title: Homology between cellulase genes of Trichoderma reesei: complete nucleotide sequence of the endoglucanase I gene.
abstract: The filamentous fungus Trichoderma reesei produces several endoglucanases (EG) and cellobiohydrolases (CBH) which are involved in cellulose hydrolysis in a complex synergistic manner. We have cloned and sequenced the gene and the full-length cDNA coding for the major endoglucanase EG-I, and compared this to the cbh1 gene sequence to clarify the relationship between the EG and CBH classes of cellulases. The deduced 437-amino acids (aa) long EG-I protein with a 22-aa long signal peptide is 45% identical in aa sequence with CBH-I. The best conserved region is found at the C terminus and shows about 70% homology. The data suggest that the two enzymes have arisen from a common ancestor by gene duplication. Despite this, the intron positions have not been conserved in these genes which both contain two short introns. The deduced EG-I sequence contains six putative N-glycosylation sites, and a putative O-glycosylated region is found near the C terminus, closely resembling a similar region at the C terminus of CBH-I. Comparison of the aa sequences suggests that the evolutionary divergence of EG-I from CBH-I has involved four separate 10-20 aa "deletions" from the ancestral protein.
mesh_terms: D000595:Amino Acid Sequence; D001230:Aspergillus / Q000235:genetics; D001483:Base Sequence; D002480:Cellulase / Q000235:genetics*; D004247:DNA / Q000302:isolation & purification; D004926:Escherichia coli / Q000235:genetics; D005796:Genes; D005800:Genes, Fungal; D003904:Mitosporic Fungi / Q000235:genetics*; D009492:Neurospora crassa / Q000235:genetics; D012440:Saccharomyces / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D014242:Trichoderma / Q000201:enzymology / Q000235:genetics*
chemical_list: D004247:DNA; D002480:Cellulase