Addition of substrate-binding domains increases substrate-binding capacityand specific activity of a chitinase from Trichoderma harzianum

Chitinase Chit42 from Trichoderma harzianum CECT 2413 is considered to play ;an important role in the biocontrol activity of this fungus against plant pathogens. Chit42 lacks a chitin-binding domain (ChBD). We have produced hy brid chitinases with stronger chitin-binding capacity by fusing to Chit42 a ChBD from Nicotiana tabacum ChiA chitinase and the cellulose-binding domai n from cellobiohydrolase II of Trichoderma reesei. The chimeric chitinases had similar activities towards soluble substrate but higher hydrolytic acti vity than the native chitinase on high molecular mass insoluble substrates such as ground chitin or chitin-rich fungal cell walls. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.