title: The poxvirus encoded ubiquitin ligase, p28, is regulated by proteasomal degradation and autoubiquitination.
abstract: Virus manipulation of the ubiquitin-proteasome system has become increasingly apparent. Ubiquitin is a 76 amino acid protein that is post-translationally conjugated to target proteins, while poly-ubiquitination subsequently leads to degradation via the 26S proteasome. Target specificity is determined by a large family of ubiquitin ligases. Poxviruses encode p28, a highly conserved ubiquitin ligase expressed in a wide range of poxviruses (J. Virol. 79:597). Here we investigate the relationship between p28 and ubiquitination. Confocal microscopy indicated that orthologs of p28 co-localized with ubiquitin at the virus factory. Flow cytometry assays further demonstrated that p28 was regulated by proteasomal degradation. Moreover, when the ubiquitin ligase activity of p28 was disrupted by mutating the RING domain conjugated ubiquitin still localized to the viral factories, indicating that an unknown ubiquitin ligase(s) was responsible for regulating p28. Our observations indicate that p28 is a ubiquitin ligase that is regulated by ubiquitination and proteasomal degradation.
authors.affiliation: Li Ka Shing Institute of Virology, Department of Medical Microbiology and Immunology, 621 HMRC, University of Alberta, Edmonton, Alberta, Canada T6G 2S2.
authors.forename: Kelly
authors.initials: K
authors.lastname: Mottet
authors.affiliation: Li Ka Shing Institute of Virology, Department of Medical Microbiology and Immunology, 621 HMRC, University of Alberta, Edmonton, Alberta, Canada T6G 2S2.
authors.forename: Bettina
authors.initials: B
authors.lastname: Bareiss
authors.affiliation: Li Ka Shing Institute of Virology, Department of Medical Microbiology and Immunology, 621 HMRC, University of Alberta, Edmonton, Alberta, Canada T6G 2S2.
authors.forename: Craig D
authors.initials: CD
authors.lastname: Milne
authors.affiliation: Li Ka Shing Institute of Virology, Department of Medical Microbiology and Immunology, 621 HMRC, University of Alberta, Edmonton, Alberta, Canada T6G 2S2. Electronic address: michele.barry@ualberta.ca.
authors.forename: Michele
authors.initials: M
authors.lastname: Barry
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D015967:Gene Expression Regulation, Viral / Q000502:physiology*; D000882:Haplorhini; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination; D014616:Vaccinia virus / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D014779:Virus Replication
chemical_list: D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex
keywords: Poxvirus; Proteasome; Ubiquitin ligase; Ubiquitination; p28