TY - JOUR
T1 - Characterization of the ubiquitin-specific protease activity of the mouse/human Unp/Unph oncoprotein
AU - Gilchrist, Catherine A.
AU - T. Baker, Rohan
PY - 2000/9/29
Y1 - 2000/9/29
N2 - The ubiquitin-specific proteases (Ubps) are a family of largely dissimilar enzymes with two major conserved sequence regions, containing either a conserved cysteine residue or two conserved histidine residues, respectively. The murine Unp oncoprotein and its human homologue, Unph, both contain regions similar to the conserved Cys and His boxes common to all the Ubps. In this study we show that Unp and Unph are active deubiquitinating enzymes, being able to cleave ubiquitin from both natural and engineered linear ubiquitin-protein fusions, including the polyubiquitin precursor. Mutation of the conserved Unp Cys and His residues abolishes this activity, and identifies the likely His residue in the catalytic triad. Unp is tumorigenic when overexpressed in mice, leading to the suggestion that Unp may play a role in the regulation of ubiquitin-dependent protein degradation. We have demonstrated here that the high-level expression of Unp in yeast does not disrupt the degradation of the N-end rule substrate Tyr-β-galactosidase (βgal), the non-N-end rule substrate ubiquitin-Pro-βgal, or the degradation of abnormal, canavanine-containing proteins. These data suggest that Unp is not a general modulator of ubiquitin-dependent proteolysis. However, Unp may have a role in the regulation of the degradation of a specific, as yet undescribed, substrate(s). (C) 2000 Elsevier Science B.V.
AB - The ubiquitin-specific proteases (Ubps) are a family of largely dissimilar enzymes with two major conserved sequence regions, containing either a conserved cysteine residue or two conserved histidine residues, respectively. The murine Unp oncoprotein and its human homologue, Unph, both contain regions similar to the conserved Cys and His boxes common to all the Ubps. In this study we show that Unp and Unph are active deubiquitinating enzymes, being able to cleave ubiquitin from both natural and engineered linear ubiquitin-protein fusions, including the polyubiquitin precursor. Mutation of the conserved Unp Cys and His residues abolishes this activity, and identifies the likely His residue in the catalytic triad. Unp is tumorigenic when overexpressed in mice, leading to the suggestion that Unp may play a role in the regulation of ubiquitin-dependent protein degradation. We have demonstrated here that the high-level expression of Unp in yeast does not disrupt the degradation of the N-end rule substrate Tyr-β-galactosidase (βgal), the non-N-end rule substrate ubiquitin-Pro-βgal, or the degradation of abnormal, canavanine-containing proteins. These data suggest that Unp is not a general modulator of ubiquitin-dependent proteolysis. However, Unp may have a role in the regulation of the degradation of a specific, as yet undescribed, substrate(s). (C) 2000 Elsevier Science B.V.
KW - Deubiquitinating enzyme
KW - Proteolysis
KW - USP4
KW - Ubiquitin
KW - Ubiquitin-specific protease
KW - Unp
UR - http://www.scopus.com/inward/record.url?scp=0034730694&partnerID=8YFLogxK
U2 - 10.1016/S0167-4838(00)00134-5
DO - 10.1016/S0167-4838(00)00134-5
M3 - Article
SN - 0167-4838
VL - 1481
SP - 297
EP - 309
JO - Biochimica et Biophysica Acta - Protein Structure and Molecular Enzymology
JF - Biochimica et Biophysica Acta - Protein Structure and Molecular Enzymology
IS - 2
ER -