BACKGROUND The molecular chaperone TRAP1, the mitochondrial isoform of cytosolic HSP90, remains poorly understood with respect to its pivotal role in the regulation of mitochondrial metabolism. Most studies have found it to be an inhibitor of mitochondrial oxidative phosphorylation (OXPHOS) and an inducer of the Warburg phenotype of cancer cells. However, others have reported the opposite, and there is no consensus on the relevant TRAP1 interactors. This calls for a more comprehensive analysis of the TRAP1 interactome and of how TRAP1 and mitochondrial metabolism mutually affect each other. RESULTS We show that the disruption of the gene for TRAP1 in a panel of cell lines dysregulates OXPHOS by a metabolic rewiring that induces the anaplerotic utilization of glutamine metabolism to replenish TCA cycle intermediates. Restoration of wild-type levels of OXPHOS requires full-length TRAP1. Whereas the TRAP1 ATPase activity is dispensable for this function, it modulates the interactions of TRAP1 with various mitochondrial proteins. Quantitatively by far, the major interactors of TRAP1 are the mitochondrial chaperones mtHSP70 and HSP60. However, we find that the most stable stoichiometric TRAP1 complex is a TRAP1 tetramer, whose levels change in response to both a decline and an increase in OXPHOS. CONCLUSIONS Our work provides a roadmap for further investigations of how TRAP1 and its interactors such as the ATP synthase regulate cellular energy metabolism. Our results highlight that TRAP1 function in metabolism and cancer cannot be understood without a focus on TRAP1 tetramers as potentially the most relevant functional entity.

中文翻译：

---

线粒体HSP90旁系同源物TRAP1形成OXPHOS调控的四聚体，并参与线粒体代谢稳态。

背景技术关于分子伴侣TRAP1，即细胞质HSP90的线粒体同工型，就其在调节线粒体代谢中的关键作用而言仍知之甚少。大多数研究发现它是线粒体氧化磷酸化（OXPHOS）的抑制剂，也是癌细胞Warburg表型的诱导剂。但是，其他人则报道了相反的情况，有关TRAP1相互作用子尚无共识。这要求对TRAP1相互作用基因组以及TRAP1和线粒体代谢如何相互影响进行更全面的分析。结果我们显示，一组细胞系中TRAP1基因的破坏通过代谢重新布线而异常调节OXPHOS，该代谢重新布线诱导谷氨酰胺代谢的过早利用来补充TCA循环中间体。恢复OXPHOS的野生型水平需要全长TRAP1。TRAP1 ATPase活性对于此功能是必不可少的，但它调节TRAP1与各种线粒体蛋白的相互作用。到目前为止，TRAP1的主要相互作用物是线粒体伴侣蛋白mtHSP70和HSP60。但是，我们发现最稳定的化学计量TRAP1复合物是TRAP1四聚体，其水平随着OXPHOS的下降和增加而变化。结论我们的工作为进一步研究TRAP1及其相互作用因子（如ATP合酶）调节细胞能量代谢提供了路线图。我们的结果表明，如果不关注TRAP1四聚体作为潜在的最相关的功能实体，就无法理解TRAP1在代谢和癌症中的功能。