Tel2 structure and function in the Hsp90-dependent maturation of mTOR and ATR complexes
Tel2 structure and function in the Hsp90-dependent maturation of mTOR and ATR complexes
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DOI：
10.1101/gad.1956410
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发表时间：
2010-09-15
影响因子：
10.5
通讯作者：
Pavletich, Nikola P.
中科院分区：
文献类型：
--
作者：
Takai, Hiroyuki;Xie, Yihu;Pavletich, Nikola P.
我们以前曾报道，所有哺乳动物磷脂酰肌醇3-激酶相关蛋白激酶(PIKKs)的稳定性取决于它们与TEL2的相互作用，TEL2是酵母TEL2和秀丽线虫CLK-2的同源基因。在这里，我们提供了TEL2与Hsp90在Pikk复合体成熟过程中作用的证据。定量免疫印迹显示，TEL2的丰度低于PIKKs，TEL2优先结合新合成的ATM、ATR、mTOR和DNA-PKcs。除Tti1-Tti2外，TEL2复合体中还含有Hsp90分子伴侣，Hsp90的抑制作用干扰了TEL2与PIKK的相互作用。对体内标记的新生蛋白复合体的分析表明，TEL2和Hsp90介导了mTOR、TORC1和TORC2复合体的形成以及ATR与ATAP的结合。这里报道的酵母菌TEL2的结构表明，TEL2由类似热的螺旋重复序列组成，这些重复序列组装成两个独立的a螺线管。通过突变，我们在体外鉴定了与Tti1-Tti2复合体结合的保守残基的表面补丁。在体内，这个保守的补丁的突变影响细胞生长、PIKKs水平和ATM/ATR介导的检查点信号，突显了Tti1-Tti2结合对TEL2功能的重要性。综上所述，我们的数据表明TEL2-Tti1-Tti2复合体是Hsp90的Pikk特异性辅伴侣。
We reported previously that the stability of all mammalian phosphatidylinositol 3-kinase-related protein kinases (PIKKs) depends on their interaction with Tel2, the ortholog of yeast Tel2 and Caenorhabditis elegans Clk-2. Here we provide evidence that Tel2 acts with Hsp90 in the maturation of PIKK complexes. Quantitative immuno-blotting showed that the abundance of Tel2 is low compared with the PIKKs, and Tel2 preferentially bound newly synthesized ATM, ATR, mTOR, and DNA-PKcs. Tel2 complexes contained, in addition to Tti1-Tti2, the Hsp90 chaperone, and inhibition of Hsp90 interfered with the interaction of Tel2 with the PIKKs. Analysis of in vivo labeled nascent protein complexes showed that Tel2 and Hsp90 mediate the formation of the mTOR TORC1 and TORC2 complexes and the association of ATR with ATRIP. The structure of yeast Tel2, reported here, shows that Tel2 consists of HEAT-like helical repeats that assemble into two separate a-solenoids. Through mutagenesis, we identify a surface patch of conserved residues involved in binding to the Tti1-Tti2 complex in vitro. In vivo, mutation of this conserved patch affects cell growth, levels of PIKKs, and ATM/ATR-mediated checkpoint signaling, highlighting the importance of Tti1-Tti2 binding to the function of Tel2. Taken together, our data suggest that the Tel2-Tti1-Tti2 complex is a PIKK-specific cochaperone for Hsp90.