The Modes of Action of ChiIII, a Chitinase from Mushroom Coprinopsis cinerea, Shift with Changes in the Length of GlcNAc Oligomers
The Modes of Action of ChiIII, a Chitinase from Mushroom Coprinopsis cinerea, Shift with Changes in the Length of GlcNAc Oligomers
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ChiIII 是一种来自蘑菇灰霉的几丁质酶，其作用模式随着 GlcNAc 寡聚物长度的变化而变化
DOI：
10.1021/acs.jafc.6b03086
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发表时间：
2016
影响因子：
6.1
通讯作者：
Sheng Yuan
中科院分区：
文献类型：
--
作者：
Xin Niu;Cui-Cui Liu;Yuan-Jing Xiong;Ming-Mei Yang;Fei Ma;Zhong-Hua Liu;Sheng Yuan
一个可能的III类几丁质酶(ChiIII)以前被报道主要在平菇的子实体中表达，并且它的表达水平随子实体的成熟而增加。本文进一步报道了ChiIII是一种新的具有内外两种活性的几丁质酶。当底物为(GlcNAc)3-5时，ChiIII呈现外源活性，从(GlcNAc)3-5的还原端依次释放GlcNAc；当底物为(GlcNAc)6-7时，ChiIII的活性转移到内切酶，将甲壳素低聚糖随机分解为各种较短的寡糖。这种作用方式的转变可能与其较强的降解真菌细胞壁中甲壳素的能力有关。预测的结构表明，ChiIII缺乏α+β结构域的插入，但其底物结合裂隙似乎比常见的内切酶深，但比常见的外切酶更浅和更开放，这可能与其外切和内切活性有关。
A putative class III endochitinase (ChiIII) was reported previously to be expressed dominantly in fruiting bodies ofCoprinopsis cinerea, and its expression levels increased with the maturation of the fruiting bodies. This paper further reports that ChiIII is a novel chitinase with exo- and endoactivities. When the substrate was (GlcNAc)3–5, ChiIII exhibited exoactivity, releasing GlcNAc processively from the reducing end of (GlcNAc)3–5; when the substrate was (GlcNAc)6–7, the activity of ChiIII shifted to an endoacting enzyme, randomly splitting chitin oligosaccharides to various shorter oligosaccharides. This shift in the mode of action of ChiIII may be related to its stronger hydrolytic capacity to degrade chitin in fungal cell walls. The predicted structure of ChiIII shows that it lacks the α+β domain insertion; however, its substrate binding cleft seems to be deeper than that of common endochitinases but shallower and more open than that of common exochitinases, which may be related to its exo- and endohydrolytic activities.