Mechanisms controlling membrane recruitment and activation of the autoinhibited SHIP1 inositol 5-phosphatase.
Mechanisms controlling membrane recruitment and activation of the autoinhibited SHIP1 inositol 5-phosphatase.
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DOI：
10.1016/j.jbc.2023.105022
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发表时间：
2023-08
影响因子：
4.8
通讯作者：
Hansen, Scott D.
中科院分区：
文献类型：
--
作者：
Waddell, Grace L.;Drew, Emma E.;Rupp, Henry P.;Hansen, Scott D.
生长因子和免疫受体活化的下游信号转导依赖于PI 3 K产生磷脂酰肌醇-（3，4，5）-三磷酸（PI（3，4，5）P3）脂质。含有Src同源2结构域的肌醇5-磷酸酶1（SHIP 1）调节免疫细胞中PI 3 K信号传导的强度和持续时间，控制PI（3，4，5）P3的去磷酸化以产生磷脂酰肌醇-（3，4）-二磷酸。虽然SHIP 1已被证明可以调节嗜中性粒细胞趋化性、B细胞信号传导和肥大细胞中的皮质振荡，但脂质和蛋白质相互作用在控制SHIP 1膜募集和活性中的作用仍不清楚。使用单分子全内反射荧光显微镜，我们直接可视化支持的脂质双层和细胞质膜上的SHIP 1的膜募集和激活。我们发现，定位的中央催化结构域的SHIP 1是不敏感的PI（3，4，5）P3和磷脂酰肌醇-（3，4）-二磷酸在体外和体内的动态变化。只有当膜含有磷脂酰丝氨酸和PI（3，4，5）P3脂质的组合时，才检测到非常短暂的SHIP 1膜相互作用。分子解剖表明，SHIP 1是自抑制的N-末端Src同源2结构域在抑制磷酸酶活性中发挥关键作用。稳固的SHIP 1膜定位和自抑制的缓解可以通过与免疫受体衍生的磷酸肽的相互作用来实现，所述磷酸肽存在于溶液中或与膜缀合。总体而言，这项工作提供了有关脂质结合特异性、蛋白质-蛋白质相互作用和自抑制SHIP 1激活之间动态相互作用的新机制细节。
Signal transduction downstream of growth factor and immune receptor activation relies on the production of phosphatidylinositol-(3,4,5)-trisphosphate (PI(3,4,5)P3) lipids by PI3K. Regulating the strength and duration of PI3K signaling in immune cells, Src homology 2 domain–containing inositol 5-phosphatase 1 (SHIP1) controls the dephosphorylation of PI(3,4,5)P3 to generate phosphatidylinositol-(3,4)-bisphosphate. Although SHIP1 has been shown to regulate neutrophil chemotaxis, B-cell signaling, and cortical oscillations in mast cells, the role that lipid and protein interactions serve in controlling SHIP1 membrane recruitment and activity remains unclear. Using single-molecule total internal reflection fluorescence microscopy, we directly visualized membrane recruitment and activation of SHIP1 on supported lipid bilayers and the cellular plasma membrane. We find that localization of the central catalytic domain of SHIP1 is insensitive to dynamic changes in PI(3,4,5)P3 and phosphatidylinositol-(3,4)-bisphosphate both in vitro and in vivo. Very transient SHIP1 membrane interactions were detected only when membranes contained a combination of phosphatidylserine and PI(3,4,5)P3 lipids. Molecular dissection reveals that SHIP1 is autoinhibited with the N-terminal Src homology 2 domain playing a critical role in suppressing phosphatase activity. Robust SHIP1 membrane localization and relief of autoinhibition can be achieved through interactions with immunoreceptor-derived phosphopeptides presented either in solution or conjugated to a membrane. Overall, this work provides new mechanistic details concerning the dynamic interplay between lipid-binding specificity, protein–protein interactions, and the activation of autoinhibited SHIP1.
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