1
|
Chitin Synthase Genes Are Differentially Required for Growth, Stress Response, and Virulence in Verticillium dahliae. J Fungi (Basel) 2022; 8:jof8070681. [PMID: 35887437 PMCID: PMC9320267 DOI: 10.3390/jof8070681] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 06/17/2022] [Accepted: 06/27/2022] [Indexed: 11/17/2022] Open
Abstract
Crop wilt disease caused by Verticillium dahliae usually leads to serious yield loss. Chitin, an important component of most fungal cell walls, functions to maintain the rigidity of cell walls and septa. Chitin synthesis mainly relies on the activity of chitin synthase (CHS). Eight CHS genes have been predicted in V. dahliae. In this study, we characterized the functions of these genes in terms of growth, stress responses, penetration, and virulence. Results showed that VdCHS5 is important for conidia germination and resistance to hyperosmotic stress. Conidial production is significantly decreased in Vdchs1, Vdchs4, and Vdchs8 mutants. VdCHS1, VdCHS2, VdCHS4, VdCHS6, VdCHS7, and VdCHS8 genes are important for cell wall integrity, while all mutants are important for cell membrane integrity. All of the VdCHS genes, except for VdCHS3, are required for the full pathogenicity of V. dahliae to Arabidopsis thaliana and cotton plants. The in vitro and in vivo penetration of Vdchs1, Vdchs4, Vdchs6, and Vdchs7 mutants was impaired, while that of the other mutants was normal. Overall, our results indicate that the VdCHS genes exert diverse functions to regulate the growth and development, conidial germination, conidial production, stress response, penetration, and virulence in V. dahliae.
Collapse
|
2
|
Gandía M, Garrigues S, Bolós B, Manzanares P, Marcos JF. The Myosin Motor Domain-Containing Chitin Synthases Are Involved in Cell Wall Integrity and Sensitivity to Antifungal Proteins in Penicillium digitatum. Front Microbiol 2019; 10:2400. [PMID: 31681248 PMCID: PMC6813208 DOI: 10.3389/fmicb.2019.02400] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 10/04/2019] [Indexed: 12/16/2022] Open
Abstract
Penicillium digitatum is the main postharvest pathogen of citrus fruit and is responsible for important economic losses in spite of the massive use of fungicides. The fungal cell wall (CW) and its specific component chitin are potential targets for the development of new antifungal molecules. Among these are the antifungal peptides and proteins that specifically interact with fungal CW. Chitin is synthesized by a complex family of chitin synthases (Chs), classified into up to eight classes within three divisions. Previously, we obtained and characterized a mutant of P. digitatum in the class VII gene (ΔchsVII), which contains a short myosin motor-like domain (MMD). In this report, we extend our previous studies to the characterization of mutants in chsII and in the gene coding for the other MMD-Chs (chsV), and study the role of chitin synthases in the sensitivity of P. digitatum to the self-antifungal protein AfpB, and to AfpA obtained from P. expansum. The ΔchsII mutant showed no significant phenotypic and virulence differences with the wild type strain, except in the production and morphology of the conidia. In contrast, mutants in chsV showed a more dramatic phenotype than the previous ΔchsVII, with reduced growth and conidial production, increased chitin content, changes in mycelial morphology and a decrease in virulence to citrus fruit. Mutants in chsVII were specifically more tolerant than the wild type to nikkomycin Z, an antifungal inhibitor of chitin biosynthesis. Treatment of P. digitatum with its own antifungal protein AfpB resulted in an overall reduction in the expression of the chitin synthase genes. The mutants corresponding to MMD chitin synthases exhibited differential sensitivity to the antifungal proteins AfpA and AfpB, ΔchsVII being more susceptible than its parental strain and ΔchsV being slightly more tolerant despite its reduced growth in liquid broth. Taking these results together, we conclude that the MMD-containing chitin synthases affect cell wall integrity and sensitivity to antifungal proteins in P. digitatum.
Collapse
Affiliation(s)
- Mónica Gandía
- Department of Biotechnology, Instituto de Agroquímica y Tecnología de Alimentos, Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | | | | | | | | |
Collapse
|
3
|
Patel PK, Free SJ. The Genetics and Biochemistry of Cell Wall Structure and Synthesis in Neurospora crassa, a Model Filamentous Fungus. Front Microbiol 2019; 10:2294. [PMID: 31649638 PMCID: PMC6796803 DOI: 10.3389/fmicb.2019.02294] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 09/20/2019] [Indexed: 01/25/2023] Open
Abstract
This review discusses the wealth of information available for the N. crassa cell wall. The basic organization and structure of the cell wall is presented and how the wall changes during the N. crassa life cycle is discussed. Over forty cell wall glycoproteins have been identified by proteomic analyses. Genetic and biochemical studies have identified many of the key enzymes needed for cell wall biogenesis, and the roles these enzymes play in cell wall biogenesis are discussed. The review includes a discussion of how the major cell wall components (chitin, β-1,3-glucan, mixed β-1,3-/ β-1,4- glucans, glycoproteins, and melanin) are synthesized and incorporated into the cell wall. We present a four-step model for how cell wall glycoproteins are covalently incorporated into the cell wall. In N. crassa, the covalent incorporation of cell wall glycoproteins into the wall occurs through a glycosidic linkage between lichenin (a mixed β-1,3-/β-1,4- glucan) and a "processed" galactomannan that has been attached to the glycoprotein N-linked oligosaccharides. The first step is the addition of the galactomannan to the N-linked oligosaccharide. Mutants affected in galactomannan formation are unable to incorporate glycoproteins into their cell walls. The second step is carried out by the enzymes from the GH76 family of α-1,6-mannanases, which cleave the galactomannan to generate a processed galactomannan. The model suggests that the third and fourth steps are carried out by members of the GH72 family of glucanosyltransferases. In the third step the glucanosyltransferases cleave lichenin and generate enzyme/substrate intermediates in which the lichenin is covalently attached to the active site of the glucanosyltransferases. In the final step, the glucanosyltransferases attach the lichenin onto the processed galactomannans, which creates new glycosidic bonds and effectively incorporates the glycoproteins into the cross-linked cell wall glucan/chitin matrix.
Collapse
Affiliation(s)
| | - Stephen J. Free
- Department of Biological Sciences, SUNY University at Buffalo, Buffalo, NY, United States
| |
Collapse
|
4
|
Targeting the fungal cell wall: current therapies and implications for development of alternative antifungal agents. Future Med Chem 2019; 11:869-883. [PMID: 30994368 DOI: 10.4155/fmc-2018-0465] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Fungal infections are a worldwide problem associated with high morbidity and mortality. There are relatively few antifungal agents, and resistance has emerged within these pathogens for the newest antifungal drugs. As the fungal cell wall is critical for growth and development, it is one of the most important targets for drug development. In this review, the currently available cell wall inhibitors and suitable drug candidates for the treatment of fungal infections are explored. Future studies of the fungal cell wall and compounds that have detrimental effects on this important outer structural layer could aid in antifungal drug discovery and lead to the development of alternative cell wall inhibitors to fill gaps in clinical therapies for difficult-to-treat fungal infections.
