Chemical epigenetic manipulation was applied to the zoanthid-derived fungus Cochliobolus lunatus(TA26-46)with a histone deacetylation modifier(100μmol L^(−1) nicotinamide),resulting in the isolation of a new 14-membe...Chemical epigenetic manipulation was applied to the zoanthid-derived fungus Cochliobolus lunatus(TA26-46)with a histone deacetylation modifier(100μmol L^(−1) nicotinamide),resulting in the isolation of a new 14-membered resorcylic acid lactone named 7′(Z)-zeaenol(1),together with six known analogues(2−7)from the treated broth.The planar structure of 1 was determined by comprehensive NMR spectroscopy and HRESIMS data.The absolute configuration of 1 was elucidated by ECD spectrum,^(13)C NMR shift calculations,and on the basis of biogenetic considerations.Compound 5 exhibited cytotoxic activity against the human tumor cell lines A549,HCT-116,HT-29,Hela,MCF-7,and K562 with the IC_(50) values ranging from 2.54 to 7.44μmolL^(−1).展开更多
Phytopathogenic fungi are heterotrophic organisms that excrete a complex array of enzymes for digestion of plant host tissues. Regulation and coordination of extracellular enzyme production, according to growth condit...Phytopathogenic fungi are heterotrophic organisms that excrete a complex array of enzymes for digestion of plant host tissues. Regulation and coordination of extracellular enzyme production, according to growth conditions and fungus nutritional needs, may be controlled by conserved eukaryotic signaling elements such as G-protein subunits and mitogen-activated protein kinase (MAPK). These pathways are known to mediate a complex set of responses in fungi involved in development, reproduction and pathogenicity. Here, we used a series of mutants, deficient in G-protein α (cga1) or/and β subunits or in MAPK, to test their contribution to the ability of Cochliobolus heterostrophus to utilize different carbon sources. In saprophytic culture, the G-protein α subunit mutant strains had WT levels of cellulase, pectinase and protease degradation activities, but it grew significantly slower on minimal medium containing maltose. This weakened ability implies an essential role of the CGA1 signaling in some poor nutritional environments. Remarkably, the MAPK null mutant failed to achieve the WT (and cga1) growth rate on cellulose as a sole carbon and did not grow at all for the first seven days of culture. An enzymatic activity test revealed that this strain significantly reduced cellulose extracellular degradation activity when grew on this medium. Deficiency in the MAPK encoding gene also led to reduced ability to grow on pectin, protein sources and maltose as a sole carbon. The evidence presented indicates a significant and nutrient-specific role of the G-protein and MAPK pathways in mediating growth of this fungus in different environments.展开更多
Conserved eukaryotic signaling proteins participate in development and disease in plant pathogenic fungi. Mutants in CGA1, a heterotrimeric G protein Ga subunit gene of the maize pathogen Cochliobolus heterostrophus, ...Conserved eukaryotic signaling proteins participate in development and disease in plant pathogenic fungi. Mutants in CGA1, a heterotrimeric G protein Ga subunit gene of the maize pathogen Cochliobolus heterostrophus, are defective in several developmental pathways. Conidia from CGA1 mutants germinate as abnormal, straight-growing germ tubes that form few appressoria, and the mutants are female-sterile. The CGA1, Gα subunit, is also thought to act as a down regulator of hydrophobin expression and secretion in this fungus and in related Ascomycete species. Although cga1 mutants can cause normal lesions on plants there are host physiology conditions under which full virulence requires signal transduction through CGA1-mediated pathways. A Gα activated mutant, cga1Q204L was created to help establish the role of CGA1 in growth and development, and in mediating hydrophobin secretion and expression. The activated Gα allele was transformed into a cga1 mutant strain. The transgenic lines showed phenotypes resembling the null mutant in development, sporulation and hydrophobicity, indicating a possible role for CGA1 as a stabilizer of these traits.展开更多
Cochliobolus heterostrophus is an agriculturally important and emerging model pathogen for studying the signaling hierarchies' role during the maize host colonization. In particular, G-protein and MAPK-linked path...Cochliobolus heterostrophus is an agriculturally important and emerging model pathogen for studying the signaling hierarchies' role during the maize host colonization. In particular, G-protein and MAPK-linked pathways are playing a major role during pathogenesis. Although gene disruption studies are an efficient way of identifying the role of these cascades, differentiating between the mutant strains’ virulence ability may become an intricate task. For example, in C. heterostrophus, mutants in a G-protein α subunit gene, cga1, are defective in mating and appressorium formation, but unlike mutants in homologous genes in other fungal pathogens, the cga1 mutants remained highly virulent to corn under some host physiological conditions. Here, we used the cga1 strain as a model for developing an in vivo sensitive and accurate pathogenicity assay. A detailed and well controlled analysis of wild type (WT) and cga1 pathogenic behavior revealed that detached leaves are significantly more vulnerable to the disease than intact ones. In intact leaves, cga1 mutants were less infective of maize under most conditions. This difference was maximized when the first seedling leaf was chosen for inoculation and when the infected leaves, with spores or mycelia fragments droplets, were incubated for a period of four days. This optimal condition set enabled us to classify the C. heterostrophus G-protein signaling mutants deficient in α, β or both subunits in order of decreasing virulence: WT > cga1> cgb1> cga1 cgb1. The method presented proved to be accurate and sensitive enough to identify even slight variations in virulence. Moreover, it could be modified for use in studies of other foliar phytoparasitic fungi.展开更多
