Recombinant expression, reconstitution and structure of human anaphase-promoting complex (APC/C).
Mechanistic and structural studies of large multi-subunit assemblies are greatly facilitated by their reconstitution in heterologous recombinant systems. In the present paper, we describe the generation of recombinant human APC/C (anaphase-promoting complex/cyclosome), an E3 ubiquitin ligase that regulates cell-cycle progression. Human APC/C is composed of 14 distinct proteins that assemble into a complex of at least 19 subunits with a combined molecular mass of ~1.2 MDa. We show that recombinant human APC/C is correctly assembled, as judged by its capacity to ubiquitinate the budding yeast APC/C substrate Hsl1 (histone synthetic lethal 1) dependent on the APC/C co-activator Cdh1 [Cdc (cell division cycle) 20 homologue 1], and its three-dimensional reconstruction by electron microscopy and single-particle analysis. Successful reconstitution validates the subunit composition of human APC/C. The structure of human APC/C is compatible with the Saccharomyces cerevisiae APC/C homology model, and in contrast with endogenous human APC/C, no evidence for conformational flexibility of the TPR (tetratricopeptide repeat) lobe is observed. Additional density present in the human APC/C structure, proximal to Apc3/Cdc27 of the TPR lobe, is assigned to the TPR subunit Apc7, a subunit specific to vertebrate APC/C.
Pubmed ID: 23078409 RIS Download
Anaphase-Promoting Complex-Cyclosome | Animals | Apc3 Subunit, Anaphase-Promoting Complex-Cyclosome | Apc7 Subunit, Anaphase-Promoting Complex-Cyclosome | Cell Cycle Proteins | Cell Line | Humans | Microscopy, Electron | Models, Molecular | Multiprotein Complexes | Protein Multimerization | Protein Structure, Quaternary | Protein Subunits | Recombinant Proteins | Substrate Specificity | Ubiquitin-Protein Ligase Complexes | Ubiquitin-Protein Ligases | Ubiquitination