SALMONELLA-TYPHIMURIUM ACTIVATES VIRULENCE GENE-TRANSCRIPTION WITHIN ACIDIFIED MACROPHAGE PHAGOSOMES
SALMONELLA-TYPHIMURIUM ACTIVATES VIRULENCE GENE-TRANSCRIPTION WITHIN ACIDIFIED MACROPHAGE PHAGOSOMES
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DOI：
10.1073/pnas.89.21.10079
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发表时间：
1992-11-01
影响因子：
11.1
通讯作者：
MILLER, SI
中科院分区：
文献类型：
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作者：
ARANDA, CMA;SWANSON, JA;MILLER, SI
鼠伤寒沙门菌在巨噬细胞吞噬体内的生存需要细菌基因产物的协同表达。本报告探讨了吞噬体pH值作为鼠伤寒沙门氏菌毒力调节因子PhoP和PhoQ正调控基因表达的信号的作用。小鼠骨髓源性巨噬细胞吞噬细菌数小时后，phop活化基因转录增加50- 77倍。相比之下，在培养的上皮细胞感染后，PhoQ激活基因的表达没有差异，这表明膜传感器PhoQ识别巨噬细胞吞噬体特有的信号。当巨噬细胞培养基中含有提高酸性区室pH的弱碱NH4Cl或氯喹时，phop调控基因表达的增加被消除。pH值测量表明，鼠伤寒沙门氏菌延缓和减弱其细胞内区室的酸化。含有鼠伤寒沙门氏菌的吞噬体需要4-5小时才能达到pH < 5.0。相比之下，在1小时内，在pH < 4.5时测量含有热杀死细菌的液泡。吞噬体最终酸化至pH < 5.0的时间与php依赖性基因最大表达的时间有关。这些观察结果暗示吞噬体酸化是phop调控基因表达的细胞内诱导剂，并表明沙门氏菌的存活依赖于其减弱吞噬体酸化的能力。
Survival of Salmonella typhimurium within macrophage phagosomes requires the coordinate expression of bacterial gene products. This report examines the contribution of phagosomal pH as a signal for expression of genes positively regulated by the S. typhimurium virulence regulators PhoP and PhoQ. Several hours after bacterial phagocytosis by murine bone marrow-derived macrophages, PhoP-activated gene transcription increased 50- to 77-fold. In contrast, no difference in PhoP-activated gene expression was observed after infection of cultured epithelial cells, suggesting that the membrane sensor PhoQ recognized signals unique to macrophage phagosomes. The increase in PhoP-regulated gene expression was abolished when macrophage culture medium contained NH4Cl or chloroquine, weak bases that raise the pH of acidic compartments. Measurements of pH documented that S. typhimurium delayed and attenuated acidification of its intracellular compartment. Phagosomes containing S. typhimurium required 4-5 hr to reach pH < 5.0. In contrast, within 1 hr vacuoles containing heat-killed bacteria were measured at pH < 4.5. The eventual acidification of phagosomes to pH < 5.0 correlated with the period of maximal PhoP-dependent gene expression. These observations implicate phagosome acidification as an intracellular inducer of PhoP-regulated gene expression and suggest that Salmonella survival is dependent on its ability to attenuate phagosome acidification.