Catalytic Efficiency Improvement in Cellobiohydrolase I by Cross-Species Domain Exchange Engineering

文献类型： 外文期刊

第一作者： Xue, Jing

作者： Xue, Jing;Jiang, Xianzhang;Li, Anjing;Huang, Jianzhong;Qin, Lina;Li, Jiaxin;Su, Xiaoyun

作者机构：

关键词： Cellobiohydrolase I (CBHI); cellulose; carbohydrate-binding module (CBM); Trichoderma reesei; Chaetomium thermophilum

期刊名称：INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES （ 影响因子：4.9； 五年影响因子：5.7 ）

ISSN： 1661-6596

年卷期： 2025 年 26 卷 9 期

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收录情况： SCI

摘要： Understanding the molecular mechanisms of cellobiohydrolase I (CBHI), a key enzyme in cellulase complexes, is crucial for developing efficient enzymes for the degradation of lignocellulosic biomasses (LCB). Building on our previous discovery that Chaetomium thermophilum CBHI (C-CBH) exhibits significantly higher specific activity than Trichoderma reesei CBHI (T-CBH), systematic domain-swapping experiments were conducted to elucidate the structural determinants of catalytic efficiency in CBHI. Herein, the carbohydrate-binding modules (CBM) of the CBHIs from Trichoderma reesei (T-CBH) and Chaetomium thermophilum (C-CBH) were interchanged and to obtain two chimeric mutants TC-CBH and CT-CBH. These four CBHs were expressed in T. reesei, and the enzyme properties were analyzed. Comparative characterization revealed that while module exchange preserved native temperature/pH adaptability, it significantly altered substrate specificity and catalytic performance. The CT-CBH variant was identified as the most efficient biocatalyst, exhibiting four key advantages over T-CBH: (1) protein expression levels that far exceed those of T-CBH, (2) specific activity enhanced by 2.6-fold (734.5 U/mu M vs. 282.5 U/mu M on MU-cellobiose), (3) superior degradation capacities for filter paper (1.6-fold) and xylan, and (4) improved binding affinity for crystalline cellulose. These findings establish cross-species domain engineering as a viable strategy for creating high-performance cellulases, providing both mechanistic insights and practical solutions for lignocellulose degradation.

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