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Li H, Mo P, Zhang J, Xie Z, Liu X, Chen H, Yang L, Liu M, Zhang H, Wang P, Zhang Z. Methionine biosynthesis enzyme MoMet2 is required for rice blast fungus pathogenicity by promoting virulence gene expression via reducing 5mC modification. PLoS Genet 2023; 19:e1010927. [PMID: 37733784 PMCID: PMC10547190 DOI: 10.1371/journal.pgen.1010927] [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: 04/12/2023] [Revised: 10/03/2023] [Accepted: 08/20/2023] [Indexed: 09/23/2023] Open
Abstract
The emergence of fungicide resistance severely threatens crop production by limiting the availability and application of established fungicides. Therefore, it is urgent to identify new fungicidal targets for controlling plant diseases. Here, we characterized the function of a conserved homoserine O-acetyltransferase (HOA) from the rice blast fungus Magnaporthe oryzae that could serve as the candidate antifungal target. Deletion of the MoMET2 and MoCYS2 genes encoding HOAs perturbed the biosynthesis of methionine and S-adenyl methionine, a methyl group donor for epigenetic modifications, and severely attenuated the development and virulence of M. oryzae. The ∆Momet2 mutant is significantly increased in 5-methylcytosine (5mC) modification that represses the expression of genes required for pathogenicity, including MoGLIK and MoCDH-CYT. We further showed that host-induced gene silencing (HIGS) targeting MoMET2 and MoCYS2 effectively controls rice blasts. Our studies revealed the importance of HOA in the development and virulence of M. oryzae, which suggests the potential feasibility of HOA as new targets for novel anti-rice blast measurements.
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Affiliation(s)
- Huimin Li
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Pengcheng Mo
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Jun Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Zhuoer Xie
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Xinyu Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Han Chen
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Leiyun Yang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Muxing Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Haifeng Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
| | - Ping Wang
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Zhengguang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
- The Key Laboratory of Plant Immunity, Nanjing Agricultural University, Nanjing, China
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PoMet3 and PoMet14 associated with sulfate assimilation are essential for conidiogenesis and pathogenicity in Pyricularia oryzae. Curr Genet 2020; 66:765-774. [PMID: 32125494 DOI: 10.1007/s00294-020-01055-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 01/06/2020] [Accepted: 01/21/2020] [Indexed: 12/20/2022]
Abstract
Pyricularia oryzae is the causal agent of blast disease on staple gramineous crops. Sulphur is an essential element for the biosynthesis of cysteine and methionine in fungi. Here, we targeted the P. oryzae PoMET3 encoding the enzyme ATP sulfurylase, and PoMET14 encoding the APS (adenosine-5'-phosphosulphate) kinase that are involved in sulfate assimilation and sulphur-containing amino acids biosynthesis. In P. oryzae, deletion of PoMET3 or PoMET14 separately results in defects of conidiophore formation, significant impairments in conidiation, methionine and cysteine auxotrophy, limited invasive hypha extension, and remarkably reduced virulence on rice and barley. Furthermore, the defects of the null mutants could be restored by supplementing with exogenous cysteine or methionine. Our study explored the biological functions of sulfur assimilation and sulphur-containing amino acids biosynthesis in P. oryzae.
