title: E2-binding surface on Uba3 β-grasp domain undergoes a conformational transition.
abstract: The covalent attachment of ubiquitin (Ub) and ubiquitin-like (Ubl) proteins to various eukaryotic targets plays critical roles in regulating numerous cellular processes. E1-activating enzymes are critical, because they catalyze activation of their cognate Ub/Ubl protein and are responsible for its transfer to the correct E2-conjugating enzyme(s). The activating enzyme for neural-precursor-cell-expressed developmentally downregulated 8 (NEDD8) is a heterodimer composed of APPBP1 and Uba3 subunits. The carboxyl terminal ubiquitin-like β-grasp domain of human Uba3 (Uba3-βGD) has been suggested as a key E2-binding site defining E2 specificity. In crystal structures of free E1 and the NEDD8-E1 complex, the E2-binding surface on the domain was missing from the electron density. However, when complexed with various E2s, this missing segment adopts a kinked α-helix. Here, we demonstrate that Uba3-βGD is an independently folded domain in solution and that residues involved in E2 binding are absent from the NMR spectrum, indicating that the E2-binding surface on Uba3-βGD interconverts between multiple conformations, analogous to a similar conformational transition observed in the E2-binding surface of SUMO E1. These results suggest that access to multiple conformational substates is an important feature of the E1-E2 interaction.
authors: Department of Chemistry, Muğla Sıtkı Koçman University, Muğla 48000, Turkey. selgin@mu.edu.tr
authors: E Sonay
authors: ES
authors: Elgin
authors: Nazlı
authors: N
authors: Sökmen
authors: Francis C
authors: FC
authors: Peterson
authors: Brian F
authors: BF
authors: Volkman
authors: Cağdaş
authors: C
authors: Dağ
authors: Arthur L
authors: AL
authors: Haas
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D051381:Rats; D016415:Sequence Alignment; D044764:Ubiquitin-Activating Enzymes / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D044764:Ubiquitin-Activating Enzymes; C491802:NAE protein, human