Molecular mechanism and functional role of brefeldin A-mediated ADP-ribosylation of CtBP1/BARS
Molecular mechanism and functional role of brefeldin A-mediated ADP-ribosylation of CtBP1/BARS
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DOI：
10.1073/pnas.1222413110
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发表时间：
2013-06-11
影响因子：
11.1
通讯作者：
Corda, Daniela
中科院分区：
文献类型：
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作者：
Colanzi, Antonino;Grimaldi, Giovanna;Corda, Daniela
adp核糖基化是一种翻译后修饰，可调节许多靶蛋白的功能。我们之前的研究表明，真菌毒素brefeldin A （BFA）诱导c -末端结合蛋白-1短形式/BFA- adp -核糖基化底物（CtBP1-S/BARS）的adp -核糖基化，CtBP1-S/BARS是一种双功能蛋白，在细胞核中作为转录因子，在细胞质中作为高尔基复合体胞内运输和有丝分裂分配过程中膜裂变的调节剂。在这里，我们报道了BFA对CtBP1-S/BARS的adp -核糖基化是通过一种非常规的机制发生的，该机制包括两个步骤：(i)由adp -核糖环化酶CD38合成BFA- adp -核糖缀合物；（ii） BFA- adp -核糖缀合物与CtBP1-S/BARS NAD（+）结合口袋的共价结合。这导致CtBP1-S/BARS锁定在二聚体构象中，从而阻止其与已知参与膜裂变的相互作用物结合，从而抑制有丝分裂高尔基分割中涉及的裂变机制。由于这种抑制可能导致G2细胞周期的停滞，这些发现为设计表达高水平CD38的肿瘤细胞细胞周期的药物阻滞剂提供了策略。
ADP-ribosylation is a posttranslational modification that modulates the functions of many target proteins. We previously showed that the fungal toxin brefeldin A (BFA) induces the ADP-ribosylation of C-terminal-binding protein-1 short-form/BFA-ADP-ribosylation substrate (CtBP1-S/BARS), a bifunctional protein with roles in the nucleus as a transcription factor and in the cytosol as a regulator of membrane fission during intracellular trafficking and mitotic partitioning of the Golgi complex. Here, we report that ADP-ribosylation of CtBP1-S/BARS by BFA occurs via a nonconventional mechanism that comprises two steps: (i) synthesis of a BFA-ADP-ribose conjugate by the ADP-ribosyl cyclase CD38 and (ii) covalent binding of the BFA-ADP-ribose conjugate into the CtBP1-S/BARS NAD(+)-binding pocket. This results in the locking of CtBP1-S/BARS in a dimeric conformation, which prevents its binding to interactors known to be involved in membrane fission and, hence, in the inhibition of the fission machinery involved in mitotic Golgi partitioning. As this inhibition may lead to arrest of the cell cycle in G2, these findings provide a strategy for the design of pharmacological blockers of cell cycle in tumor cells that express high levels of CD38.