Collapse
|
5
|
Hinkel L, Ospina-Giraldo MD. Structural characterization of a putative chitin synthase gene in Phytophthora spp. and analysis of its transcriptional activity during pathogenesis on potato and soybean plants. Curr Genet 2017; 63:909-921. [PMID: 28314907 DOI: 10.1007/s00294-017-0687-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 02/06/2017] [Accepted: 02/20/2017] [Indexed: 12/13/2022]
Abstract
Although chitin is a major component of the fungal cell wall, in oomycetes (fungal-like organisms), this compound has only been found in very little amounts, mostly in the cell wall of members of the genera Achlya and Saprolegnia. In the oomycetes Phytophthora infestans and P. sojae the presence of chitin has not been demonstrated; however, the gene putatively encoding chitin synthase (CHS), the enzyme that synthesizes chitin, is present in their genomes. The evolutionary significance of the CHS gene in P. infestans and P. sojae genomes is not fully understood and, therefore, further studies are warranted. We have cloned and characterized the putative CHS genes from two Phytophthora spp. and multiple isolates of P. infestans and P. sojae and analyzed their phylogenetic relationships. We also conducted CHS inhibition assays and measured CHS transcriptional activity in Phytophthora spp. during infection of susceptible plants. Results of our investigations suggest that CHS contains all the motifs that are typical in CHS genes of fungal origin and is expressed, at least at the mRNA level, during in vitro and in planta growth. In infected tissues, the highest levels of expression occurred in the first 12 h post inoculation. In addition, results from our inhibition experiments appear to suggest that CHS activity is important for P. infestans normal vegetative growth. Because of the considerable variation in expression during infection when compared to basal expression observed in in vitro cultures of non-sporulating mycelium, we hypothesize that CHS may have a meaningful role in Phytophthora pathogenicity.
Collapse
Affiliation(s)
- Lauren Hinkel
- Biology Department, Lafayette College, Easton, PA, USA
- Department of Cellular, Molecular, and Biomedical Sciences, University of Vermont, Burlington, VT, USA
| | | |
Collapse
|
6
|
Aspergillus fumigatus Trehalose-Regulatory Subunit Homolog Moonlights To Mediate Cell Wall Homeostasis through Modulation of Chitin Synthase Activity. mBio 2017; 8:mBio.00056-17. [PMID: 28442603 PMCID: PMC5405227 DOI: 10.1128/mbio.00056-17] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Trehalose biosynthesis is found in fungi but not humans. Proteins involved in trehalose biosynthesis are essential for fungal pathogen virulence in humans and plants through multiple mechanisms. Loss of canonical trehalose biosynthesis genes in the human pathogen Aspergillus fumigatus significantly alters cell wall structure and integrity, though the mechanistic link between these virulence-associated pathways remains enigmatic. Here we characterize genes, called tslA and tslB, which encode proteins that contain domains similar to those corresponding to trehalose-6-phosphate phosphatase but lack critical catalytic residues for phosphatase activity. Loss of tslA reduces trehalose content in both conidia and mycelia, impairs cell wall integrity, and significantly alters cell wall structure. To gain mechanistic insights into the role that TslA plays in cell wall homeostasis, immunoprecipitation assays coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to reveal a direct interaction between TslA and CsmA, a type V chitin synthase enzyme. TslA regulates not only chitin synthase activity but also CsmA sub-cellular localization. Loss of TslA impacts the immunopathogenesis of murine invasive pulmonary aspergillosis through altering cytokine production and immune cell recruitment. In conclusion, our data provide a novel model whereby proteins in the trehalose pathway play a direct role in fungal cell wall homeostasis and consequently impact fungus-host interactions. Human fungal infections are increasing globally due to HIV infections and increased use of immunosuppressive therapies for many diseases. Therefore, new antifungal drugs with reduced side effects and increased efficacy are needed to improve treatment outcomes. Trehalose biosynthesis exists in pathogenic fungi and is absent in humans. Components of the trehalose biosynthesis pathway are important for the virulence of human-pathogenic fungi, including Aspergillus fumigatus. Consequently, it has been proposed that components of this pathway are potential targets for antifungal drug development. However, how trehalose biosynthesis influences the fungus-host interaction remains enigmatic. One phenotype associated with fungal trehalose biosynthesis mutants that remains enigmatic is cell wall perturbation. Here we discovered a novel moonlighting role for a regulatory-like subunit of the trehalose biosynthesis pathway in A. fumigatus that regulates cell wall homeostasis through modulation of chitin synthase localization and activity. As the cell wall is a current and promising therapeutic target for fungal infections, understanding the role of trehalose biosynthesis in cell wall homeostasis and virulence is expected to help define new therapeutic opportunities.
Collapse
|
7
|
Herold I, Yarden O. Regulation of Neurospora crassa cell wall remodeling via the cot-1 pathway is mediated by gul-1. Curr Genet 2016; 63:145-159. [PMID: 27363849 DOI: 10.1007/s00294-016-0625-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 06/14/2016] [Accepted: 06/16/2016] [Indexed: 11/29/2022]
Abstract
Impairment of the Neurospora crassa Nuclear DBF2-related kinase-encoding gene cot-1 results in pleiotropic effects, including abnormally thick hyphal cell walls and septa. An increase in the transcript abundance of genes encoding chitin and glucan synthases and the chitinase gh18-5, but not the cell wall integrity pathway transcription factor rlm-1, accompany the phenotypic changes observed. Deletion of chs-5 or chs-7 in a cot-1 background results in a reduction of hyperbranching frequency characteristic of the cot-1 parent. gul-1 (a homologue of the yeast SSD1 gene) encodes a translational regulator and has been shown to partially suppress cot-1. We demonstrate that the high expression levels of the cell wall remodeling genes analyzed is curbed, and reaches near wild type levels, when gul-1 is inactivated. This is accompanied by morphological changes that include reduced cell wall thickness and restoration of normal chitin levels. We conclude that gul-1 is a mediator of cell wall remodeling within the cot-1 pathway.
Collapse
Affiliation(s)
- Inbal Herold
- Department of Plant Pathology and Microbiology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, 7610000, Rehovot, Israel
| | - Oded Yarden
- Department of Plant Pathology and Microbiology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, 7610000, Rehovot, Israel.
| |
Collapse
|
8
|
Koch L, Lodin A, Herold I, Ilan M, Carmeli S, Yarden O. Sensitivity of Neurospora crassa to a marine-derived Aspergillus tubingensis anhydride exhibiting antifungal activity that is mediated by the MAS1 protein. Mar Drugs 2014; 12:4713-31. [PMID: 25257783 PMCID: PMC4178490 DOI: 10.3390/md12094713] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 08/20/2014] [Accepted: 08/21/2014] [Indexed: 02/04/2023] Open
Abstract
The fungus Aspergillustubingensis (strain OY907) was isolated from the Mediterranean marine sponge Ircinia variabilis. Extracellular extracts produced by this strain were found to inhibit the growth of several fungi. Among the secreted extract components, a novel anhydride metabolite, tubingenoic anhydride A (1) as well as the known 2-carboxymethyl-3-hexylmaleic acid anhydride, asperic acid, and campyrone A and C were purified and their structure elucidated. Compound 1 and 2-carboxymethyl-3-hexylmaleic acid anhydride inhibited Neurospora crassa growth (MIC = 330 and 207 μM, respectively) and affected hyphal morphology. We produced a N. crassa mutant exhibiting tolerance to 1 and found that a yet-uncharacterized gene, designated mas-1, whose product is a cytosolic protein, confers sensitivity to this compound. The ∆mas-1 strain showed increased tolerance to sublethal concentrations of the chitin synthase inhibitor polyoxin D, when compared to the wild type. In addition, the expression of chitin synthase genes was highly elevated in the ∆mas-1 strain, suggesting the gene product is involved in cell wall biosynthesis and the novel anhydride interferes with its function.
