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Activation of a Primed RING E3-E2–Ubiquitin Complex by Non-Covalent Ubiquitin

DOI: 10.1016/j.molcel.2015.02.017 DOI Help
PMID: 25801170 PMID Help

Authors: Lori Buetow (Beatson Institute for Cancer Research) , Mads Gabrielsen (University of Glasgow) , Nahoum g Anthony (Strathclyde Institute of Pharmacy and Biomedical Science) , Hao Dou (Beatson Institute for Cancer Research) , Amrita Patel (Beatson Institute for Cancer Research) , Hazel Aitkenhead (Beatson Institute for Cancer Research) , Gary j Sibbet (Cancer Research UK Beatson Institute) , Brian o Smith (University of Glasgow) , Danny Huang (Beatson Institute for Cancer Research)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Molecular Cell , VOL 58 , PAGES 297--310

State: Published (Approved)
Published: March 2015
Diamond Proposal Number(s): 8659

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 alpha1 and alpha1 & beta1 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.

Subject Areas: Biology and Bio-materials


Instruments: I02-Macromolecular Crystallography , I24-Microfocus Macromolecular Crystallography