Analysis of phosphoinositide binding domain properties within the myotubularin-related protein MTMR3
Analysis of phosphoinositide binding domain properties within the myotubularin-related protein MTMR3
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DOI：
10.1242/jcs.02325
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发表时间：
2005-05-01
影响因子：
4
通讯作者：
Clague, MJ
中科院分区：
文献类型：
--
作者：
Lorenzo, O;Urbé, S;Clague, MJ
肌管蛋白是一个磷酸肌醇特异性磷酸酶大家族，对PtdIns3P和PtdIns(3,5)P-2具有底物特异性。除了n端PH-GRAM （PH-G）结构域和与其他家族成员共享的特征催化结构域外，MTMR3还包含一个c端FYVE结构域。我们发现MTMR3的FYVE结构域是不典型的，因为它既不赋予内体定位，也不与脂质PtdIns3P结合。此外，FYVE结构域不是MTMR3体外酶活性所必需的。相反，PH-GRAM结构域能够与磷酸肌醇脂结合，其中变构调节因子PtdIns5P是首选伙伴。因此，通过细菌磷酸酶IpgD的异位表达在质膜上产生PtdIns5P，导致MTMR3的易位，这需要PH-G结构域。PH-G结构域的缺失导致体外MTMR3活性的丧失，令人惊讶的是，当与活性位点突变结合时，高尔基复合体上的蛋白质积累。
The myotubularins are a large family of phosphoinositide-specific phosphatases with substrate specificity for PtdIns3P and PtdIns(3,5)P-2. In addition to an N-terminal PH-GRAM (PH-G) domain and a signature catalytic domain shared with other family members, MTMR3 contains a C-terminal FYVE domain. We show that the FYVE domain of MTMR3 is atypical in that it neither confers endosomal localisation nor binds to the lipid PtdIns3P. Furthermore the FYVE domain is not required for in vitro enzyme activity of MTMR3. In contrast, the PH-GRAM domain is able to,bind to phosphoinositide lipids, of which the allosteric regulator PtdIns5P is the preferred partner. Consequently, generation of PtdIns5P at the plasma membrane by ectopic expression of the bacterial phosphatase IpgD leads to a translocation of MTMR3 that requires the PH-G domain. Deletion of the PH-G domain leads to loss of activity of MTMR3 in vitro, and surprisingly, when combined with an active site mutation, accumulates the protein on the Golgi complex.