Collapse
Affiliation(s)
- Liat Koch
- Department of Plant Pathology and Microbiology, The R.H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
| | - Anat Lodin
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv 69978, Israel.
| | - Inbal Herold
- Department of Plant Pathology and Microbiology, The R.H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
| | - Micha Ilan
- Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Shmuel Carmeli
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv 69978, Israel.
| | - Oded Yarden
- Department of Plant Pathology and Microbiology, The R.H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
| |
Collapse
|
9
|
Functional Differentiation of Chitin Synthases inYarrowia lipolytica. Biosci Biotechnol Biochem 2014; 77:1275-81. [DOI: 10.1271/bbb.130111] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
10
|
Morcx S, Kunz C, Choquer M, Assie S, Blondet E, Simond-Côte E, Gajek K, Chapeland-Leclerc F, Expert D, Soulie MC. Disruption of Bcchs4, Bcchs6 or Bcchs7 chitin synthase genes in Botrytis cinerea and the essential role of class VI chitin synthase (Bcchs6). Fungal Genet Biol 2012; 52:1-8. [PMID: 23268147 DOI: 10.1016/j.fgb.2012.11.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 11/15/2012] [Accepted: 11/26/2012] [Indexed: 11/29/2022]
Abstract
Chitin synthases play critical roles in hyphal development and fungal pathogenicity. Previous studies on Botrytis cinerea, a model organism for necrotrophic pathogens, have shown that disruption of Bcchs1 and more particularly Bcchs3a genes have a drastic impact on virulence (Soulié et al., 2003, 2006). In this work, we investigate the role of other CHS including BcCHS4, BcCHS6 and BcCHS7 during the life cycle of B. cinerea. Single deletions of corresponding genes were carried out. Phenotypic analysis indicates that: (i) BcCHS4 enzyme is not essential for development and pathogenicity of the fungus; (ii) BcCHS7 is required for pathogenicity in a host dependant manner. For Bcchs6 gene disruption, we obtained only heterokaryotic strains. Indeed, sexual or asexual purification assays were unsuccessful. We concluded that class VI chitin synthase could be essential for B. cinerea and therefore BcCHS6 represents a valuable antifungal target.
Collapse
Affiliation(s)
- Serena Morcx
- UPMC Univ. Paris 06, UMR217, 75005 Paris, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Chitin synthases with a myosin motor-like domain control the resistance of Aspergillus fumigatus to echinocandins. Antimicrob Agents Chemother 2012; 56:6121-31. [PMID: 22964252 DOI: 10.1128/aac.00752-12] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aspergillus fumigatus has two chitin synthases (CSMA and CSMB) with a myosin motor-like domain (MMD) arranged in a head-to-head configuration. To understand the function of these chitin synthases, single and double csm mutant strains were constructed and analyzed. Although there was a slight reduction in mycelial growth of the mutants, the total chitin synthase activity and the cell wall chitin content were similar in the mycelium of all of the mutants and the parental strain. In the conidia, chitin content in the ΔcsmA strain cell wall was less than half the amount found in the parental strain. In contrast, the ΔcsmB mutant strain and, unexpectedly, the ΔcsmA/ΔcsmB mutant strain did not show any modification of chitin content in their conidial cell walls. In contrast to the hydrophobic conidia of the parental strain, conidia of all of the csm mutants were hydrophilic due to the presence of an amorphous material covering the hydrophobic surface-rodlet layer. The deletion of CSM genes also resulted in an increased susceptibility of resting and germinating conidia to echinocandins. These results show that the deletion of the CSMA and CSMB genes induced a significant disorganization of the cell wall structure, even though they contribute only weakly to the overall cell wall chitin synthesis.
Collapse
|
12
|
Kong LA, Yang J, Li GT, Qi LL, Zhang YJ, Wang CF, Zhao WS, Xu JR, Peng YL. Different chitin synthase genes are required for various developmental and plant infection processes in the rice blast fungus Magnaporthe oryzae. PLoS Pathog 2012; 8:e1002526. [PMID: 22346755 PMCID: PMC3276572 DOI: 10.1371/journal.ppat.1002526] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 12/24/2011] [Indexed: 11/18/2022] Open
Abstract
Chitin is a major component of fungal cell wall and is synthesized by chitin synthases (Chs). Plant pathogenic fungi normally have multiple chitin synthase genes. To determine their roles in development and pathogenesis, we functionally characterized all seven CHS genes in Magnaporthe oryzae. Three of them, CHS1, CHS6, and CHS7, were found to be important for plant infection. While the chs6 mutant was non-pathogenic, the chs1 and chs7 mutants were significantly reduced in virulence. CHS1 plays a specific role in conidiogenesis, an essential step for natural infection cycle. Most of chs1 conidia had no septum and spore tip mucilage. The chs6 mutant was reduced in hyphal growth and conidiation. It failed to penetrate and grow invasively in plant cells. The two MMD-containing chitin synthase genes, CHS5 and CHS6, have a similar expression pattern. Although deletion of CHS5 had no detectable phenotype, the chs5 chs6 double mutant had more severe defects than the chs6 mutant, indicating that they may have overlapping functions in maintaining polarized growth in vegetative and invasive hyphae. Unlike the other CHS genes, CHS7 has a unique function in appressorium formation. Although it was blocked in appressorium formation by germ tubes on artificial hydrophobic surfaces, the chs7 mutant still produced melanized appressoria by hyphal tips or on plant surfaces, indicating that chitin synthase genes have distinct impacts on appressorium formation by hyphal tip and germ tube. The chs7 mutant also was defective in appressorium penetration and invasive growth. Overall, our results indicate that individual CHS genes play diverse roles in hyphal growth, conidiogenesis, appressorium development, and pathogenesis in M. oryzae, and provided potential new leads in the control of this devastating pathogen by targeting specific chitin synthases.
