Yan Xinyuan, Waghmare Pankajkumar Ramdas, Meng Xiaoli, Zhang Jianhui, Ding Shaoming, Lei Yu, Yue Jun, Liu Guodong
State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China.
Baiyin Sainuo Biotechnology Co., Ltd., Baiyin 730913, China.
J Fungi (Basel). 2025 Jul 18;11(7):536. doi: 10.3390/jof11070536.
The cellulose-binding domain and inter-domain linker play crucial roles in the degradation of crystalline cellulose by cellulases. Although significant differences exist in the degradation efficiency of cellobiohydrolase I (CBH I) derived from different fungal sources, the relationship between this efficiency diversity and variations in the non-catalytic region remains poorly understood. In this study, we found significant differences in the length and amino acid composition of the linker region of CBH I derived from Sordariomycetes and Eurotiomycetes. By replacing the non-catalytic region of CBH I with the corresponding segment from , the cellulose conversion efficiency of the extracellular enzyme system doubled under the same protein dosage, and the adsorption of CBH I onto cellulose was improved. While replacing only the cellulose-binding domain improved the degradation efficiency of the enzyme system, additional replacement of the linker region resulted in greater enhancement. Improved degradation efficiency due to non-catalytic region replacement was observed under various conditions, including higher cellulose substrate concentration, reduced cellulose crystallinity, use of pretreated straw as a substrate, and degradation at physiological temperature. These findings provide novel insights into the molecular mechanisms underlying crystalline cellulose degradation by filamentous fungi.
纤维素结合结构域和结构域间连接区在纤维素酶降解结晶纤维素过程中发挥着关键作用。尽管源自不同真菌来源的纤维二糖水解酶I（CBH I）在降解效率上存在显著差异，但这种效率多样性与非催化区域变化之间的关系仍知之甚少。在本研究中，我们发现源自粪壳菌纲和散囊菌纲的CBH I连接区在长度和氨基酸组成上存在显著差异。通过用来自[具体来源未提及]的相应片段替换CBH I的非催化区域，在相同蛋白质剂量下，细胞外酶系统的纤维素转化效率提高了一倍，并且CBH I在纤维素上的吸附得到改善。虽然仅替换纤维素结合结构域提高了酶系统的降解效率，但额外替换连接区则带来了更大的提升。在各种条件下，包括更高的纤维素底物浓度、降低的纤维素结晶度、使用预处理秸秆作为底物以及在生理温度下进行降解，均观察到由于非催化区域替换而导致的降解效率提高。这些发现为丝状真菌降解结晶纤维素的分子机制提供了新的见解。
