A new protease required for cell-cycle progression in yeast

Abstract

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.

Yeast homolog of human SAG/ROC2/Rbx2/Hrt2 is essential for cell growth, but not for germination: chip profiling implicates its role in cell cycle regulation

“…First of all, disruption of either gene is lethal but can be rescued by their human homologs. Second, cells became enlarged upon withdrawal of either gene, and thirdly, withdrawal of either gene showed a similar FACS pattern that is more broad and skewed to right with more DNA content (Li and Hochstrasser, 1999;and this report). These observations indicate that the ligase/protease involved in either conjugation or deconjugation of proteins during proteolysis plays an important role in precise regulation of cell cycle progression.…”

“…The transcription factors/co-activators that binds to the consensus sequences such as AACGCG, AAACCC, or ACTCTC (see Results section) might be potential cellular targets of SAG-SCF E3 ubiquitin ligase. It is also interesting to note that Upl1, a protease speci®c to deconjugate protein from yeast ubiquitinlike protein, SUMO-1/Smt3, but not from ubiquitin (Li and Hochstrasser, 1999) share some phenotypic similarities with ySAG. First of all, disruption of either gene is lethal but can be rescued by their human homologs.…”

E2FBP1/hDril1 modulates cell growth through downregulation of promyelocytic leukemia bodies

“…The reaction mixture was then subjected to immunoblotting. As a control, an aliquot of the PML-IP was incubated with a GST-tagged yeast desumoylating enzyme, Ulp1 27 (Figure 3b, lanes 5 and 10, top panels). GST-Ulp1 caused disappearance of slowly migrating forms of Figure 3c, lanes 1 and 2).…”

Small ubiquitin-like modifying protein isopeptidase assay based on poliovirus RNA polymerase activity

“…Cleavage using SUMO protease C-terminal, His-tagged, SUMO protease 1 [Ulp1 (403-621)p] [9,39] was expressed from pET24d in Rosetta-(DE3) pLysS (Novagen). The recombinant protein (apparent M by SDS-PAGE ~31 kDa) was purified using Ni-NTA resin and buffer-exchanged into 20 mM TrisHCl (pH 8.0), 150 mM NaCl, and 5 mM of 2-mercaptoethanol using a PD-10 column (Amersham Biosciences).…”

“…In addition to the classical UBP/USP (ubiquitin-specific protease) and UCH (ubiquitin C-terminal hydrolase) enzymes, there are at least three distinct groups of enzymes capable of removing ubiquitin or a related UBL (e.g., SUMO) from a protein substrate. Proteases specific for SUMO conjugates include yeast Ulp1 and Ulp2 [9,10] and human SENP1 and SENP2 [11,12]. Other known ULPs include UBP43, which cleaves ISG15 conjugates [13], and DEN1 (SENP8), which deconjugates Nedd8 from protein substrates [14,15].…”