Collapse
Affiliation(s)
- Ling-An Kong
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Plant Pathology, China Agricultural University, Beijing, China
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Jun Yang
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Plant Pathology, China Agricultural University, Beijing, China
| | - Guo-Tian Li
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Lin-Lu Qi
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Plant Pathology, China Agricultural University, Beijing, China
| | - Yu-Jun Zhang
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Plant Pathology, China Agricultural University, Beijing, China
| | - Chen-Fang Wang
- College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Wen-Sheng Zhao
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Plant Pathology, China Agricultural University, Beijing, China
| | - Jin-Rong Xu
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - You-Liang Peng
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Plant Pathology, China Agricultural University, Beijing, China
| |
Collapse
|
13
|
Rogg LE, Fortwendel JR, Juvvadi PR, Steinbach WJ. Regulation of expression, activity and localization of fungal chitin synthases. Med Mycol 2012; 50:2-17. [PMID: 21526913 PMCID: PMC3660733 DOI: 10.3109/13693786.2011.577104] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The fungal cell wall represents an attractive target for pharmacologic inhibition, as many of the components are fungal-specific. Though targeted inhibition of β-glucan synthesis is effective treatment for certain fungal infections, the ability of the cell wall to dynamically compensate via the cell wall integrity pathway may limit overall efficacy. To date, chitin synthesis inhibitors have not been successfully deployed in the clinical setting. Fungal chitin synthesis is a complex and highly regulated process. Regulation of chitin synthesis occurs on multiple levels, thus targeting of these regulatory pathways may represent an exciting alternative approach. A variety of signaling pathways have been implicated in chitin synthase regulation, at both transcriptional and post-transcriptional levels. Recent research suggests that localization of chitin synthases likely represents a major regulatory mechanism. However, much of the regulatory machinery is not necessarily shared among different chitin synthases. Thus, an in-depth understanding of the precise roles of each protein in cell wall maintenance and repair will be essential to identifying the most likely therapeutic targets.
Collapse
Affiliation(s)
- Luise E. Rogg
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham NC, USA
| | - Jarrod R. Fortwendel
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham NC, USA
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham NC, USA
| | - Praveen R. Juvvadi
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham NC, USA
| | - William J. Steinbach
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham NC, USA
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham NC, USA
| |
Collapse
|
14
|
Advances in understanding hyphal morphogenesis: Ontogeny, phylogeny and cellular localization of chitin synthases. FUNGAL BIOL REV 2008. [DOI: 10.1016/j.fbr.2008.05.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
15
|
Werner S, Sugui JA, Steinberg G, Deising HB. A chitin synthase with a myosin-like motor domain is essential for hyphal growth, appressorium differentiation, and pathogenicity of the maize anthracnose fungus Colletotrichum graminicola. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2007; 20:1555-1567. [PMID: 17990963 DOI: 10.1094/mpmi-20-12-1555] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Chitin synthesis contributes to cell wall biogenesis and is essential for invasion of solid substrata and pathogenicity of filamentous fungi. In contrast to yeasts, filamentous fungi contain up to 10 chitin synthases (CHS), which might reflect overlapping functions and indicate their complex lifestyle. Previous studies have shown that a class VI CHS of the maize anthracnose fungus Colletotrichum graminicola is essential for cell wall synthesis of conidia and vegetative hyphae. Here, we report on cloning and characterization of three additional CHS genes, CgChsI, CgChsIII, and CgChsV, encoding class I, III, and V CHS, respectively. All CHS genes are expressed during vegetative and pathogenic development. DeltaCgChsI and DeltaCgChsIII mutants did not differ significantly from the wild-type isolate with respect to hyphal growth and pathogenicity. In contrast, null mutants in the CgChsV gene, which encodes a CHS with an N-terminal myosin-like motor domain, are strongly impaired in vegetative growth and pathogenicity. Even in osmotically stabilized media, vegetative hyphae of DeltaCgChsV mutants exhibited large balloon-like swellings, appressorial walls appeared to disintegrate during maturation, and infection cells were nonfunctional. Surprisingly, DeltaCgChsV mutants were able to form dome-shaped hyphopodia that exerted force and showed host cell wall penetration rates comparable with the wild type. However, infection hyphae that formed within the plant cells exhibited severe swellings and were not able to proceed with plant colonization efficiently. Consequently, DeltaCgChsV mutants did not develop macroscopically visible anthracnose disease symptoms and, thus, were nonpathogenic.
Collapse
Affiliation(s)
- Stefan Werner
- Institute of Agricultural and Nutritional Sciences, Martin-Luther-Universität-Halle-Wittenberg, Halle (Saale), Germany
| | | | | | | |
Collapse
|
16
|
Mandel MA, Galgiani JN, Kroken S, Orbach MJ. Coccidioides posadasii contains single chitin synthase genes corresponding to classes I to VII. Fungal Genet Biol 2006; 43:775-88. [PMID: 16857399 DOI: 10.1016/j.fgb.2006.05.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Revised: 05/17/2006] [Accepted: 05/23/2006] [Indexed: 11/20/2022]
Abstract
Coccidioides posadasii is a dimorphic fungal pathogen of humans and other mammals. The switch between saprobic and parasitic growth involves synthesis of new cell walls of which chitin is a significant component. To determine whether particular subsets of chitin synthases (CHSes) are responsible for production of chitin at different stages of differentiation, we have isolated six CHS genes from this fungus. They correspond, together with another reported CHS gene, to single members of the seven defined classes of chitin synthases (classes I-VII). Using Real-Time RT-PCR we show their pattern of expression during morphogenesis. CpCHS2, CpCHS3, and CpCHS6 are preferentially expressed during the saprobic phase, while CpCHS1 and CpCHS4 are more highly expressed during the parasitic phase. CpCHS5 and CpCHS7 expression is similar in both saprobic and parasitic phases. Because C. posadasii contains single members of the seven classes of CHSes found in fungi, it is a good model to investigate the putatively different roles of these genes in fungal growth and differentiation.
Collapse
Affiliation(s)
- M Alejandra Mandel
- Department of Plant Sciences, Division of Plant Pathology and Microbiology, University of Arizona, Tucson, AZ 85721-0036, USA
| | | | | | | |
Collapse
|
17
|
Zheng L, Mendoza L, Wang Z, Liu H, Park C, Kauffman S, Becker JM, Szaniszlo PJ. WdChs1p, a class II chitin synthase, is more responsible than WdChs2p (Class I) for normal yeast reproductive growth in the polymorphic, pathogenic fungus Wangiella (Exophiala) dermatitidis. Arch Microbiol 2006; 185:316-29. [PMID: 16544168 PMCID: PMC1482791 DOI: 10.1007/s00203-006-0101-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2005] [Revised: 02/18/2006] [Accepted: 02/20/2006] [Indexed: 10/24/2022]
Abstract
The chitin synthase gene WdCHS1 was isolated from a partial genomic DNA library of the pathogenic polymorphic fungus Wangiella dermatitidis. Sequencing showed that WdCHS1 encoded a class II chitin synthase composed of 988 amino acids. Disruption of WdCHS1 produced strains that were hyperpigmented in rich media, grew as yeast at wild-type rates at both 25 and 37 degrees C and were as virulent as the wild type in a mouse model. However, detailed morphological and cytological studies of the wdchs1Delta mutants showed that yeast cells often failed to separate, tended to be enriched with chitin in septal regions and, sometimes, were enlarged with multiple nuclei, had broader mother cell-daughter bud regions and had other cell wall defects seen considerably less often than in the wild type or wdchs2 Delta strains. Disruption of WdCHS1 and WdCHS2 in the same background revealed that WdChs1p had functions synergistic to those of WdChs2p, because mutants devoid of both isozymes produced growth that was very abnormal at 25 degrees C and was not viable at 37 degrees C unless osmotically stabilized. These results suggested that WdChs1p was more responsible than WdChs2p for normal yeast cell reproductive growth because strains with defects in the latter exhibited no morphological abnormalities, whereas those with defects in WdChs1p were frequently impaired in one or more yeast developmental processes.
