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Glucose does not activate the plasma-membrane-bound H+-ATPase but affects pmaA transcript abundance in Aspergillus
B M Abdallah1, T Simões, A R Fernandes
1Section of Microbial Biochemistry, Institute of Biochemical Technology and Microbiology, Vienna, Austria.
Abstract:
The addition of glucose to starved cells of Aspergillus nidulans increased the abundance of the pmaA transcript only transiently (15 min) and to a very low degree (1.3-fold), but strongly decreased its abundance during further incubation. This down-regulation was CreA (carbon catabolite repressor protein)-dependent. Glucose failed to stimulate the plasma membrane (PM)-ATPase activity of A. nidulans, whereas under the same experimental conditions the activity of the enzyme from Saccharomyces cerevisiae was enhanced four-fold within 5-10 min following glucose addition. Glucose stimulated the PM-ATPase of Neurospora crassa only 1.3-fold. Sequence comparison of the C-terminal end of the PM-ATPase from S. cerevisiae, N. crassa, A. nidulans, Fusarium sporotrichoides and Penicillium simplicissimum showed that the two regulatory sites necessary for glucose stimulation in S. cerevisiae are conserved in N. crassa and F. sporotrichoides but not in A. nidulans and P. simplicissimum, and their presence therefore does not correlate with glucose stimulation. We conclude that, in contrast to S. cerevisiae, which has become a paradigm of fungal glucose metabolism, glucose does not up-regulate the activity of the plasma membrane ATPase in the filamentous fungi examined.
Insights
Glucose addition transiently increases pmaA transcript in Aspergillus nidulans but down-regulates plasma membrane ATPase activity. Unlike Saccharomyces cerevisiae, filamentous fungi examined do not show glucose-stimulated PM-ATPase activity.
Area of Science:
- Fungal physiology
- Molecular biology
- Biochemistry
Background:
- Glucose metabolism regulation is crucial in fungi.
- Plasma membrane (PM)-ATPase activity is vital for cellular homeostasis.
- Saccharomyces cerevisiae serves as a model for fungal glucose response.
Purpose of the Study:
- To investigate the effect of glucose on PM-ATPase activity in Aspergillus nidulans.
- To compare glucose-mediated regulation of PM-ATPase across different fungal species.
- To identify potential regulatory mechanisms for PM-ATPase in filamentous fungi.
Main Methods:
- Culturing starved Aspergillus nidulans cells and adding glucose.
- Measuring pmaA transcript abundance and PM-ATPase activity.
- Comparing PM-ATPase sequences across fungal species (S. cerevisiae, N. crassa, A. nidulans, F. sporotrichoides, P. simplicissimum).
Main Results:
- Glucose transiently increased pmaA transcript in A. nidulans (1.3-fold at 15 min) but decreased it later, dependent on CreA (carbon catabolite repressor protein).
- Glucose failed to stimulate PM-ATPase activity in A. nidulans, unlike in S. cerevisiae (4-fold increase).
- Sequence analysis revealed conserved regulatory sites in S. cerevisiae, N. crassa, and F. sporotrichoides, but not A. nidulans and P. simplicissimum, indicating these sites do not correlate with glucose stimulation.
Conclusions:
- Glucose does not up-regulate plasma membrane ATPase activity in the examined filamentous fungi.
- The regulatory mechanisms for PM-ATPase differ significantly between S. cerevisiae and filamentous fungi.
- CreA-dependent down-regulation of pmaA transcript occurs in A. nidulans upon glucose addition.