Weiss Stefanie M, Ladwein Markus, Schmidt Dorothea, Ehinger Julia, Lommel Silvia, Städing Kai, Beutling Ulrike, Disanza Andrea, Frank Ronald, Jänsch Lothar, Scita Giorgio, Gunzer Florian, Rottner Klemens, Stradal Theresia E B
Signalling and Motility Group, Helmholtz Centre for Infection Research, D-38124 Braunschweig, Germany.
Cell Host Microbe. 2009 Mar 19;5(3):244-58. doi: 10.1016/j.chom.2009.02.003.
Actin pedestal formation by pathogenic E. coli requires signaling by the bacterial intimin receptor Tir, which induces host cell actin polymerization mediated by N-WASP and the Arp2/3 complex. Whereas canonical enteropathogenic E. coli (EPEC) recruit these actin regulators through tyrosine kinase signaling cascades, enterohemorrhagic E. coli (EHEC) O157:H7 employ the bacterial effector EspF(U) (TccP), a potent N-WASP activator. Here, we show that IRSp53 family members, key regulators of membrane and actin dynamics, directly interact with both Tir and EspF(U). IRSp53 colocalizes with EspF(U) and N-WASP in actin pedestals. In addition, targeting of IRSp53 is independent of EspF(U) and N-WASP but requires Tir residues 454-463, previously shown to be essential for EspF(U)-dependent actin assembly. Genetic and functional loss of IRSp53 abrogates actin assembly mediated by EHEC. Collectively, these data indentify IRSp53 family proteins as the missing host cell factors linking bacterial Tir and EspF(U) in EHEC pedestal formation.
致病性大肠杆菌形成肌动蛋白基座需要细菌内毒素受体Tir发出信号，该信号可诱导由N-WASP和Arp2/3复合物介导的宿主细胞肌动蛋白聚合。典型的肠致病性大肠杆菌（EPEC）通过酪氨酸激酶信号级联招募这些肌动蛋白调节因子，而肠出血性大肠杆菌（EHEC）O157:H7则利用细菌效应蛋白EspF(U)（TccP），一种强大的N-WASP激活剂。在这里，我们表明IRSp53家族成员，膜和肌动蛋白动力学的关键调节因子，直接与Tir和EspF(U)相互作用。IRSp53与EspF(U)和N-WASP在肌动蛋白基座中共定位。此外，IRSp53的靶向作用独立于EspF(U)和N-WASP，但需要Tir的454-463位残基，此前已证明该残基对于EspF(U)依赖的肌动蛋白组装至关重要。IRSp53的基因缺失和功能丧失消除了EHEC介导的肌动蛋白组装。总的来说，这些数据确定IRSp53家族蛋白是在EHEC基座形成过程中连接细菌Tir和EspF(U)的缺失的宿主细胞因子。
