6a73 | pdb_00006a73
Complex structure of CSN2 with IP6
Structural highlights
Function[CSN2_HUMAN] Essential component of the COP9 signalosome complex (CSN), a complex involved in various cellular and developmental processes. The CSN complex is an essential regulator of the ubiquitin (Ubl) conjugation pathway by mediating the deneddylation of the cullin subunits of SCF-type E3 ligase complexes, leading to decrease the Ubl ligase activity of SCF-type complexes such as SCF, CSA or DDB2. The complex is also involved in phosphorylation of p53/TP53, c-jun/JUN, IkappaBalpha/NFKBIA, ITPK1 and IRF8/ICSBP, possibly via its association with CK2 and PKD kinases. CSN-dependent phosphorylation of TP53 and JUN promotes and protects degradation by the Ubl system, respectively. Involved in early stage of neuronal differentiation via its interaction with NIF3L1.[1] [2] [3] [4] [5] Publication Abstract from PubMedThe Cullin-RING ligases (CRLs) are the largest family of ubiquitin E3s activated by neddylation and regulated by the deneddylase COP9 signalosome (CSN). The inositol polyphosphate metabolites promote the formation of CRL-CSN complexes, but with unclear mechanism of action. Here, we provide structural and genetic evidence supporting inositol hexakisphosphate (IP6) as a general CSN cofactor recruiting CRLs. We determined the crystal structure of IP6 in complex with CSN subunit 2 (CSN2), based on which we identified the IP6-corresponding electron density in the cryoelectron microscopy map of a CRL4A-CSN complex. IP6 binds to a cognate pocket formed by conserved lysine residues from CSN2 and Rbx1/Roc1, thereby strengthening CRL-CSN interactions to dislodge the E2 CDC34/UBE2R from CRL and to promote CRL deneddylation. IP6 binding-deficient Csn2 (K70E/K70E) knockin mice are embryonic lethal. The same mutation disabled Schizosaccharomyces pombe Csn2 from rescuing UV-hypersensitivity of csn2-null yeast. These data suggest that CRL transition from the E2-bound active state to the CSN-bound sequestered state is critically assisted by an interfacial IP6 small molecule, whose metabolism may be coupled to CRL-CSN complex dynamics. Basis for metabolite-dependent Cullin-RING ligase deneddylation by the COP9 signalosome.,Lin H, Zhang X, Liu L, Fu Q, Zang C, Ding Y, Su Y, Xu Z, He S, Yang X, Wei X, Mao H, Cui Y, Wei Y, Zhou C, Du L, Huang N, Zheng N, Wang T, Rao F Proc Natl Acad Sci U S A. 2020 Feb 11. pii: 1911998117. doi:, 10.1073/pnas.1911998117. PMID:32047038[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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