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Phytotoxin production in Aspergillus terreus is regulated by independent environmental signals.

Gressler M, Meyer F, Heine D, Hortschansky P, Hertweck C, Brock M - Elife (2015)

Bottom Line: Here, signals, mediators, and biological effects of terrein production were studied in the fungus Aspergillus terreus to elucidate the contribution of terrein to ecological competition.Terrein causes fruit surface lesions and inhibits plant seed germination.Independent signal transduction allows complex sensing of the environment and, combined with its broad spectrum of biological activities, terrein provides a prominent example of adapted secondary metabolite production in response to environmental competition.

View Article: PubMed Central - PubMed

Affiliation: Microbial Biochemistry and Physiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute, Jena, Germany.

ABSTRACT
Secondary metabolites have a great potential as pharmaceuticals, but there are only a few examples where regulation of gene cluster expression has been correlated with ecological and physiological relevance for the producer. Here, signals, mediators, and biological effects of terrein production were studied in the fungus Aspergillus terreus to elucidate the contribution of terrein to ecological competition. Terrein causes fruit surface lesions and inhibits plant seed germination. Additionally, terrein is moderately antifungal and reduces ferric iron, thereby supporting growth of A. terreus under iron starvation. In accordance, the lack of nitrogen or iron or elevated methionine levels induced terrein production and was dependent on either the nitrogen response regulators AreA and AtfA or the iron response regulator HapX. Independent signal transduction allows complex sensing of the environment and, combined with its broad spectrum of biological activities, terrein provides a prominent example of adapted secondary metabolite production in response to environmental competition.

No MeSH data available.


Related in: MedlinePlus

pH- and time-dependent Fe(III) reduction by terrein assayed by TPTZ.10 µM FeCl3 were incubated with 4 mM fixed concentration of terrein in acetate buffer in a pH range from 3.0 to 6.0. The analyses were performed from duplicates.DOI:http://dx.doi.org/10.7554/eLife.07861.022
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fig5s3: pH- and time-dependent Fe(III) reduction by terrein assayed by TPTZ.10 µM FeCl3 were incubated with 4 mM fixed concentration of terrein in acetate buffer in a pH range from 3.0 to 6.0. The analyses were performed from duplicates.DOI:http://dx.doi.org/10.7554/eLife.07861.022

Mentions: Since some antioxidative properties of terrein had previously been described (Trabolsy et al., 2014), the ability of terrein in reducing ferric (Fe3+) to ferrous (Fe2+) iron was investigated by using the ferrous iron chelator 2,4,6-tripyridyl-S-triazine (TPTZ). The strong antioxidant ascorbic acid (Elmagirbi et al., 2012) served as control (Figure 5E). Although ascorbic acid showed a much higher reducing potential, terrein was also able to convert ferric to ferrous iron in a concentration-dependent (Figure 5E) and pH-dependent (Figure 5—figure supplement 3) manner with a pH optimum of 3–4. In this respect, we noticed a significant fall in the culture pH under iron limitation from 6.5 to about 3.5, which agrees with the optimum pH for terrein-mediated iron reduction. Thus, since terrein is produced during growth under iron limitation, the combination with a fall in pH could indeed increase iron availability.


Phytotoxin production in Aspergillus terreus is regulated by independent environmental signals.

Gressler M, Meyer F, Heine D, Hortschansky P, Hertweck C, Brock M - Elife (2015)

pH- and time-dependent Fe(III) reduction by terrein assayed by TPTZ.10 µM FeCl3 were incubated with 4 mM fixed concentration of terrein in acetate buffer in a pH range from 3.0 to 6.0. The analyses were performed from duplicates.DOI:http://dx.doi.org/10.7554/eLife.07861.022
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4528345&req=5

fig5s3: pH- and time-dependent Fe(III) reduction by terrein assayed by TPTZ.10 µM FeCl3 were incubated with 4 mM fixed concentration of terrein in acetate buffer in a pH range from 3.0 to 6.0. The analyses were performed from duplicates.DOI:http://dx.doi.org/10.7554/eLife.07861.022
Mentions: Since some antioxidative properties of terrein had previously been described (Trabolsy et al., 2014), the ability of terrein in reducing ferric (Fe3+) to ferrous (Fe2+) iron was investigated by using the ferrous iron chelator 2,4,6-tripyridyl-S-triazine (TPTZ). The strong antioxidant ascorbic acid (Elmagirbi et al., 2012) served as control (Figure 5E). Although ascorbic acid showed a much higher reducing potential, terrein was also able to convert ferric to ferrous iron in a concentration-dependent (Figure 5E) and pH-dependent (Figure 5—figure supplement 3) manner with a pH optimum of 3–4. In this respect, we noticed a significant fall in the culture pH under iron limitation from 6.5 to about 3.5, which agrees with the optimum pH for terrein-mediated iron reduction. Thus, since terrein is produced during growth under iron limitation, the combination with a fall in pH could indeed increase iron availability.

Bottom Line: Here, signals, mediators, and biological effects of terrein production were studied in the fungus Aspergillus terreus to elucidate the contribution of terrein to ecological competition.Terrein causes fruit surface lesions and inhibits plant seed germination.Independent signal transduction allows complex sensing of the environment and, combined with its broad spectrum of biological activities, terrein provides a prominent example of adapted secondary metabolite production in response to environmental competition.

View Article: PubMed Central - PubMed

Affiliation: Microbial Biochemistry and Physiology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute, Jena, Germany.

ABSTRACT
Secondary metabolites have a great potential as pharmaceuticals, but there are only a few examples where regulation of gene cluster expression has been correlated with ecological and physiological relevance for the producer. Here, signals, mediators, and biological effects of terrein production were studied in the fungus Aspergillus terreus to elucidate the contribution of terrein to ecological competition. Terrein causes fruit surface lesions and inhibits plant seed germination. Additionally, terrein is moderately antifungal and reduces ferric iron, thereby supporting growth of A. terreus under iron starvation. In accordance, the lack of nitrogen or iron or elevated methionine levels induced terrein production and was dependent on either the nitrogen response regulators AreA and AtfA or the iron response regulator HapX. Independent signal transduction allows complex sensing of the environment and, combined with its broad spectrum of biological activities, terrein provides a prominent example of adapted secondary metabolite production in response to environmental competition.

No MeSH data available.


Related in: MedlinePlus