Activities of pseudomonas aeruginosa effectors secreted by the type III secretion system in vitro and during infection
Activities of pseudomonas aeruginosa effectors secreted by the type III secretion system in vitro and during infection
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DOI：
10.1128/iai.73.3.1695-1705.2005
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发表时间：
2005-03-01
影响因子：
3.1
通讯作者：
Lory, S
中科院分区：
文献类型：
--
作者：
Lee, VT;Smith, RS;Lory, S
铜绿假单胞菌利用许多不同的途径来分泌在感染过程中发挥各种作用的蛋白质。其中包括 II 型分泌系统，该系统负责将大多数外产物分泌到周围环境中，包括毒素和降解酶。相反，III型分泌系统介导将蛋白质效应物直接递送至宿主细胞的细胞质中。使用组织培养测定和小鼠急性肺炎模型，我们确定了每种 III 型效应器在感染过程中的贡献。在 PAK 菌株中，ExoS 是感染期间定植和传播所需的主要细胞毒素。 ExoT 可以保护组织培养细胞免受 III 型依赖性裂解，而 ExoY 似乎对细胞毒性影响不大。 ExoU 的细胞毒性比 ExoS 高 100 倍以上。在删除毒性更强的 III 型分泌系统的基因后，确定了 II 型分泌的细胞毒性。这些分泌系统在囊性纤维化（CF）患者终生定植过程中的参与尚不清楚。经过。通过比较同一患者在铜绿假单胞菌感染初期和十多年后慢性定植后分离出的克隆菌株，我们发现初始菌株比已进化为减少 III 型分泌的慢性菌株具有更强的细胞毒性。 III型分泌系统基因的组成型表达恢复了ExoS分泌，但并不总是重新建立细胞毒性，这表明CF菌株积累了许多突变以减少细菌对宿主的毒性。
Pseudomonas aeruginosa utilizes a number of distinct pathways to secrete proteins that play various roles during infection. These include the type II secretion system, which is responsible for the secretion of the majority of exoproducts into the surrounding environment, including toxins and degradative enzymes. In contrast, the type III secretion system mediates the delivery of protein effectors directly into the cytoplasm of the host cell. Using tissue culture assays and a mouse acute-pneumonia model, we have determined the contribution of each of the type III effectors during infection. In strain PAK, ExoS is the major cytotoxin required for colonization and dissemination during infection. ExoT confers protection of tissue culture cells from type III-dependent lysis, while ExoY seemed to have little effect on cytotoxicity. ExoU is over 100-fold more cytotoxic than ExoS. The cytotoxicity of type II secretion was determined following deletion of the genes for the more toxic type III secretion system. The participation of these secretion systems during lifelong colonization of cystic fibrosis (CF) patients is unclear. By. comparing clonal strains from the same patient isolated at the initial onset of P. aeruginosa infection and more than a decade later, after chronic colonization has been established, we show that initial strains are more cytotoxic than chronic strains that have evolved to reduce type III secretion. Constitutive expression of genes for the type III secretion system restored ExoS secretion but did not always reestablish cytotoxicity, suggesting that CF strains accumulate a number of mutations to reduce bacterial toxicity to the host.