Phosphoserine modification of the enteropathogenic Escherichia coli Tir molecule is required to trigger conformational changes in Tir and efficient pedestal elongation
Phosphoserine modification of the enteropathogenic Escherichia coli Tir molecule is required to trigger conformational changes in Tir and efficient pedestal elongation
复制标题
需要对致病性大肠杆菌 Tir 分子进行磷酸丝氨酸修饰，以触发 Tir 的构象变化和有效的基座伸长
作者：
J. Warawa;B. Kenny
肠致病性大肠杆菌（EPEC）的毒力与紧密粘附于肠道上皮细胞、吸收性微绒毛的丧失以及宿主细胞骨架蛋白重组为粘附细菌下方的基座样结构相关。这些过程依赖于Tir（i）插入质膜;（ii）酪氨酸磷酸化;和（iii）与细菌外膜蛋白，内膜蛋白相互作用。然而，在其他未定义的残基上的磷酸化导致宿主细胞内Tir表观分子量增加105kDa和102kDa。 在这项研究中，我们表明，等价的位移可以诱导在体外由蛋白激酶A（PKA）的两个丝氨酸（S434和S463）残基上的Tir的磷酸化。我们的数据表明，顺序添加的两个磷酸基团触发的构象变化的TIR结构，可以提供能量插入到质膜的TIR。PKA还显示修饰宿主细胞内S434上的Tir以诱导约5kDa的移位。 虽然S434的修饰对于产生肌动蛋白成核分子不是必需的，但需要Tir有效地诱导基座延伸。这项研究不仅增加了我们对磷酸化诱导Tir表观分子量变化的机制的理解，并提出了Tir可能插入质膜的机制，而且还揭示了非酪氨酸磷酸化在Tir功能中的作用，并确定了第一个可以在体外或体内修饰Tir的激酶。
Enteropathogenic Escherichia coli (EPEC) virulence is correlated with intimate adherence to gut epithelial cells, loss of absorptive microvilli and reorganization of host cytoskeletal proteins into pedestal‐like structures beneath the adherent bacteria. These processes depend on Tir (i) being inserted into the plasma membrane; (ii) being tyrosine phosphorylated; and (iii) interacting with the bacterial outer membrane protein, intimin. However, phosphorylation on other undefined residues leads to ≈ 5 kDa and ≈ 2 kDa increases in Tir apparent molecular mass within host cells. In this study, we show that equivalent shifts can be induced in vitro by phosphorylation of Tir on two serine (S434 and S463) residues by protein kinase A (PKA). Our data suggest that the sequential addition of two phosphate groups triggers conformational changes in Tir structure that may supply the energy to insert Tir into the plasma membrane. PKA was also shown to modify Tir within host cells on S434 to induce the ≈ 5 kDa shift. Whereas modification of S434 was not essential to generate an actin‐nucleating molecule, it was required for Tir to induce pedestal elongation efficiently. This study not only increases our understanding of the mechanism by which phosphorylation induces shifts in Tir apparent molecular mass and suggests a mechanism by which Tir may be inserted into the plasma membrane, but also reveals a role for non‐tyrosine phosphorylation in Tir function and identifies the first kinase that can modify Tir in vitro or in vivo.
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DOI：
10.1073/pnas.81.11.3471
发表时间：
1984-01-01
期刊：
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA-BIOLOGICAL SCIENCES
影响因子：
--
作者：
MILLER, VL;MEKALANOS, JJ
通讯作者：
MEKALANOS, JJ
影响因子：
15.9
作者：
McNamara, BP;Koutsouris, A;Hecht, G
通讯作者：
Hecht, G
DOI：
10.1073/pnas.92.17.7996
发表时间：
1995-08-15
影响因子：
11.1
作者：
JARVIS, KG;GIRON, JA;KAPER, JB
通讯作者：
KAPER, JB
影响因子：
56.9
作者：
GIRON, JA;HO, ASY;SCHOOLNIK, GK
通讯作者：
SCHOOLNIK, GK