Bacterial pathogens deliver water/solute-permeable channels as a virulence strategy.
Bacterial pathogens deliver water/solute-permeable channels as a virulence strategy.
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细菌病原体提供水/溶质可渗透通道作为毒力策略。
DOI：
10.1101/2023.07.29.547699
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
He,ShengYang
中科院分区：
文献类型：
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作者：
Nomura,Kinya;Andreazza,Felipe;Cheng,Jie;Dong,Ke;Zhou,Pei;He,ShengYang
许多动物和植物病原菌利用III型分泌系统将效应蛋白递送到宿主细胞中1，2。阐明这些效应蛋白在宿主细胞中的功能对于理解动物和植物中的感染性疾病至关重要3 -5。广泛保守的AvrE/DspE家族效应子在多种植物病原性细菌的发病机制中起核心作用6。这些保守的效应子参与诱导“水浸”和宿主细胞死亡，这有助于感染组织中的细菌增殖。然而，三十年来，AvrE/DspE家族效应子的确切生物化学功能一直受到机制理解的限制。在这里，我们表明AvrE/DspE家族效应子折叠成类似于细菌孔蛋白的β桶结构。非洲爪蟾卵母细胞中AvrE和DspE的表达导致（i）内向和外向电流，（ii）对水的渗透性和（iii）渗透压依赖性卵母细胞肿胀和破裂。脂质体重构证实，单独的DspE通道足以允许小分子如荧光素染料通过。基于DspE通道的预测孔径（15-20 μ m）的化学阻断剂的靶向筛选鉴定了聚酰胺胺（PAMAM）树枝状聚合物作为DspE/AvrE通道的抑制剂。值得注意的是，PAMAMs广泛抑制非洲爪蟾卵母细胞中的AvrE/DspE毒力活动，并在梨火疫病菌和假单胞菌感染。因此，我们已经解开了一个重要的细菌效应子家族的神秘功能，在细菌发病机制的研究中具有重要的概念和实际意义。
Many animal and plant pathogenic bacteria utilize a type III secretion system to deliver effector proteins into the host cell1,2. Elucidation of how these effector proteins function in the host cell is critical for understanding infectious diseases in animals and plants3–5. The widely conserved AvrE/DspE-family effectors play a central role in the pathogenesis of diverse phytopathogenic bacteria6. These conserved effectors are involved in the induction of “water-soaking” and host cell death that are conducive to bacterial multiplication in infected tissues. However, the exact biochemical functions of AvrE/DspE-family effectors have been recalcitrant to mechanistic understanding for three decades. Here we show that AvrE/DspE-family effectors fold into a β-barrel structure that resembles bacterial porins. Expression of AvrE and DspE in Xenopus oocytes results in (i) inward and outward currents, (ii) permeability to water and (iii) osmolarity-dependent oocyte swelling and bursting. Liposome reconstitution confirmed that the DspE channel alone is sufficient to allow the passage of small molecules such as fluorescein dye. Targeted screening of chemical blockers based on the predicted pore size (15–20 Å) of the DspE channel identified polyamidoamine (PAMAM) dendrimers as inhibitors of the DspE/AvrE channels. Remarkably, PAMAMs broadly inhibit AvrE/DspE virulence activities in Xenopus oocytes and during Erwinia amylovora and Pseudomonas syringae infections. Thus, we have unraveled the enigmatic function of a centrally important family of bacterial effectors with significant conceptual and practical implications in the study of bacterial pathogenesis.