G-protein-linked pathways have evolved to allow responses to extracellular agonists (hormones, neurotransmitters, odors, chemoattractants, light and nutrients) in eukaryotic cells, ranging from simpler systems, includ...G-protein-linked pathways have evolved to allow responses to extracellular agonists (hormones, neurotransmitters, odors, chemoattractants, light and nutrients) in eukaryotic cells, ranging from simpler systems, including yeasts, filamentous fungi and slime molds, to more complex organisms, such as mammals. Although the role of G-protein and mitogen-activated protein kinase (MAPK) in filamentous fungi has been studied for over a decade, downstream elements are less known, and the study of target genes has evolved mainly in recent years. Here, we examined the involvement of G-protein subunits and MAPK in controlling the expression of two distinct target genes. These genes were selected from an array database according to their unique expression profile and the role of closely related genes found in other Ascomycetes. One of these genes is BPH, which encodes the enzyme responsible for cytochrome P450-dependent benzoate hydroxylation in microsomes. The other gene is CIPA, which encodes isoflavone reductase (IfR), an enzyme involved in the synthesis of phytoalexin, which catalyzes an intermediate step in pisatin biosynthesis. The expression profile of these two genes was determined in a series of signaling deficiency mutants that were grown on different media using a DNA microarray. Comparison of the expression profile in the two wild type strains and mutants deficient in the G-protein α or β subunits or in MAPK, revealed a unique control mechanism for the BPH and CIPA genes. The two genes are highly expressed during the infection of the host plant leaves and may associate with the fungal response to the host. Signaling via G-protein or MAPK was shown to be related to cascades that altered the expression of these genes in response to the growth condition. This work demonstrates that signal transduction pathways are controlling genes that, although sharing an environmental dependent response, participate in distinct biosynthesis pathways. Moreover, the transcriptional profile may point to distinct and shared roles of the signaling components.展开更多
基金supported by the National Natural Science Foundation of China(Nos.81673350,81703411,41776156)the National Science and Technology Major Project for Significant New Drugs Development,China(No.2018ZX09735-004)+1 种基金the Fundamental Research Funds for the Central Universities of China(No.201962002)the Taishan Scholars Program,China.
文摘Chemical epigenetic manipulation was applied to the zoanthid-derived fungus Cochliobolus lunatus(TA26-46)with a histone deacetylation modifier(100μmol L^(−1) nicotinamide),resulting in the isolation of a new 14-membered resorcylic acid lactone named 7′(Z)-zeaenol(1),together with six known analogues(2−7)from the treated broth.The planar structure of 1 was determined by comprehensive NMR spectroscopy and HRESIMS data.The absolute configuration of 1 was elucidated by ECD spectrum,^(13)C NMR shift calculations,and on the basis of biogenetic considerations.Compound 5 exhibited cytotoxic activity against the human tumor cell lines A549,HCT-116,HT-29,Hela,MCF-7,and K562 with the IC_(50) values ranging from 2.54 to 7.44μmolL^(−1).
文摘Phytopathogenic fungi are heterotrophic organisms that excrete a complex array of enzymes for digestion of plant host tissues. Regulation and coordination of extracellular enzyme production, according to growth conditions and fungus nutritional needs, may be controlled by conserved eukaryotic signaling elements such as G-protein subunits and mitogen-activated protein kinase (MAPK). These pathways are known to mediate a complex set of responses in fungi involved in development, reproduction and pathogenicity. Here, we used a series of mutants, deficient in G-protein α (cga1) or/and β subunits or in MAPK, to test their contribution to the ability of Cochliobolus heterostrophus to utilize different carbon sources. In saprophytic culture, the G-protein α subunit mutant strains had WT levels of cellulase, pectinase and protease degradation activities, but it grew significantly slower on minimal medium containing maltose. This weakened ability implies an essential role of the CGA1 signaling in some poor nutritional environments. Remarkably, the MAPK null mutant failed to achieve the WT (and cga1) growth rate on cellulose as a sole carbon and did not grow at all for the first seven days of culture. An enzymatic activity test revealed that this strain significantly reduced cellulose extracellular degradation activity when grew on this medium. Deficiency in the MAPK encoding gene also led to reduced ability to grow on pectin, protein sources and maltose as a sole carbon. The evidence presented indicates a significant and nutrient-specific role of the G-protein and MAPK pathways in mediating growth of this fungus in different environments.
