Download MendeleyThe Apc/C Subunit Cdc16/Cut9 is a Contiguous Tetratricopeptide Superhelix with a Homo-Dimer Interface Similar to Cdc27
Zhang, Z., Kulkarni, K.A., Hanrahan, S.J., Thompson, A.J., Barford, D.(2010) EMBO J 29: 3733
- PubMed: 20924356
- DOI: https://doi.org/10.1038/emboj.2010.247
- Primary Citation of Related Structures:
2XPI - PubMed Abstract:
The anaphase-promoting complex/cyclosome (APC/C), an E3 ubiquitin ligase responsible for controlling cell cycle transitions, is a multisubunit complex assembled from 13 different proteins. Numerous APC/C subunits incorporate multiple copies of the tetratricopeptide repeat (TPR). Here, we report the crystal structure of Schizosaccharomyces pombe Cut9 (Cdc16/Apc6) in complex with Hcn1 (Cdc26), showing that Cdc16/Cut9 is a contiguous TPR superhelix of 14 TPR units. A C-terminal block of TPR motifs interacts with Hcn1, whereas an N-terminal TPR block mediates Cdc16/Cut9 self-association through a homotypic interface. This dimer interface is structurally related to the N-terminal dimerization domain of Cdc27, demonstrating that both Cdc16/Cut9 and Cdc27 form homo-dimers through a conserved mechanism. The acetylated N-terminal Met residue of Hcn1 is enclosed within a chamber created from the Cut9 TPR superhelix. Thus, in complex with Cdc16/Cut9, the N-acetyl-Met residue of Hcn1, a putative degron for the Doa10 E3 ubiquitin ligase, is inaccessible for Doa10 recognition, protecting Hcn1/Cdc26 from ubiquitin-dependent degradation. This finding may provide a structural explanation for a mechanism to control the stoichiometry of proteins participating in multisubunit complexes.
Organizational Affiliation:
Section of Structural Biology, Institute of Cancer Research, Chester Beatty Laboratories, London, UK.
