Kelly G, Prasannan S, Daniell S, Fleming K, Frankel G, Dougan G, Connerton I, Matthews S
Department of Biochemistry and Centre for Structural Biology, Imperial College of Science, Technology and Medicine, South Kensington, London, UK.
Nat Struct Biol. 1999 Apr;6(4):313-8. doi: 10.1038/7545.
Enteropathogenic Escherichia coli (EPEC) induce gross cytoskeletal rearrangement within epithelial cells, immediately beneath the attached bacterium. The C-terminal 280 amino acid residues of intimin (Int280; 30.1 kDa), a bacterial cell-adhesion molecule, mediate the intimate bacterial host-cell interaction. Recently, interest in this process has been stimulated by the discovery that the bacterial intimin receptor protein (Tir) is translocated into the host cell membrane, phosphorylated, and after binding intimin triggers the intimate attachment. Using multidimensional nuclear magnetic resonance (NMR) and combining perdeuteration with site-specific protonation of methyl groups, we have determined the global fold of Int280. This represents one of the largest, non-oligomeric protein structures to be determined by NMR that has not been previously resolved by X-ray crystallography. Int280 comprises three domains; two immunoglobulin-like domains and a C-type lectin-like module, which define a new family of bacterial adhesion molecules. These findings also imply that carbohydrate recognition may be important in intimin-mediated cell adhesion.
肠致病性大肠杆菌（EPEC）可在上皮细胞内紧邻附着细菌的位置诱导明显的细胞骨架重排。细菌细胞粘附分子紧密素（Int280；30.1 kDa）的C末端280个氨基酸残基介导细菌与宿主细胞的紧密相互作用。最近，细菌紧密素受体蛋白（Tir）被转运到宿主细胞膜中、磷酸化，并且在结合紧密素后触发紧密附着这一发现激发了人们对该过程的兴趣。通过多维核磁共振（NMR）并结合甲基基团的全氘代化与位点特异性质子化，我们确定了Int280的整体折叠结构。这是通过NMR确定的最大的非寡聚蛋白结构之一，此前尚未通过X射线晶体学解析。Int280包含三个结构域；两个免疫球蛋白样结构域和一个C型凝集素样模块，它们定义了一个新的细菌粘附分子家族。这些发现还意味着碳水化合物识别在紧密素介导的细胞粘附中可能很重要。
