SUMO-1 controls the protein stability and the biological function of phosducin
SUMO-1 controls the protein stability and the biological function of phosducin
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DOI：
10.1074/jbc.m513703200
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发表时间：
2006-03-31
影响因子：
4.8
通讯作者：
Lohse, MJ
中科院分区：
文献类型：
--
作者：
Klenk, C;Humrich, J;Lohse, MJ
Phosducin通过与异源三聚体G蛋白的Gβ伽马亚基结合来调节Gβ伽马刺激的信号转导。通过磷酸化来控制光导蛋白的活性已经得到了很好的证实。然而，人们对其他可能控制光滑蛋白活性的机制知之甚少。在这里，我们报告了在翻译后水平上，通过与泛素相关的小修饰物SUMO进行修饰来调节磷酸脱氢酶。我们展示了相扑对在细胞中表达的体外硫代蛋白以及从视网膜和心脏中纯化的天然硫代蛋白的修饰。在32-35位氨基酸的硫代磷酸脱氢酶中发现了一个共同的SUMO化基序。该基序中保守的赖氨酸33突变为精氨酸，取消了硫代蛋白的SUMO化，表明SUMO与硫代蛋白的赖氨酸33结合。在转基因细胞中，K33R突变蛋白的稳态表达水平远低于野生型。对野生型和K33R蛋白稳定性的研究表明，苏氨酸化缺陷突变体的蛋白质稳定性降低。蛋白质稳定性的降低与SUMO化缺陷突变体泛素化的增加有关。这些发现表明，SUMO化可以保护光解蛋白免受蛋白酶体的降解。硫代蛋白的苏莫化降低了其与G-β-γ的结合能力。PhlP是PhlP家族中的一个密切相关的成员，它不是SUMO化的目标，但它的SUMO化可以通过在PhlP保守的N端插入一个氨基酸来实现。综上所述，这些发现表明，光导蛋白是一个以前未被认识的相扑修饰的靶标，SUMO化控制着光导蛋白在细胞中的稳定性及其功能特性。
Phosducin regulates G beta gamma- stimulated signaling by binding to G beta gamma subunits of heterotrimeric G- proteins. Control of phosducin activity by phosphorylation is well established. However, little is known about other mechanisms that may control phosducin activity. Here we report that phosducin is regulated at the posttranslational level by modification with the small ubiquitin- related modifier, SUMO. We demonstrate modification with SUMO for phosducin in vitro expressed in cells and for native phosducin purified from retina and the heart. A consensus motif for SUMOylation was identified in phosducin at amino acid positions 32 - 35. Mutation of the conserved lysine 33 to arginine in this motif abolished SUMOylation of phosducin, indicating that SUMO is attached to lysine 33 of phosducin. In transfected cells the steady- state levels of the K33R mutant protein were much lower compared with wildtype phosducin. The investigation of the stability of wild- type phosducin and of phosducin(K33R) showed a decreased protein stability of the SUMOylation- deficient mutant. The decreased protein stability correlated with increased ubiquitinylation of the SUMOylation- deficient mutant. These findings indicate that SUMOylation protects phosducin from proteasomal degradation. SUMOylation of phosducin decreased its ability to bind G beta gamma. PhlP, a closely related member of the phosducin family, was not a target for SUMOylation, but its SUMOylation can be achieved by a single amino acid insertion in the conserved N terminus of PhlP. Together, these findings show that phosducin is a previously unrecognized target of SUMO modification and that SUMOylation controls phosducin stability in cells as well as its functional properties.