TY - JOUR
T1 - The 2μm plasmid causes cell death in Saccharomyces cerevisiae with a mutation in Ulp1 protease
AU - Dobson, Melanie J.
AU - Pickett, Andrew J.
AU - Velmurugan, Soundarapandian
AU - Pinder, Jordan B.
AU - Barrett, Lori A.
AU - Jayaram, Makkuni
AU - Chew, Joyce S.K.
PY - 2005/5
Y1 - 2005/5
N2 - The 2μm circle plasmid confers no phenotype in wild-type Saccharomyces cerevisiae but in a nib1 mutant, an elevated plasmid copy number is associated with cell death. 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. The nib1 mutation replaces conserved tryptophan 490 with leucine in the protease domain of Ulp1. Complete deletion of ULP1 is lethal, even in a strain that lacks the 2μm circle. Partial deletion of ULP1, like the nib1 mutation, results in clonal variations in plasmid copy number. In addition, a subset of these mutant cells produces lineages in which all cells have reduced proliferative capacity, and this phenotype is dependent upon the presence of the 2μm circle. Segregation of the 2μm 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. These associations and the observation of missegregation of a fluorescently tagged 2μm circle reporter plasmid in a subset of ulp1 mutant cells suggest that Smt3 modification plays a role in both plasmid copy number control and segregation.
AB - The 2μm circle plasmid confers no phenotype in wild-type Saccharomyces cerevisiae but in a nib1 mutant, an elevated plasmid copy number is associated with cell death. 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. The nib1 mutation replaces conserved tryptophan 490 with leucine in the protease domain of Ulp1. Complete deletion of ULP1 is lethal, even in a strain that lacks the 2μm circle. Partial deletion of ULP1, like the nib1 mutation, results in clonal variations in plasmid copy number. In addition, a subset of these mutant cells produces lineages in which all cells have reduced proliferative capacity, and this phenotype is dependent upon the presence of the 2μm circle. Segregation of the 2μm 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. These associations and the observation of missegregation of a fluorescently tagged 2μm circle reporter plasmid in a subset of ulp1 mutant cells suggest that Smt3 modification plays a role in both plasmid copy number control and segregation.
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U2 - 10.1128/MCB.25.10.4299-4310.2005
DO - 10.1128/MCB.25.10.4299-4310.2005
M3 - Article
C2 - 15870298
AN - SCOPUS:18144426798
SN - 0270-7306
VL - 25
SP - 4299
EP - 4310
JO - Molecular and cellular biology
JF - Molecular and cellular biology
IS - 10
ER -