| Structural highlights
Function
[ANC2_HUMAN] Together with the RING-H2 protein ANAPC11, constitutes the catalytic component of the anaphase promoting complex/cyclosome (APC/C), a cell cycle-regulated E3 ubiquitin ligase that controls progression through mitosis and the G1 phase of the cell cycle. The APC/C complex acts by mediating ubiquitination and subsequent degradation of target proteins: it mainly mediates the formation of 'Lys-11'-linked polyubiquitin chains and, to a lower extent, the formation of 'Lys-48'- and 'Lys-63'-linked polyubiquitin chains. The CDC20-APC/C complex positively regulates the formation of synaptic vesicle clustering at active zone to the presynaptic membrane in postmitotic neurons. CDC20-APC/C-induced degradation of NEUROD2 drives presynaptic differentiation.[1] [2]
Publication Abstract from PubMed
Ubiquitin (Ub)-mediated proteolysis is a fundamental mechanism used by eukaryotic cells to maintain homeostasis and protein quality, and to control timing in biological processes. Two essential aspects of Ub regulation are conjugation through E1-E2-E3 enzymatic cascades and recognition by Ub-binding domains. An emerging theme in the Ub field is that these 2 properties are often amalgamated in conjugation enzymes. In addition to covalent thioester linkage to Ub's C terminus for Ub transfer reactions, conjugation enzymes often bind noncovalently and weakly to Ub at "exosites." However, identification of such sites is typically empirical and particularly challenging in large molecular machines. Here, studying the 1.2-MDa E3 ligase anaphase-promoting complex/cyclosome (APC/C), which controls cell division and many aspects of neurobiology, we discover a method for identifying unexpected Ub-binding sites. Using a panel of Ub variants (UbVs), we identify a protein-based inhibitor that blocks Ub ligation to APC/C substrates in vitro and ex vivo. Biochemistry, NMR, and cryo-electron microscopy (cryo-EM) structurally define the UbV interaction, explain its inhibitory activity through binding the surface on the APC2 subunit that recruits the E2 enzyme UBE2C, and ultimately reveal that this APC2 surface is also a Ub-binding exosite with preference for K48-linked chains. The results provide a tool for probing APC/C activity, have implications for the coordination of K48-linked Ub chain binding by APC/C with the multistep process of substrate polyubiquitylation, and demonstrate the power of UbV technology for identifying cryptic Ub-binding sites within large multiprotein complexes.
Protein engineering of a ubiquitin-variant inhibitor of APC/C identifies a cryptic K48 ubiquitin chain binding site.,Watson ER, Grace CRR, Zhang W, Miller DJ, Davidson IF, Prabu JR, Yu S, Bolhuis DL, Kulko ET, Vollrath R, Haselbach D, Stark H, Peters JM, Brown NG, Sidhu SS, Schulman BA Proc Natl Acad Sci U S A. 2019 Jul 26. pii: 1902889116. doi:, 10.1073/pnas.1902889116. PMID:31350353[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Tang Z, Li B, Bharadwaj R, Zhu H, Ozkan E, Hakala K, Deisenhofer J, Yu H. APC2 Cullin protein and APC11 RING protein comprise the minimal ubiquitin ligase module of the anaphase-promoting complex. Mol Biol Cell. 2001 Dec;12(12):3839-51. PMID:11739784
- ↑ Jin L, Williamson A, Banerjee S, Philipp I, Rape M. Mechanism of ubiquitin-chain formation by the human anaphase-promoting complex. Cell. 2008 May 16;133(4):653-65. doi: 10.1016/j.cell.2008.04.012. PMID:18485873 doi:http://dx.doi.org/10.1016/j.cell.2008.04.012
- ↑ Watson ER, Grace CRR, Zhang W, Miller DJ, Davidson IF, Prabu JR, Yu S, Bolhuis DL, Kulko ET, Vollrath R, Haselbach D, Stark H, Peters JM, Brown NG, Sidhu SS, Schulman BA. Protein engineering of a ubiquitin-variant inhibitor of APC/C identifies a cryptic K48 ubiquitin chain binding site. Proc Natl Acad Sci U S A. 2019 Jul 26. pii: 1902889116. doi:, 10.1073/pnas.1902889116. PMID:31350353 doi:http://dx.doi.org/10.1073/pnas.1902889116
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