Tryptophan 272: an essential determinant of crystalline cellulose degradation by Trichoderma reesei cellobiohydrolase Cel6A

FEBS Letters

Drakenberg, Torbjörn¹  Koivula, Anu³  Kinnari, Tiina³  Ruohonen, Laura³  Rouvinen, Juha²  Teeri, Tuula T.³  Teleman, Anita¹  Harjunpää, Vesa¹  Jones, T.Alwyn² 

[1] VTT Chemical Technology, P.O. Box 1401, FIN-02044 VTT, Espoo, Finland;Department of Molecular Biology, BMC, P.O. Box 590, S-75124 Uppsala, Sweden;VTT Biotechnology and Food Research, P.O. Box 1500, FIN-02044 VTT, Espoo, Finland

关键词: Cellulase;    Crystalline cellulose;    Mutagenesis;    Oligosaccharide;    Sugar binding site;    Ac;    acetate;    BMCC;    bacterial microcrystalline cellulose;    CBD;    cellulose-binding domain;    CBH;    cellobiohydrolase;    DP;    degree of polymerisation;    Glc1-Glc6;    glucose-cellohexaose;    wt;    wild-type;   

DOI  :  10.1016/S0014-5793(98)00596-1

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Trichoderma reesei cellobiohydrolase Cel6A (formerly CBHII) has a tunnel shaped active site with four internal subsites for the glucose units. We have predicted an additional ring stacking interaction for a sixth glucose moiety with a tryptophan residue (W272) found on the domain surface. Mutagenesis of this residue selectively impairs the enzyme function on crystalline cellulose but not on soluble or amorphous substrates. Our data shows that W272 forms an additional subsite at the entrance of the active site tunnel and suggests it has a specialised role in crystalline cellulose degradation, possibly in guiding a glucan chain into the tunnel.

【 授权许可】

Unknown