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 cbhl 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.
Original language | English |
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Pages (from-to) | 253-263 |
Journal | Gene |
Volume | 45 |
Issue number | 3 |
DOIs | |
Publication status | Published - 1 Jan 1986 |
MoE publication type | A1 Journal article-refereed |
Funding
We want to thank warmly Prof. T.-M. Enari, Drs. M.-L. Niku-Paavola, I. Salovuori and T.T. Teeri (VTT Biotechnical Laboratory, Finland), P.L. Jorgensen (D.T.H., Technical University, Denmark) and G. Pettersson (BMC Uppsala University, Sweden) for many useful discussions and for providing unpublished results. The excellent technical assistance of K. Berg, R. Nurmi, P. Veijola-Bailey and P. Vallius is also greatly acknowledged. This work was financially supported by the Neste Oy’s Foundation.
Keywords
- cDNA
- cellobiohydrolase
- filamentous fungus
- gene family
- glycosylation
- introns
- phage λ clones
- Recombinant DNA