亲密素和侵袭素是致病性格兰氏阴性菌产生的毒素因子，具有重要的临床病理意义。它们包含负责粘附宿主细胞的C末端的膜外信使结构域和插入细胞外膜的N末端β结构域。5月31日Cell杂志子刊Structure在线发表了Fairman等人的研究论文，进一步揭示了其结构的奥秘。
研究者确定了E.coli大肠杆菌亲密素β结构域的边界，并利用这一信息解析了它的结构，以及Y型假结核病侵袭素的β结构域的结构。研究者获得了单聚体β结构域晶体，研究显示过去被认为是β结构域的一部分蛋白结构实际上也包括了信使结构域的一部分。
此外，基于高度保守的亲密素和侵袭素β结构域的边界信息，研究者还确定了146个亲密素/侵袭素家族的非冗余、典型性成员。他们还结合这些序列信息和蛋白结构数据，发现并作图描绘了β结构域内在进化上保守的氨基酸残基序列。(生物谷bioon.com)
doi:10.1016/j.cell.2011.10.017
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Crystal Structures of the Outer Membrane Domain of Intimin and Invasin from Enterohemorrhagic E. coli and Enteropathogenic Y. pseudotuberculosis
James W. Fairman, Nathalie Dautin, Damian Wojtowicz, et al.
Summary
Intimins and invasins are virulence factors produced by pathogenic Gram-negative bacteria. They contain C-terminal extracellular passenger domains that are involved in adhesion to host cells and N-terminal β domains that are embedded in the outer membrane. Here, we identify the domain boundaries of an E. coli intimin β domain and use this information to solve its structure and the β domain structure of a Y. pseudotuberculosis invasin. Both β domain structures crystallized as monomers and reveal that the previous range of residues assigned to the β domain also includes a protease-resistant domain that is part of the passenger. Additionally, we identify 146 nonredundant representative members of the intimin/invasin family based on the boundaries of the highly conserved intimin and invasin β domains. We then use this set of sequences along with our structural data to find and map the evolutionarily constrained residues within the β domain.