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Shrivastava AK, Pandey S, Yadav S, Mishra Y, Singh PK, Rai R, Singh S, Rai S, Rai LC. Comparative proteomics of wild type, An+ahpC and An∆ahpC strains of Anabaena sp. PCC7120 demonstrates AhpC mediated augmentation of photosynthesis, N2-fixation and modulation of regulatory network of antioxidative proteins. J Proteomics 2016; 140:81-99. [PMID: 27102494 DOI: 10.1016/j.jprot.2016.04.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 04/04/2016] [Accepted: 04/06/2016] [Indexed: 12/30/2022]
Abstract
UNLABELLED Alkylhydroperoxide reductase (AhpC), a 1-Cys peroxiredoxin is well known for maintaining the cellular homeostasis. Present study employs proteome approach to analyze and compare alterations in proteome of Anabaena PCC7120 in overexpressing (An+ahpC), deletion (An∆ahpC) and its wild type. 2-DE based analysis revealed that the major portion of identified protein belongs to energy metabolism, protein folding, modification and stress related proteins and carbohydrate metabolism. The two major traits discernible from An+ahpC were (i) augmentation of photosynthesis and nitrogen fixation (ii) modulation of regulatory network of antioxidative proteins. Increased accumulation of proteins of light reaction, dark reaction, pentose phosphate pathway and electron transfer agent FDX for nitrogenase in An+ahpC and their simultaneous downregulation in AnΔahpC demonstrates its role in augmenting photosynthesis and nitrogen fixation. Proteomic data was nicely corroborated with physiological, biochemical parameters displaying upregulation of nitrogenase (1.6 fold) PSI (1.08) and PSII (2.137) in An+ahpC. Furthermore, in silico analysis not only attested association of AhpC with peroxiredoxins but also with other players of antioxidative defense system viz. thioredoxin and thioredoxin reductase. Above mentioned findings are in agreement with 33-40% and 40-60% better growth performance of An+ahpC over wild type and An∆ahpC respectively under abiotic stresses, suggesting its role in maintenance of metabolic machinery under stress. SIGNIFICANCE Present work explores key role of AhpC in mitigating stress in Anabaena PCC7120 through combined proteomic, biochemical and in silico investigations. This study is the first attempt to analyze and compare alterations in proteome of Anabaena PCC7120 following addition (overexpressing strain An+ahpC) and deletion (mutant An∆ahpC) of AhpC against its wild type. The effort resulted in two major traits in An+ahpC as (i) augmentation of photosynthesis and nitrogen fixation (ii) modulation of regulatory network of antioxidative proteins.
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Affiliation(s)
- Alok K Shrivastava
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Sarita Pandey
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Shivam Yadav
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Yogesh Mishra
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Prashant K Singh
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Ruchi Rai
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Shilpi Singh
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Snigdha Rai
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - L C Rai
- Molecular Biology Section, Centre of Advanced Study in Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India
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Manzanares-Miralles L, Sarikaya-Bayram Ö, Smith EB, Dolan SK, Bayram Ö, Jones GW, Doyle S. Quantitative proteomics reveals the mechanism and consequence of gliotoxin-mediated dysregulation of the methionine cycle in Aspergillus niger. J Proteomics 2016; 131:149-162. [DOI: 10.1016/j.jprot.2015.10.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 10/14/2015] [Accepted: 10/18/2015] [Indexed: 12/25/2022]
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Saint-Macary ME, Barbisan C, Gagey MJ, Frelin O, Beffa R, Lebrun MH, Droux M. Methionine biosynthesis is essential for infection in the rice blast fungus Magnaporthe oryzae. PLoS One 2015; 10:e0111108. [PMID: 25856162 PMCID: PMC4391826 DOI: 10.1371/journal.pone.0111108] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 09/29/2014] [Indexed: 02/02/2023] Open
Abstract
Methionine is a sulfur amino acid standing at the crossroads of several biosynthetic pathways. In fungi, the last step of methionine biosynthesis is catalyzed by a cobalamine-independent methionine synthase (Met6, EC 2.1.1.14). In the present work, we studied the role of Met6 in the infection process of the rice blast fungus, Magnaporthe oryzae. To this end MET6 null mutants were obtained by targeted gene replacement. On minimum medium, MET6 null mutants were auxotrophic for methionine. Even when grown in presence of excess methionine, these mutants displayed developmental defects, such as reduced mycelium pigmentation, aerial hypha formation and sporulation. They also displayed characteristic metabolic signatures such as increased levels of cysteine, cystathionine, homocysteine, S-adenosylmethionine, S-adenosylhomocysteine while methionine and glutathione levels remained unchanged. These metabolic perturbations were associated with the over-expression of MgCBS1 involved in the reversed transsulfuration pathway that metabolizes homocysteine into cysteine and MgSAM1 and MgSAHH1 involved in the methyl cycle. This suggests a physiological adaptation of M. oryzae to metabolic defects induced by the loss of Met6, in particular an increase in homocysteine levels. Pathogenicity assays showed that MET6 null mutants were non-pathogenic on both barley and rice leaves. These mutants were defective in appressorium-mediated penetration and invasive infectious growth. These pathogenicity defects were rescued by addition of exogenous methionine and S-methylmethionine. These results show that M. oryzae cannot assimilate sufficient methionine from plant tissues and must synthesize this amino acid de novo to fulfill its sulfur amino acid requirement during infection.
