Functional role of carbohydrate-binding modules in multi-modular chitinase OfChtII

文献类型： 外文期刊

第一作者： Qu, Mingbo

作者： Qu, Mingbo;Guo, Xiaoxi;Qu, Mingbo;Ando, Toshio;Yang, Qing;Yang, Qing

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期刊名称：JOURNAL OF BIOLOGICAL CHEMISTRY （ 影响因子：3.9； 五年影响因子：4.3 ）

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年卷期： 2024 年 300 卷 9 期

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收录情况： SCI

摘要： The primary distinction between insect and bacterial chitin degradation systems lies in the presence of a multi-modular endo-acting chitinase ChtII, in contrast to a processive exoacting chitinase. Although the essential role of ChtII during insect development and its synergistic action with processive chitinase during chitin degradation has been established, the mechanistic understanding of how it deconstructs chitin remains largely elusive. Here OfChtII from the insect Ostrinia furnacalis was investigated employing comprehensive approaches encompassing biochemical and microscopic analyses. The results demonstrated that OfChtII truncations with more hydrolysis activity, effectively yielding a greater proportion of fibrillary fractions from the compacted chitin substrate. At the single-molecule level, the CBMs in these OfChtII truncations have been shown to primarily facilitate chitin substrate association rather than dissociation. Furthermore, a greater number of CBMs was demonstrated to be essential for the enzyme to effectively bind to chitin substrates with high crystallinity. Through real-time imaging by high-speed atomic force microscopy, the OfChtII-B4C1 truncation with three CBMs was observed to shear chitin fibers, thereby generating fibrillary fragments and deconstructing the compacted chitin structure. This work pioneers in revealing the nanoscale mechanism of endo-acting multi-modular chitinase involved in chitin degradation, which provides an important reference for the rational design of chitinases or other glycoside hydrolases.

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