E2-RING Expansion of the NEDD8 Cascade Confers Specificity to Cullin Modification

• Published in: Molecular cell Vol. 33; no. 4; pp. 483 - 495
• Main Authors: Huang, Danny T., Ayrault, Olivier, Hunt, Harold W., Taherbhoy, Asad M., Duda, David M., Scott, Daniel C., Borg, Laura A., Neale, Geoffrey, Murray, Peter J., Roussel, Martine F., Schulman, Brenda A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 27-02-2009
• Subjects: Amino Acid Sequence; Animals; BASIC BIOLOGICAL SCIENCES; Binding Sites; Cells, Cultured; Cullin Proteins - metabolism; ENZYMES; FLEXIBILITY; FUNCTIONALS; GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; IN VITRO; IN VIVO; LIGASES; LYSINE; Mice; Models, Molecular; MODIFICATIONS; Molecular Sequence Data; NIH 3T3 Cells; PLASTICITY; Protein Conformation; Protein Folding; PROTEINS; SPECIFICITY; TARGETS; Ubiquitin-Protein Ligases - chemistry; Ubiquitin-Protein Ligases - metabolism; Ubiquitins - chemistry; Ubiquitins - metabolism; PROTEINS
• ISSN: 1097-2765; 1097-4164
• DOI: 10.1016/j.molcel.2009.01.011

Ubiquitin and ubiquitin-like proteins (UBLs) are directed to targets by cascades of E1, E2, and E3 enzymes. The largest ubiquitin E3 subclass consists of cullin-RING ligases (CRLs), which contain one each of several cullins (CUL1, -2, -3, -4, or -5) and RING proteins (RBX1 or -2). CRLs are activated by ligation of the UBL NEDD8 to a conserved cullin lysine. How is cullin NEDD8ylation specificity established? Here we report that, like UBE2M (also known as UBC12), the previously uncharacterized E2 UBE2F is a NEDD8-conjugating enzyme in vitro and in vivo. Biochemical and structural analyses indicate how plasticity of hydrophobic E1-E2 interactions and E1 conformational flexibility allow one E1 to charge multiple E2s. The E2s have distinct functions, with UBE2M/RBX1 and UBE2F/RBX2 displaying different target cullin specificities. Together, these studies reveal the molecular basis for and functional importance of hierarchical expansion of the NEDD8 conjugation system in establishing selective CRL activation.