School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Perth WA, Australia.
ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Perth WA, Australia.
J Exp Bot. 2019 Nov 18;70(21):6005-6018. doi: 10.1093/jxb/erz365.
The endosymbiotic origin of the mitochondrion and the subsequent transfer of its genome to the host nucleus has resulted in intricate mechanisms of regulating mitochondrial biogenesis and protein content. The majority of mitochondrial proteins are nuclear encoded and synthesized in the cytosol, thus requiring specialized and dedicated machinery for the correct targeting import and sorting of its proteome. Most proteins targeted to the mitochondria utilize N-terminal targeting signals called presequences that are cleaved upon import. This cleavage is carried out by a variety of peptidases, generating free peptides that can be detrimental to organellar and cellular activity. Research over the last few decades has elucidated a range of mitochondrial peptidases that are involved in the initial removal of the targeting signal and its sequential degradation, allowing for the recovery of single amino acids. The significance of these processing pathways goes beyond presequence degradation after protein import, whereby the deletion of processing peptidases induces plant stress responses, compromises mitochondrial respiratory capability, and alters overall plant growth and development. Here, we review the multitude of plant mitochondrial peptidases that are known to be involved in protein import and processing of targeting signals to detail how their activities can affect organellar protein homeostasis and overall plant growth.
线粒体的内共生起源以及随后其基因组转移到宿主核内，导致了调节线粒体生物发生和蛋白质含量的复杂机制。大多数线粒体蛋白是由核编码并在细胞质中合成的，因此需要专门的机制来正确靶向、导入和分拣其蛋白质组。大多数靶向线粒体的蛋白质利用 N 端靶向信号（称为前导序列），这些序列在导入时被切割。这种切割是由多种肽酶完成的，生成的游离肽可能对细胞器和细胞活动有害。过去几十年的研究阐明了一系列参与初始靶向信号去除及其连续降解的线粒体肽酶，从而允许回收单个氨基酸。这些加工途径的意义不仅在于蛋白质导入后前导序列的降解，而且在删除加工肽酶后会诱导植物应激反应、损害线粒体呼吸能力，并改变植物的整体生长和发育。在这里，我们综述了已知参与蛋白质导入和靶向信号加工的多种植物线粒体肽酶，详细介绍了它们的活性如何影响细胞器蛋白质平衡和植物的整体生长。
