A cAMP-activable Ca 2' -dependent neutral trehalase was identified in germinating conidia of Aspergillus nidulans and Neurospora crassa. Using a PCR approach, Aspergillus nidulans and Neurospora crassa genes encoding homologues of the neutral trehalases found in several yeasts were cloned and sequenced. Disruption of the AntreB gene encoding A. nidulans neutral trehalase revealed that it is responsible for intracellular trehalose mobilization at the onset of conidial germination and that this phenomenon is partially involved in the transient accumulation of glycerol in the germinating conidia. While trehalose mobilization is not essential for the completion of spore germination and filamentous growth in A. nidulans, it is required to achieve wild-type germination rates under carbon limitation suggesting that intracellular trehalose can partially contribute the energy requirements of spore germination. Furthermore, it was shown that trehalose accumulation in A. nidulans can protect germinating conidia against an otherwise lethal heat shock. Since transcription of the treB genes is not increased following a heat-shock but induced upon heat-shock recovery, it is proposed that, in filamentous fungi, mobilization of trehalose during the return to appropriate growth is promoted by transcriptional and post-translational regulatory mechanisms, in particular cAMP-dependent protein kinase-mediated phosphorylation.
Fungal Genet. Newsl. 46 (Supl):
Full conference title:
Fungal Genetics Conference 20th
- Fungal Genetics Conference 20th (1999)