@article{68aca637b3c5494bb48e5dcb4765e949,
title = "Flavonol Activation Defines an Unanticipated Ligand-Binding Site in the Kinase-RNase Domain of IRE1",
abstract = "Signaling in the most conserved branch of the endoplasmic reticulum (ER) unfolded protein response (UPR) is initiated by sequence-specific cleavage of the HAC1/XBP1 mRNA by the ER stress-induced kinase-endonuclease IRE1. We have discovered that the flavonol quercetin activates yeast IRE1's RNase and potentiates activation by ADP, a natural activating ligand that engages the IRE1 nucleotide-binding cleft. Enzyme kinetics and the structure of a cocrystal of IRE1 complexed with ADP and quercetin reveal engagement by quercetin of an unanticipated ligand-binding pocket at the dimer interface of IRE1's kinase extension nuclease (KEN) domain. Analytical ultracentrifugation and crosslinking studies support the preeminence of enhanced dimer formation in quercetin's mechanism of action. These findings hint at the existence of endogenous cytoplasmic ligands that may function alongside stress signals from the ER lumen to modulate IRE1 activity and at the potential for the development of drugs that modify UPR signaling from this unanticipated site.",
author = "Wiseman, {R. Luke} and Yuhong Zhang and Lee, {Kenneth P.K.} and Harding, {Heather P.} and Haynes, {Cole M.} and Joshua Price and Frank Sicheri and David Ron",
note = "Funding Information: We thank Tim Cardozo and Hong Wang (NYU), Tom Dever and Madusudan Dey (NICHD), Jeff Kelly (Scripps), Spencer Williams (University of Melbourne), and members of the Sicheri Lab for fruitful discussions; Chris Lima (MSKCC) for the Ulp1 and Smt3 expression plasmids; Andy Ryan and Matt Shoulders (Scripps) for their help in docking cholesterol to the IRE1 Q-site; the staff of the Northeastern Collaborative Access Team (NE-CAT) at the Advanced Photon Source (APS) at Argonne National Laboratories, where diffraction data were collected; and Steffan Knapp (Structural Genomics Consortium; Oxford, UK) for assistance with small-molecule screening. This work was supported by grants DK047119, DK075311, and ES08681 to D.R. and grant F32-ES014775 to R.L.W. and by Canadian Institutes for Health Research grant MOP-84370 to F.S. K.P.K.L. is a recipient of a Canadian Institutes for Health Research Canada Graduate Scholarship, and D.R. is a Wellcome Trust Principal Research Fellow. ",
year = "2010",
month = apr,
day = "23",
doi = "10.1016/j.molcel.2010.04.001",
language = "English (US)",
volume = "38",
pages = "291--304",
journal = "Molecular Cell",
issn = "1097-2765",
publisher = "Cell Press",
number = "2",
}