Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Department of Nephrology, Chang Gung Memorial Hospital, Linkou Branch, Taoyuan, Taiwan.
Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
Biochim Biophys Acta Bioenerg. 2020 Jul 1;1861(7):148192. doi: 10.1016/j.bbabio.2020.148192. Epub 2020 Mar 17.
Mutations of many PDSS and COQ genes are associated with primary coenzyme Q (CoQ) deficiency, whereas mitochondrial DNA (mtDNA) mutations might cause secondary CoQ deficiency. Previously, we found that COQ5 and COQ9 proteins are present in different protein complexes in the mitochondria in human 143B cells and demonstrated that COQ5 and COQ9 knockdown suppresses CoQ levels. In the present study, we characterized other PDSS and COQ proteins and examined possible crosstalk among various PDSS and COQ proteins. Specific antibodies and mitochondrial localization of mature proteins for these proteins, except PDSS1 and COQ2, were identified. Multiple isoforms of PDSS2 and COQ3 were observed. Moreover, PDSS1, PDSS2, and COQ3 played more important roles in maintaining the stability of the other proteins. Protein complexes containing PDSS2, COQ3, COQ4, COQ6, or COQ7 protein in the mitochondria were detected. Two distinct PDSS2-containing protein complexes could be identified. Transient knockdown of these genes, except COQ6 and COQ8, decreased CoQ levels, but only COQ7 knockdown hampered mitochondrial respiration and caused increased ubiquinol:ubiquinone ratios and accumulation of a putative biosynthetic intermediate with reversible redox property as CoQ. Furthermore, suppressed levels of PDSS2 and various COQ proteins (except COQ3 and COQ8A) were found in cybrids containing the pathogenic mtDNA A8344G mutation or in FCCP-treated 143B cells, which was similar to our previous findings for COQ5. These novel findings may prompt the elucidation of the putative CoQ synthome in human cells and the understanding of these PDSS and COQ protein under physiological and pathological conditions.
许多 PDSS 和 COQ 基因的突变与原发性辅酶 Q（CoQ）缺乏有关，而线粒体 DNA（mtDNA）突变可能导致继发性 CoQ 缺乏。以前，我们发现 COQ5 和 COQ9 蛋白存在于人 143B 细胞线粒体中的不同蛋白复合物中，并证明 COQ5 和 COQ9 的敲低会抑制 CoQ 水平。在本研究中，我们对其他 PDSS 和 COQ 蛋白进行了表征，并检查了各种 PDSS 和 COQ 蛋白之间可能的串扰。除了 PDSS1 和 COQ2 之外，还鉴定了这些蛋白的特定抗体和成熟蛋白的线粒体定位。观察到 PDSS2 和 COQ3 的多个同工型。此外，PDSS1、PDSS2 和 COQ3 在维持其他蛋白的稳定性方面发挥了更重要的作用。在线粒体中检测到含有 PDSS2、COQ3、COQ4、COQ6 或 COQ7 蛋白的蛋白复合物。可以鉴定出两种不同的 PDSS2 包含的蛋白复合物。除了 COQ6 和 COQ8 之外，这些基因的瞬时敲低会降低 CoQ 水平，但只有 COQ7 的敲低会阻碍线粒体呼吸，并导致可还原氧化性质的假定生物合成中间产物的积累和 ubiquinol:ubiquinone 比值增加。此外，在含有致病性 mtDNA A8344G 突变的细胞杂种或 FCCP 处理的 143B 细胞中，发现 PDSS2 和各种 COQ 蛋白（除 COQ3 和 COQ8A 外）的水平受到抑制，这与我们以前对 COQ5 的研究结果相似。这些新发现可能会促使阐明人细胞中假定的 CoQ 合成酶组，并在生理和病理条件下理解这些 PDSS 和 COQ 蛋白。
