Outer membrane vesicle production by Escherichia coli is independent of membrane instability
Outer membrane vesicle production by Escherichia coli is independent of membrane instability
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DOI：
10.1128/jb.00498-06
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发表时间：
2006-08-01
影响因子：
3.2
通讯作者：
Kuehn, Meta J.
中科院分区：
文献类型：
--
作者：
McBroom, Amanda J.;Johnson, Alexandra P.;Kuehn, Meta J.
人们早就注意到革兰氏阴性菌产生外膜囊泡，最近的数据表明，致病菌株释放的囊泡可以将毒力因子传递给宿主细胞。然而，囊泡释放的机制仍然没有确定。这项遗传学研究解决了这些结构是否仅仅是膜不稳定的结果，或者是由一个更直接的过程形成的。为了阐明囊泡形成的调控机制和生理基础，我们在大肠杆菌中进行了筛选，以确定导致囊泡过度或生产不足的基因中断。只有少数低囊泡化突变体和无效突变体被回收，这表明囊泡化可能是革兰氏阴性细菌生长的一个基本特征。基因破坏被确定为引起囊泡生产的差异，范围从5倍减少到200倍增加相对于野生型水平。这些破坏包括控制外膜组分和肽聚糖合成以及sigma（E）细胞包膜应激反应的基因座。引起囊泡过度产生的突变没有导致编码主要外膜蛋白的ompC基因的上调。洗涤剂的敏感性，泄漏性，和新的囊泡突变株的生长特性与囊泡形成水平没有相关性，表明囊泡的产生是不能预测的包膜不稳定性。
It has been long noted that gram-negative bacteria produce outer membrane vesicles, and recent data demonstrate that vesicles released by pathogenic strains can transmit virulence factors to host cells. However, the mechanism of vesicle release has remained undetermined. This genetic study addresses whether these structures are merely a result of membrane instability or are formed by a more directed process. To elucidate the regulatory mechanisms and physiological basis of vesiculation, we conducted a screen in Escherichia coli to identify gene disruptions that caused vesicle over- or underproduction. Only a few low-vesiculation mutants and no null mutants were recovered, suggesting that vesiculation may be a fundamental characteristic of gram-negative bacterial growth. Gene disruptions were identified that caused differences in vesicle production ranging from a 5-fold decrease to a 200-fold increase relative to wild-type levels. These disruptions included loci governing outer membrane components and peptidoglycan synthesis as well as the sigma(E) cell envelope stress response. Mutations causing vesicle overproduction did not result in upregulation of the ompC gene encoding a major outer membrane protein. Detergent sensitivity, leakiness, and growth characteristics of the novel vesiculation mutant strains did not correlate with vesiculation levels, demonstrating that vesicle production is not predictive of envelope instability.