Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Straße 13, 67663 Kaiserslautern, Germany.
Computational Systems Biology, University of Kaiserslautern, Erwin-Schrödinger-Straße 23, 67663 Kaiserslautern, Germany.
Biochim Biophys Acta Bioenerg. 2020 Nov 1;1861(11):148275. doi: 10.1016/j.bbabio.2020.148275. Epub 2020 Jul 23.
Why mitochondria still retain their own genome is a puzzle given the enormous effort to maintain a mitochondrial translation machinery. Most mitochondrially encoded proteins are membrane-embedded subunits of the respiratory chain. Their hydrophobicity presumably impedes their import into mitochondria. However, many mitochondrial genomes also encode protein subunits of the mitochondrial ribosome. These proteins lack transmembrane domains and hydrophobicity cannot explain why their genes remained in mitochondria. In this review, we provide an overview about mitochondrially encoded subunits of mitochondrial ribosomes of fungi, plants and protists. Moreover, we discuss and evaluate different hypotheses which were put forward to explain why (ribosomal) proteins remained mitochondrially encoded. It seems likely that the synthesis of ribosomal proteins in the mitochondrial matrix is used to regulate the assembly of the mitochondrial ribosome within mitochondria and to avoid problems that mitochondrial proteins might pose for cytosolic proteostasis and for the assembly of cytosolic ribosomes.
为什么线粒体仍然保留自己的基因组是一个谜，因为维持线粒体翻译机制需要付出巨大的努力。大多数线粒体编码的蛋白质是呼吸链的膜嵌入亚基。它们的疏水性大概会阻碍它们进入线粒体。然而，许多线粒体基因组也编码线粒体核糖体的蛋白亚基。这些蛋白质缺乏跨膜结构域，疏水性不能解释为什么它们的基因仍然存在于线粒体中。在这篇综述中，我们提供了关于真菌、植物和原生动物线粒体核糖体的线粒体编码亚基的概述。此外，我们讨论并评估了不同的假说，这些假说被提出以解释为什么（核糖体）蛋白仍然是线粒体编码的。似乎很可能是在线粒体基质中合成核糖体蛋白用于调节线粒体核糖体在线粒体中的组装，并避免线粒体蛋白对细胞质蛋白稳态和细胞质核糖体组装造成的问题。
