Identification of transferrin-binding domains in TbpB expressed by Neisseria gonorrhoeaev
Identification of transferrin-binding domains in TbpB expressed by Neisseria gonorrhoeaev
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DOI：
10.1128/iai.00072-07
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发表时间：
2007-07-01
影响因子：
3.1
通讯作者：
Cornelissen, Cynthia Nau
中科院分区：
文献类型：
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作者：
DeRocco, Amanda J.;Cornelissen, Cynthia Nau
淋球菌的转铁蛋白铁获取系统是人类宿主从转铁蛋白摄取铁所必需的，并且需要两种不同蛋白质的参与：ThpA和TbpB。TbpA是一种TonB依赖性外膜转运蛋白，负责将铁转运到细胞中。TbpB是一种脂质修饰的蛋白质，其在受体功能中的确切作用尚未阐明。这些受体复合物蛋白显示出作为疫苗候选物的前景;因此，重要的是鉴定野生型功能所需的蛋白质的表面暴露区域。在这项研究中，我们研究了TbpB，据报道，这是表面暴露在其整体，但是，这一假设从未经过实验验证。我们将血凝素（HA）表位放入TbpB中，目的是检查特定表位的表面暴露及其对受体功能的影响。产生九个插入突变体，将表位置于信号肽酶II切割位点的下游。我们报告说，HA表位在所有突变体中是表面可及的，表明全长TbpB是完全表面暴露的。通过在N.在淋病中，我们能够检查每个插入对TbpB功能和转铁蛋白获取过程的影响。我们建议，TbpB是由两个转铁蛋白结合的主管叶，这两个都是至关重要的，从人转铁蛋白的有效吸收铁。
The transferrin iron acquisition system of Neisseria gonorrhoeae is necessary for iron uptake from transferrin in the human host and requires the participation of two distinct proteins: ThpA and TbpB. TbpA is a TonB-dependent outer membrane transporter responsible for the transport of iron into the cell. TbpB is a lipid-modified protein, for which a precise role in receptor function has not yet been elucidated. These receptor complex proteins show promise as vaccine candidates; therefore, it is important to identify surface-exposed regions of the proteins required for wild-type functions. In this study we examined TbpB, which has been reported to be surface exposed in its entirety; however, this hypothesis has never been tested experimentally. We placed the hemagglutinin (HA) epitope into TbpB with the dual purpose of examining the surface exposure of particular epitopes as well as their impact on receptor function. Nine insertion mutants were created, placing the epitope downstream of the signal peptidase II cleavage site. We report that the HA epitope is surface accessible in all mutants, indicating that the full-length TbpB is completely surface exposed. By expressing the TbpB-HA fusion proteins in N. gonorrhoeae, we were able to examine the impact of each insertion on the function of TbpB and the transferrin acquisition process. We propose that TbpB is comprised of two transferrin-binding-competent lobes, both of which are critical for efficient iron uptake from human transferrin.