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Affiliation(s)
| | - Crystel Barbisan
- Biochemistry Department, Bayer CropScience, F-69263, Lyon, France
| | - Marie Josèphe Gagey
- UMR 5240 MAP, UMR 5240 CNRS-UCB-INSA-BCS, Bayer CropScience, F-69263, Lyon, France
| | - Océane Frelin
- UMR 5240 MAP, UMR 5240 CNRS-UCB-INSA-BCS, Bayer CropScience, F-69263, Lyon, France
| | - Roland Beffa
- Biochemistry Department, Bayer CropScience, F-69263, Lyon, France
| | - Marc Henri Lebrun
- UMR 5240 MAP, UMR 5240 CNRS-UCB-INSA-BCS, Bayer CropScience, F-69263, Lyon, France
- * E-mail:
| | - Michel Droux
- UMR 5240 MAP, UMR 5240 CNRS-UCB-INSA-BCS, Bayer CropScience, F-69263, Lyon, France
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Inhibitors of amino acids biosynthesis as antifungal agents. Amino Acids 2014; 47:227-49. [PMID: 25408465 PMCID: PMC4302243 DOI: 10.1007/s00726-014-1873-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 11/05/2014] [Indexed: 12/22/2022]
Abstract
Fungal microorganisms, including the human pathogenic yeast and filamentous fungi, are able to synthesize all proteinogenic amino acids, including nine that are essential for humans. A number of enzymes catalyzing particular steps of human-essential amino acid biosynthesis are fungi specific. Numerous studies have shown that auxotrophic mutants of human pathogenic fungi impaired in biosynthesis of particular amino acids exhibit growth defect or at least reduced virulence under in vivo conditions. Several chemical compounds inhibiting activity of one of these enzymes exhibit good antifungal in vitro activity in minimal growth media, which is not always confirmed under in vivo conditions. This article provides a comprehensive overview of the present knowledge on pathways of amino acids biosynthesis in fungi, with a special emphasis put on enzymes catalyzing particular steps of these pathways as potential targets for antifungal chemotherapy.
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The MET13 methylenetetrahydrofolate reductase gene is essential for infection-related morphogenesis in the rice blast fungus Magnaporthe oryzae. PLoS One 2013; 8:e76914. [PMID: 24116181 PMCID: PMC3792160 DOI: 10.1371/journal.pone.0076914] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 08/27/2013] [Indexed: 11/19/2022] Open
Abstract
Methylenetetrahydrofolate reductases (MTHFRs) play a key role in the biosynthesis of methionine in both prokaryotic and eukaryotic organisms. In this study, we report the identification of a novel T-DNA-tagged mutant WH672 in the rice blast fungus Magnaporthe oryzae, which was defective in vegetative growth, conidiation and pathogenicity. Analysis of the mutation confirmed a single T-DNA insertion upstream of MET13, which encodes a 626-amino-acid protein encoding a MTHFR. Targeted gene deletion of MET13 resulted in mutants that were non-pathogenic and significantly impaired in aerial growth and melanin pigmentation. All phenotypes associated with Δmet13 mutants could be overcome by addition of exogenous methionine. The M. oryzae genome contains a second predicted MTHFR-encoding gene, MET12. The deduced amino acid sequences of Met13 and Met12 share 32% identity. Interestingly, Δmet12 mutants produced significantly less conidia compared with the isogenic wild-type strain and grew very poorly in the absence of methionine, but were fully pathogenic. Deletion of both genes resulted in Δmet13Δmet12 mutants that showed similar phenotypes to single Δmet13 mutants. Taken together, we conclude that the MTHFR gene, MET13, is essential for infection-related morphogenesis by the rice blast fungus M. oryzae.
