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The two-component sensor kinase TcsC and its role in stress resistance of the human-pathogenic mold Aspergillus fumigatus.

McCormick A, Jacobsen ID, Broniszewska M, Beck J, Heesemann J, Ebel F - PLoS ONE (2012)

Bottom Line: Both hyperosmotic stress and treatment with fludioxonil result in a TcsC-dependent phosphorylation of SakA, the final MAP kinase in the high osmolarity glycerol (HOG) pathway, confirming a role for TcsC in this signaling pathway.Several types of stress, such as hypoxia, exposure to farnesol or elevated concentrations of certain divalent cations, trigger a differentiation in A. fumigatus toward a "fluffy" growth phenotype resulting in white, dome-shaped colonies.Although TcsC plays a role in the adaptation of A. fumigatus to hypoxia, it seems to be dispensable for virulence.

View Article: PubMed Central - PubMed

Affiliation: Max-von-Pettenkofer-Institut, Ludwig-Maximilians-University, Munich, Germany.

ABSTRACT
Two-component signaling systems are widespread in bacteria, but also found in fungi. In this study, we have characterized TcsC, the only Group III two-component sensor kinase of Aspergillus fumigatus. TcsC is required for growth under hyperosmotic stress, but dispensable for normal growth, sporulation and conidial viability. A characteristic feature of the ΔtcsC mutant is its resistance to certain fungicides, like fludioxonil. Both hyperosmotic stress and treatment with fludioxonil result in a TcsC-dependent phosphorylation of SakA, the final MAP kinase in the high osmolarity glycerol (HOG) pathway, confirming a role for TcsC in this signaling pathway. In wild type cells fludioxonil induces a TcsC-dependent swelling and a complete, but reversible block of growth and cytokinesis. Several types of stress, such as hypoxia, exposure to farnesol or elevated concentrations of certain divalent cations, trigger a differentiation in A. fumigatus toward a "fluffy" growth phenotype resulting in white, dome-shaped colonies. The ΔtcsC mutant is clearly more susceptible to these morphogenetic changes suggesting that TcsC normally antagonizes this process. Although TcsC plays a role in the adaptation of A. fumigatus to hypoxia, it seems to be dispensable for virulence.

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Related in: MedlinePlus

Impact of fludioxonil on A. fumigatus germ tubes.Conidia of the ΔtcsC mutant (panels A, C, E, G) and its parental strain AfS35 (panels B, D, F, H) were seeded on glass cover slips and incubated overnight in AMM at 30°C. The resulting germ tubes were treated with 1 µg/ml fludioxonil for 2 h (A, B), 4 h (C, D) and 6 h (E–H) at 37°C. A DAPI staining is shown in panels G and H. Arrows indicate lysed cells that lack intracellular nuclei and are associated with amorphous extracellular material. All bars represent 10 µm.
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pone-0038262-g004: Impact of fludioxonil on A. fumigatus germ tubes.Conidia of the ΔtcsC mutant (panels A, C, E, G) and its parental strain AfS35 (panels B, D, F, H) were seeded on glass cover slips and incubated overnight in AMM at 30°C. The resulting germ tubes were treated with 1 µg/ml fludioxonil for 2 h (A, B), 4 h (C, D) and 6 h (E–H) at 37°C. A DAPI staining is shown in panels G and H. Arrows indicate lysed cells that lack intracellular nuclei and are associated with amorphous extracellular material. All bars represent 10 µm.

Mentions: To obtain more information on the impact of fludioxonil at the level of individual cells, germlings were incubated in the presence of 1 µg/ml fludioxonil. No obvious morphological changes were apparent after 2 h (Figure 4A and B), but 4 h and 6 h after addition of fludioxonil growth of the wild type (Figure 4D and F) and the complemented mutant (data not shown) stopped and the cells began to swell, whereas the growth and morphology of the ΔtcsC mutant remained normal (Figure 4C and E). Similar results were obtained with 25 µg/ml iprodione (data not shown). DAPI staining of germlings treated with fludioxonil for 6 h revealed a normal distribution of nuclei in hyphae of the mutant (Figure 4G), but an unusually high number of nuclei in the swollen cells of the wild type (Figure 4H) and the complemented mutant (data not shown).


