI site, from mycelia at the early sexual developmental (ESD) stage of Aspergillus nidulans. By comparison of these ESTs with those obtained previously from the vegetative stage and from the late sexual developmental stage followed by Northern blot analyses, genes of 17 ESTs were identified as being expressed more abundantly at the ESD stage than at the vegetative stage. Five of 17 genes were expressed more abundantly in the presence of the veA gene or the nsdD gene, suggesting that these 5 genes may be involved in sexual development. In a gene of one EST, appearing three times among 305 ESTs and identified by GenBank, polyadenylation seemed to occur at two sites. Nucleotide sequences of the gene having the EST and its cDNA revealed that the gene can code for a 202-amino-acid polypeptide with an estimated molecular mass of 23 kDa. The deduced amino acid showed 73% identity to Saccharomyces cerevisiae ribosomal protein L16A (RPL16A), and therefore the gene was named rpl16a. A. nidulans RPL16A had a putative leucine zipper motif and a basic leucine zipper motif like those of other organisms. The expression level of the rpl16a gene, present as a single copy in this organism, reached a maximum after 2 h, decreased thereafter, and increased again 30 to 50 h after the end of induction of sexual development. These results clearly indicated that the rpl16a gene is expressed differentially during sexual development.
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Affiliation(s)
- H Y Jeong
- Institute for Molecular Biology and Genetics, and Division of Biological Sciences, Chonbuk National University, Chonju, 561-756, Republic of Korea
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Lee M, O'Regan S, Moreau JL, Johnson AL, Johnston LH, Goding CR. Regulation of the Pcl7-Pho85 cyclin-cdk complex by Pho81. Mol Microbiol 2000; 38:411-22. [PMID: 11069666 DOI: 10.1046/j.1365-2958.2000.02140.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Saccharomyces cerevisiae strains lacking a functional Pho85 cyclin-dependent kinase (cdk) exhibit a complex phenotype, including deregulation of phosphatase genes controlled by the transcription factor Pho4, slow growth on rich media, failure to grow using galactose, lactate or glycerol as a carbon source and hyperaccumulation of glycogen. The ability of Pho85 to regulate the transcription factor Pho4 is mediated by its association the Pho80 cyclin. Some other regulatory functions of the Pho85 cdk have been shown to be mediated via its interaction with a recently identified family of Pho80-related cyclins (Pcls). Here, we show that the poorly characterized Pho80-like protein Pcl7 forms a functional kinase complex with the Pho85 cdk, and that the activity of this complex is inhibited in response to phosphate starvation. Additionally, we show that Pcl7 interacts with the phosphate-regulated cyclin-cdk inhibitor Pho81, and that the regulation of the Pcl7-Pho85 complex in response to changes in phosphate levels is dependent on Pho81. Thus, we demonstrate for the first time that the Pho81 regulator is not dedicated to regulating Pho80, but may act to co-ordinate the activity of both the Pho80-Pho85 and Pcl7-Pho85 cyclin-cdk complexes in response to phosphate levels. We also demonstrate that expression of Pcl7 is cell cycle regulated, with maximal activity occurring in mid to late S-phase, perhaps suggesting a role for Pcl7 in cell cycle progression. Finally, we describe the phenotype of pcl7Delta and pcl6Delta yeast strains that have defects in carbon source utilization.
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Affiliation(s)
- M Lee
- Eukaryotic Transcription Laboratory, Marie Curie Research Institute, The Chart, Oxted, Surrey RH8 OTL, UK
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Tanaka K, Okayama H. A pcl-like cyclin activates the Res2p-Cdc10p cell cycle "start" transcriptional factor complex in fission yeast. Mol Biol Cell 2000; 11:2845-62. [PMID: 10982385 PMCID: PMC14960 DOI: 10.1091/mbc.11.9.2845] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2000] [Revised: 06/02/2000] [Accepted: 06/26/2000] [Indexed: 11/11/2022] Open
Abstract
In the fission yeast Schizosaccharomyces pombe, the "start" of the cell cycle is controlled by the two functionally redundant transcriptional regulator complexes, Res1p-Cdc10p and Res2p-Cdc10p, that activate genes essential for the onset and progression of S phase. The activity of the Res2p-Cdc10p complex is regulated at least by the availability of the Rep2 trans-activator subunit in the mitotic cell cycle. We have recently isolated the pas1(+) gene as a multicopy suppressor of the res1 null mutant. This gene encodes a novel cyclin that shares homology with the Pho85 kinase-associated cyclins of the budding yeast Saccharomyces cerevisiae. Genetic analysis reveals that Pas1 cyclin is unrelated to phosphate metabolism and stimulates the G(1)-S transition by specifically activating the Res2p-Cdc10p complex independently of Rep2p. Pas1 cyclin also controls mating pheromone signaling. Cells lacking pas1(+) are highly sensitive to mating pheromone, responding with facilitated G(1) arrest and premature commitment to conjugation. Pas1 cyclin associates in vivo with both Cdc2 and Pef1 kinases, the latter of which is a fission yeast counterpart of the budding yeast Pho85 kinase, but genetic analysis indicates that the Pef1p-associated Pas1p is responsible for the activation of Res2p-Cdc10p during the G(1)-S transition.
