PDF(Pubmed)
Abstract：
Legionella pneumophila strains harboring wild-type rpsL such as Lp02rpsLWT cannot replicate in mouse bone marrow-derived macrophages (BMDMs) due to induction of extensive lysosome damage and apoptosis. The bacterial factor directly responsible for inducing such cell death and the host factor involved in initiating the signaling cascade that leads to lysosome damage remain unknown. Similarly, host factors that may alleviate cell death induced by these bacterial strains have not yet been investigated. Using a genome-wide CRISPR/Cas9 screening, we identified Hmg20a and Nol9 as host factors important for restricting strain Lp02rpsLWT in BMDMs. Depletion of Hmg20a protects macrophages from infection-induced lysosomal damage and apoptosis, allowing productive bacterial replication. The restriction imposed by Hmg20a was mediated by repressing the expression of several endo-lysosomal proteins, including the small GTPase Rab7. We found that SUMOylated Rab7 is recruited to the bacterial phagosome via SulF, a Dot/Icm effector that harbors a SUMO-interacting motif (SIM). Moreover, overexpression of Rab7 rescues intracellular growth of strain Lp02rpsLWT in BMDMs. Our results establish that L. pneumophila exploits the lysosomal network for the biogenesis of its phagosome in BMDMs.
摘要：
携带野生型rpsL如Lp02rpsLWT的嗜肺军团菌菌株由于诱导广泛的溶酶体损伤和凋亡而不能在小鼠骨髓源性巨噬细胞(BMDMs)中复制。直接负责诱导这种细胞死亡的细菌因子和参与启动导致溶酶体损伤的信号级联的宿主因子仍然未知。同样，可以减轻这些细菌菌株诱导的细胞死亡的宿主因子尚未被研究。使用全基因组CRISPR/Cas9筛查，我们确定Hmg20a和Nol9是限制菌株Lp02rpsLWT在BMDMs中的重要宿主因子。允许生产性细菌复制。Hmg20a施加的限制是通过抑制几种内溶酶体蛋白的表达来介导的，包括小GTPaseRab7.我们发现SUMOylatedRab7通过SulF被招募到细菌吞噬体，带有SUMO相互作用基序（SIM）的点/Icm效应器。此外，Rab7的过表达挽救了BMDMs中Lp02rpsLWT菌株的细胞内生长。我们的结果确定，嗜肺乳杆菌利用溶酶体网络进行BMDMs中吞噬体的生物发生。
