Correlation between cellulose binding and activity of cellulose-binding domain mutants of Humicola grisea cellobiohydrolase 1

• Published in: FEBS letters Vol. 581; no. 30; pp. 5891 - 5896
• Main Authors: Takashima, Shou, Ohno, Mitsuhiro, Hidaka, Makoto, Nakamura, Akira, Masaki, Haruhiko, Uozumi, Takeshi
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 22.12.2007
• Subjects: Amino Acid Sequence; CBD; CBH; Cellobiohydrolase; Cellulose - metabolism; Cellulose 1,4-beta-Cellobiosidase - chemistry; Cellulose 1,4-beta-Cellobiosidase - metabolism; Cellulose-binding domain; Chromatography; Crystalline cellulose; EGL; endoglucanase; Humicola grisea; Hydrophobic and Hydrophilic Interactions; Mitosporic Fungi - enzymology; Models, Molecular; Molecular Sequence Data; Mutant Proteins; Mutation - genetics; p-nitrophenol; p-nitrophenyl-β-d-cellobioside; PNP; PNPC; Protein Structure, Tertiary; SDS–PAGE; Sequence Alignment; sodium dodecyl sulfate–polyacrylamide gel electrophoresis; Crystalline cellulose; Humicola grisea; PNP; CBD; PNPC; Cellobiohydrolase; CBH; Cellulose-binding domain; EGL; SDS–PAGE
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/j.febslet.2007.11.068

The cellulose-binding domains (CBDs) of fungal cellulases interact with crystalline cellulose through their hydrophobic flat surface formed by three conserved aromatic amino acid residues. To analyze the functional importance of these residues, we constructed CBD mutants of cellobiohydrolase 1 (CBH1) of the thermophilic fungus Humicola grisea, and examined their cellulose-binding ability and enzymatic activities. High activity on crystalline cellulose correlated with high cellulose-binding ability and was dependent on the combination and configuration of the three aromatic residues. Tyrosine works best in the middle of the flat surface, while tryptophan is the best residue in the two outer positions.