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Affiliation(s)
- K Tanaka
- Department of Biochemistry and Molecular Biology, The University of Tokyo, Graduate School of Medicine, Bunkyo-ku, Tokyo 113-0033, Japan
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Miyakawa Y. Identification of a Candida albicans homologue of the PHO85 gene, a negative regulator of the PHO system in Saccharomyces cerevisiae. Yeast 2000; 16:1045-51. [PMID: 10923026 DOI: 10.1002/1097-0061(200008)16:11<1045::aid-yea595>3.0.co;2-l] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
In a screen for the protein kinase genes of the human pathogenic yeast Candida albicans, a putative homologue (CaPHO85) of PHO85, a negative regulator of the PHO system of Saccharomyces cerevisiae, which is one of the cyclin-dependent protein kinases (CDKs), was isolated. An open reading frame (ORF) of this gene was identified encoding a predicted protein of 326 amino acids with a calculated molecular weight of 37.6 kDa. The amino acid sequence is highly homologous to S. cerevisiae Pho85 (62% identity) and its Aspergillus nidulans homologue (70% identity), but less homologous to Cdc28 (50% identity) of S. cerevisiae and to its C. albicans homologue CaCdc28 (49% identity), both of which are also CDK. The coding region for the C. albicans gene was interrupted by an intron of 81 nucleotides near the sequence encoding the N-terminal region, similarly to the case of the S. cerevisiae PHO85 gene. Alignment of CaPho85 with various yeast CDKs revealed that most of the domains for ATP-binding and protein kinase activity are conserved among fungal species. Southern blot analysis indicated that CaPHO85 is most likely present as a single copy gene. This gene complemented the pho85 mutation of S. cerevisiae by transformation.
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Affiliation(s)
- Y Miyakawa
- Department of Life Sciences, Yamanashi Medical College, Tamaho, Yamanashi 409-3898, Japan.
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Hoffmann B, Wanke C, Lapaglia SK, Braus GH. c-Jun and RACK1 homologues regulate a control point for sexual development in Aspergillus nidulans. Mol Microbiol 2000; 37:28-41. [PMID: 10931303 DOI: 10.1046/j.1365-2958.2000.01954.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Amino acid limitation results in impaired sexual fruit body formation in filamentous fungi such as Aspergillus nidulans. The starvation signal is perceived by the cross-pathway regulatory network controlling the biosynthesis of translational precursors and results in increased expression of a transcriptional activator encoded by a c-Jun homologue. In the presence of amino acids, the gene product of the mammalian RACK1 homologue cpcB is required to repress the network. Growth under amino acid starvation conditions permits the initiation of the sexual developmental programme of the fungus, but blocks fruit body formation before completion of meiosis. Accordingly, arrest at this defined control point results in microcleistothecia filled with hyphae. Addition of amino acids results in release of the block and completion of development to mature ascospores. The same developmental block is induced by either overexpression of c-Jun homologues or deletion of the RACK1 homologue cpcB of A. nidulans in the presence of amino acids. Therefore, the amino acid starvation signal regulates sexual development through the network that also controls the amino acid biosynthetic genes. Expression of the RACK1 gene suppresses the block in development caused by a deletion of cpcB. These data illuminate a connection between metabolism and sexual development in filamentous fungi.
