Glucose does not activate the plasma-membrane-bound H+-ATPase but affects pmaA transcript abundance in Aspergillus nidulans.

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.