A cellulose-binding module of the Trichoderma reesei @b-mannanase Man5A increases the mannan-hydrolysis of complex substrates

Summary, in English

Endo-@b-1,4-d-mannanases (@b-mannanase; EC 3.2.1.78) are endohydrolases that participate in the degradation of hemicellulose, which is closely associated with cellulose in plant cell walls. The @b-mannanase from Trichoderma reesei (Man5A) is composed of an N-terminal catalytic module and a C-terminal carbohydrate-binding module (CBM). In order to study the properties of the CBM, a construct encoding a mutant of Man5A lacking the part encoding the CBM (Man5A@DCBM), was expressed in T. reesei under the regulation of the Aspergillus nidulans gpdA promoter. The wild-type enzyme was expressed in the same way and both proteins were purified to electrophoretic homogeneity using ion-exchange chromatography. Both enzymes hydrolysed mannopentaose, soluble locust bean gum galactomannan and insoluble ivory nut mannan with similar rates. With a mannan/cellulose complex, however, the deletion mutant lacking the CBM showed a significant decrease in hydrolysis. Binding experiments using activity detection of Man5A and Man5A@DCBM suggests that the CBM binds to cellulose but not to mannan. Moreover, the binding of Man5A to cellulose was compared with that of an endoglucanase (Cel7B) from T. reesei.

• Author: Per Hägglund; Torny Eriksson; Anna Collén; Wim Nerinckx; Marc Claeyssens; Henrik Stålbrand
• Department/s: Biochemistry and Structural Biology
• Publishing year: 2003
• Language: English
• Pages: 37-48
• Publication/Series: Journal of Biotechnology
• Volume: 101
• Issue: 1
• Links: http://dx.doi.org/10.1016/S0168-1656(02)00290-0
• Document type: Journal article
• Publisher: Elsevier
• Topic: Biological Sciences
• Keywords: Carbohydrate-binding module; Hemicellulase; Cellulose; Hemicellulose; Endoglucanase
• Status: Published
• ISBN/ISSN/Other: ISSN: 1873-4863