Rad23 stabilizes Rad4 from degradation by the Ub/proteasome pathway
Rad23 stabilizes Rad4 from degradation by the Ub/proteasome pathway
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DOI：
10.1093/nar/gkh987
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发表时间：
2004-01-01
影响因子：
14.9
通讯作者：
Madura, K
中科院分区：
文献类型：
--
作者：
Ortolan, TG;Chen, L;Madura, K
Rad 23蛋白与核苷酸切除-修复（NER）因子Rad 4相互作用，并且二聚体可以结合受损的DNA。Rad 23还结合泛素化蛋白并促进其被蛋白酶体降解。Rad 23/蛋白酶体相互作用是有效的NER所必需的，尽管Ub/蛋白酶体系统在DNA修复中的具体作用尚不清楚。我们报告说，Rad 4的可用性有助于显着的细胞耐受紫外线。蛋白酶体和编码泛素结合酶Ubc 4和Ubc 5的基因的突变稳定了Rad 4，并增加了对紫外线的耐受性。先前在人Rad 23中鉴定的短氨基酸序列介导Rad 23和Rad 4之间的相互作用。我们确定该基序是稳定Rad 4所必需的，并且可以独立于完整蛋白发挥功能。Rad 23中的泛素样（UbL）结构域结合蛋白酶体，并且是赋予对DNA损伤的完全抗性所必需的。然而，Rad 23/蛋白酶体相互作用似乎与Rad 23介导的Rad 4稳定无关。具体地说，同时表达的Rad 23突变体，不能结合蛋白酶体，突变体不能与Rad 4相互作用，完全抑制了紫外线的敏感性rad 23三角洲，表明Rad 23执行两个独立的，但并发NER的作用。
Rad23 protein interacts with the nucleotide excision-repair (NER) factor Rad4, and the dimer can bind damaged DNA. Rad23 also binds ubiquitinated proteins and promotes their degradation by the proteasome. Rad23/proteasome interaction is required for efficient NER, although the specific role of the Ub/proteasome system in DNA repair is unclear. We report that the availability of Rad4 contributes significantly to the cellular tolerance to UV light. Mutations in the proteasome, and in genes encoding the ubiquitin-conjugating enzymes Ubc4 and Ubc5, stabilized Rad4 and increased tolerance to UV light. A short amino acid sequence, previously identified in human Rad23, mediates the interaction between Rad23 and Rad4. We determined that this motif was required for stabilizing Rad4, and could function independently of the intact protein. A ubiquitin-like (UbL) domain in Rad23 binds the proteasome, and is required for conferring full resistance to DNA damage. However, Rad23/proteasome interaction appears unrelated to Rad23-mediated stabilization of Rad4. Specifically, simultaneous expression of a Rad23 mutant that could not bind the proteasome, with a mutant that could not interact with Rad4, fully suppressed the UV sensitivity of rad23 Delta, demonstrating that Rad23 performs two independent, but concurrent roles in NER.