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Signaling governed by G proteins and cAMP is crucial for growth, secondary metabolism and sexual development in Fusarium fujikuroi.

Studt L, Humpf HU, Tudzynski B - PLoS ONE (2013)

Bottom Line: Here we studied the impact of the heterotrimeric G protein and the cAMP-mediated signaling network, including the regulatory subunits of the cAMP-dependent protein kinase (PKA), to study their effect on colony morphology, sexual development and regulation of bikaverins, fusarubins and GAs.In contrast, bikaverin biosynthesis is significantly reduced in ffg1 and ffg3 deletion mutants and positively regulated by FfAC and FfPKA1, while GA biosynthesis depends on the active FfAC and FfPKA2 in an FfG1- and FfG3-independent manner.In addition, we provide evidence that G Protein-mediated/cAMP signaling is important for growth in F. fujikuroi because deletion of ffg3, ffac and ffpka1 resulted in impaired growth on minimal and rich media.

View Article: PubMed Central - PubMed

Affiliation: Institut für Lebensmittelchemie, Westfälische Wilhelms-Universität, Münster, Germany.

ABSTRACT
The plant-pathogenic fungus Fusarium fujikuroi is a notorious rice pathogen causing hyper-elongation of infected plants due to the production of gibberellic acids (GAs). In addition to GAs, F. fujikuroi produces a wide range of other secondary metabolites, such as fusarins, fusaric acid or the red polyketides bikaverins and fusarubins. The recent availability of the fungal genome sequence for this species has revealed the potential of many more putative secondary metabolite gene clusters whose products remain to be identified. However, the complex regulation of secondary metabolism is far from being understood. Here we studied the impact of the heterotrimeric G protein and the cAMP-mediated signaling network, including the regulatory subunits of the cAMP-dependent protein kinase (PKA), to study their effect on colony morphology, sexual development and regulation of bikaverins, fusarubins and GAs. We demonstrated that fusarubin biosynthesis is negatively regulated by at least two Gα subunits, FfG1 and FfG3, which both function as stimulators of the adenylyl cyclase FfAC. Surprisingly, the primary downstream target of the adenylyl cyclase, the PKA, is not involved in the regulation of fusarubins, suggesting that additional, yet unidentified, cAMP-binding protein(s) exist. In contrast, bikaverin biosynthesis is significantly reduced in ffg1 and ffg3 deletion mutants and positively regulated by FfAC and FfPKA1, while GA biosynthesis depends on the active FfAC and FfPKA2 in an FfG1- and FfG3-independent manner. In addition, we provide evidence that G Protein-mediated/cAMP signaling is important for growth in F. fujikuroi because deletion of ffg3, ffac and ffpka1 resulted in impaired growth on minimal and rich media. Finally, sexual crosses of ffg1 mutants showed the importance of a functional FfG1 protein for development of perithecia in the mating strain that carries the MAT1-1 idiomorph.

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Phylogenetic relationship between Fusarium fujikuroi FfG1, FfG2, FfG3 and Gα proteins from other fungi.The phylogram was generated based on multiple sequence alignments [41] using the following G proteins: FadA, GanA and GanB from Aspergillus nidulans[15], [24]; BcG1, BcG2 and BcG3 from Botrytis cinerea[17], [26]; FfG1, FfG2, FfG3 from Fusarium fujikuroi (this paper); GPA1, GPA2 from F. graminearum[19]; FGA1, FGA2 from F. oxysporum[47], [49]; MAGB, MAGC and MAGA from Magnaporthe oryzae[27]; GNA-1, GNA-2 and GNA-3 from Neurospora crassa[46], [48]; GPA1 and GPA2 from Saccharomyces cerevisiae[86] and GPA1, GPA2, GPA3 and GPA4 from Ustilago maydis[87]. The Gα protein class IV GPA2 that is unique for U. maydis was used as out-group. The bar presents 0.6 character change. Organisms: An Aspergillus nidulans, Bc Botrytis cinerea, Ff Fusarium fujikuroi, Fg F. graminearum, Fo F. oxysporum, Mo Magnaporthe grisea, Nc Neurospora crassa, Sc Saccharomyces cerevisiae and Um U. maydis.
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pone-0058185-g001: Phylogenetic relationship between Fusarium fujikuroi FfG1, FfG2, FfG3 and Gα proteins from other fungi.The phylogram was generated based on multiple sequence alignments [41] using the following G proteins: FadA, GanA and GanB from Aspergillus nidulans[15], [24]; BcG1, BcG2 and BcG3 from Botrytis cinerea[17], [26]; FfG1, FfG2, FfG3 from Fusarium fujikuroi (this paper); GPA1, GPA2 from F. graminearum[19]; FGA1, FGA2 from F. oxysporum[47], [49]; MAGB, MAGC and MAGA from Magnaporthe oryzae[27]; GNA-1, GNA-2 and GNA-3 from Neurospora crassa[46], [48]; GPA1 and GPA2 from Saccharomyces cerevisiae[86] and GPA1, GPA2, GPA3 and GPA4 from Ustilago maydis[87]. The Gα protein class IV GPA2 that is unique for U. maydis was used as out-group. The bar presents 0.6 character change. Organisms: An Aspergillus nidulans, Bc Botrytis cinerea, Ff Fusarium fujikuroi, Fg F. graminearum, Fo F. oxysporum, Mo Magnaporthe grisea, Nc Neurospora crassa, Sc Saccharomyces cerevisiae and Um U. maydis.