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Affiliation(s)
- B Hoffmann
- Institute of Microbiology and Genetics, Georg-August-University, Grisebachstrasse 8, D-37077 Göttingen, Germany
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Osmani AH, May GS, Osmani SA. The extremely conserved pyroA gene of Aspergillus nidulans is required for pyridoxine synthesis and is required indirectly for resistance to photosensitizers. J Biol Chem 1999; 274:23565-9. [PMID: 10438537 DOI: 10.1074/jbc.274.33.23565] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Numerous disparate studies in plants, filamentous fungi, yeast, Archaea, and bacteria have identified one of the most highly conserved proteins (SNZ family) for which no function was previously defined. Members have been implicated in the stress response of plants and yeast and resistance to singlet oxygen toxicity in the plant pathogen Cercospora. However, it is found in some anaerobic bacteria and is absent in some aerobic bacteria. We have cloned the Aspergillus nidulans homologue (pyroA) of this highly conserved gene and define this gene family as encoding an enzyme specifically required for pyridoxine biosynthesis. This realization has enabled us to define a second pathway for pyridoxine biosynthesis. Some bacteria utilize the pdx pyridoxine biosynthetic pathway defined in Escherichia coli and others utilize the pyroA pathway. However, Eukarya and Archaea exclusively use the pyroA pathway. We also found that pyridoxine is destroyed in the presence of singlet oxygen, helping to explain the connection to singlet oxygen sensitivity defined in Cercospora. These data bring clarity to the previously confusing data on this gene family. However, a new conundrum now exists; why have highly related bacteria evolved with different pathways for pyridoxine biosynthesis?
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Affiliation(s)
- A H Osmani
- Henry Hood Research Program, Weis Center for Research, Pennsylvania State University College of Medicine, Danville, Pennsylvania 17822, USA
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Détivaud L, Pettit GR, Meijer L. Characterization of a novel cdk1-related kinase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 264:55-66. [PMID: 10447673 DOI: 10.1046/j.1432-1327.1999.00576.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: 11/20/2022]
Abstract
The p13suc1/p9CKShs proteins bind tightly to the cyclin-dependent kinases cdk1 and cdk2. The distantly related protein, p15cdk-BP, binds cdk4/6, cdk5 and cdk8. We now show that immobilized p15cdk-BP binds both an HMG-I kinase and a 35-kDa protein that cross-reacts with anti-PSTAIRE antibodies (PSTAIRE is a totally conserved motif located in subdomain III of cdk). This 'cdkX' and the HMG-I kinase also bind to an immobilized inhibitor of cdks (HD). Several properties clearly distinguish cdkX, and its associated HMG-I kinase, from known anti-PSTAIRE cross-reactive cdks: (a) cdkX migrates, in SDS/PAGE, in a position intermediate between prophase phosphorylated cdk1 and metaphase dephosphorylated cdk1; (b) in contrast with cdk1, cdkX and associated HMG-I kinase activity do not decrease following successive depletions on p9CKShs1-sepharose; (c) cdkX and associated HMG-I kinase activity, but not cdk1, decrease following depletions on immobilized inhibitor; (d) cdkX is expressed during the early development of sea urchin embryos; in contrast with cdk1/cyclin B kinase, the p15cdk-BP-bound HMG-I kinase is active throughout the cell cycle; compared with cdk1 it is active later in development; (e) p15cdk-BP-bound HMG-I kinase is essentially insensitive to powerful inhibitors of cdk such as purvalanol, roscovitine, olomoucine, p21cip1 and p16INK4A; HD is only moderately inhibitory. Altogether these results suggest the existence of a new cdk1-related kinase, possibly involved in the regulation of early development. The presence of this kinase in all organisms investigated so far, from plants to mammals, calls for its definitive identification.
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Affiliation(s)
- L Détivaud
- CNRS, Station Biologique, Roscoff, France
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Bussink HJ, Osmani SA. A mitogen-activated protein kinase (MPKA) is involved in polarized growth in the filamentous fungus, Aspergillus nidulans. FEMS Microbiol Lett 1999; 173:117-25. [PMID: 10220889 DOI: 10.1111/j.1574-6968.1999.tb13492.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
An Aspergillus nidulans kinase gene, which encodes a protein kinase with high similarity to mitogen-activated protein kinases involved in cell wall construction and morphogenesis in yeast species, was cloned and sequenced. Targeted deletion of the Aspergillus nidulans kinase gene indicates that this kinase is involved in germination of conidial spores and polarized growth. These defects were largely remedied on complex high osmolarity media, although abnormal swellings of hyphal tips were still observed. Glycerol (1 M) only supported the growth of compact colonies. The Aspergillus nidulans kinase gene is, thus, required for normal polarized growth at several stages of colony formation in the filamentous fungus A. nidulans.
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Affiliation(s)
- H J Bussink
- Henry Hood Research Program, Weis Center for Research, Pennsylvania State University College of Medicine, Danville 17822, USA
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