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The Janus transcription factor HapX controls fungal adaptation to both iron starvation and iron excess.

Gsaller F, Hortschansky P, Beattie SR, Klammer V, Tuppatsch K, Lechner BE, Rietzschel N, Werner ER, Vogan AA, Chung D, Mühlenhoff U, Kato M, Cramer RA, Brakhage AA, Haas H - EMBO J. (2014)

Bottom Line: We further demonstrate that a HapX homodimer and the CCAAT-binding complex (CBC) cooperatively bind an evolutionary conserved DNA motif in a target promoter.The latter reveals the mode of discrimination between general CBC and specific HapX/CBC target genes.Collectively, our study uncovers a novel regulatory mechanism mediating both iron resistance and adaptation to iron starvation by the same transcription factor complex with activating and repressing functions depending on ambient iron availability.

View Article: PubMed Central - PubMed

Affiliation: Division of Molecular Biology, Biocenter, Innsbruck Medical University, Innsbruck, Austria.

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The HapX C-terminus is crucial for adaption to iron starvation but not iron detoxificationA Strains were grown for 48 h at 37°C on agar plates with the given iron concentration.B Production of biomass during iron starvation (−Fe), iron sufficiency (0.03 mM, +Fe), and iron excess (3 mM, hFe), as well as production of siderophores and PpIX under iron starvation was monitored after liquid growth for 24 h at 37°C. The data represent the mean ± SD of biological triplicates; the values were normalized to the wild-type. Statistically significant differences compared to the wild-type are shown in red (two-tailed, unpaired t-test; P < 0.05). Original data ± SD are found in Supplementary Table S1.C Northern blot analyses were performed after liquid growth for 24 h at 37°C under iron limitation (−Fe) or after a subsequent 1-h shift to iron sufficiency (sFe). rRNA is shown as a control for RNA quantity and quality.D Schematic view of the HapX truncations analyzed.Data information: Strains are derivatives of A. fumigatus AfS77.
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fig05: The HapX C-terminus is crucial for adaption to iron starvation but not iron detoxificationA Strains were grown for 48 h at 37°C on agar plates with the given iron concentration.B Production of biomass during iron starvation (−Fe), iron sufficiency (0.03 mM, +Fe), and iron excess (3 mM, hFe), as well as production of siderophores and PpIX under iron starvation was monitored after liquid growth for 24 h at 37°C. The data represent the mean ± SD of biological triplicates; the values were normalized to the wild-type. Statistically significant differences compared to the wild-type are shown in red (two-tailed, unpaired t-test; P < 0.05). Original data ± SD are found in Supplementary Table S1.C Northern blot analyses were performed after liquid growth for 24 h at 37°C under iron limitation (−Fe) or after a subsequent 1-h shift to iron sufficiency (sFe). rRNA is shown as a control for RNA quantity and quality.D Schematic view of the HapX truncations analyzed.Data information: Strains are derivatives of A. fumigatus AfS77.

Mentions: To further characterize HapX domains, we generated A. fumigatus strains expressing different C-terminal hapX truncations (strains hapX464 – hapX158), here untagged, under the control of the endogenous promoter and integrated at the hapX locus in ΔhapX (Fig5D).


The Janus transcription factor HapX controls fungal adaptation to both iron starvation and iron excess.

Gsaller F, Hortschansky P, Beattie SR, Klammer V, Tuppatsch K, Lechner BE, Rietzschel N, Werner ER, Vogan AA, Chung D, Mühlenhoff U, Kato M, Cramer RA, Brakhage AA, Haas H - EMBO J. (2014)

The HapX C-terminus is crucial for adaption to iron starvation but not iron detoxificationA Strains were grown for 48 h at 37°C on agar plates with the given iron concentration.B Production of biomass during iron starvation (−Fe), iron sufficiency (0.03 mM, +Fe), and iron excess (3 mM, hFe), as well as production of siderophores and PpIX under iron starvation was monitored after liquid growth for 24 h at 37°C. The data represent the mean ± SD of biological triplicates; the values were normalized to the wild-type. Statistically significant differences compared to the wild-type are shown in red (two-tailed, unpaired t-test; P < 0.05). Original data ± SD are found in Supplementary Table S1.C Northern blot analyses were performed after liquid growth for 24 h at 37°C under iron limitation (−Fe) or after a subsequent 1-h shift to iron sufficiency (sFe). rRNA is shown as a control for RNA quantity and quality.D Schematic view of the HapX truncations analyzed.Data information: Strains are derivatives of A. fumigatus AfS77.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4232046&req=5

fig05: The HapX C-terminus is crucial for adaption to iron starvation but not iron detoxificationA Strains were grown for 48 h at 37°C on agar plates with the given iron concentration.B Production of biomass during iron starvation (−Fe), iron sufficiency (0.03 mM, +Fe), and iron excess (3 mM, hFe), as well as production of siderophores and PpIX under iron starvation was monitored after liquid growth for 24 h at 37°C. The data represent the mean ± SD of biological triplicates; the values were normalized to the wild-type. Statistically significant differences compared to the wild-type are shown in red (two-tailed, unpaired t-test; P < 0.05). Original data ± SD are found in Supplementary Table S1.C Northern blot analyses were performed after liquid growth for 24 h at 37°C under iron limitation (−Fe) or after a subsequent 1-h shift to iron sufficiency (sFe). rRNA is shown as a control for RNA quantity and quality.D Schematic view of the HapX truncations analyzed.Data information: Strains are derivatives of A. fumigatus AfS77.
Mentions: To further characterize HapX domains, we generated A. fumigatus strains expressing different C-terminal hapX truncations (strains hapX464 – hapX158), here untagged, under the control of the endogenous promoter and integrated at the hapX locus in ΔhapX (Fig5D).

Bottom Line: We further demonstrate that a HapX homodimer and the CCAAT-binding complex (CBC) cooperatively bind an evolutionary conserved DNA motif in a target promoter.The latter reveals the mode of discrimination between general CBC and specific HapX/CBC target genes.Collectively, our study uncovers a novel regulatory mechanism mediating both iron resistance and adaptation to iron starvation by the same transcription factor complex with activating and repressing functions depending on ambient iron availability.

View Article: PubMed Central - PubMed

Affiliation: Division of Molecular Biology, Biocenter, Innsbruck Medical University, Innsbruck, Austria.

Show MeSH
Related in: MedlinePlus