PDF(Pubmed)
Abstract：
Small GTPases of the Ras subfamily are best known for their role as proto-oncoproteins, while their function during microbial infection has remained elusive. Here, we show that Legionella pneumophila hijacks the small GTPase NRas to the Legionella-containing vacuole (LCV) surface. A CRISPR interference screen identifies a single L. pneumophila effector, DenR (Lpg1909), required for this process. Recruitment is specific for NRas, while its homologs KRas and HRas are excluded from LCVs. The C-terminal hypervariable tail of NRas is sufficient for recruitment, and interference with either NRas farnesylation or S-acylation sites abrogates recruitment. Intriguingly, we detect markers of active NRas signaling on the LCV, suggesting it acts as a signaling platform. Subsequent phosphoproteomics analyses show that DenR rewires the host NRas signaling landscape, including dampening of the canonical mitogen-activated protein kinase pathway. These results provide evidence for L. pneumophila targeting NRas and suggest a link between NRas GTPase signaling and microbial infection.
摘要：
Ras亚家族的小GTP酶以其作为原癌蛋白的作用而闻名，而它们在微生物感染期间的功能仍然难以捉摸。这里,我们表明，嗜肺军团菌将小的GTPaseNRas劫持到含军团菌的液泡（LCV）表面。CRISPR干扰筛选可识别单个嗜肺乳杆菌效应物，DenR(Lpg1909),这个过程所需要的。招聘是针对NRas的，而其同源物KRas和HRas被排除在LCV之外。NRas的C端高变尾足以进行招募，对Nras法尼基化或S-酰化位点的干扰可消除募集。有趣的是，我们在LCV上检测到活跃的NRas信号的标记，暗示它作为一个信号平台。随后的磷酸化蛋白质组学分析显示，DenR重新连接宿主NRas信号景观，包括抑制典型的丝裂原活化蛋白激酶途径。这些结果为针对NRas的嗜肺乳杆菌提供了证据，并提示了NRasGTP酶信号传导与微生物感染之间的联系。
