McCullough Alix, Jabeena C A, Steiert Brianna, Faris Robert, Weber Mary M
Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA, USA.
Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, USA.
bioRxiv. 2024 Oct 31:2024.10.31.621191. doi: 10.1101/2024.10.31.621191.
() is the causative agent of several human diseases, including the sexually transmitted infection chlamydia and eye infection trachoma. As an obligate intracellular bacterial pathogen, invasion is essential for establishing infection and subsequent pathogenesis. To facilitate invasion, secretes effector proteins through its type III secretion system (T3SS). These effectors facilitate bacterial entry by manipulating multiple pathways involved in host actin cytoskeletal regulation. Previous studies have demonstrated that the T3SS effector protein TmeA is crucial for invasion, as it recruits and activates N-WASP. This interaction leads to recruitment and activation of the Arp2/3 complex, promoting cytoskeletal rearrangements at the invasion site to facilitate uptake. In this study, we define the role of the N-WASP CRIB domain in mediating this interaction, showing that TmeA acts as a functional mimic of Cdc42 in activating N-WASP. Additionally, we identified TOCA-1 as another host protein that directly interacts with TmeA. In other bacterial pathogens, notably Enterohemorrhagic , N-WASP and TOCA-1 are hijacked to mediate pedestal formation. Using siRNA to knockdown N-WASP and TOCA-1, followed by transmission electron microscopic, we observed that both N-WASP and TOCA-1 are important for in -mediated pedestal formation. Collectively, these findings reveal a unique mechanism of TmeA-mediated invasion, where direct interactions with N-WASP and TOCA-1 facilitate pedestal formation.
()是多种人类疾病的病原体,包括性传播感染衣原体和眼部感染沙眼。作为一种专性细胞内细菌病原体,入侵对于建立感染及后续发病机制至关重要。为便于入侵,()通过其三型分泌系统(T3SS)分泌效应蛋白。这些效应蛋白通过操纵宿主肌动蛋白细胞骨架调节中涉及的多种途径来促进细菌进入。先前的研究表明,T3SS效应蛋白TmeA对()的入侵至关重要,因为它招募并激活N-WASP。这种相互作用导致Arp2/3复合体的招募和激活,促进入侵部位的细胞骨架重排以利于()摄取。在本研究中,我们确定了N-WASP CRIB结构域在介导这种相互作用中的作用,表明TmeA在激活N-WASP时充当Cdc42的功能模拟物。此外,我们鉴定出TOCA-1是另一种直接与TmeA相互作用的宿主蛋白。在其他细菌病原体中,尤其是肠出血性(),N-WASP和TOCA-1被劫持以介导基座形成。使用小干扰RNA敲低N-WASP和TOCA-1,随后进行透射电子显微镜观察,我们发现N-WASP和TOCA-1对于()介导的基座形成都很重要。总的来说,这些发现揭示了TmeA介导入侵的独特机制,即与N-WASP和TOCA-1的直接相互作用促进基座形成。