Dual role for phosphoinositides in regulation of yeast and mammalian phospholipase D enzymes.
Dual role for phosphoinositides in regulation of yeast and mammalian phospholipase D enzymes.
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DOI：
10.1083/jcb.200205056
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发表时间：
2002-12-23
影响因子：
7.8
通讯作者：
Morris, Andrew J
中科院分区：
文献类型：
--
作者：
Sciorra, Vicki A;Rudge, Simon A;Wang, Jiyao;McLaughlin, Stuart;Engebrecht, JoAnne;Morris, Andrew J
磷脂酶D（PLD）产生脂质信号，协调膜运输与细胞信号。PLD在体外和体内的活性依赖于具有邻位4，5-磷酸对的磷酸肌醇。酵母和哺乳动物PLD含有NH 2-末端普列克底物蛋白同源（PH）结构域，推测其通过与磷脂酰肌醇4，5-二磷酸（PI[4，5]P2）的相互作用来指定亚细胞定位和PLD活性的调节。我们报告说，酵母和哺乳动物PLD酶的PH结构域的突变产生催化活性PI（4，5）P2调节的酶与受损的生物功能。哺乳动物PLD 2的PH结构域的破坏导致蛋白质从含有PI（4，5）P2的质膜重新定位到核内体。作为这种错误定位的结果，PH结构域内的突变使得蛋白质对体内活化无反应。此外，PH结构域的完整性对于酵母PLD在减数分裂和分泌中的功能至关重要。酸性磷脂增强了PLD 2与模型膜的结合。PLD 2衍生肽的研究表明，这种结合涉及先前鉴定的多元基序，其介导PI（4，5）P2对酶的激活。相比之下，PLD 2 PH结构域以较低的亲和力结合PI（4，5）P2，但具有足够的选择性，与多元基序协同作用，将蛋白质靶向富含PI（4，5）P2的膜。因此，磷酸肌醇在PLD调节中具有双重作用：由PH结构域介导的膜靶向和由多元基序介导的催化刺激。
Phospholipase D (PLD) generates lipid signals that coordinate membrane trafficking with cellular signaling. PLD activity in vitro and in vivo is dependent on phosphoinositides with a vicinal 4,5-phosphate pair. Yeast and mammalian PLDs contain an NH2-terminal pleckstrin homology (PH) domain that has been speculated to specify both subcellular localization and regulation of PLD activity through interaction with phosphatidylinositol 4,5-bisphosphate (PI[4,5]P2). We report that mutation of the PH domains of yeast and mammalian PLD enzymes generates catalytically active PI(4,5)P2-regulated enzymes with impaired biological functions. Disruption of the PH domain of mammalian PLD2 results in relocalization of the protein from the PI(4,5)P2-containing plasma membrane to endosomes. As a result of this mislocalization, mutations within the PH domain render the protein unresponsive to activation in vivo. Furthermore, the integrity of the PH domain is vital for yeast PLD function in both meiosis and secretion. Binding of PLD2 to model membranes is enhanced by acidic phospholipids. Studies with PLD2-derived peptides suggest that this binding involves a previously identified polybasic motif that mediates activation of the enzyme by PI(4,5)P2. By comparison, the PLD2 PH domain binds PI(4,5)P2 with lower affinity but sufficient selectivity to function in concert with the polybasic motif to target the protein to PI(4,5)P2-rich membranes. Phosphoinositides therefore have a dual role in PLD regulation: membrane targeting mediated by the PH domain and stimulation of catalysis mediated by the polybasic motif.