A parasite-surface trans-sialidase of Trypanosma family

锥虫家族寄生虫表面唾液酸转移酶

基本信息

批准号：
06044183
负责人：
UEMURA Haruki
金额：
$ 3.78万
依托单位：
Nagasaki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

Trans-sialidase (TS) is a unique enzyme found in protozoan Trypanosoma. This enzyme catalyzes sialic acid transfer reaction from host derived glycoconjugates to parasite surface acceptor molecules. This enzyme is first found in trypomasitigote stage of Trypanosoma cruzi, causative agent of Chagas' disease The sialic acids, transferred to the parasite surface glycoprotein are suggested to be important for cell invasion and escape from host defense systems.Sequence analysis of T.cruzi TS genes have shown that trans-sialidase is encoded by several gene family and only some members of this family encode enzymatically active proteins. The active and inactive forms of the genes contain. different numbers of carboxy terminal twelve amino acid repeat units and also some substitutions in the amino terminal catalytic domains. We reported that difference in activity is not due to carboxy-terminal region, but due to single amino acid differences at the animo-terminal domain.To examine the ratio of active and inactive protein genes, we amplified the region where is important for enzyme activity and contains most of amino acid substitutions. We obtained the result taht half of the genes are active and the other half inactive types. In addition, sequencing of these amplifid clones revealed there are several additional types of substitutions in this region.Then, we analyzed TS gene organization and obtained the result that different types of genes are distributed in more than one chromosomal band. In the Y-strain, all repeat-containing genes are localized in one chromosomal band of 1.1 megabases, while the repeat-minus genes are in two other chromosome s of 0.82 and 0.79 megabases.Eichinger's group has obtained the sialidase gene from T.rangeli. A comparative analysis of T.cruzi TS and T.rangeli sialidase is helpful to determine the feature of TS protein which contribute to its unique sialic acid transfer reaction.

转唾液酸酶 (TS) 是原生动物锥虫中发现的一种独特酶。该酶催化唾液酸从宿主衍生的糖缀合物到寄生虫表面受体分子的转移反应。这种酶首先在克氏锥虫（恰加斯病的病原体）的锥虫期被发现。转移到寄生虫表面糖蛋白的唾液酸对于细胞入侵和逃离宿主防御系统非常重要。克氏锥虫 TS 的序列分析基因显示，转唾液酸酶由几个基因家族编码，并且该家族中只有一些成员编码酶活性蛋白。基因包含活性和非活性形式。不同数量的羧基末端十二个氨基酸重复单元以及氨基末端催化结构域中的一些取代。我们报道活性的差异不是由于羧基末端区域，而是由于氨基末端结构域的单个氨基酸差异。为了检查活性和非活性蛋白质基因的比率，我们扩增了对酶活性重要的区域并含有大部分氨基酸取代。我们得到的结果是一半的基因是活跃的，另一半是不活跃的。此外，对这些扩增克隆的测序表明，该区域还存在几种额外类型的取代。然后，我们分析了TS基因的组织结构，得出不同类型的基因分布在多个染色体带上的结果。在Y株中，所有含有重复的基因都定位在一条1.1兆碱基的染色体带上，而缺失重复的基因则位于另外两条分别为0.82和0.79兆碱基的染色体上。Eichinger的研究小组从T.rangeli获得了唾液酸酶基因。。 T.cruzi TS和T.rangeli唾液酸酶的比较分析有助于确定TS蛋白的特性，从而有助于其独特的唾液酸转移反应。