title: Binding of cellulose binding modules reveal differences between cellulose substrates.
abstract: The interaction between cellulase enzymes and their substrates is of central importance to several technological and scientific challenges. Here we report that the binding of cellulose binding modules (CBM) from Trichoderma reesei cellulases Cel6A and Cel7A show a major difference in how they interact with substrates originating from wood compared to bacterial cellulose. We found that the CBM from TrCel7A recognizes the two substrates differently and as a consequence shows an unexpected way of binding. We show that the substrate has a large impact on the exchange rate of the studied CBM, and moreover, CBM-TrCel7A seems to have an additional mode of binding on wood derived cellulose but not on cellulose originating from bacterial source. This mode is not seen in double CBM (DCBM) constructs comprising both CBM-TrCel7A and CBM-TrCel6A. The linker length of DCBMs affects the binding properties, and slows down the exchange rates of the proteins and thus, can be used to analyze the differences between the single CBM. These results have impact on the cellulase research and offer new understanding on how these industrially relevant enzymes act.
authors.affiliation: School of Science, Aalto University, P. O. Box 11100, FI-00076, Aalto, Finland.|School of Chemical Technology, Aalto University, P.O. Box 16100, FI-00076, Aalto, Finland.|VTT, Technical Research Centre of Finland, Bio and process technology, P.O.Box 1000, FIN-02044 VTT, Finland.
authors.forename: Suvi
authors.initials: S
authors.lastname: Arola
authors.affiliation: School of Chemical Technology, Aalto University, P.O. Box 16100, FI-00076, Aalto, Finland.
authors.forename: Markus B
authors.initials: MB
authors.lastname: Linder
mesh_terms: D001665:Binding Sites; D020134:Catalytic Domain; D002480:Cellulase / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry*; D043366:Cellulose 1,4-beta-Cellobiosidase / Q000737:chemistry; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry; D005656:Fungal Proteins / Q000737:chemistry*; D011485:Protein Binding; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013816:Thermodynamics; D014242:Trichoderma / Q000201:enzymology*
chemical_list: D005656:Fungal Proteins; D002482:Cellulose; D002480:Cellulase; D043364:Endo-1,4-beta Xylanases; D043366:Cellulose 1,4-beta-Cellobiosidase