title: The α2 helix in the DNA ligase IV BRCT-1 domain is required for targeted degradation of ligase IV during adenovirus infection.
abstract: In adenovirus E4 mutant infections, viral DNAs form concatemers through a process that requires host Non-homologous End Joining (NHEJ) proteins including DNA Ligase IV (LigIV). Adenovirus proteins E4 34k and E1b 55k form the substrate-selection component of an E3 ubiquitin ligase and prevent concatenation by targeting LigIV for proteasomal degradation. The mechanisms and sites involved in targeting this and other E3 ligase substrates generally are poorly-understood. Through genetic analysis, we identified the α2 helix of one LigIV BRCT domain (BRCT-1) as essential for adenovirus-mediated degradation. Replacement of the BRCT domain of DNA ligase III (LigIII), which is resistant to degradation, with LigIV BRCT-1 does not promote degradation. A humanized mouse LigIV that possesses a BRCT-1 α2 helix identical to the human protein, like its parent, is also resistant to adenovirus-mediated degradation. Thus, both the BRCT-1 α2 helix and an element outside BRCT-1 are required for adenovirus-mediated degradation of LigIV.
authors.affiliation: Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
authors.forename: Timra
authors.initials: T
authors.lastname: Gilson
authors.forename: Amy E
authors.initials: AE
authors.lastname: Greer
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vindigni
authors.forename: Gary
authors.initials: G
authors.lastname: Ketner
authors.forename: Leslyn A
authors.initials: LA
authors.lastname: Hanakahi
mesh_terms: D000258:Adenovirus Infections, Human / Q000201:enzymology* / Q000235:genetics / Q000821:virology; D000260:Adenoviruses, Human / Q000235:genetics / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D059748:Proteolysis; D016415:Sequence Alignment; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C000607893:LIG4 protein, human; D014764:Viral Proteins; D011088:DNA Ligases; D000072481:DNA Ligase ATP