Molecular characterization and heterologous expression of an endo-beta-1,6-glucanase gene from the mycoparasitic fungus Trichoderma harzianum.

Hydrolytic enzymes from the filamentous fungus Trichoderma harzianum have been described as critical elements of the mycoparasitic action of Trichoderma against fungal plant pathogens. In this report we describe the first genomic and cDNA clones encoding a beta-1,6-endoglucanase gene. The deduced protein sequence has limited homology with other beta-glucanases. Northern experiments show a marked repression of mRNA accumulation by glucose. The protein has been successfully produced in Saccharomyces cerevisiae upon construction of a transcriptional fusion of the cDNA with a yeast promoter. This S. cerevisiae recombinant strain shows a strong lytic action on agar plates containing beta-1,6-glucan.