6bva | pdb_00006bva
Ubiquitin Variant (UbV.Fl10.1) bound to a human Skp1-Fbl10 fragment complex.
Structural highlights
Function[SKP1_HUMAN] Essential component of the SCF (SKP1-CUL1-F-box protein) ubiquitin ligase complex, which mediates the ubiquitination of proteins involved in cell cycle progression, signal transduction and transcription. In the SCF complex, serves as an adapter that links the F-box protein to CUL1. SCF(BTRC) mediates the ubiquitination of NFKBIA at 'Lys-21' and 'Lys-22'; the degradation frees the associated NFKB1-RELA dimer to translocate into the nucleus and to activate transcription. SCF(Cyclin F) directs ubiquitination of CP110.[1] [2] [UBB_HUMAN] Ubiquitin exists either covalently attached to another protein, or free (unanchored). When covalently bound, it is conjugated to target proteins via an isopeptide bond either as a monomer (monoubiquitin), a polymer linked via different Lys residues of the ubiquitin (polyubiquitin chains) or a linear polymer linked via the initiator Met of the ubiquitin (linear polyubiquitin chains). Polyubiquitin chains, when attached to a target protein, have different functions depending on the Lys residue of the ubiquitin that is linked: Lys-6-linked may be involved in DNA repair; Lys-11-linked is involved in ERAD (endoplasmic reticulum-associated degradation) and in cell-cycle regulation; Lys-29-linked is involved in lysosomal degradation; Lys-33-linked is involved in kinase modification; Lys-48-linked is involved in protein degradation via the proteasome; Lys-63-linked is involved in endocytosis, DNA-damage responses as well as in signaling processes leading to activation of the transcription factor NF-kappa-B. Linear polymer chains formed via attachment by the initiator Met lead to cell signaling. Ubiquitin is usually conjugated to Lys residues of target proteins, however, in rare cases, conjugation to Cys or Ser residues has been observed. When polyubiquitin is free (unanchored-polyubiquitin), it also has distinct roles, such as in activation of protein kinases, and in signaling.[3] [4] [KDM2B_HUMAN] Histone demethylase that demethylates 'Lys-4' and 'Lys-36' of histone H3, thereby playing a central role in histone code. Preferentially demethylates trimethylated H3 'Lys-4' and dimethylated H3 'Lys-36' residue while it has weak or no activity for mono- and tri-methylated H3 'Lys-36'. Preferentially binds the transcribed region of ribosomal RNA and represses the transcription of ribosomal RNA genes which inhibits cell growth and proliferation. May also serve as a substrate-recognition component of the SCF (SKP1-CUL1-F-box protein)-type E3 ubiquitin ligase complex.[5] [6] Publication Abstract from PubMedSkp1-Cul1-F-box (SCF) E3 ligases constitute the largest and best-characterized family of the multisubunit E3 ligases with important cellular functions and numerous disease links. The specificity of an SCF E3 ligase is established by one of the 69 human F-box proteins that are recruited to Cul1 through the Skp1 adaptor. We previously reported generation of ubiquitin variants (UbVs) targeting Fbw7 and Fbw11, which inhibit ligase activity by binding at the F-box-Skp1 interface to competitively displace Cul1. In the present study, we employed an optimized engineering strategy to generate specific binding UbVs against 17 additional Skp1-F-box complexes. We validated our design strategy and uncovered the structural basis of binding specificity by crystallographic analyses of representative UbVs bound to Skp1-Fbl10 and Skp1-Fbl11. Our study highlights the power of combining phage display with structure-based design to develop UbVs targeting specific protein surfaces. A Structure-Based Strategy for Engineering Selective Ubiquitin Variant Inhibitors of Skp1-Cul1-F-Box Ubiquitin Ligases.,Gorelik M, Manczyk N, Pavlenco A, Kurinov I, Sidhu SS, Sicheri F Structure. 2018 Jun 26. pii: S0969-2126(18)30210-7. doi:, 10.1016/j.str.2018.06.004. PMID:30033217[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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