College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China.
Laboratory for Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China.
J Agric Food Chem. 2022 May 25;70(20):6168-6176. doi: 10.1021/acs.jafc.2c01577. Epub 2022 May 13.
In the present study, we carried out a comprehensive investigation of glycoside hydrolase (GH) 46 model-chitosanases based on cleavage specificity classification to understand their unknown bifunctional activity. We for the first time show that GH46 chitosanase CsnMHK1 from MH-K1, which was previously thought to be strictly exclusive to chitosan, can hydrolyze both chito- and cello-substrates. We determined the digestion direction of bifunctional chitosanase CsnMHK1 from class III and compared it with class II chitosanase belonging to GH8, providing insight into unique substrate specificities and a new perspective on its reclassification. The results lead us to challenge the current understanding of chitosanase substrate specificity based on GH taxonomy classification and suggest that the prevalence from the common bifunctional activity may have occurred. Altogether, these data contribute to the understanding of chitosanase recognition and hydrolysis toward chito- and cello-substrates, which is valuable for future studies on chitosanases.
在本研究中，我们基于裂解特异性分类对糖苷水解酶 (GH)46 型壳聚糖酶进行了全面研究，以了解其未知的双功能活性。我们首次表明，先前认为严格仅限于壳聚糖的 MH-K1 中的 GH46 壳聚糖酶 CsnMHK1 可以水解壳聚糖和纤维素底物。我们确定了来自 III 类的双功能壳聚糖酶 CsnMHK1 的消化方向，并将其与属于 GH8 的 II 类壳聚糖酶进行了比较，为其独特的底物特异性提供了新的视角，并对其重新分类提出了新的看法。这些结果使我们对基于 GH 分类学分类的壳聚糖酶底物特异性的现有理解提出了挑战，并表明普遍存在的双功能活性可能已经发生。总之，这些数据有助于了解壳聚糖酶对壳聚糖和纤维素底物的识别和水解，这对未来的壳聚糖酶研究具有重要价值。
