Moraes TF, Yu RH, Strynadka NCJ, Schryvers AB. Insights into the bacterial transferrin receptor: the structure of transferrin-binding protein B from Actinobacillus pleuropneumoniae.
Mol Cell 2009;
35:523-33. [PMID:
19716795 DOI:
10.1016/j.molcel.2009.06.029]
[Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 05/09/2009] [Accepted: 06/11/2009] [Indexed: 11/17/2022]
Abstract
Pathogenic bacteria from the Neisseriaceae and Pasteurellacea families acquire iron directly from the host iron-binding glycoprotein, transferrin (Tf), in a process mediated by surface receptor proteins that directly bind host Tf, extract the iron, and transport it across the outer membrane. The bacterial Tf receptor is comprised of a surface exposed lipoprotein, Tf-binding protein B (TbpB), and an integral outer-membrane protein, Tf-binding protein A (TbpA), both of which are essential for survival in the host. In this study, we report the 1.98 A resolution structure of TbpB from the porcine pathogen Actinobacillus pleuropneumoniae, providing insights into the mechanism of Tf binding and the role of TbpB. A model for the complex of TbpB bound to Tf is proposed. Mutation of a single surface-exposed Phe residue on TbpB within the predicted interface completely abolishes binding to Tf, suggesting that the TbpB N lobe comprises the sole high-affinity binding region for Tf.
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