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首页> 外文期刊>Molecular and Cellular Biology >CNS1 Encodes an Essential p60/Sti1 Homolog in Saccharomyces cerevisiae That Suppresses Cyclophilin 40 Mutations and Interacts with Hsp90
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CNS1 Encodes an Essential p60/Sti1 Homolog in Saccharomyces cerevisiae That Suppresses Cyclophilin 40 Mutations and Interacts with Hsp90

机译:CNS1在酿酒酵母中编码必需的p60 / Sti1同源物,该同源物可抑制亲环蛋白40突变并与Hsp90相互作用

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Cyclophilins are cis-trans-peptidyl-prolyl isomerases that bind to and are inhibited by the immunosuppressant cyclosporin A (CsA). The toxic effects of CsA are mediated by the 18-kDa cyclophilin A protein. A larger cyclophilin of 40 kDa, cyclophilin 40, is a component of Hsp90-steroid receptor complexes and contains two domains, an amino-terminal prolyl isomerase domain and a carboxy-terminal tetratricopeptide repeat (TPR) domain. There are two cyclophilin 40 homologs in the yeast Saccharomyces cerevisiae, encoded by the CPR6 and CPR7 genes. Yeast strains lacking the Cpr7 enzyme are viable but exhibit a slow-growth phenotype. In addition, we show here that cpr7 mutant strains are hypersensitive to the Hsp90 inhibitor geldanamycin. When overexpressed, the TPR domain of Cpr7 alone complements both cpr7 mutant phenotypes, while overexpression of the cyclophilin domain of Cpr7, full-length Cpr6, or human cyclophilin 40 does not. The open reading frame YBR155w, which has moderate identity to the yeast p60 homologSTI1, was isolated as a high-copy-number suppressor of thecpr7 slow-growth phenotype. We show that this Sti1 homolog Cns1 (cyclophilin seven suppressor) is constitutively expressed, essential, and found in protein complexes with both yeast Hsp90 and Cpr7 but not with Cpr6. Cyclosporin A inhibited Cpr7 interactions with Cns1 but not with Hsp90. In summary, our findings identify a novel component of the Hsp90 chaperone complex that shares function with cyclophilin 40 and provide evidence that there are functional differences between two conserved sets of Hsp90 binding proteins in yeast.
机译:亲环蛋白是与免疫抑制剂环孢菌素A(CsA)结合并受其抑制的顺-反-肽基-脯氨酰异构酶。 CsA的毒性作用是由18-kDa亲环蛋白A蛋白介导的。 40 kDa的较大亲环蛋白,即亲环蛋白40,是Hsp90-类固醇受体复合物的一个组成部分,包含两个域,一个氨基末端的脯氨酰异构酶域和一个羧基末端的四肽重复(TPR)域。酵母酿酒酵母中有两个亲环蛋白40同源物,由 CPR6 CPR7 基因编码。缺乏Cpr7酶的酵母菌株是可行的,但表现出缓慢生长的表型。此外,我们在这里显示 cpr7 突变株对Hsp90抑制剂格尔德霉素高度敏感。当过表达时,仅Cpr7的TPR结构域与 cpr7 突变表型互补,而Cpr7的亲环蛋白结构域,全长Cpr6或人亲环蛋白40的过表达则没有。分离出与酵母p60同源物 STI1 具有中等同一性的开放阅读框YBR155w,作为 cpr7 慢生长表型的高拷贝数抑制剂。我们显示,此Sti1同源Cns1(亲环素7抑制剂)组成性表达,必要,并在与酵母Hsp90和Cpr7而不是Cpr6​​的蛋白质复合物中发现。环孢菌素A抑制Cpr7与Cns1的相互作用,但不与Hsp90相互作用。总而言之,我们的发现确定了Hsp90分子伴侣复合物的一个新成分,该复合物与亲环蛋白40共享功能,并提供证据表明酵母中两个保守的Hsp90结合蛋白组之间存在功能差异。

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