Fig. 2: CRL shaping of UBE2R2’s synergy loop promotes millisecond poly-ubiquitylation by stabilizing donor and acceptor ubiquitins.
From: Mechanism of millisecond Lys48-linked poly-ubiquitin chain formation by cullin-RING ligases
a, Ribbon diagram and cryo-EM density of the catalytic core, highlighting stabilizing interfaces between UBE2R2’s synergy loop and the CRL subunit RBX1 (e), donor ubiquitin (UBD) (c) and acceptor ubiquitin (UBA) (d). b, Catalytic core cryo-EM density showing a close-up view of Asp102, Glu108 and Arg113 within the interaction hub. Subunits have been colored as in a. c, Same as in b, but showing proximity between residues Ser106 and Glu112 in the loop and Arg74 and Arg72 in the donor ubiquitin, respectively. d, Same as in b, but highlighting the interaction between residue Asp103 in the loop and His68 in the acceptor ubiquitin. e, Same as in b, but showing the interaction between residue Glu108 in the synergy loop and Arg91 in RBX1. f, Bar graph comparing the Km values of unanchored acceptor ubiquitin for UBE2R2 and with WT or mutant proteins. Bars showing a ‘>ʼ reflect reactions in which saturation of UBE2R2 with acceptor ubiquitin was not possible (the top concentration in the dilution series is shown). The value of each bar represents the estimated value for Km based on n = 3 technical replicates.
