Autoinhibition Mechanism of the Ubiquitin-Conjugating Enzyme UBE2S by Autoubiquitination.
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Ubiquitin-conjugating enzymes (E2s) govern key aspects of ubiquitin signaling. Emerging evidence suggests that the activities of E2s are modulated by posttranslational modifications; the structural underpinnings, however, are largely unclear. Here, we unravel the structural basis and mechanistic consequences of a conserved autoubiquitination event near the catalytic center of E2s, using the human anaphase-promoting complex/cyclosome-associated UBE2S as a model system. Crystal structures we determined of the catalytic ubiquitin carrier protein domain combined with MD simulations reveal that the active-site region is malleable, which permits an adjacent ubiquitin acceptor site, Lys<sup>+5</sup>, to be ubiquitinated intramolecularly. We demonstrate by NMR that the Lys<sup>+5</sup>-linked ubiquitin inhibits UBE2S by obstructing its reloading with ubiquitin. By immunoprecipitation, quantitative mass spectrometry, and siRNA-and-rescue experiments we show that Lys<sup>+5</sup> ubiquitination of UBE2S decreases during mitotic exit but does not influence proteasomal turnover of this E2. These findings suggest that UBE2S activity underlies inherent regulation during the cell cycle.
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Gene Expression Regulation
Molecular Dynamics Simulation
Post-translational modifications and cell proliferation
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Structure (London, England : 1993), 2019, 27 (8), pp. 1195 - 1210.e7