Rab small GTPases control membrane trafficking through effectors that recruit downstream mediators such as motor proteins. Subcellular trafficking typically involves multiple Rabs, with each specific step mediated by a distinct Rab protein. We describe a collaboration between two distinct Rab-protein-orchestrated trafficking circuits in bladder epithelial cells (BECs) that expels intracellular uropathogenic Escherichia coli (UPEC) from their intracellular niche. RAB11a and RAB27b and their trafficking circuitry are simultaneously involved in UPEC expulsion. While RAB11a recruits its effector RAB11FIP3 and cytoskeletal motor Dynein, RAB27b mobilizes the effector MyRIP and motor Myosin VIIa to mediate bacterial expulsion. This collaboration is coordinated by deposition of the exocyst complex on bacteria-containing vesicles, an event triggered by the innate receptor Toll-like receptor 4. Both RAB11a and RAB27b are recruited and activated by the exocyst complex components SEC6/SEC15. Thus, the cell autonomous defense system can mobilize and coalesce multiple subcellular trafficking circuitries to combat infections.

Rab 小 GTP 酶通过招募下游介质（例如运动蛋白）的效应器控制膜运输。亚细胞运输通常涉及多个 Rab，每个特定步骤均由不同的 Rab 蛋白介导。我们描述了膀胱上皮细胞（BEC）中两个不同的 Rab 蛋白协调运输回路之间的合作，将细胞内尿路致病性大肠杆菌（UPEC）从其细胞内生态位中驱逐出去。 RAB11a 和 RAB27b 及其贩运回路同时参与 UPEC 驱逐。 RAB11a 招募其效应器 RAB11FIP3 和细胞骨架运动动力蛋白，而 RAB27b 则动员效应器 MyRIP 和运动肌球蛋白 VIIa 来介导细菌排出。这种合作是通过外囊复合物沉积在含细菌的囊泡上来协调的，这是由先天受体 Toll 样受体 4 触发的事件。RAB11a 和 RAB27b 都由外囊复合物成分 SEC6/SEC15 招募和激活。因此，细胞自主防御系统可以动员和合并多个亚细胞运输回路来对抗感染。