Molecular characterization of serine-, alanine-, and proline-rich proteins of Trypanosoma cruzi and their possible role in host cell infection
Molecular characterization of serine-, alanine-, and proline-rich proteins of Trypanosoma cruzi and their possible role in host cell infection
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DOI：
10.1128/iai.74.3.1537-1546.2006
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发表时间：
2006-03-01
影响因子：
3.1
通讯作者：
da Silveira, JF
中科院分区：
文献类型：
--
作者：
Baida, RCP;Santos, WRM;da Silveira, JF
我们之前报道了从克氏锥虫中分离到一个新的蛋白基因家族，称为SAP（富含丝氨酸、丙氨酸和脯氨酸的蛋白）。借助克氏T. cruzi完整基因组序列的可用性，我们现在已经鉴定出39个SAP全长序列，6个假基因和4个部分基因。sap共享约55个氨基酸的中心结构域，并可根据其氨基(N)端和羧基(C)端序列分为四组。一些sap具有保守的N端和c端结构域，分别编码一个信号肽和一个糖基磷脂酰肌醇锚定加成位点。利用双向电泳和免疫印迹技术对超环锥体中SAPs的表达进行分析，结果表明SAPs可能在体内被翻译后修饰。我们还证明了一些sap会脱落到细胞外介质中。重组SAP显示出对哺乳动物细胞的粘附能力，其结合是剂量依赖性和可饱和的，表明可能存在配体-受体相互作用。SAP触发寄生物内化所需的宿主细胞Ca2+反应。在SAP存在下进行的细胞侵袭试验显示抑制CL菌株的元环形式的内化。综上所述，这些结果表明SAP参与了亚环锥乳线虫对哺乳动物细胞的入侵，并证实了传染性锥乳线虫利用一系列表面糖蛋白和脱落蛋白来诱导内化所需的信号事件的假设。
We previously reported the isolation of a novel protein gene family, termed SAP (serine-, alanine-, and proline-rich protein), from Trypanosoma cruzi. Aided by the availability of the completed genome sequence of T. cruzi, we have now identified 39 full-length sequences of SAP, six pseudogenes and four partial genes. SAPs share a central domain of about 55 amino acids and can be divided into four groups based on their amino (N)- and carboxy (C)-terminal sequences. Some SAPs have conserved N- and C-terminal domains encoding a signal peptide and a glycosylphosphatidylinositol anchor addition site, respectively. Analysis of the expression of SAPs in metacyclic trypomastigotes by two-dimensional electrophoresis and immunoblotting revealed that they are likely to be posttranslationally modified in vivo. We have also demonstrated that some SAPs are shed into the extracellular medium. The recombinant SAP exhibited an adhesive capacity toward mammalian cells, where binding was dose dependent and saturable, indicating a possible ligand-receptor interaction. SAP triggered the host cell Ca2+ response required for parasite internalization. A cell invasion assay performed in the presence of SAP showed inhibition of internalization of the metacyclic forms of the CL strain. Taken together, these results show that SAP is involved in the invasion of mammalian cells by metacyclic trypomastigotes, and they confirm the hypothesis that infective trypomastigotes exploit an arsenal of surface glycoproteins and shed proteins to induce signaling events required for their internalization.