Department of Microbiology and Infectious Diseases, University of Calgary, Calgary T2N 4N1 Alberta, Canada.
J Biol Chem. 2011 Dec 30;286(52):45165-73. doi: 10.1074/jbc.M110.214171. Epub 2011 Nov 8.
Gram-negative bacterial pathogens belonging to the Pasteurellaceae, Moraxellaceae, and Neisseriaceae families rely on an iron acquisition system that acquires iron directly from host transferrin (Tf). The process is mediated by a surface receptor composed of transferrin-binding proteins A and B (TbpA and TbpB). TbpA is an integral outer membrane protein that functions as a gated channel for the passage of iron into the periplasm. TbpB is a surface-exposed lipoprotein that facilitates the iron uptake process. In this study, we demonstrate that the region encompassing amino acids 7-40 of Actinobacillus pleuropneumoniae TbpB is required for forming a complex with TbpA and that the formation of the complex requires the presence of porcine Tf. These results are consistent with a model in which TbpB is responsible for the initial capture of iron-loaded Tf and subsequently interacts with TbpA through the anchor peptide. We propose that TonB binding to TbpA initiates the formation of the TbpB-TbpA complex and transfer of Tf to TbpA.
革兰氏阴性细菌病原体属于巴斯德氏菌科、莫拉氏菌科和奈瑟氏球菌科，它们依赖于一种从宿主转铁蛋白（Tf）中直接获取铁的摄取系统。这个过程由一个由转铁蛋白结合蛋白 A 和 B（TbpA 和 TbpB）组成的表面受体介导。TbpA 是一种完整的外膜蛋白，作为铁进入周质的门控通道发挥作用。TbpB 是一种表面暴露的脂蛋白，有助于铁摄取过程。在这项研究中，我们证明了胸膜肺炎放线杆菌 TbpB 的氨基酸 7-40 区域对于与 TbpA 形成复合物是必需的，并且该复合物的形成需要猪转铁蛋白的存在。这些结果与以下模型一致，即 TbpB 负责最初捕获负载铁的 Tf，然后通过锚肽与 TbpA 相互作用。我们提出 TonB 与 TbpA 的结合启动了 TbpB-TbpA 复合物的形成以及 Tf 向 TbpA 的转移。
