Noncatalytic role of the FKBP52 peptidyl-prolyl isomerase domain in the regulation of steroid hormone signaling
Noncatalytic role of the FKBP52 peptidyl-prolyl isomerase domain in the regulation of steroid hormone signaling
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DOI：
10.1128/mcb.00985-07
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发表时间：
2007-12-01
影响因子：
5.3
通讯作者：
Smith, David F.
中科院分区：
文献类型：
--
作者：
Riggs, Daniel L.;Cox, Marc B.;Smith, David F.
Hsp90 相关辅助伴侣蛋白 FKBP52 增强了几种类固醇激素受体的激素依赖性反式激活，但密切相关的 FKBP51 却没有增强这种作用。在这里，我们分析了 FKBP51 和 FKBP52 的增强机制以及功能差异。虽然两者都具有肽基-脯氨酰异构酶活性，但这并不是增强所必需的，因为消除异构酶活性的突变不会影响增强。为了在随机突变的 FKBP51 基因文库中获得增强活性，在酿酒酵母中进行了遗传选择，确定了 N 端 FK1 结构域中第 119 位的单个残基是这两种蛋白质之间的关键差异。在酵母模型和哺乳动物细胞中，FKBP51 突变 L119P 位于催化口袋上方的发夹环中，并引入 FKBP52 中发现的脯氨酸，赋予显着的增强活性，而 FKBP52 中的反向 P119L 突变降低了增强活性。该环中的第二个残基 A116 也会影响增强水平；事实上，FKBP51-A116V L119P 双突变体与野生型 FKBP52 一样增强了激素信号传导。这些结果表明 FK1 结构域，特别是悬垂在催化袋上的环，在受体相互作用和受体活性中至关重要。
Hormone-dependent transactivation by several of the steroid hormone receptors is potentiated by the Hsp90-associated cochaperone FKBP52, although not by the closely related FKBP51. Here we analyze the mechanisms of potentiation and the functional differences between FKBP51 and FKBP52. While both have peptidyl-prolyl isomerase activity, this is not required for potentiation, as mutations abolishing isomerase activity did not affect potentiation. Genetic selection in Saccharomyces cerevisiae for gain of potentiation activity in a library of randomly mutated FKBP51 genes identified a single residue at position 119 in the N-terminal FK1 domain as being a critical difference between these two proteins. In both the yeast model and mammalian cells, the FKBP51 mutation L119P, which is located in a hairpin loop overhanging the catalytic pocket and introduces the proline found in FKBP52, conferred significant potentiation activity, whereas the converse P119L mutation in FKBP52 decreased potentiation. A second residue in this loop, A116, also influences potentiation levels; in fact, the FKBP51-A116V L119P double mutant potentiated hormone signaling as well as wild-type FKBP52 did. These results suggest that the FK1 domain, and in particular the loop overhanging the catalytic pocket, is critically involved in receptor interactions and receptor activity.