The peptidyl-prolyl isomerase domain of the CyP-40 cyclophilin homolog Cpr7 is not required to support growth or glucocorticoid receptor activity in Saccharomyces cerevisiae
The peptidyl-prolyl isomerase domain of the CyP-40 cyclophilin homolog Cpr7 is not required to support growth or glucocorticoid receptor activity in Saccharomyces cerevisiae
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DOI：
10.1074/jbc.273.18.10819
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发表时间：
1998-05-01
影响因子：
4.8
通讯作者：
Gaber, RF
中科院分区：
文献类型：
--
作者：
Duina, AA;Marsh, JA;Gaber, RF
CYP-40亲环素与分子伴侣Hsp90-类固醇受体复合体结合。这些亲环素的氨基末端含有特征性的多肽-脯氨基异构酶(PPIase)结构域，而四肽(TPR)基序的三个拷贝(参与蛋白质-蛋白质相互作用的结构)和一个可能的钙调蛋白结合域位于蛋白质的羧基末端。TPR结构域介导与Hsp90的结合，但尚未建立对PPIase结构域的要求。为了解决这个问题，我们研究了改变酿酒酵母CYP-40同源物Cpr7的PPIase结构域的突变的影响。由于Cpr7是快速生长和完整的Hsp90活性所必需的，因此可以在体内对PPIase结构域进行功能评估。催化区域的突变改变了预计对异构酶活性至关重要的保守位置，并没有影响Cpr7的功能。此外，整个PPIase结构域的缺失不会显著影响生长或Hsp90介导的类固醇受体活性。这些结果表明，Cpr7的含有TPR的羧基末端足以进行基本的Cpr7依赖活性。
CyP-40 cyclophilins are found in association with molecular chaperone Hsp90-steroid receptor complexes. The amino-terminal portion of these cyclophilins harbors the characteristic peptidyl-prolyl isomerase (PPIase) domain, whereas three copies of the tetratricopeptide (TPR) motif, a structure shown to be involved in protein-protein interactions, and a putative calmodulin-binding domain are located in the carboxyl-terminal half of the protein. The TPR domains mediate binding to Hsp90, but a requirement for the PPIase domain has not been established. To address this, we have investigated the effects of mutations that alter the PPIase domain of the Saccharomyces cerevisiae CyP-40 homolog, Cpr7. Because Cpr7 is required for rapid growth and full Hsp90 activity, a functional assessment of the PPIase domain could be performed in vivo. A mutation in the catalytic domain altering a conserved site predicted to be essential for isomerase activity did not compromise Cpr7 function. Furthermore, deletion of the entire PPIase domain did not significantly affect growth or Hsp90-mediated steroid receptor activity. These results indicate that the TPR-containing carboxyl terminus of Cpr7 is sufficient for fundamental Cpr7-dependent activity.