2xpi

Crystal structure of APC/C hetero-tetramer Cut9-Hcn1

spinqualitylabelsall models 2xpi, resolution 2.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2xpi is a 4 chain structure with sequence from Cbs 356. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: AUC NonStd Res: ACE Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed 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. The APC/C subunit Cdc16/Cut9 is a contiguous tetratricopeptide repeat superhelix with a homo-dimer interface similar to Cdc27.,Zhang Z, Kulkarni K, Hanrahan SJ, Thompson AJ, Barford D EMBO J. 2010 Nov 3;29(21):3733-44. Epub 2010 Oct 5. PMID:20924356 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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