Collapse
Affiliation(s)
- Li Zheng
- Section of Molecular Genetics and Microbiology, School of Biological Science and Institute for Cellular and Molecular Biology, University of Texas at Austin, 1 University Station A5000, Austin, TX 78712-0162, USA
| | - Leonel Mendoza
- Section of Molecular Genetics and Microbiology, School of Biological Science and Institute for Cellular and Molecular Biology, University of Texas at Austin, 1 University Station A5000, Austin, TX 78712-0162, USA
| | - Zheng Wang
- Section of Molecular Genetics and Microbiology, School of Biological Science and Institute for Cellular and Molecular Biology, University of Texas at Austin, 1 University Station A5000, Austin, TX 78712-0162, USA
| | - Hongbo Liu
- Section of Molecular Genetics and Microbiology, School of Biological Science and Institute for Cellular and Molecular Biology, University of Texas at Austin, 1 University Station A5000, Austin, TX 78712-0162, USA
| | - Changwon Park
- Section of Molecular Genetics and Microbiology, School of Biological Science and Institute for Cellular and Molecular Biology, University of Texas at Austin, 1 University Station A5000, Austin, TX 78712-0162, USA
| | - Sarah Kauffman
- Microbiology Department, University of Tennessee, Knoxville, TN 37919, USA
| | - Jeffrey M. Becker
- Microbiology Department, University of Tennessee, Knoxville, TN 37919, USA
| | - Paul J. Szaniszlo
- Section of Molecular Genetics and Microbiology, School of Biological Science and Institute for Cellular and Molecular Biology, University of Texas at Austin, 1 University Station A5000, Austin, TX 78712-0162, USA
- E-mail: , Tel.: +1-512-4713384, Fax: +1-512-4717088
| |
Collapse
|
18
|
Liu H, Kauffman S, Becker JM, Szaniszlo PJ. Wangiella (Exophiala) dermatitidis WdChs5p, a class V chitin synthase, is essential for sustained cell growth at temperature of infection. EUKARYOTIC CELL 2004; 3:40-51. [PMID: 14871935 PMCID: PMC329517 DOI: 10.1128/ec.3.1.40-51.2004] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The chitin synthase structural gene WdCHS5 was isolated from the black fungal pathogen of humans Wangiella dermatitidis. Sequence analysis revealed that the gene has a myosin motor-like-encoding region at its 5' end and a chitin synthase (class V)-encoding region at its 3' end. Northern blotting showed that WdCHS5 is expressed at high levels under conditions of stress. Analysis of the 5' upstream region of WdCHS5 fused to a reporter gene indicated that one or more of the potential regulatory elements present may have contributed to the high expression levels. Disruption of WdCHS5 produced mutants that grow normally at 25 degrees C but have severe growth and cellular abnormalities at 37 degrees C. Osmotic stabilizers, such as sorbitol and sucrose, rescued the wild-type phenotype, which indicated that the loss of WdChs5p causes cell wall integrity defects. Animal survival tests with a mouse model of acute infection showed that all wdchs5Delta mutants are less virulent than the parental strain. Reintroduction of the WdCHS5 gene into the wdchs5Delta mutants abolished the temperature-sensitive phenotype and reestablished their virulence. We conclude that the product of WdCHS5 is required for the sustained growth of W. dermatitidis at 37 degrees C and is of critical importance to its virulence.
Collapse
Affiliation(s)
- Hongbo Liu
- Section of Molecular Genetics and Microbiology, School of Biological Science and Institute of Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | | | | | | |
Collapse
|
19
|
Lee JI, Choi JH, Park BC, Park YH, Lee MY, Park HM, Maeng PJ. Differential expression of the chitin synthase genes of Aspergillus nidulans, chsA, chsB, and chsC, in response to developmental status and environmental factors. Fungal Genet Biol 2004; 41:635-46. [PMID: 15121085 DOI: 10.1016/j.fgb.2004.01.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2003] [Accepted: 01/23/2004] [Indexed: 11/23/2022]
Abstract
To understand the role of the chitin synthase genes of Aspergillus nidulans, we analyzed the expression of chsA, chsB, and chsC both by Northern blotting and by a vital reporter system with sgfp encoding a modified version of green fluorescent protein, sGFP. chsA was expressed specifically during asexual differentiation, but not during either vegetative growth or sexual differentiation. The expression of chsB was ubiquitous throughout the fungal body and relatively independent of the change in developmental status of the cells. chsC was expressed moderately during sexual development as well as during the early phase of vegetative growth, but was expressed weakly in old vegetative mycelia and in asexual structures. Furthermore its expression was spatially differentiated, i.e., relatively strong in young cleistothecia and in mature ascospores, but negligible in Hülle cells. Osmostress caused by high concentrations (up to 1.2M) of KCl or NaCl stimulated the expression of chsA and chsC, but not that of chsB. Sodium acetate, especially at high concentration (3%), strongly enhanced the expression of all the three genes. Neither heat shock nor the sugar carbon sources tested (glucose, sucrose, or lactose) affected the expression of any of the three chitin synthase genes.
Collapse
Affiliation(s)
- Jeong Im Lee
- Department of Microbiology, Chungnam National University, Daejeon 305-764, Republic of Korea
| | | | | | | | | | | | | |
Collapse
|
20
|
Soulié MC, Piffeteau A, Choquer M, Boccara M, Vidal-Cros A. Disruption of Botrytis cinerea class I chitin synthase gene Bcchs1 results in cell wall weakening and reduced virulence. Fungal Genet Biol 2003; 40:38-46. [PMID: 12948512 DOI: 10.1016/s1087-1845(03)00065-3] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
To get a better insight into the relationship between cell wall integrity and pathogenicity of the fungus Botrytis cinerea, we have constructed chitin synthase mutants. A 620 bp class I chitin synthase gene fragment (Bcchs1) obtained by PCR amplification was used to disrupt the corresponding gene in the genome. Disruption of Bcchs1 occurred at a frequency of 8%. Nine independent mutants were obtained and the Bcchs1 mutant phenotype compared to that of transformants in which the gene was not disrupted. These disruption mutants were dramatically reduced in their in vitro Mg2+, Mn2+, and Co2+-dependent chitin synthase activity. Chitin content was reduced by 30%, indicating that Bcchs1p contributes substantially to cell wall composition. Enzymatic degradation by a cocktail of glucanases revealed cell wall weakening in the mutant. Bcchs1 was transcribed at a constant level during vegetative exponential growth, suggesting that it was necessary throughout hyphal development. Bcchs1 mutant growth was identical to undisrupted control transformant growth, however, the mutant exhibited reduced pathogenicity on vine leaves. It can be assumed that disruption of Bcchs1 leads to cell wall weakening which might slow down in planta fungal progression.
