The cyst wall of Entamoeba invadens contains chitosan (deacetylated chitin)
The cyst wall of Entamoeba invadens contains chitosan (deacetylated chitin)
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DOI：
10.1016/j.molbiopara.2006.03.002
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发表时间：
2006-07-01
影响因子：
1.5
通讯作者：
Samuelson, John
中科院分区：
文献类型：
--
作者：
Das, Suchismita;Van Dellen, Katrina;Samuelson, John
入侵内阿米巴(EI)的囊壁含有甲壳素，甲壳素是β-1，4-乙酰氨基葡萄糖(GlcNAc)的均聚物。在真菌和制造结瘤因子的细菌中，几丁质脱乙酰酶制造壳聚糖，壳聚糖是GlcNAc和氨基葡萄糖的混合物，因此具有正电荷。当去蛋白的囊壁在用商业几丁质酶处理之前进行化学乙酰化处理时，释放的GlcNAc增加了3-4倍，从而揭示了EI几丁质脱乙酰酶的活性。由于这种几丁质酶释放GlcNAc，但不释放GlcN，乙酰化后释放的GlcNAc增加，表明EI囊壁中存在壳聚糖。5个推测的Ei和Eh几丁质脱乙酰酶基因与真菌和细菌的基因相似。预测的Eh甲壳素脱乙酰酶与枯草芽孢杆菌多肽葡聚糖脱乙酰酶的三维结构非常匹配。在酿酒酵母中表达的重组Eh甲壳素脱乙酰基酶能体外脱乙酰化壳低聚糖。这些结果与EI几丁质脱乙酰酶在EI囊壁中修饰几丁质以产生壳聚糖的观点一致。(C)2006爱思唯尔B.V.保留所有权利。
The cyst wall of Entamoeba invadens (Ei), a model for the human pathogen Entamoeba histolytica, contains chitin, which is a homopolymer of beta-1, 4-linked N-acetyl-glucosamine (GlcNAc). In fungi and in bacteria that make nodulation factors, chitin deacetylases make chitosan, which is a mixture of GlcNAc and glucosamine and so has a positive charge. The activity of an Ei chitin deacetylase was revealed by a 3-4-fold increase in released GlcNAc when deproteinated cyst walls were chemically acetylated prior to treatment with a commerical chitinase. Because this chitinase releases GlcNAc but not GlcN, increases in released GlcNAc after acetylation suggested the presence of chitosan in Ei cyst walls. Five putative Ei and Eh chitin deacetylase genes resembled those of fungi and bacteria. A predicted Eh chitin deacetylase matched closely the three-dimensional structure of a Bacillus subtilis peptiodglycan deacetylase. A recombinant Eh chitin deacetylase, expressed in Saccharomyces cerevisiae, deacetylated chitooligosaccharides in vitro. These results are consistent with the idea that Ei chitin deacetylases modify chitin to produce chitosan in the Ei cyst wall. (c) 2006 Elsevier B.V. All rights reserved.