Mentions: Like most other filamentous fungi F. fujikuroi possesses three Gα subunits, designated as FfG1 (AJ315470), FfG2 (HF563556) and FfG3 (HF563557). These three proteins were identified in the genome of the F. fujikuroi wild-type strain IMI58289 by a BlastP search [45] using the protein sequences of BCG1 (GenBank: CCD53386.1), BCG2 (GenBank: CCD44342.1) and BCG3 (GenBank: CCD47156.1) from Botrytis cinerea as a reference [17], [26]. Gα proteins from different fungi, including F. fujikuroi, can be divided into three main classes based on amino acid sequence similarities: FfG1 groups together with homologues in other fungi into class I, e.g. FadA from A. nidulans[46], MAGB from M. oryzae[27], GNA-1 from N. crassa[47], FGA1 from F. oxysporum[48] and GPA1 from F. graminearum[19]. This class of Gα proteins shares sequence similarities with the mammalian Gαi proteins that are thought to inhibit adenylyl cyclase activity [12]. FfG3 grouped together with homologues in class III, e.g. GanB from A. nidulans[24], MAGA from M. oryzae[27], GNA-3 from N. crassa[49] and GPA2 from F. graminearum[50] all showing high similarity with mammalian Gαs which stimulate adenylyl cyclase activity [12]. Finally, FfG2 belongs to the fungal Gα class II which has no mammalian counterpart [12] (fig. 1).


Signaling governed by G proteins and cAMP is crucial for growth, secondary metabolism and sexual development in Fusarium fujikuroi.

Studt L, Humpf HU, Tudzynski B - PLoS ONE (2013)

Phylogenetic relationship between Fusarium fujikuroi FfG1, FfG2, FfG3 and Gα proteins from other fungi.The phylogram was generated based on multiple sequence alignments [41] using the following G proteins: FadA, GanA and GanB from Aspergillus nidulans[15], [24]; BcG1, BcG2 and BcG3 from Botrytis cinerea[17], [26]; FfG1, FfG2, FfG3 from Fusarium fujikuroi (this paper); GPA1, GPA2 from F. graminearum[19]; FGA1, FGA2 from F. oxysporum[47], [49]; MAGB, MAGC and MAGA from Magnaporthe oryzae[27]; GNA-1, GNA-2 and GNA-3 from Neurospora crassa[46], [48]; GPA1 and GPA2 from Saccharomyces cerevisiae[86] and GPA1, GPA2, GPA3 and GPA4 from Ustilago maydis[87]. The Gα protein class IV GPA2 that is unique for U. maydis was used as out-group. The bar presents 0.6 character change. Organisms: An Aspergillus nidulans, Bc Botrytis cinerea, Ff Fusarium fujikuroi, Fg F. graminearum, Fo F. oxysporum, Mo Magnaporthe grisea, Nc Neurospora crassa, Sc Saccharomyces cerevisiae and Um U. maydis.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585259&req=5