Collapse
Affiliation(s)
- M-C Soulié
- Laboratoire de Pathologie Végétale, UMR 217 INRA-Paris VI-INAP-G, 16 rue Claude Bernard, 75005 Paris, France.
| | | | | | | | | |
Collapse
|
21
|
Amnuaykanjanasin A, Epstein L. A class V chitin synthase gene, chsA is essential for conidial and hyphal wall strength in the fungus Colletotrichum graminicola (Glomerella graminicola). Fungal Genet Biol 2003; 38:272-85. [PMID: 12684017 DOI: 10.1016/s1087-1845(02)00563-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The Colletotrichum graminicola tagged mutant T30 has conidia that burst and hyphal tips that swell in media with low osmotic pressure. The disrupted gene in T30 was identified as a class V chitin synthase (CSV) "chsA," which has an open reading frame of 1783 amino acids and two introns that are 52 and 54 bp. C. graminicola has one copy of chsA and no other highly homologous class V CHSs. Reverse transcriptase PCR indicated that the T30 mutant does not express the chsA transcript fragment in the conserved region in CSVs. Complementation of the mutant with chsA indicates that the encoded protein is responsible for approximately 29% of the chitin in conidial walls, is essential for conidial wall strength in media with high water potential and contributes to strength of hyphal tips. Analysis of the aligned deduced amino acid sequences of the 10 fully sequenced CSVs suggests that they are in two subgroups.
Collapse
|
22
|
Madrid MP, Di Pietro A, Roncero MIG. Class V chitin synthase determines pathogenesis in the vascular wilt fungus Fusarium oxysporum and mediates resistance to plant defence compounds. Mol Microbiol 2003; 47:257-66. [PMID: 12492869 DOI: 10.1046/j.1365-2958.2003.03299.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Chitin, a beta-1,4-linked polysaccharide of N-acetylglucosamine, is a major structural component of fungal cell walls. Fungi have multiple classes of chitin synthases that catalyse N-acetylglucosamine polymerization. Here, we demonstrate the requirement for a class V chitin synthase during host infection by the vascular wilt pathogen Fusarium oxysporum. The chsV gene was identified in an insertional mutagenesis screen for pathogenicity mutants. ChsV has a putative myosin motor and a chitin synthase domain characteristic of class V chitin synthases. The chsV insertional mutant and a gene replacement mutant of F. oxysporum display morphological abnormalities such as hyphal swellings that are indicative of alterations in cell wall structure and can be partially restored by osmotic stabilizer. The mutants are unable to infect and colonize tomato plants or to grow invasively on tomato fruit tissue. They are also hypersensitive to plant antimicrobial defence compounds such as the tomato phytoanticipin alpha-tomatine or H2O2. Reintroduction of a functional chsV copy into the mutant restored the growth phenotype of the wild-type strain. These data suggest that F. oxysporum requires a specific class V chitin synthase for pathogenesis, most probably to protect itself against plant defence mechanisms.
Collapse
Affiliation(s)
- Martan P Madrid
- Departamento de Genética, Universidad de Córdoba, Campus Rabanales C5, 14071 Córdoba, Spain
| | | | | |
Collapse
|
23
|
Takeshita N, Ohta A, Horiuchi H. csmA, a gene encoding a class V chitin synthase with a myosin motor-like domain of Aspergillus nidulans, is translated as a single polypeptide and regulated in response to osmotic conditions. Biochem Biophys Res Commun 2002; 298:103-9. [PMID: 12379226 DOI: 10.1016/s0006-291x(02)02418-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The csmA gene of Aspergillus nidulans encodes a polypeptide that consists of an N-terminal myosin motor-like domain and a C-terminal chitin synthase domain. csmA null mutants showed marked abnormalities in polarized growth, hyphal wall integrity, and conidiophore development. Furthermore, the growth of the csmA null mutants was sensitive to low osmotic conditions. In an effort to investigate the intracellular behavior of the csmA product (CsmA) and the regulation of its production, we constructed strains that produced CsmA tagged with nine repeats of the hemagglutinin A (HA) epitope at its COOH terminus (CsmA-HA) instead of CsmA. Western blot analysis with anti-HA antibody showed that the entire coding region of csmA was translated as a single polypeptide with an approximate molecular mass of 210kDa. CsmA-HA was produced during vegetative growth; however, its yield was significantly reduced under high osmotic conditions, suggesting that the role of CsmA in growth and morphogenesis is particularly important under low osmotic conditions.
Collapse
Affiliation(s)
- Norio Takeshita
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
| | | | | |
Collapse
|
24
|
Szaniszlo PJ. Molecular genetic studies of the model dematiaceous pathogen Wangiella dermatitidis. Int J Med Microbiol 2002; 292:381-90. [PMID: 12452284 DOI: 10.1078/1438-4221-00221] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The rapidly improving molecular genetic tractability of Wangiella (Exophiala) dermatitidis significantly enhances its usefulness as a model for the more than 100 other dematiaceous (melanized) agents of human disease. Previously this model was based almost exclusively on its vegetative polymorphism, which at the simplest level is expressed as three well-characterized modes of growth (e.g., blastic, apical and isotropic) that produce myriad yeast, hyphal and sclerotic phenotypes. This cellular plasticity is important for a dematiaceous model pathogen because some are hyphal in nature but exist almost exclusively as sclerotic bodies in infected tissue, whereas others are hyphal both in nature and in tissue, and still others exist in nature predominantly as yeast, but as mixtures of yeast, hyphae and sclerotic bodies in tissue. By exploiting the polymorphism of W. dermatitidis, any phenotype of another dematiaceous pathogen can be produced for study of the regulation of its development and its contribution to pathogenicity and virulence. The coupling of this asset with the recent finding that its haploid, uninucleate yeast cell is easily transformed molecularly, and the even more recent development of systems for both random and targeted gene disruptions and for site-specific, integrative gene overexpression studies suggest that it will continue as the preferred model for the dematiaceous fungi and irrespective of the mycosis involved. The results reviewed here aim to confirm this contention, stimulate others to study this fungus, and demonstrate that W. dermatitidis is exceptionally useful for discovering by molecular genetic techniques cell wall-associated virulence factors in fungi, and in particular in the dematiaceous fungi.
Collapse
Affiliation(s)
- Paul J Szaniszlo
- Section of Molecular Genetics and Microbiology, The University of Texas at Austin, Austin, TX 78712-1095, USA.
| |
Collapse
|
25
|
Ichinomiya M, Horiuchi H, Ohta A. Different functions of the class I and class II chitin synthase genes, chsC and chsA, are revealed by repression of chsB expression in Aspergillus nidulans. Curr Genet 2002; 42:51-8. [PMID: 12420146 DOI: 10.1007/s00294-002-0329-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2002] [Revised: 08/05/2002] [Accepted: 08/12/2002] [Indexed: 11/29/2022]
Abstract
The filamentous fungus, Aspergillus nidulans, genome contains at least five chitin synthase-encoding genes. chsB is essential for normal hyphal growth. chsA and chsC are likely to be cooperatively required for hyphal wall integrity. In this study, we constructed chsA chsB and chsC chsB double mutants, in which chsB expression was under a repressible promoter [ alcA(p)]. While chsA or chsC single mutants did not show obvious growth defects, the chsA chsB and chsC chsB double mutants showed different phenotypes from the chsB single mutant and from each other under alcA(p)-repressing conditions. The chsA chsB double mutant produced fewer aerial hyphae and the chsC chsB double mutant showed reduced cell mass. These observations support the idea that chsA and chsC each play a different role in hyphal morphogenesis. In addition, the chitin contents of these double mutants were higher than those of the chsB single mutant. When chsA was expressed ectopically under the chsB promoter in the chsB mutant, the growth defects caused by chsB repression were not remedied at all, although an increased level of chsA mRNA was observed. Thus, it is suggested that the gene products of chsA and chsB themselves have different functions in hyphal morphogenesis.
