Department of Biochemistry and Molecular Biology and the Centre for Blood Research, University of British Columbia, Vancouver, V6T 1Z3, BC, Canada.
HRMEM facility, University of British Columbia, Vancouver, V6T 1Z3, BC, Canada.
Nat Commun. 2018 Sep 21;9(1):3840. doi: 10.1038/s41467-018-06298-8.
The bacterial type III secretion system, or injectisome, is a syringe shaped nanomachine essential for the virulence of many disease causing Gram-negative bacteria. At the core of the injectisome structure is the needle complex, a continuous channel formed by the highly oligomerized inner and outer membrane hollow rings and a polymerized helical needle filament which spans through and projects into the infected host cell. Here we present the near-atomic resolution structure of a needle complex from the prototypical Salmonella Typhimurium SPI-1 type III secretion system, with local masking protocols allowing for model building and refinement of the major membrane spanning components of the needle complex base in addition to an isolated needle filament. This work provides significant insight into injectisome structure and assembly and importantly captures the molecular basis for substrate induced gating in the giant outer membrane secretin portal family.
细菌 III 型分泌系统，或注入器，是一种注射器状的纳米机器，对许多引起革兰氏阴性菌疾病的毒力至关重要。在注入器结构的核心是针复合物，由高度寡聚化的内膜和外膜空心环以及贯穿并突出到感染宿主细胞的聚合螺旋针丝形成的连续通道。在这里，我们展示了来自典型沙门氏菌 Typhimurium SPI-1 型 III 型分泌系统的针复合物的近原子分辨率结构，局部掩蔽方案允许构建和细化针复合物底座的主要跨膜成分，以及分离的针丝。这项工作提供了对注入器结构和组装的重要见解，并重要地捕获了用于在巨型外膜分泌素门家族中诱导底物门控的分子基础。