pone-0058185-g001: Phylogenetic relationship between Fusarium fujikuroi FfG1, FfG2, FfG3 and Gα proteins from other fungi.The phylogram was generated based on multiple sequence alignments [41] using the following G proteins: FadA, GanA and GanB from Aspergillus nidulans[15], [24]; BcG1, BcG2 and BcG3 from Botrytis cinerea[17], [26]; FfG1, FfG2, FfG3 from Fusarium fujikuroi (this paper); GPA1, GPA2 from F. graminearum[19]; FGA1, FGA2 from F. oxysporum[47], [49]; MAGB, MAGC and MAGA from Magnaporthe oryzae[27]; GNA-1, GNA-2 and GNA-3 from Neurospora crassa[46], [48]; GPA1 and GPA2 from Saccharomyces cerevisiae[86] and GPA1, GPA2, GPA3 and GPA4 from Ustilago maydis[87]. The Gα protein class IV GPA2 that is unique for U. maydis was used as out-group. The bar presents 0.6 character change. Organisms: An Aspergillus nidulans, Bc Botrytis cinerea, Ff Fusarium fujikuroi, Fg F. graminearum, Fo F. oxysporum, Mo Magnaporthe grisea, Nc Neurospora crassa, Sc Saccharomyces cerevisiae and Um U. maydis.
Mentions: Like most other filamentous fungi F. fujikuroi possesses three Gα subunits, designated as FfG1 (AJ315470), FfG2 (HF563556) and FfG3 (HF563557). These three proteins were identified in the genome of the F. fujikuroi wild-type strain IMI58289 by a BlastP search [45] using the protein sequences of BCG1 (GenBank: CCD53386.1), BCG2 (GenBank: CCD44342.1) and BCG3 (GenBank: CCD47156.1) from Botrytis cinerea as a reference [17], [26]. Gα proteins from different fungi, including F. fujikuroi, can be divided into three main classes based on amino acid sequence similarities: FfG1 groups together with homologues in other fungi into class I, e.g. FadA from A. nidulans[46], MAGB from M. oryzae[27], GNA-1 from N. crassa[47], FGA1 from F. oxysporum[48] and GPA1 from F. graminearum[19]. This class of Gα proteins shares sequence similarities with the mammalian Gαi proteins that are thought to inhibit adenylyl cyclase activity [12]. FfG3 grouped together with homologues in class III, e.g. GanB from A. nidulans[24], MAGA from M. oryzae[27], GNA-3 from N. crassa[49] and GPA2 from F. graminearum[50] all showing high similarity with mammalian Gαs which stimulate adenylyl cyclase activity [12]. Finally, FfG2 belongs to the fungal Gα class II which has no mammalian counterpart [12] (fig. 1).

Bottom Line: Here we studied the impact of the heterotrimeric G protein and the cAMP-mediated signaling network, including the regulatory subunits of the cAMP-dependent protein kinase (PKA), to study their effect on colony morphology, sexual development and regulation of bikaverins, fusarubins and GAs.In contrast, bikaverin biosynthesis is significantly reduced in ffg1 and ffg3 deletion mutants and positively regulated by FfAC and FfPKA1, while GA biosynthesis depends on the active FfAC and FfPKA2 in an FfG1- and FfG3-independent manner.In addition, we provide evidence that G Protein-mediated/cAMP signaling is important for growth in F. fujikuroi because deletion of ffg3, ffac and ffpka1 resulted in impaired growth on minimal and rich media.

View Article: PubMed Central - PubMed

Affiliation: Institut für Lebensmittelchemie, Westfälische Wilhelms-Universität, Münster, Germany.

ABSTRACT
The plant-pathogenic fungus Fusarium fujikuroi is a notorious rice pathogen causing hyper-elongation of infected plants due to the production of gibberellic acids (GAs). In addition to GAs, F. fujikuroi produces a wide range of other secondary metabolites, such as fusarins, fusaric acid or the red polyketides bikaverins and fusarubins. The recent availability of the fungal genome sequence for this species has revealed the potential of many more putative secondary metabolite gene clusters whose products remain to be identified. However, the complex regulation of secondary metabolism is far from being understood. Here we studied the impact of the heterotrimeric G protein and the cAMP-mediated signaling network, including the regulatory subunits of the cAMP-dependent protein kinase (PKA), to study their effect on colony morphology, sexual development and regulation of bikaverins, fusarubins and GAs. We demonstrated that fusarubin biosynthesis is negatively regulated by at least two Gα subunits, FfG1 and FfG3, which both function as stimulators of the adenylyl cyclase FfAC. Surprisingly, the primary downstream target of the adenylyl cyclase, the PKA, is not involved in the regulation of fusarubins, suggesting that additional, yet unidentified, cAMP-binding protein(s) exist. In contrast, bikaverin biosynthesis is significantly reduced in ffg1 and ffg3 deletion mutants and positively regulated by FfAC and FfPKA1, while GA biosynthesis depends on the active FfAC and FfPKA2 in an FfG1- and FfG3-independent manner. In addition, we provide evidence that G Protein-mediated/cAMP signaling is important for growth in F. fujikuroi because deletion of ffg3, ffac and ffpka1 resulted in impaired growth on minimal and rich media. Finally, sexual crosses of ffg1 mutants showed the importance of a functional FfG1 protein for development of perithecia in the mating strain that carries the MAT1-1 idiomorph.

Show MeSH
Related in: MedlinePlus