Collapse
Affiliation(s)
- Masayuki Ichinomiya
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Japan
| | | | | |
Collapse
|
26
|
Chitnis MV, Munro CA, Brown AJP, Gooday GW, Gow NAR, Deshpande MV. The zygomycetous fungus, Benjaminiella poitrasii contains a large family of differentially regulated chitin synthase genes. Fungal Genet Biol 2002; 36:215-23. [PMID: 12135577 DOI: 10.1016/s1087-1845(02)00015-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Benjaminiella poitrasii is a zygomycetous, non-pathogenic dimorphic fungus. Chitin synthases are the membrane bound enzymes involved in the synthesis of chitin and are key enzymes in the cell wall metabolism. Multiplicity of these enzymes is a common occurrence. Here, we identify eight distinct CHS genes in B. poitrasii as confirmed through DNA sequence and Southern analysis. These genes are related to other fungal CHS genes. BpCHS1-4 are class I-III chitin synthases while BpCHS5-8 are class IV-V chitin synthases. These eight genes are differentially expressed during morphogenesis and under different growth conditions. Two of these genes viz. BpCHS2 and BpCHS3 appear to be specific to the mycelial growth form. These are the first B. poitrasii sequences to be reported. Based on CHS gene sequences, B. poitrasii chitin synthase genes place it with other zygomycetes on a fungal phylogenetic tree.
Collapse
Affiliation(s)
- Manisha V Chitnis
- Biochemical Sciences Division, National Chemical Laboratory, Pune, India
| | | | | | | | | | | |
Collapse
|
27
|
Ichinomiya M, Motoyama T, Fujiwara M, Takagi M, Horiuchi H, Ohta A. Repression of chsB expression reveals the functional importance of class IV chitin synthase gene chsD in hyphal growth and conidiation of Aspergillus nidulans. MICROBIOLOGY (READING, ENGLAND) 2002; 148:1335-47. [PMID: 11988507 DOI: 10.1099/00221287-148-5-1335] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The functions of two previously identified chitin synthase genes in Aspergillus nidulans, chsB and chsD, were analysed. First, a conditional chsB mutant was constructed in which the expression of chsB is under the control of a repressible promoter, the alcA promoter, of A. nidulans. Under repressing conditions, the mutant grew slowly and produced highly branched hyphae, supporting the idea that chsB is involved in normal hyphal growth. The involvement of chsB in conidiation was also demonstrated. Next, double mutants of chsB and chsD were constructed, in which chsB was placed under the control of the alcA promoter and chsD was replaced with the argB gene of A. nidulans. These double mutants grew more slowly than the chsB single mutant under high-osmolarity conditions. The hyphae of the double mutant appeared to be more disorganized than those of the chsB single mutant. It was also found that ChsD was functionally implicated in conidiation when the expression of chsB was limited. These results indicate the importance of the ChsD function in the absence of chsB expression. The roles of ChsB and ChsD in hyphal growth and in conidiation were supported by the analysis of the spatial expression patterns of chsB and chsD, using lacZ of Escherichia coli as a reporter gene.
Collapse
Affiliation(s)
- Masayuki Ichinomiya
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | | | | | | | | | | |
Collapse
|
28
|
Wang Z, Zheng L, Liu H, Wang Q, Hauser M, Kauffman S, Becker JM, Szaniszlo PJ. WdChs2p, a class I chitin synthase, together with WdChs3p (class III) contributes to virulence in Wangiella (Exophiala) dermatitidis. Infect Immun 2001; 69:7517-26. [PMID: 11705928 PMCID: PMC98842 DOI: 10.1128/iai.69.12.7517-7526.2001] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The chitin synthase structural gene WdCHS2 was isolated by screening a subgenomic DNA library of Wangiella dermatitidis by using a 0.6-kb PCR product of the gene as a probe. The nucleotide sequence revealed a 2,784-bp open reading frame, which encoded 928 amino acids, with a 59-bp intron near its 5' end. Derived protein sequences showed highest amino acid identities with those derived from the CiCHS1 gene of Coccidioides immitis and the AnCHSC gene of Aspergillus nidulans. The derived sequence also indicated that WdChs2p is an orthologous enzyme of Chs1p of Saccharomyces cerevisiae, which defines the class I chitin synthases. Disruptions of WdCHS2 produced strains that showed no obvious morphological defects in yeast vegetative growth or in ability to carry out polymorphic transitions from yeast cells to hyphae or to isotropic forms. However, assays showed that membranes of wdchs2Delta mutants were drastically reduced in chitin synthase activity. Other assays of membranes from a wdchs1Deltawdchs3Deltawdchs4Delta triple mutant showed that their residual chitin synthase activity was extremely sensitive to trypsin activation and was responsible for the majority of zymogenic activity. Although no loss of virulence was detected when wdchs2Delta strains were tested in a mouse model of acute infection, wdchs2Deltawdchs3Delta disruptants were considerably less virulent in the same model, even though wdchs3Delta strains also had previously shown no loss of virulence. This virulence attenuation in the wdchs2Deltawdchs3Delta mutants was similarly documented in a limited fashion in more-sensitive cyclophosphamide-induced immunocompromised mice. The importance of WdChs2p and WdChs3p to the virulence of W. dermatitidis was then confirmed by reconstituting virulence in the double mutant by the reintroduction of either WdCHS2 or WdCHS3 into the wdchs2Deltawdchs3Delta mutant background.
Collapse
Affiliation(s)
- Z Wang
- Section of Molecular Genetics and Microbiology, School of Biological Science and Institute for Cellular and Molecular Biology, The University of Texas at Austin, 78712, USA
| | | | | | | | | | | | | | | |
Collapse
|
29
|
Balestrini R, Mainieri D, Soragni E, Garnero L, Rollino S, Viotti A, Ottonello S, Bonfante P. Differential expression of chitin synthase III and IV mRNAs in ascomata of Tuber borchii Vittad. Fungal Genet Biol 2000; 31:219-32. [PMID: 11273683 DOI: 10.1006/fgbi.2000.1242] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A full-length genomic clone encoding a class III chitin synthase (CHS) and one DNA fragment corresponding to a class IV CHS were isolated from the mycorrhizal fungus Tuber borchii and used for an extensive expression analysis, together with a previously identified DNA fragment corresponding to a class II CHS. All three Chs mRNAs are constitutively expressed in vegetative mycelia, regardless of the age, mode of growth, and proliferation capacity of the hyphae. A strikingly different situation was observed in ascomata, where class III and IV, but not class II, mRNAs are differentially expressed in a maturation stage-dependent manner and accumulate, respectively, in sporogenic and vegetative hyphae. These data, the first on the expression of distinct Chs mRNAs during fruitbody development, point to the different cellular roles that can be played by distinct chitin synthases in the differentiation of spores of sexual origin (CHS III) or in ascoma enlargement promoted by the growth of vegetative hyphae (CHS IV).
