The yeast ULP2 (SMT4) gene encodes a novel protease specific for the ubiquitin-like Smt3 protein
The yeast ULP2 (SMT4) gene encodes a novel protease specific for the ubiquitin-like Smt3 protein
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DOI：
10.1128/mcb.20.7.2367-2377.2000
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发表时间：
2000-04-01
影响因子：
5.3
通讯作者：
Hochstrasser, M
中科院分区：
文献类型：
--
作者：
Li, SJ;Hochstrasser, M
酵母Smt 3及其脊椎动物同源物SUMO-1是与其他蛋白可逆连接的泛素样蛋白（Ubls）。与SMT 3一样，SMT 4最初是作为一种有缺陷的着丝粒结合蛋白的高拷贝数抑制基因分离出来的。我们在这里表明，SMT 4编码的Smt 3-解偶联酶，Ulp 2，在细胞缺乏Ulp 2，特定的Smt 3蛋白质共轭物积累，共轭模式是不同的，从观察到的ulp 1（TS）菌株，这是一个遥远的相关Smt 3特异性蛋白酶，Ulp 1缺陷。ulp 2 Delta突变体表现出多效性表型，包括温度敏感性生长、异常细胞形态、质粒和染色体稳定性降低以及严重的孢子形成缺陷。该突变体也对DNA损伤剂、羟基脲和苯菌灵过敏。虽然细胞周期检查点阻滞响应于DNA损伤、复制抑制或纺锤体缺陷以正常动力学发生，但从阻滞中恢复受损。令人惊讶的是，引入ulp 1（ts）突变或过量产生催化失活的ulp 1可以基本上克服ulp 2 Delta缺陷。失活的Ulp 2也抑制几个ulp 1（TS）的缺陷，和双突变体积累少得多的Smt 3蛋白结合物比任何一个单一的突变体。我们的数据表明，存在一种反馈机制，限制Smt 3蛋白连接时，Smt 3解共轭Ulp 1和Ulp 2受到损害，允许部分恢复细胞功能。
Yeast Smt3 and its vertebrate homolog SUMO-1 are ubiquitin-like proteins (Ubls) that are reversibly ligated to other proteins. Like SMT3, SMT4 was first isolated as a high-copy-number suppressor of a defective centromere-binding protein. We show here that SMT4 encodes an Smt3-deconjugating enzyme, Ulp2, In cells lacking Ulp2, specific Smt3-protein conjugates accumulate, and the conjugate pattern is distinct from that observed in a ulp1(ts) strain, which is defective for a distantly related Smt3-specific protease, Ulp1. The ulp2 Delta mutant exhibits a pleiotropic phenotype that includes temperature-sensitive growth, abnormal cell morphology, decreased plasmid and chromosome stability, and a severe sporulation defect. The mutant is also hypersensitive to DNA-damaging agents, hydroxyurea, and benomyl, Although cell cycle checkpoint arrest in response to DNA damage, replication inhibition, or spindle defects occurs with normal kinetics, recovery from arrest is impaired. Surprisingly, either introduction of a ulp1(ts) mutation or overproduction of catalytically inactive Ulp1 can substantially overcome the ulp2 Delta defects. Inactivation of Ulp2 also suppresses several ulp1(ts) defects, and the double mutant accumulates far fewer Smt3-protein conjugates than either single mutant. Our data suggest the existence of a feedback mechanism that limits Smt3-protein ligation when Smt3 deconjugation by both Ulp1 and Ulp2 is compromised, allowing a partial recovery of cell function.