An interdomain helix in IRE1α mediates the conformational change required for the sensor's activation.
An interdomain helix in IRE1α mediates the conformational change required for the sensor's activation.
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DOI：
10.1016/j.jbc.2021.100781
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发表时间：
2021-01
期刊：
影响因子：
--
通讯作者：
Argon Y
中科院分区：
文献类型：
--
作者：
Ricci D;Tutton S;Marrocco I;Ying M;Blumenthal D;Eletto D;Vargas J;Boyle S;Fazelinia H;Qian L;Suresh K;Taylor D;Paton JC;Paton AW;Tang CA;Hu CA;Radhakrishnan R;Gidalevitz T;Argon Y
未折叠的蛋白质反应在动态平衡中扮演着进化上保守的角色，它的失调经常导致人类疾病，包括糖尿病和癌症。IRE1α是一种通过生化信号传递内质网应激的主要转导分子，但我们对应激的检测如何转化为几种分子结果之一的理解仍然存在重大差距。已知，当通过其内质网腔结构域感觉到未折叠的蛋白质时，IRE1α二聚化，然后寡聚(通常显示为聚集)。一旦组装，激活域反式自动磷酸化相邻的IRE1RNA，引起构象变化，激活α效应域。然而，信号如何传输的完整细节尚不清楚。在这里，我们描述了一个以前未知的螺旋αK的作用，它位于IRE1α的激酶和核糖核酸酶结构域之间，在传递这一关键的构象变化中。使用在这个结构域间螺旋中包含突变的构建物，我们表明不同的替换对IRE1RNA的寡聚化、激酶活性和核糖核酸酶活性有不同的影响。此外，使用生化和计算方法，我们发现827位的不同残基在蛋白质的远端位置上有不同的构象，例如在RNase域中。重要的是，RNase失活突变体L827P仍然可以与野生型单体二聚化，但这种突变会使野生型分子失活，使白血病细胞更容易受到压力的影响。我们推测，螺旋αK是逆境反应中激活IRE1α的通道。
The unfolded protein response plays an evolutionarily conserved role in homeostasis, and its dysregulation often leads to human disease, including diabetes and cancer. IRE1α is a major transducer that conveys endoplasmic reticulum stress via biochemical signals, yet major gaps persist in our understanding of how the detection of stress is converted to one of several molecular outcomes. It is known that, upon sensing unfolded proteins via its endoplasmic reticulum luminal domain, IRE1α dimerizes and then oligomerizes (often visualized as clustering). Once assembled, the kinase domain trans-autophosphorylates a neighboring IRE1α, inducing a conformational change that activates the RNase effector domain. However, the full details of how the signal is transmitted are not known. Here, we describe a previously unrecognized role for helix αK, located between the kinase and RNase domains of IRE1α, in conveying this critical conformational change. Using constructs containing mutations within this interdomain helix, we show that distinct substitutions affect oligomerization, kinase activity, and the RNase activity of IRE1α differentially. Furthermore, using both biochemical and computational methods, we found that different residues at position 827 specify distinct conformations at distal sites of the protein, such as in the RNase domain. Of importance, an RNase-inactive mutant, L827P, can still dimerize with wildtype monomers, but this mutation inactivates the wildtype molecule and renders leukemic cells more susceptible to stress. We surmise that helix αK is a conduit for the activation of IRE1α in response to stress.
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影响因子：
3.6
作者：
Concha, Nestor O.;Smallwood, Angela;DeYoung, M. Phillip
通讯作者：
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影响因子：
64.5
作者：
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影响因子：
56.9
作者：
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影响因子：
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作者：
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通讯作者：
Walter P
影响因子：
14.9
作者：
Pandurangan AP;Ochoa-Montaño B;Ascher DB;Blundell TL
通讯作者：
Blundell TL