Herpes simplex virus type 1 immediate-early protein ICP0 and is isolated RING finger domain act as ubiquitin E3 ligases in vitro.
Proteasome-dependent degradation of ubiquitinated proteins plays a key role in many important cellular processes. Ubiquitination requires the E1 ubiquitin activating enzyme, an E2 ubiquitin conjugating enzyme, and frequently a substrate-specific ubiquitin protein ligase (E3). One class of E3 ubiquitin ligases has been shown to contain a common zinc-binding RING finger motif. We have previously shown that herpes simplex virus type 1 ICP0, itself a RING finger protein, induces the proteasome-dependent degradation of several cellular proteins and induces the accumulation of colocalizing conjugated ubiquitin in vivo. We now report that both full-length ICP0 and its isolated RING finger domain induce the accumulation of polyubiquitin chains in vitro in the presence of E1 and the E2 enzymes UbcH5a and UbcH6. Mutations within the RING finger region that abolish the in vitro ubiquitination activity also cause severe reductions in ICP0 activity in other assays. We conclude that ICP0 has the potential to act as an E3 ubiquitin ligase during viral infection and to target specific cellular proteins for destruction by the 26S proteasome.
Boutell
Chris
C
Medical Research Council Virology Unit, Glasgow G11 5JR, Scotland, United Kingdom.
Sadis
Seth
S
Everett
Roger D
RD
D020816:Amino Acid Motifs; D004789:Enzyme Activation; D018259:Herpesvirus 1, Human / Q000201:enzymology* / Q000378:metabolism; D006801:Humans; D017874:Immediate-Early Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D033862:Iron-Binding Proteins; D008025:Ligases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010447:Peptide Hydrolases / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013816:Thermodynamics; D014162:Transfection; D014407:Tumor Cells, Cultured; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases
D017874:Immediate-Early Proteins; D033862:Iron-Binding Proteins; D012367:RNA, Viral; D011993:Recombinant Fusion Proteins; C097308:UBE2D1 protein, human; C489967:UBE2J1 protein, human; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases; C051804:Vmw110 protein, Human herpesvirus 1; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D008025:Ligases