Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, 3086, Victoria, Australia.
Department of Immunology and Pathology, Monash University, Melbourne, 3004, Victoria, Australia.
Sci Rep. 2018 Aug 27;8(1):12862. doi: 10.1038/s41598-018-30311-1.
The maintenance of mitochondrial protein homeostasis (proteostasis) is crucial for correct cellular function. Recently, several mutations in the mitochondrial protease CLPP have been identified in patients with Perrault syndrome 3 (PRLTS3). These mutations can be arranged into two groups, those that cluster near the docking site (hydrophobic pocket, Hp) for the cognate unfoldase CLPX (i.e. T145P and C147S) and those that are adjacent to the active site of the peptidase (i.e. Y229D). Here we report the biochemical consequence of mutations in both regions. The Y229D mutant not only inhibited CLPP-peptidase activity, but unexpectedly also prevented CLPX-docking, thereby blocking the turnover of both peptide and protein substrates. In contrast, Hp mutations cause a range of biochemical defects in CLPP, from no observable change to CLPP activity for the C147S mutant, to dramatic disruption of most activities for the "gain-of-function" mutant T145P - including loss of oligomeric assembly and enhanced peptidase activity.
线粒体蛋白稳态（蛋白质稳态）的维持对于细胞的正常功能至关重要。最近，在 Perrault 综合征 3 型（PRLTS3）患者中发现了几种线粒体蛋白酶 CLPP 的突变。这些突变可以分为两组，一组聚集在同源解折叠酶 CLPX 的对接位点（疏水性口袋，Hp）附近（即 T145P 和 C147S），另一组位于肽酶的活性位点附近（即 Y229D）。在这里，我们报告了这两个区域突变的生化后果。Y229D 突变不仅抑制了 CLPP-肽酶活性，而且出人意料地还阻止了 CLPX 对接，从而阻止了肽和蛋白质底物的周转。相比之下，Hp 突变导致 CLPP 的一系列生化缺陷，从没有观察到 C147S 突变的 CLPP 活性变化，到“获得功能”突变 T145P 引起的大多数活性的剧烈破坏，包括寡聚组装的丧失和增强的肽酶活性。
