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Cryo-EM structure and biochemical analysis reveal the basis of the functional difference between human PI3KC3-C1 and -C2.
Cell Research ( IF 44.1 ) Pub Date : 2017-Aug-01 , DOI: 10.1038/cr.2017.94
Meisheng Ma , Jun-Jie Liu , Yan Li , Yuwei Huang , Na Ta , Yang Chen , Hua Fu , Ming-Da Ye , Yuehe Ding , Weijiao Huang , Jia Wang , Meng-Qiu Dong , Li Yu , Hong-Wei Wang

Phosphatidylinositol 3-phosphate (PI3P) plays essential roles in vesicular trafficking, organelle biogenesis and autophagy. Two class III phosphatidylinositol 3-kinase (PI3KC3) complexes have been identified in mammals, the ATG14L complex (PI3KC3-C1) and the UVRAG complex (PI3KC3-C2). PI3KC3-C1 is crucial for autophagosome biogenesis, and PI3KC3-C2 is involved in various membrane trafficking events. Here we report the cryo-EM structures of human PI3KC3-C1 and PI3KC3-C2 at sub-nanometer resolution. The two structures share a common L-shaped overall architecture with distinct features. EM examination revealed that PI3KC3-C1 "stands up" on lipid monolayers, with the ATG14L BATs domain and the VPS34 C-terminal domain (CTD) directly contacting the membrane. Biochemical dissection indicated that the ATG14L BATs domain is responsible for membrane anchoring, whereas the CTD of VPS34 determines the orientation. Furthermore, PI3KC3-C2 binds much more weakly than PI3KC3-C1 to both PI-containing liposomes and purified endoplasmic reticulum (ER) vesicles, a property that is specifically determined by the ATG14L BATs domain. The in vivo ER localization analysis indicated that the BATs domain was required for ER localization of PI3KC3. We propose that the different lipid binding capacity is the key factor that differentiates the functions of PI3KC3-C1 and PI3KC3-C2 in autophagy.

中文翻译:

冷冻EM结构和生化分析揭示了人类PI3KC3-C1和-C2之间功能差异的基础。

3-磷酸​​磷脂酰肌醇(PI3P)在水泡运输,细胞器生物发生和自噬中起重要作用。在哺乳动物中已经鉴定出两种III类磷脂酰肌醇3-激酶(PI3KC3)复合物,即ATG14L复合物(PI3KC3-C1)和UVRAG复合物(PI3KC3-C2)。PI3KC3-C1对于自噬体生物发生至关重要,而PI3KC3-C2参与各种膜运输事件。在这里,我们在亚纳米分辨率下报告人PI3KC3-C1和PI3KC3-C2的冷冻电磁结构。这两个结构共享具有不同特征的通用L形总体架构。EM检查显示PI3KC3-C1在脂质单层上“站立”,ATG14L BATs域和VPS34 C末端域(CTD)直接接触膜。生化解剖表明,ATG14L BATs域负责膜锚定,而VPS34的CTD决定方向。此外,PI3KC3-C2与PI3KC3-C1的结合比含PI的脂质体和纯化的内质网(ER)囊泡的结合弱得多,这是由ATG14L BATs域特异性确定的。体内ER定位分析表明,BAT3结构域是PI3KC3 ER定位所必需的。我们提出,不同的脂质结合能力是区分PI3KC3-C1和PI3KC3-C2在自噬中功能的关键因素。由ATG14L BATs域专门确定的属性。体内ER定位分析表明,BAT3结构域是PI3KC3 ER定位所必需的。我们提出,不同的脂质结合能力是区分PI3KC3-C1和PI3KC3-C2在自噬中功能的关键因素。由ATG14L BATs域专门确定的属性。体内ER定位分析表明,BAT3结构域是PI3KC3 ER定位所必需的。我们提出,不同的脂质结合能力是区分PI3KC3-C1和PI3KC3-C2在自噬中功能的关键因素。
更新日期:2017-07-25
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