The two-component sensor kinase TcsC and its role in stress resistance of the human-pathogenic mold Aspergillus fumigatus.

McCormick A, Jacobsen ID, Broniszewska M, Beck J, Heesemann J, Ebel F - PLoS ONE (2012)

Impact of fludioxonil on A. fumigatus germ tubes.Conidia of the ΔtcsC mutant (panels A, C, E, G) and its parental strain AfS35 (panels B, D, F, H) were seeded on glass cover slips and incubated overnight in AMM at 30°C. The resulting germ tubes were treated with 1 µg/ml fludioxonil for 2 h (A, B), 4 h (C, D) and 6 h (E–H) at 37°C. A DAPI staining is shown in panels G and H. Arrows indicate lysed cells that lack intracellular nuclei and are associated with amorphous extracellular material. All bars represent 10 µm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3366943&req=5

pone-0038262-g004: Impact of fludioxonil on A. fumigatus germ tubes.Conidia of the ΔtcsC mutant (panels A, C, E, G) and its parental strain AfS35 (panels B, D, F, H) were seeded on glass cover slips and incubated overnight in AMM at 30°C. The resulting germ tubes were treated with 1 µg/ml fludioxonil for 2 h (A, B), 4 h (C, D) and 6 h (E–H) at 37°C. A DAPI staining is shown in panels G and H. Arrows indicate lysed cells that lack intracellular nuclei and are associated with amorphous extracellular material. All bars represent 10 µm.
Mentions: To obtain more information on the impact of fludioxonil at the level of individual cells, germlings were incubated in the presence of 1 µg/ml fludioxonil. No obvious morphological changes were apparent after 2 h (Figure 4A and B), but 4 h and 6 h after addition of fludioxonil growth of the wild type (Figure 4D and F) and the complemented mutant (data not shown) stopped and the cells began to swell, whereas the growth and morphology of the ΔtcsC mutant remained normal (Figure 4C and E). Similar results were obtained with 25 µg/ml iprodione (data not shown). DAPI staining of germlings treated with fludioxonil for 6 h revealed a normal distribution of nuclei in hyphae of the mutant (Figure 4G), but an unusually high number of nuclei in the swollen cells of the wild type (Figure 4H) and the complemented mutant (data not shown).

Bottom Line: Both hyperosmotic stress and treatment with fludioxonil result in a TcsC-dependent phosphorylation of SakA, the final MAP kinase in the high osmolarity glycerol (HOG) pathway, confirming a role for TcsC in this signaling pathway.Several types of stress, such as hypoxia, exposure to farnesol or elevated concentrations of certain divalent cations, trigger a differentiation in A. fumigatus toward a "fluffy" growth phenotype resulting in white, dome-shaped colonies.Although TcsC plays a role in the adaptation of A. fumigatus to hypoxia, it seems to be dispensable for virulence.

View Article: PubMed Central - PubMed

Affiliation: Max-von-Pettenkofer-Institut, Ludwig-Maximilians-University, Munich, Germany.

ABSTRACT
Two-component signaling systems are widespread in bacteria, but also found in fungi. In this study, we have characterized TcsC, the only Group III two-component sensor kinase of Aspergillus fumigatus. TcsC is required for growth under hyperosmotic stress, but dispensable for normal growth, sporulation and conidial viability. A characteristic feature of the ΔtcsC mutant is its resistance to certain fungicides, like fludioxonil. Both hyperosmotic stress and treatment with fludioxonil result in a TcsC-dependent phosphorylation of SakA, the final MAP kinase in the high osmolarity glycerol (HOG) pathway, confirming a role for TcsC in this signaling pathway. In wild type cells fludioxonil induces a TcsC-dependent swelling and a complete, but reversible block of growth and cytokinesis. Several types of stress, such as hypoxia, exposure to farnesol or elevated concentrations of certain divalent cations, trigger a differentiation in A. fumigatus toward a "fluffy" growth phenotype resulting in white, dome-shaped colonies. The ΔtcsC mutant is clearly more susceptible to these morphogenetic changes suggesting that TcsC normally antagonizes this process. Although TcsC plays a role in the adaptation of A. fumigatus to hypoxia, it seems to be dispensable for virulence.

Show MeSH
Related in: MedlinePlus