The pseudophosphatase MK-STYX interacts with G3BP and decreases stress granule formation.
The pseudophosphatase MK-STYX interacts with G3BP and decreases stress granule formation.
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DOI：
10.1042/bj20091383
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发表时间：
2010-04-14
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影响因子：
--
通讯作者：
Tonks NK
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文献类型：
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作者：
Hinton SD;Myers MP;Roggero VR;Allison LA;Tonks NK
MK-STYX [MAPK（mitogen-activated protein kinase）phospho-serine/threonine/tyrosine-binding protein]是PTPs（protein tyrosine phosphatases）双特异性磷酸酶亚家族的假磷酸酶成员。MK-STYX是无催化活性的，这是由于缺乏磷酸酶活性所必需的特征基序中的两个氨基酸。MK-STYX的亲核半胱氨酸残基和相邻的组氨酸残基在所有活性双特异性磷酸酶中是保守的，它们分别被丝氨酸和苯丙氨酸残基取代。将组氨酸和半胱氨酸残基引入MK-STYX的活性位点的突变产生活性磷酸酶。使用MS，我们鉴定了G3 BP 1 [Ras-GAP（GTP酶激活蛋白）SH 3（Src同源性3）结构域结合蛋白-1]，一种Ras信号传导的调节剂，作为MK-STYX的结合伴侣。我们观察到G3 BP 1与天然MK-STYX结合;然而，与突变体催化活性形式的MK-STYX的结合显著降低。G3 BP 1也是一种具有内切核糖核酸酶活性的RNA结合蛋白，在应激刺激后被招募到“应激颗粒”中。应激颗粒是作为mRNA分选位点的大型亚细胞结构，其中未翻译的mRNA积累。我们已经表明，MK-STYX的表达抑制应力颗粒的形成所诱导的aresenite或G3 BP本身的表达，然而，催化活性的突变体MK-STYX的能力，抑制G3 BP诱导的应力颗粒组装受损。这些结果揭示了PTP家族成员功能的一个新方面，说明MK-STYX在调节G3 BP 1整合生长因子刺激和环境应激变化与调节蛋白质合成的能力中的作用。
MK-STYX [MAPK (mitogen-activated protein kinase) phospho-serine/threonine/tyrosine-binding protein] is a pseudophosphatase member of the dual-specificity phosphatase subfamily of the PTPs (protein tyrosine phosphatases). MK-STYX is catalytically inactive due to the absence of two amino acids from the signature motif that are essential for phosphatase activity. The nucleophilic cysteine residue and the adjacent histidine residue, which are conserved in all active dual-specificity phosphatases, are replaced by serine and phenylalanine residues respectively in MK-STYX. Mutations to introduce histidine and cysteine residues into the active site of MK-STYX generated an active phosphatase. Using MS, we identified G3BP1 [Ras-GAP (GTPase-activating protein) SH3 (Src homology 3) domain-binding protein-1], a regulator of Ras signalling, as a binding partner of MK-STYX. We observed that G3BP1 bound to native MK-STYX; however, binding to the mutant catalytically active form of MK-STYX was dramatically reduced. G3BP1 is also an RNA-binding protein with endoribonuclease activity that is recruited to ‘stress granules’ after stress stimuli. Stress granules are large subcellular structures that serve as sites of mRNA sorting, in which untranslated mRNAs accumulate. We have shown that expression of MK-STYX inhibited stress granule formation induced either by aresenite or expression of G3BP itself; however, the catalytically active mutant MK-STYX was impaired in its ability to inhibit G3BP-induced stress granule assembly. These results reveal a novel facet of the function of a member of the PTP family, illustrating a role for MK-STYX in regulating the ability of G3BP1 to integrate changes in growth-factor stimulation and environmental stress with the regulation of protein synthesis.