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Towards defining nutrient conditions encountered by the rice blast fungus during host infection. PLoS One 2012; 7:e47392. [PMID: 23071797 PMCID: PMC3468542 DOI: 10.1371/journal.pone.0047392] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 09/13/2012] [Indexed: 11/29/2022] Open
Abstract
Fungal diseases cause enormous crop losses, but defining the nutrient conditions encountered by the pathogen remains elusive. Here, we generated a mutant strain of the devastating rice pathogen Magnaporthe oryzae impaired for de novo methionine biosynthesis. The resulting methionine-requiring strain grew strongly on synthetic minimal media supplemented with methionine, aspartate or complex mixtures of partially digested proteins, but could not establish disease in rice leaves. Live-cell-imaging showed the mutant could produce normal appressoria and enter host cells but failed to develop, indicating the availability or accessibility of aspartate and methionine is limited in the plant. This is the first report to demonstrate the utility of combining biochemical genetics, plate growth tests and live-cell-imaging to indicate what nutrients might not be readily available to the fungal pathogen in rice host cells.
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Sieńko M, Natorff R, Owczarek S, Olewiecki I, Paszewski A. Aspergillus nidulans genes encoding reverse transsulfuration enzymes belong to homocysteine regulon. Curr Genet 2009; 55:561-70. [PMID: 19685245 DOI: 10.1007/s00294-009-0269-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Revised: 07/29/2009] [Accepted: 07/31/2009] [Indexed: 11/26/2022]
Abstract
Homocysteine is an intermediate in methionine synthesis in Aspergillus nidulans, but it can also be converted to cysteine by the reverse transsulfuration pathway involving cystathionine beta-synthase (CBS) and cystathionine gamma-lyase (CGL). Because homocysteine is toxic to the cell at high concentrations, this pathway also functions as a means of removal of its excess. We found that the transcription of the mecA and mecB genes encoding CBS and CGL was upregulated by excess of homocysteine as well as by shortage of cysteine. Homocysteine induced transcription of both genes when added to the growth medium or overproduced in a regulatory mutant. The derepressing effect of cysteine shortage was observed in some mutants and in the wild-type strain during sulfur starvation. An increase in the level of mecA or mecB transcript roughly parallel with the elevation of the respective enzyme activity. On the basis of the mode of mecA and mecB regulation by homocysteine, these genes may be classified in a group of genes upregulated directly or indirectly by this amino acid. We call this group of genes the "homocysteine regulon".
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Affiliation(s)
- Marzena Sieńko
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawińskiego Str, 02-106, Warsaw, Poland.
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Allen TD, Dawe AL, Nuss DL. Use of cDNA microarrays to monitor transcriptional responses of the chestnut blight fungus Cryphonectria parasitica to infection by virulence-attenuating hypoviruses. EUKARYOTIC CELL 2004; 2:1253-65. [PMID: 14665460 PMCID: PMC326648 DOI: 10.1128/ec.2.6.1253-1265.2003] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hypoviruses are a family of cytoplasmically replicating RNA viruses of the chestnut blight fungus Cryphonectria parasitica. Members of this mycovirus family persistently alter virulence (hypovirulence) and related fungal developmental processes, including asexual and sexual sporulation. In order to gain a better understanding of the molecular basis for these changes, we have developed a C. parasitica cDNA microarray to monitor global transcriptional responses to hypovirus infection. In this report, a spotted DNA microarray representing approximately 2,200 C. parasitica genes was used to monitor changes in the transcriptional profile after infection by the prototypic hypovirus CHV1-EP713. Altered transcript abundance was identified for 295 clones (13.4% of the 2,200 unique cDNAs) as a result of CHV1-EP713 infection-132 up-regulated and 163 down-regulated. In comparison, less than 20 specific C. parasitica genes were previously identified by Northern analysis and mRNA differential display as being responsive to hypovirus infection. A 93% validation rate was achieved between real-time reverse transcription-PCR results and microarray predictions. Differentially expressed genes represented a broad spectrum of biological functions, including stress responses, carbon metabolism, and transcriptional regulation. These findings are consistent with the view that infection by a 12.7-kbp hypovirus RNA results in a persistent reprogramming of a significant portion of the C. parasitica transcriptome. The potential impact of microarray studies on current and future efforts to establish links between hypovirus-mediated changes in cellular gene expression and phenotypes is discussed.
