MOLECULAR CHARACTERIZATION OF THE ASPERGILLUS-NIDULANS TREA GENE ENCODING AN ACID TREHALASE REQUIRED FOR GROWTH ON TREHALOSE

Aspergillus nidulans conidiospores contain high levels of the non-redu cing disaccharide trehalose. We show that upon induction of conidiospo re germination, the trehalose pool is rapidly degraded and a glycerol pool is transiently accumulated. A trehalase with an acidic pH optimum was purified from conidiospores. Characterization of the treA gene en coding this trehalase shows that it Is homologous to Saccharomyces cer evisiae vacuolar acid trehalase, the product of the ATH1 gene, and to two related proteins of unknown function identified in Mycobacterium t uberculosis and Mycobacterium leprae. A. nidulans mutants that lack ac id trehalase activity were constructed by gene replacement at the treA locus. Analysis of these mutants suggests that the treA gene product is localized in the conidiospore wall, is required for growth on treha lose as a carbon source, and is not involved in the mobilization of th e intracellular pool of trehalose. Therefore, it is proposed that a cy toplasmic regulatory trehalase is controlling this latter process.