High impact information on ULP1

• The pattern of Smt3-coupled proteins in yeast changes markedly throughout the cell cycle, and specific conjugates accumulate in ulp1 mutants [1].
• Ulp1 has several functions, including an essential role in the G2/M phase of the cell cycle [1].
• Yeast has two SUMO-1-deconjugating enzymes, Ulp1 and Ulp2, which are located at nuclear pores and in the nucleoplasm, respectively [2].
• This is achieved by the noncatalytic N-domain, which tethers Ulp1 to the nuclear pores [2].
• Here we show that the catalytic C-domain of Ulp1 must be excluded from the nucleoplasm for cell viability [2].

Biological context of ULP1

• Partial deletion of ULP1, like the nib1 mutation, results in clonal variations in plasmid copy number [3].
• We also show that deleting MLPs or the localization domains of Ulp1 results in DNA damage sensitivity and clonal lethality, the latter of which is caused by increased levels of 2-micron circle DNA [4].
• Together, our results reveal that Mlps play important roles in regulating Ulp1 and subsequently affect sumoylation stasis, growth, and DNA repair [4].
• The Ulp1 SUMO isopeptidase: distinct domains required for viability, nuclear envelope localization, and substrate specificity [5].
• A new Saccharomyces cerevisiae strain with a mutant Smt3-deconjugating Ulp1 protein is affected in DNA replication and requires Srs2 and homologous recombination for its viability [6].

Anatomical context of ULP1

• Moreover, like Mlps, Ulp1 exhibits a unique asymmetric distribution on the nuclear envelope [4].

Associations of ULP1 with chemical compounds

• The NH2-terminal domain also includes sequences necessary and sufficient to concentrate Ulp1 at nuclear envelope sites [5].
• The nib1 mutation replaces conserved tryptophan 490 with leucine in the protease domain of Ulp1 [3].
• In this report, we show that Smt3 conjugation occurs at a single site in Dorsal (lysine 382), requires just the Smt3-activating and -conjugating enzymes, and is reversed by the deconjugating enzyme Ulp1 [7].

Physical interactions of ULP1

• Segregation of the 2 microm circle requires two plasmid-encoded proteins, Rep1 and Rep2, which were found to colocalize with Ulp1 protein in the nucleus and interact with Smt3 in a two-hybrid assay [3].

Other interactions of ULP1

• Here, we show that Mlps and Nup60, but not several other nucleoporins, are required to localize and stabilize a desumoylating enzyme Ulp1 [4].
• We show here that cNLS-dependent protein import is impaired in mutants with defective Ulp1 and Uba2, two enzymes involved in the SUMO conjugation reaction [8].
• The level of this modification was affected by Smt3-specific protease mutation ulp1-ts or overexpression of ULP1 [9].
• Complementation was used to identify nib1 as a mutant allele of the ULP1 gene that encodes a protease required for removal of a ubiquitin-like protein, Smt3/SUMO, from protein substrates [3].
• Genetic interactions between ulp1 and mutations that affect different repair pathways indicated that the RAD51-dependent homologous recombination mechanism, but not excision resynthesis, translesion synthesis, or nonhomologous end-joining processes, is required for the viability of the mutant [6].

Analytical, diagnostic and therapeutic context of ULP1

• Gle1, another NPC-associating component, also interacted with Ulp1 in the two-hybrid system and co-immunoprecipitation experiment [9].

References