Instituto de Bioingeniería, Universidad Miguel Hernández, Campus de Elche, 03202 Elche, Spain.
Int J Mol Sci. 2017 Dec 2;18(12):2595. doi: 10.3390/ijms18122595.
Mitochondria are the powerhouse of eukaryotic cells because they are responsible for energy production through the aerobic respiration required for growth and development. These organelles harbour their own genomes and translational apparatus: mitochondrial ribosomes or mitoribosomes. Deficient mitochondrial translation would impair the activity of this organelle, and is expected to severely perturb different biological processes of eukaryotic organisms. In plants, mitoribosomes consist of three rRNA molecules, encoded by the mitochondrial genome, and an undefined set of ribosomal proteins (mitoRPs), encoded by nuclear and organelle genomes. A detailed functional and structural characterisation of the mitochondrial translation apparatus in plants is currently lacking. In some plant species, presence of small gene families of mitoRPs whose members have functionally diverged has led to the proposal of the heterogeneity of the mitoribosomes. This hypothesis supports a dynamic composition of the mitoribosomes. Information on the effects of the impaired function of mitoRPs on plant development is extremely scarce. Nonetheless, several works have recently reported the phenotypic and molecular characterisation of plant mutants affected in mitoRPs that exhibit alterations in specific development aspects, such as embryogenesis, leaf morphogenesis or the formation of reproductive tissues. Some of these results would be in line with the ribosomal filter hypothesis, which proposes that ribosomes, besides being the machinery responsible for performing translation, are also able to regulate gene expression. This review describes the phenotypic effects on plant development displayed by the mutants characterised to date that are defective in genes which encode mitoRPs. The elucidation of plant mitoRPs functions will provide a better understanding of the mechanisms that control organelle gene expression and their contribution to plant growth and morphogenesis.
线粒体是真核细胞的能量工厂，因为它们负责通过有氧呼吸产生能量，而有氧呼吸是生长和发育所必需的。这些细胞器拥有自己的基因组和翻译装置：线粒体核糖体或线粒体核糖体。线粒体翻译缺陷会削弱该细胞器的活性，预计会严重扰乱真核生物的不同生物学过程。在植物中，线粒体核糖体由三个 rRNA 分子组成，由线粒体基因组编码，以及一组未定义的核糖体蛋白（mitoRPs），由核基因组和细胞器基因组编码。目前缺乏对植物中线粒体翻译装置的详细功能和结构特征的描述。在一些植物物种中，存在功能分化的 mitoRPs 小基因家族，这导致了线粒体核糖体异质性的提出。该假说支持线粒体核糖体的动态组成。关于 mitoRPs 功能受损对植物发育影响的信息极其缺乏。尽管如此，最近的几项研究报告了植物突变体在 mitoRPs 功能受损方面的表型和分子特征，这些突变体在特定的发育方面表现出改变，如胚胎发生、叶片形态发生或生殖组织的形成。其中一些结果与核糖体过滤假说一致，该假说认为核糖体不仅是执行翻译的机器，还能够调节基因表达。本综述描述了迄今已被表征的、在编码 mitoRPs 的基因缺陷的突变体中，对植物发育的表型影响。阐明植物 mitoRPs 的功能将更好地理解控制细胞器基因表达的机制及其对植物生长和形态发生的贡献。
