A new protease required for cell-cycle progression in yeast.
In eukaryotes, protein function can be modulated by ligation to ubiquitin or to ubiquitin-like proteins (Ubl proteins). The vertebrate Ubl protein SUMO-1 is only 18% identical to ubiquitin but is 48% identical to the yeast protein Smt3. Both SUMO-1 and Smt3 are ligated to cellular proteins, and protein conjugation to SUMO-1/Smt3 is involved in many physiological processes. It remained unknown, however, whether deconjugation of SUMO-1/Smt3 from proteins is also essential. Here we describe a yeast Ubl-specific protease, Ulp1, which cleaves proteins from Smt3 and SUMO-1 but not from ubiquitin. Ulp1 is unrelated to any known deubiquitinating enzyme but shows distant similarity to certain viral proteases, indicating the existence of a widely conserved protease fold. Proteins related to Ulp1 are present in many organisms, including several human pathogens. The pattern of Smt3-coupled proteins in yeast changes markedly throughout the cell cycle, and specific conjugates accumulate in ulp1 mutants. Ulp1 has several functions, including an essential role in the G2/M phase of the cell cycle.
Li
S J
SJ
University of Chicago, Department of Biochemistry & Molecular Biology, Illinois 60637, USA.
Hochstrasser
M
M
D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D003001:Cloning, Molecular; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli; D005656:Fungal Proteins / Q000302:isolation & purification / Q000378:metabolism; D016195:G2 Phase / Q000502:physiology; D006801:Humans; D008938:Mitosis / Q000502:physiology; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D025842:SUMO-1 Protein; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D025841:Small Ubiquitin-Related Modifier Proteins; D013379:Substrate Specificity; D014452:Ubiquitins / Q000378:metabolism
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C099362:SMT3 protein, S cerevisiae; D025842:SUMO-1 Protein; C117909:SUMO2 protein, human; D029701:Saccharomyces cerevisiae Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D014452:Ubiquitins; D003546:Cysteine Endopeptidases; C118083:Ulp1 protease