BopE suppresses the Rab32-dependent defense pathway to promote its intracellular replication and virulence.

Melioidosis is a serious infectious disease caused by the Gram-negative bacterium . Recently, Rab32-dependent immune vesicles emerge as a critical defense pathway to restrict the intracellular . However, can evade host immune vesicles and survive in the cytoplasm, although this mechanism is not well understood. In this study, we found Rab32-dependent vesicles could effectively combat infection, but not all intracellular were encapsulated in Rab32-positive vesicles. To explore how counteracted the Rab32-dependent defense pathway, transcriptomic profiling of was performed to characterize the response dynamics during infection. We found that the type III secretion system of was activated, and a variety of effector proteins were highly upregulated. Among them, BopE, BprD, and BipC were shown to interact with Rab32. Interestingly, BopE directly interacts with host Rab32, potentially suppressing Rab32 function by interfering with nucleotide exchange, which in turn restricts the recruitment of Rab32 to bacterial-containing vesicles. Knocking out of BopE can increase the proportion of Rab32-positive vesicles, suppressing the intracellular replication and virulence of . Collectively, our findings have demonstrated that BopE may be an important effector for to evade from the Rab32-dependent killing vesicles into the cytosol for survival and replication. Therefore, a deeper understanding of the interaction between BopE and the host Rab32-dependent restriction pathway may provide an effective therapeutic strategy for the elimination of intracellular .IMPORTANCE is facultative intracellular bacterium that has evolved numerous strategies to evade host immune vesicles and survive in the cytoplasm. Rab32-dependent vesicles are one of these immune vesicles, but the mechanism by which escape Rab32-dependent vesicles remains elusive. Here, we find infection leading the activation of the type III secretion system (T3SS-3) and increasing the expression of various effectors. Specifically, we identify that BopE, an effector secreted by T3SS-3, triggers vesicle escape to promote pathogenicity and survival. Mechanistically, BopE suppresses the activation of Rab32 by interfering with nucleotide exchange, ultimately triggering vesicle escape and intracellular survival. We also find knocking out the gene can increase the proportion of Rab32-positive vesicles that trap , dampening the survival of both and . Taken together, our findings provide insights into the molecular mechanisms of pathogen effector-induced vesicle escape, indicating a potential melioidosis treatment via blocking BopE-host Rab32 interaction.