Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA.
Proc Natl Acad Sci U S A. 2013 Feb 12;110(7):2528-33. doi: 10.1073/pnas.1300173110. Epub 2013 Jan 28.
The de novo biosynthesis of purines is carried out by a highly conserved metabolic pathway that includes several validated targets for anticancer, immunosuppressant, and anti-inflammatory chemotherapeutics. The six enzymes in humans that catalyze the 10 chemical steps from phosphoribosylpyrophosphate to inosine monophosphate were recently shown to associate into a dynamic multiprotein complex called the purinosome. Here, we demonstrate that heat shock protein 90 (Hsp90), heat shock protein 70 (Hsp70), and several cochaperones functionally colocalize with this protein complex. Knockdown of expression levels of the identified cochaperones leads to disruption of purinosomes. In addition, small molecule inhibitors of Hsp90 and Hsp70 reversibly disrupt purinosomes and are shown to have a synergistic effect with methotrexate, an anticancer agent that targets purine biosynthesis. These data implicate the Hsp90/Hsp70 chaperone machinery in the assembly of the purinosome and provide a strategy for the development of improved anticancer therapies that disrupt purine biosynthesis.
嘌呤的从头生物合成是由一条高度保守的代谢途径完成的，其中包括几个已被验证的抗癌、免疫抑制和抗炎化疗药物靶点。最近发现，人类中催化从磷酸核糖焦磷酸到肌苷单磷酸的 10 个化学步骤的 6 种酶会组装成一个称为嘌呤体的动态多蛋白复合物。在这里，我们证明热休克蛋白 90（Hsp90）、热休克蛋白 70（Hsp70）和几种共伴侣蛋白与该蛋白复合物在功能上共定位。鉴定出的共伴侣蛋白表达水平的下调会导致嘌呤体的破坏。此外，Hsp90 和 Hsp70 的小分子抑制剂可可逆地破坏嘌呤体，并显示与甲氨蝶呤（一种靶向嘌呤生物合成的抗癌药物）具有协同作用。这些数据表明 Hsp90/Hsp70 伴侣机制参与了嘌呤体的组装，并为开发破坏嘌呤生物合成的改进型抗癌疗法提供了一种策略。
