Zapisek Bartosz, Piątkowski Jakub
Postepy Biochem. 2015;61(4):403-15.
PPR proteins make up the most numerous family of RNA-binding proteins identified to date. They localize almost exclusively to plastids and mitochondria of eukaryotic organisms. The most striking feature of this family is the expansion of PPR protein-encoding genes in vascular plants, which likely coincided with plants colonizing land. PPR proteins participate in stabilizing, editing, splicing, degradation and processing of policistronic transcripts, as well as translation activation in mitochondria and plastids. Although the number of PPR proteins in non-plant organisms is significantly smaller than in plants, they still play a crucial role in regulating the expression of mtDNA. Disruptions of PPR protein-encoding genes usually result in severe phenotypic consequences. Plant PPR proteins bind RNA in a sequence-specific manner, where a single PPR motif recognizes an individual nucleotide in a given sequence. This opens up possibilities for engineering de novo synthetic protein sequences that would interact with precisely determined organellar sequences, thus enabling modulation of mtDNA and ctDNA expression.
PPR蛋白构成了迄今为止已鉴定出的数量最多的RNA结合蛋白家族。它们几乎仅定位于真核生物的质体和线粒体中。该家族最显著的特征是维管植物中PPR蛋白编码基因的扩增，这可能与植物在陆地上的定殖同时发生。PPR蛋白参与多顺反子转录本的稳定、编辑、剪接、降解和加工，以及线粒体和质体中的翻译激活。尽管非植物生物中的PPR蛋白数量明显少于植物，但它们在调节线粒体DNA（mtDNA）的表达中仍起着关键作用。PPR蛋白编码基因的破坏通常会导致严重的表型后果。植物PPR蛋白以序列特异性方式结合RNA，其中单个PPR基序识别给定序列中的单个核苷酸。这为设计从头合成的蛋白质序列开辟了可能性，这些序列将与精确确定的细胞器序列相互作用，从而能够调节mtDNA和叶绿体DNA（ctDNA）的表达。
