Discrimination between apo and iron-loaded forms of transferrin by transferrin binding protein B and its N-terminal subfragment
Discrimination between apo and iron-loaded forms of transferrin by transferrin binding protein B and its N-terminal subfragment
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DOI：
10.1006/mpat.1998.0226
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发表时间：
1998-10-01
影响因子：
3.8
通讯作者：
Schryvers, AB
中科院分区：
文献类型：
--
作者：
Retzer, MD;Yu, R;Schryvers, AB
巴氏杆菌科和新铁菌科的许多病原体都有一个表面受体，它能结合转铁蛋白(Tf)，这是铁获取过程的第一步。该受体由转铁蛋白结合蛋白A(TbpA)和转铁蛋白结合蛋白B(TbpB)两种蛋白组成。由于优先识别载铁形式的转铁蛋白的能力将是这些受体的一个有用的属性，我们在一些细菌物种中检查了这一属性。在与分离膜的固相结合分析中，只有卡他莫拉氏菌的受体能够优先结合铁负载的转铁蛋白。在我们能够分离TbpA和TbpB的竞争亲和分离实验中，所有受试物种的TbpA都被证明与载脂蛋白和载铁因子结合。在此实验条件下，卡氏支原体、睡眠嗜血杆菌和溶血性巴氏杆菌的TbpB可区分载脂蛋白和孔洞Tf，而脑膜炎奈瑟氏菌的TbpB则不能区分。在TbpA(-)背景下或通过使用重组TbpB，脑膜炎奈瑟氏菌的TbpB优先结合铁饱和的HTF的能力变得明显。在与重组融合蛋白的结合分析中，来自所有受试物种的完整TbpB和TbpB的N端一半都优先与负载铁的Tf结合，表明这可能是这些生物优化其获取铁的能力的一种保守机制。(C)1998年学术出版社。
Many pathogens of the Pasteurellaceae and Neisseriaceae possess a surface receptor that binds transferrin (Tf) as an initial step in an iron acquisition process. This receptor is comprised of two proteins, transferrin binding protein A (TbpA) and transferrin binding protein B (TbpB). Since the ability to recognize the iron-loaded form of Tf preferentially would be a useful attribute of these receptors, we examined this property in a number of bacterial species. In solid-phase binding assays with isolated membranes, only the receptor from Moraxella catarrhalis was capable of preferentially binding iron-loaded Tf. In a competitive affinity isolation assay which enabled us to resolve TbpA and TbpB, TbpA from all tested species was shown to bind both apo and iron-loaded Tf. Under these assay conditions TbpB from M. catarrhalis, Haemophilus somnus and Pasteurella haemolytica discriminated between apo and hole Tf, whereas TbpB from Neisseria meningitidis showed no discrimination. The ability of TbpB from N. meningitidis to bind iron-saturated hTf preferentially became evident in a TbpA(-) background or by using recombinant TbpB. In binding assays with recombinant fusion proteins, both intact TbpB and the N-terminal half of TbpB from all the tested species preferentially bound Fe-loaded Tf, indicating that this may be a conserved mechanism by which these organisms optimize their ability to acquire iron. (C) 1998 Academic Press.