Structural insights into SAM domain-mediated tankyrase oligomerization
Structural insights into SAM domain-mediated tankyrase oligomerization
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DOI：
10.1002/pro.2968
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发表时间：
2016-09-01
期刊：
影响因子：
8
通讯作者：
Klevit, Rachel E.
中科院分区：
文献类型：
--
作者：
DaRosa, Paul A.;Ovchinnikov, Sergey;Klevit, Rachel E.
Tankyrase 1(TNKS1；又名ARTD5)和Tankyrase2(TNKS2；又名ARTD6)是高度同源的聚(ADP-核糖)聚合酶(PARP)，在多种细胞过程中发挥作用，包括Wnt信号、Src信号、Akt信号、GLUT4小泡转位、端粒长度调节以及中心粒和纺锤体极成熟。Tankyrase蛋白包括一个无菌α基序(SAM)结构域，在体外和体内都会发生寡聚。然而，TNKS1和TNKS2的SAM结构域尚未得到结构表征，其齐聚方式也尚未确定。在这里，我们模拟了SAM结构域介导的Tankyrase的寡聚。结构模型得到了突变和核磁共振分析的支持，证明了一种螺旋的同型头尾聚合物，促进了TNKS的自结合。此外，我们还证明了TNKS1和TNKS2可以通过它们的SAM结构域形成(TNKS1SAM-TNKS2SAM)杂低聚结构。虽然野生型Tankyrase蛋白的溶解度很低，但SAM寡聚界面残基的基于模型的突变使我们能够获得可溶性的TNKS蛋白。这些结构上的见解对于研究TNKS1/2的功能和生物物理特性是非常有价值的，包括TNKS寡聚在蛋白质多聚(ADP-核糖基化)和依赖于PAR化的泛素化中的作用。
Tankyrase 1 (TNKS1; a.k.a. ARTD5) and tankyrase 2 (TNKS2; a.k.a ARTD6) are highly homologous poly(ADP-ribose) polymerases (PARPs) that function in a wide variety of cellular processes including Wnt signaling, Src signaling, Akt signaling, Glut4 vesicle translocation, telomere length regulation, and centriole and spindle pole maturation. Tankyrase proteins include a sterile alpha motif (SAM) domain that undergoes oligomerization in vitro and in vivo. However, the SAM domains of TNKS1 and TNKS2 have not been structurally characterized and the mode of oligomerization is not yet defined. Here we model the SAM domain-mediated oligomerization of tankyrase. The structural model, supported by mutagenesis and NMR analysis, demonstrates a helical, homotypic head-to-tail polymer that facilitates TNKS self-association. Furthermore, we show that TNKS1 and TNKS2 can form (TNKS1 SAM-TNKS2 SAM) hetero-oligomeric structures mediated by their SAM domains. Though wild-type tankyrase proteins have very low solubility, model-based mutations of the SAM oligomerization interface residues allowed us to obtain soluble TNKS proteins. These structural insights will be invaluable for the functional and biophysical characterization of TNKS1/2, including the role of TNKS oligomerization in protein poly(ADP-ribosyl)ation (PARylation) and PARylation-dependent ubiquitylation.