SEQUENCE-ANALYSIS AND EXPRESSION STUDIES OF A GENE ENCODING A NOVEL SERINE PLUS ALANINE-RICH PROTEIN IN TRICHODERMA-HARZIANUM

The promoters of constitutive genes have proven themselves to be usefu l parts of expression vectors for genetic engineering in different org anisms. Based on a differential screening of an induced cDNA library, we have used a new approach to isolate constitutively expressed genes which can be used for this purpose. Following this strategy, we have i solated constitutively expressed cDNA clones of the mycoparasitic fung us Trichoderma harzianum. One of these cDNA clones corresponds to a ge ne (cob4) that encodes a novel serine + alanine-rich protein. The pred icted amino acid (aa) sequence of this protein (171 aa, deduced M, 15 564, pi 12.49) displays a motif that is also found in structural prote ins of different species and in a yeast thermoinducible protein. North ern (RNA) blot analysis has demonstrated that cob4 is expressed during growth when glucose or cell walls of a phytopathogenic fungus are pro vided as carbon source. Hybridizations of T. harzianum genomic DNA ind icate that this gene most probably belongs to a multigene family.