Activation of a primed RING E3-E2–ubiquitin complex by non-covalent ubiquitin

Buetow, L., Gabrielsen, M., Anthony, N. G., Dou, H., Patel, A., Aitkenhead, H., Sibbet, G. J., Smith, B. O. and Huang, D. T. (2015) Activation of a primed RING E3-E2–ubiquitin complex by non-covalent ubiquitin. Molecular Cell, 58(2), pp. 297-310. (doi:10.1016/j.molcel.2015.02.017) (PMID:25801170)

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Abstract

RING ubiquitin ligases (E3) recruit ubiquitin-conjugate enzymes (E2) charged with ubiquitin (Ub) to catalyze ubiquitination. Non-covalent Ub binding to the backside of certain E2s promotes processive polyUb formation, but the mechanism remains elusive. Here, we show that backside bound Ub (UbB) enhances both RING-independent and RING-dependent UbcH5B-catalyzed donor Ub (UbD) transfer, but with a more prominent effect in RING-dependent transfer. UbB enhances RING E3s’ affinities for UbcH5B–Ub, and RING E3-UbcH5B–Ub complex improves UbB’s affinity for UbcH5B. A comparison of the crystal structures of a RING E3, RNF38, bound to UbcH5B–Ub in the absence and presence of UbB, together with molecular dynamics simulation and biochemical analyses, suggests UbB restricts the flexibility of UbcH5B’s α1 and α1β1 loop. UbB supports E3 function by stabilizing the RING E3-UbcH5B–Ub complex, thereby improving the catalytic efficiency of Ub transfer. Thus, UbB serves as an allosteric activator of RING E3-mediated Ub transfer.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Smith, Dr Brian and Dou, Miss Hao and Huang, Dr Danny and Gabrielsen, Dr Mads and Buetow, Dr Lori and Sibbet, Dr Gary
Authors: Buetow, L., Gabrielsen, M., Anthony, N. G., Dou, H., Patel, A., Aitkenhead, H., Sibbet, G. J., Smith, B. O., and Huang, D. T.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cancer Sciences
College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
Journal Name:Molecular Cell
Publisher:Cell Press
ISSN:1097-2765
ISSN (Online):1097-4164

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