文摘Conserved eukaryotic signaling proteins participate in development and disease in plant pathogenic fungi. Mutants in CGA1, a heterotrimeric G protein Ga subunit gene of the maize pathogen Cochliobolus heterostrophus, are defective in several developmental pathways. Conidia from CGA1 mutants germinate as abnormal, straight-growing germ tubes that form few appressoria, and the mutants are female-sterile. The CGA1, Gα subunit, is also thought to act as a down regulator of hydrophobin expression and secretion in this fungus and in related Ascomycete species. Although cga1 mutants can cause normal lesions on plants there are host physiology conditions under which full virulence requires signal transduction through CGA1-mediated pathways. A Gα activated mutant, cga1Q204L was created to help establish the role of CGA1 in growth and development, and in mediating hydrophobin secretion and expression. The activated Gα allele was transformed into a cga1 mutant strain. The transgenic lines showed phenotypes resembling the null mutant in development, sporulation and hydrophobicity, indicating a possible role for CGA1 as a stabilizer of these traits.
文摘Cochliobolus heterostrophus is an agriculturally important and emerging model pathogen for studying the signaling hierarchies' role during the maize host colonization. In particular, G-protein and MAPK-linked pathways are playing a major role during pathogenesis. Although gene disruption studies are an efficient way of identifying the role of these cascades, differentiating between the mutant strains’ virulence ability may become an intricate task. For example, in C. heterostrophus, mutants in a G-protein α subunit gene, cga1, are defective in mating and appressorium formation, but unlike mutants in homologous genes in other fungal pathogens, the cga1 mutants remained highly virulent to corn under some host physiological conditions. Here, we used the cga1 strain as a model for developing an in vivo sensitive and accurate pathogenicity assay. A detailed and well controlled analysis of wild type (WT) and cga1 pathogenic behavior revealed that detached leaves are significantly more vulnerable to the disease than intact ones. In intact leaves, cga1 mutants were less infective of maize under most conditions. This difference was maximized when the first seedling leaf was chosen for inoculation and when the infected leaves, with spores or mycelia fragments droplets, were incubated for a period of four days. This optimal condition set enabled us to classify the C. heterostrophus G-protein signaling mutants deficient in α, β or both subunits in order of decreasing virulence: WT > cga1> cgb1> cga1 cgb1. The method presented proved to be accurate and sensitive enough to identify even slight variations in virulence. Moreover, it could be modified for use in studies of other foliar phytoparasitic fungi.
文摘G-protein-linked pathways have evolved to allow responses to extracellular agonists (hormones, neurotransmitters, odors, chemoattractants, light and nutrients) in eukaryotic cells, ranging from simpler systems, including yeasts, filamentous fungi and slime molds, to more complex organisms, such as mammals. Although the role of G-protein and mitogen-activated protein kinase (MAPK) in filamentous fungi has been studied for over a decade, downstream elements are less known, and the study of target genes has evolved mainly in recent years. Here, we examined the involvement of G-protein subunits and MAPK in controlling the expression of two distinct target genes. These genes were selected from an array database according to their unique expression profile and the role of closely related genes found in other Ascomycetes. One of these genes is BPH, which encodes the enzyme responsible for cytochrome P450-dependent benzoate hydroxylation in microsomes. The other gene is CIPA, which encodes isoflavone reductase (IfR), an enzyme involved in the synthesis of phytoalexin, which catalyzes an intermediate step in pisatin biosynthesis. The expression profile of these two genes was determined in a series of signaling deficiency mutants that were grown on different media using a DNA microarray. Comparison of the expression profile in the two wild type strains and mutants deficient in the G-protein α or β subunits or in MAPK, revealed a unique control mechanism for the BPH and CIPA genes. The two genes are highly expressed during the infection of the host plant leaves and may associate with the fungal response to the host. Signaling via G-protein or MAPK was shown to be related to cascades that altered the expression of these genes in response to the growth condition. This work demonstrates that signal transduction pathways are controlling genes that, although sharing an environmental dependent response, participate in distinct biosynthesis pathways. Moreover, the transcriptional profile may point to distinct and shared roles of the signaling components.
