Dual Role for Hsc70 in the Biogenesis and Regulation of the Heme-Regulated Kinase of the α Subunit of Eukaryotic Translation Initiation Factor 2
Dual Role for Hsc70 in the Biogenesis and Regulation of the Heme-Regulated Kinase of the α Subunit of Eukaryotic Translation Initiation Factor 2
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Hsc70 在真核翻译起始因子 2 α 亚基血红素调节激酶的生物发生和调节中的双重作用
DOI：
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发表时间：
1999
影响因子：
5.3
通讯作者：
R. Matts
中科院分区：
文献类型：
--
作者：
S. Uma;V. Thulasiraman;R. Matts
真核细胞起始因子2（HRI）α亚基的血红素调节激酶在兔网织红细胞裂解物（RRL）中被激活，以响应许多环境条件，包括血红素缺乏、热休克和氧化应激。HRI的激活引起蛋白质合成起始的停滞。最近，我们已经证明，热休克同源蛋白Hsc70负调节激活的HRI在RRL在这些环境条件下作出反应。Hsc70也被认为是RRL中Hsp90分子伴侣机制的关键组成部分，其对于HRI获得和维持能够激活的构象起着必要的作用。使用从头合成的HRI在同步脉冲追踪翻译，我们已经研究了Hsc70在调节HRI的生物发生和激活的作用。与Hsp90一样，Hsc70与新生HRI和成熟到能够经历刺激诱导激活的状态的HRI（成熟有能力的HRI）相互作用。HRI与Hsc70的相互作用是HRI转化所必需的，因为Hsc70拮抗剂氯贝酸抑制HRI折叠成成熟的有能力的构象。与Hsp90不同，Hsc70也与转化的HRI相互作用。氯贝酸破坏了Hsc70与转化的HRI的相互作用，所述转化的HRI在没有药物的情况下已经成熟和转化。在血红素缺乏的RRL中，Hsc70与转化的HRI相互作用的破坏导致其超活化。此外，响应于热休克或变性蛋白的HRI的活化也导致Hsc70与转化的HRI的相互作用的类似阻断。这些结果表明Hsc70是HRI折叠和转化为活性激酶所必需的，但随后需要负性减弱转化的HRI的活化。
ABSTRACT The heme-regulated kinase of the α subunit of eukaryotic initiation factor 2 (HRI) is activated in rabbit reticulocyte lysate (RRL) in response to a number of environmental conditions, including heme deficiency, heat shock, and oxidative stress. Activation of HRI causes an arrest of initiation of protein synthesis. Recently, we have demonstrated that the heat shock cognate protein Hsc70 negatively modulates the activation of HRI in RRL in response to these environmental conditions. Hsc70 is also known to be a critical component of the Hsp90 chaperone machinery in RRL, which plays an obligatory role for HRI to acquire and maintain a conformation that is competent to activate. Using de novo-synthesized HRI in synchronized pulse-chase translations, we have examined the role of Hsc70 in the regulation of HRI biogenesis and activation. Like Hsp90, Hsc70 interacted with nascent HRI and HRI that was matured to a state which was competent to undergo stimulus-induced activation (mature-competent HRI). Interaction of HRI with Hsc70 was required for the transformation of HRI, as the Hsc70 antagonist clofibric acid inhibited the folding of HRI into a mature-competent conformation. Unlike Hsp90, Hsc70 also interacted with transformed HRI. Clofibric acid disrupted the interaction of Hsc70 with transformed HRI that had been matured and transformed in the absence of the drug. Disruption of Hsc70 interaction with transformed HRI in heme-deficient RRL resulted in its hyperactivation. Furthermore, activation of HRI in response to heat shock or denatured proteins also resulted in a similar blockage of Hsc70 interaction with transformed HRI. These results indicate that Hsc70 is required for the folding and transformation of HRI into an active kinase but is subsequently required to negatively attenuate the activation of transformed HRI.
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eIF-2(α) 磷酸化对蛋白质合成起始的调节以及逆转因子在 eIF-2 循环中的作用。
DOI：
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发表时间：
1984
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Matts,RL;London,IM
通讯作者：
London,IM
影响因子：
3.3
作者：
Eggers, DK;Welch, WJ;Hansen, WJ
通讯作者：
Hansen, WJ
影响因子：
20.3
作者：
W. Pratt;D. Toft
通讯作者：
W. Pratt;D. Toft
编码大鼠血红素敏感起始因子 2 α (eIF-2 α) 激酶的 cDNA 的克隆和表征。
DOI：
--
发表时间：
1994
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Mellor,H;Flowers,KM;Kimball,SR;Jefferson,LS
通讯作者：
Jefferson,LS
DOI：
--
发表时间：
1994
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Gross,M;Olin,A;Hessefort,S;Bender,S
通讯作者：
Bender,S