Pawelek Peter D, Croteau Nathalie, Ng-Thow-Hing Christopher, Khursigara Cezar M, Moiseeva Natalia, Allaire Marc, Coulton James W
Department of Microbiology and Immunology, McGill University, 3775 University Street, Montreal, Quebec, H3A 2B4, Canada.
Science. 2006 Jun 2;312(5778):1399-402. doi: 10.1126/science.1128057.
The cytoplasmic membrane protein TonB spans the periplasm of the Gram-negative bacterial cell envelope, contacts cognate outer membrane receptors, and facilitates siderophore transport. The outer membrane receptor FhuA from Escherichia coli mediates TonB-dependent import of ferrichrome. We report the 3.3 angstrom resolution crystal structure of the TonB carboxyl-terminal domain in complex with FhuA. TonB contacts stabilize FhuA's amino-terminal residues, including those of the consensus Ton box sequence that form an interprotein beta sheet with TonB through strand exchange. The highly conserved TonB residue arginine-166 is oriented to form multiple contacts with the FhuA cork, the globular domain enclosed by the beta barrel.
细胞质膜蛋白托蛋白B（TonB）跨越革兰氏阴性菌细胞包膜的周质，与同源外膜受体接触，并促进铁载体运输。大肠杆菌的外膜受体FhuA介导依赖托蛋白B的高铁色素转运。我们报道了与FhuA结合的托蛋白B羧基末端结构域的3.3埃分辨率晶体结构。托蛋白B接触稳定了FhuA的氨基末端残基，包括共有托盒序列中的残基，这些残基通过链交换与托蛋白B形成蛋白间β折叠。高度保守的托蛋白B残基精氨酸-166定向与FhuA软木塞（由β桶包围的球状结构域）形成多个接触。
