Li Hongtao, Xu Hao, Zhou Yan, Zhang Jie, Long Chengzu, Li Shuqin, Chen She, Zhou Jian-Min, Shao Feng
National Institute of Biological Sciences, Beijing, 102206, China.
Science. 2007 Feb 16;315(5814):1000-3. doi: 10.1126/science.1138960.
Pathogenic bacteria use the type III secretion system to deliver effector proteins into host cells to modulate the host signaling pathways. In this study, the Shigella type III effector OspF was shown to inactivate mitogen-activated protein kinases (MAPKs) [extracellular signal-regulated kinases 1 and 2 (Erk1/2), c-Jun N-terminal kinase, and p38]. OspF irreversibly removed phosphate groups from the phosphothreonine but not from the phosphotyrosine residue in the activation loop of MAPKs. Mass spectrometry revealed a mass loss of 98 daltons in p-Erk2, due to the abstraction of the alpha proton concomitant with cleavage of the C-OP bond in the phosphothreonine residue. This unexpected enzymatic activity, termed phosphothreonine lyase, appeared specific for MAPKs and was shared by other OspF family members.
致病细菌利用III型分泌系统将效应蛋白输送到宿主细胞中，以调节宿主信号通路。在本研究中，志贺氏菌III型效应蛋白OspF被证明可使丝裂原活化蛋白激酶（MAPK）[细胞外信号调节激酶1和2（Erk1/2）、c-Jun氨基末端激酶和p38]失活。OspF不可逆地从MAPK激活环中的磷酸苏氨酸残基而非磷酸酪氨酸残基上去除磷酸基团。质谱分析显示，p-Erk2的分子量损失了98道尔顿，这是由于磷酸苏氨酸残基中的C-OP键断裂伴随α质子的脱去。这种意想不到的酶活性，称为磷酸苏氨酸裂解酶，似乎对MAPK具有特异性，并且其他OspF家族成员也具有这种活性。
