Functional analysis of the chitin-binding domain of a family 19 chitinase from Streptomyces griseus HUT6037:: Substrate-binding affinity and cis-dominant increase of antifungal function
Functional analysis of the chitin-binding domain of a family 19 chitinase from Streptomyces griseus HUT6037:: Substrate-binding affinity and cis-dominant increase of antifungal function
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DOI：
10.1271/bbb.66.1084
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发表时间：
2002-05-01
影响因子：
1.6
通讯作者：
Itoh, Y
中科院分区：
文献类型：
--
作者：
Itoh, Y;Kawase, T;Itoh, Y
几丁质酶C（Chitinase C，ChiC）是在灰色链霉菌（Streptomyces griseus）HUT 6037中发现的第一个细菌家族19几丁质酶。虽然它与植物家族19几丁质酶在催化结构域中具有显著的相似性，但其N-末端几丁质结合结构域（ChBD（ChiC））与植物酶的那些不同。ChBD（ChiC）和催化结构域（CatD（ChiC））以及完整的ChiC在L. coli中，并纯化至均一。结合实验和等温滴定量热分析表明，ChBD（ChiC）结合不溶性甲壳素，可溶性甲壳素，纤维素，和N-乙酰基hitohexaose（大致在该顺序）。ChBD（ChiC）的缺失导致对不溶性几丁质底物的水解活性的中度（约50%）降低，但对里氏木霉的抗真菌活性的大部分（约90%）被废除了这种删除。因此，这个域似乎有助于更重要的抗真菌性能比催化活性。ChBD（ChiC）本身不具有抗真菌活性或对CatD（ChiC）反式抗真菌活性的协同作用。
Chitinase C (ChiC) is the first bacterial family 19 chitinase discovered in Streptomyces griseus HUT6037. While it shares significant similarity with the plant family 19 chitinases in the catalytic domain, its N-terminal chitin-binding domain (ChBD(ChiC)) differs from those of the plant enzymes. ChBD(ChiC) and the catalytic domain (CatD(ChiC)), as well as intact ChiC, were separately produced in L. coli and purified to homogeneity. Binding experiments and isothermal titration calorimetry assays demonstrated that ChBD(ChiC) binds to insoluble chitin, soluble chitin, cellulose, and N-acetylehitohexaose (roughly in that order). A deletion of ChBD(ChiC) resulted in moderate (about 50%) reduction of the hydrolyzing activity toward insoluble chitin substrates, but most (about 90%) of the antifungal activity against Trichoderma reesei was abolished by this deletion. Thus, this domain appears to contribute more importantly to antifungal properties than to catalytic activities. ChBD(ChiC) itself did not have antifungal activity or a synergistic effect on the antifungal activity of CatD(ChiC) in trans.