5G04: Structure Of The Human Apc-cdc20-hsl1 Complex

Citation:
Abstract
In eukaryotes, the anaphase-promoting complex (APC/C, also known as the cyclosome) regulates the ubiquitin-dependent proteolysis of specific cell-cycle proteins to coordinate chromosome segregation in mitosis and entry into the G1 phase. The catalytic activity of the APC/C and its ability to specify the destruction of particular proteins at different phases of the cell cycle are controlled by its interaction with two structurally related coactivator subunits, Cdc20 and Cdh1. Coactivators recognize substrate degrons, and enhance the affinity of the APC/C for its cognate E2 (refs 4-6). During mitosis, cyclin-dependent kinase (Cdk) and polo-like kinase (Plk) control Cdc20- and Cdh1-mediated activation of the APC/C. Hyperphosphorylation of APC/C subunits, notably Apc1 and Apc3, is required for Cdc20 to activate the APC/C, whereas phosphorylation of Cdh1 prevents its association with the APC/C. Since both coactivators associate with the APC/C through their common C-box and Ile-Arg tail motifs, the mechanism underlying this differential regulation is unclear, as is the role of specific APC/C phosphorylation sites. Here, using cryo-electron microscopy and biochemical analysis, we define the molecular basis of how phosphorylation of human APC/C allows for its control by Cdc20. An auto-inhibitory segment of Apc1 acts as a molecular switch that in apo unphosphorylated APC/C interacts with the C-box binding site and obstructs engagement of Cdc20. Phosphorylation of the auto-inhibitory segment displaces it from the C-box-binding site. Efficient phosphorylation of the auto-inhibitory segment, and thus relief of auto-inhibition, requires the recruitment of Cdk-cyclin in complex with a Cdk regulatory subunit (Cks) to a hyperphosphorylated loop of Apc3. We also find that the small-molecule inhibitor, tosyl-l-arginine methyl ester, preferentially suppresses APC/C(Cdc20) rather than APC/C(Cdh1), and interacts with the binding sites of both the C-box and Ile-Arg tail motifs. Our results reveal the mechanism for the regulation of mitotic APC/C by phosphorylation and provide a rationale for the development of selective inhibitors of this state.
PDB ID: 5G04Download
MMDB ID: 139537
PDB Deposition Date: 2016/3/16
Updated in MMDB: 2016/05
Experimental Method:
electron microscopy
Resolution: 4  Å
Source Organism:
Homo sapiens
Similar Structures:
Biological Unit for 5G04: 21-meric; determined by author
Molecular Components in 5G04
Label Count Molecule
Proteins (21 molecules)
1
Anaphase-promoting Complex Subunit 1(Gene symbol: ANAPC1)
Molecule annotation
1
Anaphase-promoting Complex Subunit 11(Gene symbol: ANAPC11)
Molecule annotation
2
Cell Division Cycle Protein 23 Homolog(Gene symbol: CDC23)
Molecule annotation
1
Anaphase-promoting Complex Subunit 15(Gene symbol: ANAPC15)
Molecule annotation
1
Anaphase-promoting Complex Subunit 16(Gene symbol: ANAPC16)
Molecule annotation
2
Cell Division Cycle Protein 27 Homolog(Gene symbol: CDC27)
Molecule annotation
2
Anaphase-promoting Complex Subunit Cdc26(Gene symbol: CDC26)
Molecule annotation
1
Anaphase-promoting Complex Subunit 4(Gene symbol: ANAPC4)
Molecule annotation
2
Cell Division Cycle Protein 16 Homolog(Gene symbol: CDC16)
Molecule annotation
1
Anaphase-promoting Complex Subunit 10(Gene symbol: ANAPC10)
Molecule annotation
1
Anaphase-promoting Complex Subunit 13(Gene symbol: ANAPC13)
Molecule annotation
1
Anaphase-promoting Complex Subunit 2(Gene symbol: ANAPC2)
Molecule annotation
1
Anaphase-promoting Complex Subunit 5(Gene symbol: ANAPC5)
Molecule annotation
1
Cell Division Cycle Protein 20 Homolog(Gene symbol: CDC20)
Molecule annotation
1
Probable Serine/threonine-protein Kinase Hsl1(Gene symbol: HSL1)
Molecule annotation
2
Anaphase-promoting Complex Subunit 7(Gene symbol: ANAPC7)
Molecule annotation
Chemicals (3 molecules)
1
3
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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