Conjugation of Nedd8 to CUL1 enhances the ability of the ROC1-CUL1 complex to promote ubiquitin polymerization.

摘要: The SCF-ROC1 ubiquitin-protein isopeptide ligase (E3) ubiquitin complex targets the ubiquitination and subsequent degradation of protein substrates required for regulation cell cycle progression signal transduction pathways. We have previously shown that ROC1-CUL1 is a core subassembly within complex, capable supporting polymerization ubiquitin. This report describes CUL1 subunit bacterially expressed, unmodified conjugated with Nedd8 at Lys-720 by HeLa extracts or purified conjugation system (consisting APP-BP1/Uba3, Ubc12, Nedd8). covalent linkage to both necessary sufficient markedly enhance ability promote polymerization. A mutation arginine in eliminates modification, abolishes activation significantly reduces SCFHOS/β-TRCP-ROC1 support phosphorylated IκBα. Thus, although action has been preside level recognition substrate, we demonstrate novel regulator efficiency polyubiquitin chain synthesis and, hence, promotes rapid turnover substrates.