Collapse
Affiliation(s)
- R Balestrini
- Centro di Studio sulla Micologia del Terreno, CNR, University of Torino, V.le Mattioli 25, 10125 Torino, Italy
| | | | | | | | | | | | | | | |
Collapse
|
30
|
|
31
|
Wang Z, Zheng L, Hauser M, Becker JM, Szaniszlo PJ. WdChs4p, a homolog of chitin synthase 3 in Saccharomyces cerevisiae, alone cannot support growth of Wangiella (Exophiala) dermatitidis at the temperature of infection. Infect Immun 1999; 67:6619-30. [PMID: 10569783 PMCID: PMC97075 DOI: 10.1128/iai.67.12.6619-6630.1999] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/1999] [Accepted: 09/03/1999] [Indexed: 11/20/2022] Open
Abstract
By using improved transformation methods for Wangiella dermatitidis, and a cloned fragment of its chitin synthase 4 structural gene (WdCHS4) as a marking sequence, the full-length gene was rescued from the genome of this human pathogenic fungus. The encoded chitin synthase product (WdChs4p) showed high homology with Chs3p of Saccharomyces cerevisiae and other class IV chitin synthases, and Northern blotting showed that WdCHS4 was expressed at constitutive levels under all conditions tested. Reduced chitin content, abnormal yeast clumpiness and budding kinetics, and increased melanin secretion resulted from the disruption of WdCHS4 suggesting that WdChs4p influences cell wall structure, cellular reproduction, and melanin deposition, respectively. However, no significant loss of virulence was detected when the wdchs4Delta strain was tested in an acute mouse model. Using a wdchs1Delta wdchs2Delta wdchs3Delta triple mutant of W. dermatitidis, which grew poorly but adequately at 25 degrees C, we assayed WdChs4p activity in the absence of activities contributed by its three other WdChs proteins. Maximal activity required trypsin activation, suggesting a zymogenic nature. The activity also had a pH optimum of 7.5, was most stimulated by Mg(2+), and was more inhibited by polyoxin D than by nikkomycin Z. Although the WdChs4p activity had a broad temperature optimum between 30 to 45 degrees C in vitro, this activity alone did not support the growth of the wdchs1Delta wdchs2Delta wdchs3Delta triple mutant at 37 degrees C, a temperature commensurate with infection.
Collapse
Affiliation(s)
- Z Wang
- Section of Molecular Genetics and Microbiology, School of Biological Science and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
| | | | | | | | | |
Collapse
|
32
|
Horiuchi H, Fujiwara M, Yamashita S, Ohta A, Takagi M. Proliferation of intrahyphal hyphae caused by disruption of csmA, which encodes a class V chitin synthase with a myosin motor-like domain in Aspergillus nidulans. J Bacteriol 1999; 181:3721-9. [PMID: 10368147 PMCID: PMC93850 DOI: 10.1128/jb.181.12.3721-3729.1999] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have found that the Aspergillus nidulans csmA gene encodes a novel protein which consists of an N-terminal myosin motor-like domain and a C-terminal chitin synthase domain (M. Fujiwara, H. Horiuchi, A. Ohta, and M. Takagi, Biochem. Biophys. Res. Commun. 236:75-78, 1997). To clarify the roles of csmA in fungal morphogenesis, we constructed csmA null mutants. The growth rate of the mutant colonies was almost the same as that of the wild-type strain, but hyphal growth was severely inhibited when a chitin-binding reagent, Calcofluor white or Congo red, was added to the medium. Moreover, morphological abnormalities in tip growth and septum formation were identified microscopically. Proliferation of intracellular new hyphae, called intrahyphal hyphae, which behaved as intrinsic hyphae, was the most striking phenotypic feature among them. These phenotypes were not suppressed when the only chitin synthase domain of csmA was expressed under the control of the alcA promoter, whereas they were suppressed when the intact form of csmA was expressed. Therefore, it was concluded that the product of csmA (CsmA) has important roles in polarized cell wall synthesis and maintenance of cell wall integrity and that the myosin motor-like domain is indispensable for these functions.
Collapse
Affiliation(s)
- H Horiuchi
- Department of Biotechnology, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | | | | | | | | |
Collapse
|
33
|
Motoyama T, Horiuchi H, Ohta A, Yamaguchi I, Takagi M. Isolation of a class IV chitin synthase gene from a zygomycete fungus, Rhizopus oligosporus. FEMS Microbiol Lett 1998; 169:1-8. [PMID: 9851030 DOI: 10.1111/j.1574-6968.1998.tb13291.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
We found the presence of DNA sequence which shows sequence similarity to the class IV chitin synthase gene (CHS3) of Saccharomyces cerevisiae in the genome of 14 Rhizopus species which belong to zygomycetes. We cloned a gene (chs3), which might correspond to one of these homologous sequences, from Rhizopus oligosporus by low stringency plaque hybridization probed with CHS3. The deduced amino acid sequence of this gene showed highest similarity to the class IV chitin synthase of Neurospora crassa (46.7% identity over 1087 amino acids), showing that this gene encodes a class IV chitin synthase. Northern analysis revealed the differential expression pattern of this gene in the asexual life cycle with highest expression in the early stage of asexual spore formation. This is the first report of the isolation and analysis of a class IV chitin synthase gene from zygomycete fungi.
Collapse
Affiliation(s)
- T Motoyama
- Department of Biotechnology, University of Tokyo, Japan
| | | | | | | | | |
Collapse
|
34
|
Aufauvre-Brown A, Mellado E, Gow NA, Holden DW. Aspergillus fumigatus chsE: a gene related to CHS3 of Saccharomyces cerevisiae and important for hyphal growth and conidiophore development but not pathogenicity. Fungal Genet Biol 1997; 21:141-52. [PMID: 9126623 DOI: 10.1006/fgbi.1997.0959] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The Aspergillus fumigatus chsE (AfchsE) gene was isolated from an A. fumigatus DNA library on the basis of hybridization to a segment of Saccharomyces cerevisiae CHS3 (ScCHS3). The amino acid sequence derived from AfchsE is 28% identical with ScCHS3 and 80% identical with the product of Aspergillus nidulans chsD (AnchsD). A mutant strain constructed by disruption of AfchsE has reduced levels of mycelial chitin, periodic swellings along the length of hyphae, and a block in conidiation that can be partially restored by growth in osmotic stabilizer. This phenotype is different from that reported for an AnchsD mutant, in which germinating conidia and hyphal tips undergo lysis and the colonial growth rate is significantly reduced. Despite the defects associated with the AfchsE- strain, its virulence was not significantly reduced when compared with the wild-type parental strain in a mouse model of pulmonary aspergillosis.
Collapse
Affiliation(s)
- A Aufauvre-Brown
- Department of Infectious Diseases. Royal Postgraduate Medical School, Hammersmith Hospital, London, United Kingdom
| | | | | | | |
Collapse
|