Identification of a deubiquitinating enzyme subfamily as substrates of the von Hippel-Lindau tumor suppressor.
The VHL protein (pVHL) is a component of an E3 ubiquitin ligase complex which is involved in the ubiquitination and degradation of the alpha subunits of HIF (hypoxia-inducible factor) in the presence of oxygen. However, it is of considerable interest to identify pVHL substrates other than HIF. In our previous studies, we have shown that VDU1 (pVHL-interacting deubiquitinating enzyme-1) can be ubiquitinated for rapid degradation in a pVHL-dependent manner. In this report we show that another uncharacterized deubiquitinating enzyme, named VDU2 (pVHL-interacting deubiquitinating enzyme-2), is a substrate of pVHL. Based on human and mouse cDNA sequences, VDU1 and VDU2 are identical in approximately 59% of the amino acids with strong homology in the N-terminus and C-terminus and a weaker similarity in the middle region. VDU2 contains the signature motifs of the ubiquitin-specific processing protease family and possesses deubiquitinating activity. Like VDU1, VDU2 interacts with pVHL beta-domain and these two proteins can compete with each other to bind to pVHL. Finally, we demonstrate that VDU2 can also be ubiquitinated and degraded in a pVHL-dependent manner. Based on their amino acid sequence homology and functional interaction with pVHL, VDU1 and VDU2 define a subfamily of ubiquitin specific processing proteases. Since deubiquitination, by reversing ubiquitination, has been recognized as an important regulatory step in ubiquitination-related processes, VDU1 and VDU2 could be important substrates of pVHL E3 ligase complex.
Li
Zaibo
Z
Department of Urology, University of Rochester Medical Center, 601 Elmwood Ave., Box 656, Rochester, NY 14642, USA.
Wang
Dakun
D
Na
Xi
X
Schoen
Susan R
SR
Messing
Edward M
EM
Wu
Guan
G
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002384:Catalysis; D004305:Dose-Response Relationship, Drug; D010450:Endopeptidases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008025:Ligases / Q000378:metabolism*; D008969:Molecular Sequence Data; D010957:Plasmids; D016415:Sequence Alignment; D013379:Substrate Specificity; D014162:Transfection; D025521:Tumor Suppressor Proteins; D043222:Ubiquitin Thiolesterase; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D006623:von Hippel-Lindau Disease / Q000378:metabolism
D025521:Tumor Suppressor Proteins; C459591:USP20 protein, human; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D010450:Endopeptidases; D043222:Ubiquitin Thiolesterase; C486762:Usp20 protein, mouse; D008025:Ligases; C497446:VHL protein, human