EPIYA motif is a membrane-targeting signal of Helicobacter pylori virulence factor CagA in mammalian cells
EPIYA motif is a membrane-targeting signal of Helicobacter pylori virulence factor CagA in mammalian cells
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DOI：
10.1074/jbc.m503583200
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发表时间：
2005-06-17
影响因子：
4.8
通讯作者：
Hatakeyama, M
中科院分区：
文献类型：
--
作者：
Higashi, H;Yokoyama, K;Hatakeyama, M
幽门螺杆菌会促使消化性溃疡和萎缩性胃炎的发生。此外，携带cagA基因的幽门螺杆菌菌株比cagA阴性菌株的毒性更强，且与胃腺癌的发生相关。cagA基因产物CagA会被转运至胃上皮细胞，并定位于质膜内表面，在那里它会在谷氨酸 - 脯氨酸 - 异亮氨酸 - 酪氨酸 - 丙氨酸（EPIYA）基序处发生酪氨酸磷酸化。酪氨酸磷酸化的CagA会特异性地结合并激活膜上含Src同源2结构域的蛋白酪氨酸磷酸酶 - 2（SHP - 2），从而诱导细胞呈现一种伸长的形态，称为“蜂鸟表型”。因此，CagA与膜的连接是其致病活性的必要前提。我们在此表明，CagA与膜的结合需要含EPIYA的区域，但不依赖于EPIYA酪氨酸磷酸化。我们进一步表明，特异性缺失EPIYA基序会消除CagA与膜结合的能力。相反，将EPIYA序列重新引入缺乏含EPIYA区域的CagA突变体中，可恢复CagA与膜的结合。因此，单个EPIYA基序的存在是CagA定位于膜的必要条件。我们的研究结果表明，EPIYA基序在膜结合和酪氨酸磷酸化中具有双重功能，这两者都与CagA失调细胞内信号传导的活性密切相关，并提示EPIYA基序是cagA阳性幽门螺杆菌感染的关键治疗靶点。
Helicobacter pylori contributes to the development of peptic ulcers and atrophic gastritis. Furthermore, H. pylori strains carrying the cagA gene are more virulent than cagA-negative strains and are associated with the development of gastric adenocarcinoma. The cagA gene product, CagA, is translocated into gastric epithelial cells and localizes to the inner surface of the plasma membrane, in which it undergoes tyrosine phosphorylation at the Glu-Pro-Ile-Tyr-Ala (EPIYA) motif. Tyrosine-phosphorylated CagA specifically binds to and activates Src homology 2-containing protein-tyrosine phosphatase-2 (SHP-2) at the membrane, thereby inducing an elongated cell shape termed the hummingbird phenotype. Accordingly, membrane tethering of CagA is an essential prerequisite for the pathogenic activity of CagA. We show here that membrane association of CagA requires the EPIYA-containing region but is independent of EPIYA tyrosine phosphorylation. We further show that specific deletion of the EPIYA motif abolishes the ability of CagA to associate with the membrane. Conversely, reintroduction of an EPIYA sequence into a CagA mutant that lacks the EPIYA-containing region restores membrane association of CagA. Thus, the presence of a single EPIYA motif is necessary for the membrane localization of CagA. Our results indicate that the EPIYA motif has a dual function in membrane association and tyrosine phosphorylation, both of which are critically involved in the activity of CagA to deregulate intracellular signaling, and suggest that the EPIYA motif is a crucial therapeutic target of cagA-positive H. pylori infection.