Interactions of S100A2 and S100A6 with the tetratricopeptide repeat proteins, Hsp90/Hsp70-organizing protein and kinesin light chain
Interactions of S100A2 and S100A6 with the tetratricopeptide repeat proteins, Hsp90/Hsp70-organizing protein and kinesin light chain
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DOI：
10.1074/jbc.m801473200
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发表时间：
2008-10-17
影响因子：
4.8
通讯作者：
Kobayashi, Ryoji
中科院分区：
文献类型：
--
作者：
Shimamoto, Seiko;Takata, Maki;Kobayashi, Ryoji
S100A2和S100A6以Ca2+调节的方式与几种靶蛋白相互作用。然而，S100蛋白在细胞内的确切作用尚不清楚。本研究发现Hsp70/ hsp90组织蛋白（Hop）和运动蛋白轻链（KLC）是S100A2和S100A6的新靶点。Hop通过TPR结构域直接与Hsp70和Hsp90结合，调控Hop-Hsp70和Hop-Hsp90复合物的形成。我们在体外实验中发现S100A2和S100A6与Hop的TPR结构域结合，抑制Hop- hsp70和Hop- hsp90的相互作用。虽然内源性Hsp70和Hsp90在静止的Cos-7细胞中与Hop相互作用，但不与S100A6相互作用，但离子霉素刺激这些细胞引起Hop-S100A6相互作用，导致Hsp70和Hsp90与Hop分离。同样，谷胱甘肽s -转移酶拉降和共免疫沉淀实验表明，S100A6与KLC的TPR结构域结合，导致KLC-c- jun n -末端激酶(JNK)-相互作用蛋白1 （JIP-1）在体外相互作用受到抑制。瞬时表达的JIP-1在静止的Cos-7细胞中与KLC相互作用，但不与S100A6相互作用。离子霉素刺激这些细胞也引起KLC- s100a6相互作用，导致JIP- 1与KLC分离。这些结果强烈表明，在体内和体外，S100蛋白通过Ca2+依赖性S100蛋白- tpr蛋白复合物的形成调节Hsp70-Hop-Hsp90多伴侣复合物的形成和KLC-cargo的相互作用。此外，我们已经证明S100A2和S100A6在体外与另一个TPR蛋白Tom70相互作用并调节Tom70配体相互作用。因此，我们的研究结果表明，通过S100蛋白- tpr基序相互作用，存在一种新的细胞内Ca2+信号通路。
S100A2 and S100A6 interact with several target proteins in a Ca2+-regulated manner. However, the exact intracellular roles of the S100 proteins are unclear. In this study we identified Hsp70/Hsp90-organizing protein (Hop) and kinesin light chain (KLC) as novel targets of S100A2 and S100A6. Hop directly associates with Hsp70 and Hsp90 through the tetratricopeptide (TPR) domains andregulates Hop-Hsp70 and Hop-Hsp90 complex formation. We have found that S100A2 and S100A6 bind to the TPR domain of Hop, resulting in inhibition of the Hop-Hsp70 and Hop-Hsp90 interactions in vitro. Although endogenous Hsp70 and Hsp90 interact with Hop in resting Cos-7 cells, but not with S100A6, stimulation of these cells with ionomycin caused a Hop-S100A6 interaction, resulting in the dissociation of Hsp70 and Hsp90 from Hop. Similarly, glutathione S-transferase pulldown and co-immunoprecipitation experiments revealed that S100A6 binds to the TPR domain of KLC, resulting in inhibition of the KLC-c-Jun N-terminal kinase (JNK)-interacting protein 1 (JIP-1) interaction in vitro. The transiently expressed JIP-1 interacts with KLC in resting Cos-7 cells but not with S100A6. Stimulation of these cells with ionomycin also caused a KLC-S100A6 interaction, resulting in dissociation of JIP- 1 from KLC. These results strongly suggest that the S100 proteins modulate Hsp70-Hop-Hsp90 multichaperone complex formation and KLC-cargo interaction via Ca2+-dependent S100 protein-TPR protein complex formation in vivo as well as in vitro. Moreover, we have shown that S100A2 and S100A6 interact with another TPR protein Tom70 and regulate the Tom70-ligand interaction in vitro. Thus, our findings suggest a new intracellular Ca2+-signaling pathway via S100 proteins-TPR motif interactions.