Structural highlights
Function
[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.[1] [2]
Publication Abstract from PubMed
Deubiquitinating enzymes (DUBs) regulate ubiquitin signaling by trimming ubiquitin chains or removing ubiquitin from modified substrates. Similar activities exist for ubiquitin-related modifiers, although the enzymes involved are usually not related. Here, we report human ZUFSP (also known as ZUP1 and C6orf113) and fission yeast Mug105 as founding members of a DUB family different from the six known DUB classes. The crystal structure of human ZUFSP in covalent complex with propargylated ubiquitin shows that the DUB family shares a fold with UFM1- and Atg8-specific proteases, but uses a different active site more similar to canonical DUB enzymes. ZUFSP family members differ widely in linkage specificity through differential use of modular ubiquitin-binding domains (UBDs). While the minimalistic Mug105 prefers K48 chains, ZUFSP uses multiple UBDs for its K63-specific endo-DUB activity. K63 specificity, localization, and protein interaction network suggest a role for ZUFSP in DNA damage response.
A family of unconventional deubiquitinases with modular chain specificity determinants.,Hermanns T, Pichlo C, Woiwode I, Klopffleisch K, Witting KF, Ovaa H, Baumann U, Hofmann K Nat Commun. 2018 Feb 23;9(1):799. doi: 10.1038/s41467-018-03148-5. PMID:29476094[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Huang F, Kirkpatrick D, Jiang X, Gygi S, Sorkin A. Differential regulation of EGF receptor internalization and degradation by multiubiquitination within the kinase domain. Mol Cell. 2006 Mar 17;21(6):737-48. PMID:16543144 doi:S1097-2765(06)00120-1
- ↑ Komander D. The emerging complexity of protein ubiquitination. Biochem Soc Trans. 2009 Oct;37(Pt 5):937-53. doi: 10.1042/BST0370937. PMID:19754430 doi:10.1042/BST0370937
- ↑ Hermanns T, Pichlo C, Woiwode I, Klopffleisch K, Witting KF, Ovaa H, Baumann U, Hofmann K. A family of unconventional deubiquitinases with modular chain specificity determinants. Nat Commun. 2018 Feb 23;9(1):799. doi: 10.1038/s41467-018-03148-5. PMID:29476094 doi:http://dx.doi.org/10.1038/s41467-018-03148-5
