Identification of heparin as a ligand for the A-domain of Plasmodium falciparum thrombospondin-related adhesion protein
Identification of heparin as a ligand for the A-domain of Plasmodium falciparum thrombospondin-related adhesion protein
复制标题
DOI：
10.1016/s0166-6851(99)00052-3
复制
发表时间：
1999-05-15
影响因子：
1.5
通讯作者：
Hollingdale, MR
中科院分区：
文献类型：
--
作者：
McCormick, CJ;Tuckwell, DS;Hollingdale, MR
凝血酶原蛋白相关黏附蛋白(TRAP)是恶性疟原虫的一种跨膜蛋白，表达于子孢子的微线体中，与宿主细胞的侵袭和运动有关。在TRAP的胞外区内含有一个A结构域，这是一个在许多膜、血浆和基质蛋白中发现的模块，经常参与配体识别。为了确定TRAP A结构域的功能，将其表达为谷胱甘肽S转移酶融合蛋白及其配体结合，并与其他特征谷胱甘肽S转移酶A结构域融合蛋白进行了比较。用固相分析筛选与已知的A结构域的结合，发现TRAP A结构域与肝素结合。当肝素饱和时，它与肝素的结合似乎是特异的，并被可溶性肝素、岩藻糖胶和葡聚糖硫酸盐抑制，但不被其他带负电荷的糖胺聚糖如软骨素硫酸盐所抑制。此外，与一些A结构域与配体的相互作用不同，TRAP的A结构域和白细胞整合素Mac-1在没有二价阳离子的情况下都与肝素结合。先前已经证明，TRAP中的另一个结构域与环子孢子蛋白的II-+区同源，与永生化肝细胞系HepG2上的硫脂和硫酸乙酰肝素结合。TRAP A结构域还可与硫脂和HepG2细胞结合。因此，A结构域具有某些已被归因于TRAP区域II+样结构域的结合特性，并可能有助于TRAP与肝细胞上的硫酸肝素结合。(C)1999 Elsevier Science B.V.保留所有权利。
Thrombospondin-related adhesion protein (TRAP) is a Plasmodium falciparum transmembrane protein that is expressed within the micronemes of sporozoites, and is implicated in host cell invasion and motility. Contained within the extracellular region of TRAP is an A-domain, a module found in a number of membrane, plasma and matrix proteins, that is often involved in ligand recognition. In order to determine the role of the TRAP A-domain, it has been expressed as a glutathione S-transferase fusion protein and its ligand binding compared with that of other characterised glutathione S-transferase A-domain fusion proteins. Using a solid phase assay to screen for binding to known A-domain ligands, the TRAP A-domain was found to bind heparin. Binding to heparin appeared to be specific as it was saturable, and was inhibited by soluble heparin, fucoidan and dextran sulfate, but not by other negatively charged sulfated glycosaminoglycans such as chondroitin sulfates. Furthermore, unlike some A-domain-ligand interactions, the A-domain of both TRAP and the leukocyte integrin, Mac-1, bound to heparin in the absence of divalent cations. It has been shown previously that another domain within TRAP, which is homologous to region II-plus of circumsporozoite protein, binds to sulfatide and to heparan sulfate on the immortalised hepatocyte line HepG2. The TRAP A-domain also bound to sulfatide and to HepG2 cells. Thus the A-domain shares certain binding properties already attributed to the region II-plus-like domain of TRAP, and may contribute to the binding of TRAP to heparan sulfate on hepatocytes. (C) 1999 Elsevier Science B.V. All rights reserved.