The Yersinia pestis Ail Protein Mediates Binding and Yop Delivery to Host Cells Required for Plague Virulence
The Yersinia pestis Ail Protein Mediates Binding and Yop Delivery to Host Cells Required for Plague Virulence
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DOI：
10.1128/iai.00913-08
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发表时间：
2009-02-01
影响因子：
3.1
通讯作者：
Krukonis, Eric S.
中科院分区：
文献类型：
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作者：
Felek, Suleyman;Krukonis, Eric S.
虽然与宿主细胞的黏附是鼠疫耶尔森氏菌运送细胞毒性YOP蛋白的关键步骤，但其机制尚未明确。为了确定对YOP传递至关重要的粘附素，我们使用Mariner转座子启动了两个转座子突变筛选。为了避免多余的细胞结合活性，我们用一株缺失了两种已知粘附素的菌株进行筛选，这两种粘附素是pH 6抗原和自动转运蛋白YapC，以及CAF1胶囊，众所周知，CAF1胶囊掩盖了一些粘附素。出现的突变体含有鼠疫杆菌的ail(附着和入侵基因)基因的插入。一个ail基因缺失的重组突变体(Y1324)在向Hep-2人上皮细胞输送YOPs方面存在严重缺陷，在向THP-1人单核细胞输送YOPs方面存在严重缺陷。具体地说，当监测到细胞圆整和ELK标记的YopE衍生物移位到宿主细胞中时，YOP递送缺陷是明显的。虽然ail突变体在体外只显示细胞结合能力的轻微下降，但KIM5 Delta ail突变体在小鼠身上的致死剂量增加了3000倍，50%。感染Delta ail突变体的小鼠在感染3天后，其脾、肝和肺中的细菌数量也比感染亲本菌株KIM5的小鼠少1000倍。因此，Ail蛋白对鼠疫杆菌III型体外分泌和小鼠感染都是至关重要的。
Although adhesion to host cells is a critical step in the delivery of cytotoxic Yop proteins by Yersinia pestis, the mechanism has not been defined. To identify adhesins critical for Yop delivery, we initiated two transposon mutagenesis screens using the mariner transposon. To avoid redundant cell binding activities, we initiated the screen with a strain deleted for two known adhesins, pH 6 antigen and the autotransporter, YapC, as well as the Caf1 capsule, which is known to obscure some adhesins. The mutants that emerged contained insertions within the ail ( attachment and invasion locus) gene of Y. pestis. A reconstructed mutant with a single deletion in the ail locus (y1324) was severely defective for delivery of Yops to HEp-2 human epithelial cells and significantly defective for delivery of Yops to THP-1 human monocytes. Specifically, the Yop delivery defect was apparent when cell rounding and translocation of an ELK-tagged YopE derivative into host cells were monitored. Although the ail mutant showed only a modest decrease in cell binding capacity in vitro, the KIM5 Delta ail mutant exhibited a >3,000-fold-increased 50% lethal dose in mice. Mice infected with the Delta ail mutant also had 1,000-fold fewer bacteria in their spleens, livers, and lungs 3 days after infection than did those infected with the parental strain, KIM5. Thus, the Ail protein is critical for both Y. pestis type III secretion in vitro and infection in mice.