Autoantigen Ro52 is an E3 ubiquitin ligase.
Anti-Ro/SSA antibodies are classic autoantibodies commonly found in patients with Sjögren's syndrome, a chronic autoimmune disease characterized by dryness of the eyes and mouth. The autoantibodies recognize a RING-finger protein, Ro52, whose function is still unknown. Since many RING-finger proteins have been identified as E3 ubiquitin ligases, this study was designed to determine whether Ro52 functions as an E3 ubiquitin ligase. For this purpose, recombinant Ro52 was purified from bacterial lysate and used to investigate its activity of E3 ubiquitin ligase in vitro. Its enzymatic activity was also tested in HEK293T cells using wild-type Ro52 and its RING-finger mutant. Our results indicated that Ro52 ubiquitinates itself in cooperation with E2 ubiquitin-conjugating enzyme UbcH5B, thereby validating that Ro52 is a RING-finger-type E3 ubiquitin ligase. Importantly, this ubiquitin modification is predominantly monoubiquitination, which does not target Ro52 to the proteasome for degradation.
Wada
Keiji
K
Department of Cardiology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
Kamitani
Tetsu
T
D000595:Amino Acid Sequence; D001324:Autoantigens / Q000378:metabolism*; D002460:Cell Line; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism*; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D000099207:SS-A Antigen
D001324:Autoantigens; D046988:Proteasome Endopeptidase Complex; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases; D000099207:SS-A Antigen; C097309:UBE2D2 protein, human