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Affiliation(s)
- Todd D Allen
- Center for Biosystems Research, University of Maryland Biotechnology Institute, College Park, Maryland 20742-4450, USA
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Allen TD, Nuss DL. Specific and common alterations in host gene transcript accumulation following infection of the chestnut blight fungus by mild and severe hypoviruses. J Virol 2004; 78:4145-55. [PMID: 15047830 PMCID: PMC374289 DOI: 10.1128/jvi.78.8.4145-4155.2004] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report the use of a cDNA microarray to monitor global transcriptional responses of the chestnut blight fungus, Cryphonectria parasitica, to infection by mild and severe isolates of virulence-attenuating hypoviruses that share 87 to 93% and 90 to 98% identity at the nucleotide and amino acid levels, respectively. Infection by the mild hypovirus isolate CHV1-Euro7 resulted in differential expression of 166 of the ca. 2,200 genes represented on the microarray (90 upregulated and 76 downregulated). This is roughly half the number of genes scored as differentially expressed after infection by the severe isolate, CHV1-EP713 (295 genes; 132 upregulated and 163 downregulated). Comparison of the lists of genes responsive to infection by the two hypovirus isolates revealed 80 virus-common responsive genes. Infection by CHV1-EP713 also caused changes in gene transcript accumulation that were, in general, of greater magnitude than those observed with CHV1-Euro7 infections. Thus, the host transcriptional response to infection by severe hypovirus CHV1-EP713 appears to be considerably more dynamic than the response to infection by the mild isolate CHV1-Euro7. Real-time reverse transcription-PCR was performed on 39 different clones, with false-positive rates of 3 and 8% observed for the microarray-predicted list of genes responsive to CHV1-EP713 and CHV1-Euro7 infections, respectively. This analysis has allowed an initial assignment for ca. 2,200 unique C. parasitica-expressed genes as being unresponsive to hypovirus infection, selectively responsive to a specific hypovirus, or generally responsive to hypovirus infection.
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Affiliation(s)
- Todd D Allen
- Center for Biosystems Research, University of Maryland Biotechnology Institute, College Park, Maryland 20742-4450, USA
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Lo C, Adachi K, Shuster JR, Hamer JE, Hamer L. The bacterial transposon Tn7 causes premature polyadenylation of mRNA in eukaryotic organisms: TAGKO mutagenesis in filamentous fungi. Nucleic Acids Res 2003; 31:4822-7. [PMID: 12907724 PMCID: PMC169947 DOI: 10.1093/nar/gkg676] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
TAGKO is a Tn7-based transposition system for genome wide mutagenesis in filamentous fungi. The effects of transposon insertion on the expression of TAGKO alleles were examined in Magnaporthe grisea and Mycosphaerella graminicola. Northern analysis showed that stable, truncated transcripts were expressed in the TAGKO mutants. Mapping of the 3'-ends of TAGKO cDNAs revealed that they all contain Tn7 end sequences, regardless of the transposon orientation. Polyadenylation signals characteristic of eukaryotic genes, preceded by stop codons in all frames, are located in both ends of the bacterial transposon. Thus, TAGKO transcripts are prematurely polyadenylated, and truncated proteins are predicted to be translated in the fungal mutants. Depending on the extent of protein truncation, TAGKO mutations in HPD4 (encoding p-hydroxyphenylpyruvate dioxygenase) resulted in tyrosine sensitivity in the two fungi. Similarly, a particular M.grisea CBS1 (encoding cystathionine beta-synthase) TAGKO cDNA failed to complement cysteine auxotrophy in a yeast CBS mutant. TAGKO, therefore, represents a useful tool for in vivo study of truncated gene products in filamentous fungi.
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Affiliation(s)
- Clive Lo
- Paradigm Genetics, Inc., 108 Alexander Drive, Research Triangle Park, NC 27709, USA.
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