Characterization of the interaction of Aha1 with components of the Hsp90 chaperone machine and client proteins

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• 作者：Liang Sun ; Thomas Prince¹ ; Jacob R. Manjarrez ; Bradley T. Scroggins¹ ; Robert L. Matts ; ^{robert.matts@okstate.edu}
• 关键词：Heat shock protein 90 ; Activator of Hsp90 ATPase ; Non-receptor tyrosine kinase v-Src ; Progesterone receptor ; Aha1-interacting protein ; Hsp90 inhibitor
• 刊名：Biochimica et Biophysica Acta (BBA)/Molecular Cell Research
• 出版年：2012
• 期刊代码：20_01674889
• 类别：bio
• 出版时间：June, 2012
• 卷：1823
• 期：6
• 页码：1092-1101
• 文件大小：744 K

摘要

The activator of Hsp90 ATPase, Aha1, is an Hsp90 co-chaperone that has been suggested to act as a general stimulator of Hsp90 function. In this report, we have characterized the interaction of Aha1 with Hsp90 and its co-chaperones in rabbit reticulocyte lysate (RRL) and in HeLa cell extracts. Complexes formed by Aha1 with Hsp90 in RRL were stabilized by molybdate and contained the co-chaperones FKBP52 and p23/Sba1, but lacked HOP/Sti1 and Cdc37. Aha1 complexes isolated from HeLa cell extracts also contained Hsp70 and DNAJA1. Over-expression of Aha1 has been reported to stimulate the activity of v-Src and steroid hormone receptors ectopically expressed in yeast, however, no interaction between Aha1 and nascent v-Src or the progesterone receptor could be detected in RRL. Contrary to expectations, over-expression of Aha1 also inhibited the rate of Hsp90-dependent refolding of denatured luciferase. A number of potential client proteins that specifically associated with Aha1 were identified by liquid chromatography/ tandem mass spectrometry (LC-MS/MS) and verified by Western blotting. The proteins identified suggest that Aha1 may play roles in modulating RNA splicing and DNA repair, in addition to other cellular processes.