Limits...
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.

Show MeSH

Related in: MedlinePlus

Opposite regulation of pigments by FfVEL1 and FfG1.The WT, Δffg1 and Δffvel1 were grown in ICI synthetic media in either A) bikaverin biosynthesis-favoring (6 mM glutamine (Gln)) or B) fusarubin biosynthesis-favoring (sodium nitrate (NO3−)) conditions for 3, 4 (for Northern blot analysis) or 7 days (for HPLC analysis). Liquid culture fluid was filtered and used for HPLC-DAD analysis (for details see material & methods). Photograph of flasks containing culture broth of the indicated strains after 7 days of growth and the corresponding HPLC chromatogram at 450 nm. Brackets indicate group of metabolites found in the liquid culture: bikaverins (BIK) and fusarubins (FSR). The scale for Δffvel1 was set to 20 mAU due to a lower accumulation of compounds compared to the other strains.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3585259&req=5

pone-0058185-g004: Opposite regulation of pigments by FfVEL1 and FfG1.The WT, Δffg1 and Δffvel1 were grown in ICI synthetic media in either A) bikaverin biosynthesis-favoring (6 mM glutamine (Gln)) or B) fusarubin biosynthesis-favoring (sodium nitrate (NO3−)) conditions for 3, 4 (for Northern blot analysis) or 7 days (for HPLC analysis). Liquid culture fluid was filtered and used for HPLC-DAD analysis (for details see material & methods). Photograph of flasks containing culture broth of the indicated strains after 7 days of growth and the corresponding HPLC chromatogram at 450 nm. Brackets indicate group of metabolites found in the liquid culture: bikaverins (BIK) and fusarubins (FSR). The scale for Δffvel1 was set to 20 mAU due to a lower accumulation of compounds compared to the other strains.

Mentions: Previously we have shown that the global regulator Velvet negatively regulates bikaverin production in F. fujikuroi: bikaverin biosynthetic genes are dramatically upregulated in the Δffvel1 mutant under inducing conditions [54]. Even under conditions unfavorable for bikaverin production small amounts of bikaverin can be detected in the liquid medium. Studying the impact of the ffvel1 deletion on fusarubin biosynthesis, we observed a strong inhibition under both conditions (fig. 4). Therefore, deletion of ffg1 caused opposing effects compared to the deletion of ffvel1: less bikaverin, but increased formation of fusarubins under inducing, as well as repressing, conditions in contrast to the elevated bikaverin and reduced fusarubin production in the Δffvel1 mutant (fig. 4).


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)

Opposite regulation of pigments by FfVEL1 and FfG1.The WT, Δffg1 and Δffvel1 were grown in ICI synthetic media in either A) bikaverin biosynthesis-favoring (6 mM glutamine (Gln)) or B) fusarubin biosynthesis-favoring (sodium nitrate (NO3−)) conditions for 3, 4 (for Northern blot analysis) or 7 days (for HPLC analysis). Liquid culture fluid was filtered and used for HPLC-DAD analysis (for details see material & methods). Photograph of flasks containing culture broth of the indicated strains after 7 days of growth and the corresponding HPLC chromatogram at 450 nm. Brackets indicate group of metabolites found in the liquid culture: bikaverins (BIK) and fusarubins (FSR). The scale for Δffvel1 was set to 20 mAU due to a lower accumulation of compounds compared to the other strains.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0058185-g004: Opposite regulation of pigments by FfVEL1 and FfG1.The WT, Δffg1 and Δffvel1 were grown in ICI synthetic media in either A) bikaverin biosynthesis-favoring (6 mM glutamine (Gln)) or B) fusarubin biosynthesis-favoring (sodium nitrate (NO3−)) conditions for 3, 4 (for Northern blot analysis) or 7 days (for HPLC analysis). Liquid culture fluid was filtered and used for HPLC-DAD analysis (for details see material & methods). Photograph of flasks containing culture broth of the indicated strains after 7 days of growth and the corresponding HPLC chromatogram at 450 nm. Brackets indicate group of metabolites found in the liquid culture: bikaverins (BIK) and fusarubins (FSR). The scale for Δffvel1 was set to 20 mAU due to a lower accumulation of compounds compared to the other strains.
Mentions: Previously we have shown that the global regulator Velvet negatively regulates bikaverin production in F. fujikuroi: bikaverin biosynthetic genes are dramatically upregulated in the Δffvel1 mutant under inducing conditions [54]. Even under conditions unfavorable for bikaverin production small amounts of bikaverin can be detected in the liquid medium. Studying the impact of the ffvel1 deletion on fusarubin biosynthesis, we observed a strong inhibition under both conditions (fig. 4). Therefore, deletion of ffg1 caused opposing effects compared to the deletion of ffvel1: less bikaverin, but increased formation of fusarubins under inducing, as well as repressing, conditions in contrast to the elevated bikaverin and reduced fusarubin production in the Δffvel1 mutant (fig. 4).

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