Redundant roles for met docking site tyrosines and the Gab1 pleckstrin homology domain in InlB-mediated entry of Listeria monocytogenes
Redundant roles for met docking site tyrosines and the Gab1 pleckstrin homology domain in InlB-mediated entry of Listeria monocytogenes
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DOI：
10.1128/iai.73.4.2061-2074.2005
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发表时间：
2005-04-01
影响因子：
3.1
通讯作者：
Ireton, K
中科院分区：
文献类型：
--
作者：
Basar, T;Shen, Y;Ireton, K
细菌病原体单核细胞增生李斯特菌引起食源性疾病，导致胃肠炎，脑膜炎或流产。李斯特菌通过细菌表面蛋白InIB与宿主Met受体酪氨酸激酶的相互作用诱导其内化到一些哺乳动物细胞中。InIB的结合导致Met和衔接子Gab 1的磷酸化，并激活宿主磷酸肌醇（PI）3-激酶。Met的哺乳动物配体肝细胞生长因子以依赖于受体胞质尾区1349和1356位两个对接位点酪氨酸磷酸化的方式促进细胞运动和形态发生。在这里，我们确定这些酪氨酸是否是李斯特菌进入所必需的。稳定表达缺少大部分胞质结构域的截短Met的人细胞系T47 D的衍生物不能支持In 1B介导的信号传导或进入。令人惊讶的是，表达在酪氨酸1349和1356（MetYF）中含有苯丙氨酸取代的突变Met的细胞允许进入和In[B]诱导的Gab 1磷酸化。然而，与表达野生型Met的细胞中的情况相反，MetYF细胞中的Gab 1磷酸化需要PI 3-激酶活性。的Gab 1 pleckstrin同源（PH）域组成型与细胞的质膜PI 3-激酶依赖的方式。PH结构域的过表达阻断李斯特菌进入表达MetYF的细胞，但不进入表达野生型Met的细胞。两者合计，这些结果表明，对接位点酪氨酸被标记为内化时，膜定位的Gab 1是组成。通过膜中的Met和PH结构域配体中的磷酸化酪氨酸的不同的募集途径对于细菌进入是多余的。
The bacterial pathogen Listeria monocytogenes causes food-borne illnesses leading to gastroenteritis, meningitis, or abortion. Listeria induces its internalization into some mammalian cells through interaction of the bacterial surface protein InIB with host Met receptor tyrosine kinase. Binding of InIB leads to phosphorylation of Met and the adapter Gab1 and to activation of host phosphoinositide (PI) 3-kinase. The mammalian ligand of Met, hepatocyte growth factor, promotes cell motility and morphogenesis in a manner dependent on phosphorylation of two docking site tyrosines at positions 1349 and 1356 in the receptor's cytoplasmic tail. Here we determined if these tyrosines were essential for Listeria entry. A derivative of the human cell line T47D stably expressing a truncated Met lacking most of its cytoplasmic domain was unable to support In1B-mediated signaling or entry. Surprisingly, cells expressing mutant Met containing phenylallanine substitutions in both tyrosines 1349 and 1356 (MetYF) allowed entry and In[B-induced Gab1 phosphorylation. However, in contrast to the situation in cells expressing wild-type Met, Gab1 phosphorylation in MetYF cells required PI 3-kinase activity. The Gab1 pleckstrin homology (PH) domain was constitutively associated with the plasma membrane of cells in a PI 3-kinase-dependent manner. Overexpression of the PH domain blocked entry of Listeria into cells expressing MetYF but not into cells expressing wild-type Met. Taken together, these results indicate that the docking site tyrosines are dispensable for internalization when membrane localization of Gab1 is constitutive. Distinct pathways of recruitment by phosphorylated tyrosines in Met and PH domain ligands in the membrane are redundant for bacterial entry.