THE GLUCOSE REPRESSOR GENE CRE1 OF TRICHODERMA - ISOLATION AND EXPRESSION OF A FULL-LENGTH AND A TRUNCATED MUTANT FORM

The cr el genes of the filamentous fungi Trichoderma reesei and T. har zianum were isolated and characterized, The deduced CREI proteins are 46% identical to the product of the glucose repressor gene creA of Asp ergillus nidulans, encoding a DNA-binding protein with zinc fingers of the C2H2 type. The cre1 promoters contain several sequence elements t hat are identical to the previously identified binding sites for A. ni dulans CREA. Steady-state mRNA levels for cse1 of the T. reesei strain QM9414 varied depending on the carbon source, being low on glucose-co ntaining media. These observations suggest that cre1 expression may be autoregulated. The T. reesei strain Rut-C30, a hyper-producer of cell ulolytic enzymes, was found to express a truncated form of the cre1 ge ne (cre1-1) with an ORF corresponding to a protein of 95 amino acids w ith only one zinc finger. Unlike QM9414 the strain Rut-C30 produced ce llulase mRNAs on glucose-containing medium and transformation of the f ull-length cre1 gene into this strain caused glucose repression of cbh 1 expression, demonstrating that cre1 regulates cellulase expression.