@article{d095dc61e1274402b4312e60544ae8ee,
title = "Structure of an E3:E2∼Ub Complex Reveals an Allosteric Mechanism Shared among RING/U-box Ligases",
abstract = "Despite the widespread importance of RING/U-box E3 ubiquitin ligases in ubiquitin (Ub) signaling, the mechanism by which this class of enzymes facilitates Ub transfer remains enigmatic. Here, we present a structural model for a RING/U-box E3:E2∼Ub complex poised for Ub transfer. The model and additional analyses reveal that E3 binding biases dynamic E2∼Ub ensembles toward closed conformations with enhanced reactivity for substrate lysines. We identify a key hydrogen bond between a highly conserved E3 side chain and an E2 backbone carbonyl, observed in all structures of active RING/U-Box E3/E2 pairs, as the linchpin for allosteric activation of E2∼Ub. The conformational biasing mechanism is generalizable across diverse E2s and RING/U-box E3s, but is not shared by HECT-type E3s. The results provide a structural model for a RING/U-box E3:E2∼Ub ligase complex and identify the long sought-after source of allostery for RING/U-Box activation of E2∼Ub conjugates.",
author = "Pruneda, {Jonathan N.} and Littlefield, {Peter J.} and Soss, {Sarah E.} and Nordquist, {Kyle A.} and Chazin, {Walter J.} and Brzovic, {Peter S.} and Klevit, {Rachel E.}",
note = "Funding Information: We thank V. Vittal, K. Dove, N. Zheng, A.G. Palmer, and W. Hol for discussions and critical reading of the manuscript. We acknowledge B. Larimore for performing the experiment shown in Figure S4 C in the N. Zheng and B. Clurman laboratories. A portion of this research was performed using EMSL, a national user facility sponsored by the Department of Energy{\textquoteright}s Office of Biological and Environmental Research and located at PNNL. This work was supported by National Institutes of Health Grants R01 GM088055 (R.E.K.) and R01 GM075156 (W.J.C.), and the U.S. Public Health Service Grant NRSA 2T32 GM007270 from the National Institute of General Medical Sciences (J.N.P.). Access to instrumentation was supported by Grants P30 ES0000267 (Vanderbilt University Center in Molecular Toxicology) and P50 CA068485 (Vanderbilt-Ingram Cancer Center) from the National Institutes of Health. J.N.P and P.J.L. performed all experiments, with the exception of NMR relaxation studies performed by S.E.S. and E4B autoubiquitination assays performed by K.A.N. J.N.P., P.J.L., P.S.B., and R.E.K. designed the overall study and J.N.P., P.J.L., P.S.B., W.J.C., and R.E.K. analyzed the data and wrote the manuscript. DNA constructs will be made available through Addgene.org. Coordinates for the HADDOCK ensemble of the ternary complex are available for download at http://depts.washington.edu/klvtlab/ (Protein Portraits tab). ",
year = "2012",
month = sep,
day = "28",
doi = "10.1016/j.molcel.2012.07.001",
language = "English (US)",
volume = "47",
pages = "933--942",
journal = "Molecular Cell",
issn = "1097-2765",
publisher = "Cell Press",
number = "6",
}