TY - JOUR
T1 - An interdomain helix in IRE1α mediates the conformational change required for the sensor's activation
AU - Ricci, Daniela
AU - Tutton, Stephen
AU - Marrocco, Ilaria
AU - Ying, Mingjie
AU - Blumenthal, Daniel
AU - Eletto, Daniela
AU - Vargas, Jade
AU - Boyle, Sarah
AU - Fazelinia, Hossein
AU - Qian, Lei
AU - Suresh, Krishna
AU - Taylor, Deanne
AU - Paton, James C.
AU - Paton, Adrienne W.
AU - Tang, Chih Hang Anthony
AU - Hu, Chih Chi Andrew
AU - Radhakrishnan, Ravi
AU - Gidalevitz, Tali
AU - Argon, Yair
N1 - Funding Information:
Funding and additional information—This work was funded by National Institutes of Health (NIH) grants AG18001 and GM077480 to Y. A., and AG063029 to T. G. D. E. was supported by a postdoctoral fellowship from the Italian-American Cancer Foundation. D. R. was supported by NIH training grant 5 T32 HL 7954-18. D. B. was supported by NIH grant R21 AI32828. C.-H. A. T. and C.-C. A. H. were supported by NCI, NIH grant R01CA163910. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
Publisher Copyright:
© 2021 THE AUTHORS.
PY - 2021/1/1
Y1 - 2021/1/1
N2 - 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.
AB - 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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U2 - 10.1016/J.JBC.2021.100781
DO - 10.1016/J.JBC.2021.100781
M3 - Article
C2 - 34000298
AN - SCOPUS:85108179356
VL - 296
JO - The Journal of biological chemistry
JF - The Journal of biological chemistry
SN - 0021-9258
M1 - 100781
ER -