RRC ID 64248
Author Cronin NB, Yang J, Zhang Z, Kulkarni K, Chang L, Yamano H, Barford D.
Title Atomic-Resolution Structures of the APC/C Subunits Apc4 and the Apc5 N-Terminal Domain.
Journal J Mol Biol
Abstract Many essential biological processes are mediated by complex molecular machines comprising multiple subunits. Knowledge on the architecture of individual subunits and their positions within the overall multimeric complex is key to understanding the molecular mechanisms of macromolecular assemblies. The anaphase-promoting complex/cyclosome (APC/C) is a large multisubunit complex that regulates cell cycle progression by ubiquitinating cell cycle proteins for proteolysis by the proteasome. The holo-complex is composed of 15 different proteins that assemble to generate a complex of 20 subunits. Here, we describe the crystal structures of Apc4 and the N-terminal domain of Apc5 (Apc5(N)). Apc4 comprises a WD40 domain split by a long α-helical domain, whereas Apc5(N) has an α-helical fold. In a separate study, we had fitted these atomic models to a 3.6-Å-resolution cryo-electron microscopy map of the APC/C. We describe how, in the context of the APC/C, regions of Apc4 disordered in the crystal assume order through contacts to Apc5, whereas Apc5(N) shows small conformational changes relative to its crystal structure. We discuss the complementary approaches of high-resolution electron microscopy and protein crystallography to the structure determination of subunits of multimeric complexes.
Volume 427(20)
Pages 3300-3315
Published 2015-10-9
DOI 10.1016/j.jmb.2015.08.023
PII S0022-2836(15)00488-X
PMID 26343760
PMC PMC4590430
MeSH Animals Apc4 Subunit, Anaphase-Promoting Complex-Cyclosome / ultrastructure* Apc5 Subunit, Anaphase-Promoting Complex-Cyclosome / ultrastructure* Cell Cycle / physiology Cryoelectron Microscopy Crystallography, X-Ray Protein Structure, Tertiary Protein Subunits / metabolism* Saccharomyces cerevisiae Saccharomyces cerevisiae Proteins Schizosaccharomyces Xenopus laevis