From Proteopediaproteopedia link
Crystal structure of GFP-Wrnip1 UBZ domain fusion protein in complex with ubiquitin
[UBB_MOUSE] 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.
Publication Abstract from PubMed
The ubiquitin-binding zinc finger (UBZ) is a type of zinc-coordinating beta-beta-alpha fold domain found mainly in proteins involved in DNA repair and transcriptional regulation. Here we report the crystal structure of the UBZ domain of Y-family DNA polymerase (pol) eta and the crystal structure of the complex between the UBZ domain of Werner helicase-interacting protein 1 (WRNIP1) and ubiquitin, crystallized using the green fluorescent protein fusion technique. In contrast to the pol eta UBZ, which has been proposed to bind ubiquitin via its C-terminal alpha helix, ubiquitin binds to a novel surface of WRNIP1 UBZ composed of the first beta strand and the C-terminal alpha helix. In addition, we report the structure of the tandem UBZ domains of Tax1-binding protein 1 (TAX1BP1) and show that the second UBZ of TAX1BP1 binds ubiquitin, presumably in a manner similar to that of WRNIP1 UBZ. We propose that UBZ domains can be divided into at least two different types in terms of the ubiquitin-binding surfaces: the pol eta type and the WRNIP1 type. This article is protected by copyright. All rights reserved.
A novel mode of ubiquitin recognition by the ubiquitin-binding zinc finger domain of WRNIP1.,Suzuki N, Rohaim A, Kato R, Dikic I, Wakatsuki S, Kawasaki M FEBS J. 2016 Apr 8. doi: 10.1111/febs.13734. PMID:27062441
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.