Arabidopsis Encodes Four tRNase Z Enzymes
Arabidopsis Encodes Four tRNase Z Enzymes
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DOI：
10.1104/pp.109.137950
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发表时间：
2009-07-01
期刊：
影响因子：
7.4
通讯作者：
Marchfelder, Anita
中科院分区：
文献类型：
--
作者：
Canino, Giusy;Bocian, Edyta;Marchfelder, Anita
功能性转运RNA（tRNA）分子是蛋白质生物合成的先决条件。从前体分子产生成熟的功能性tRNA需要几个加工步骤。两个早期加工步骤涉及在tRNA 5'端和tRNA 3'端的切割。虽然tRNA 5'端的加工由RNase P进行，但3'端的切割由内切核酸酶tRNase Z催化。在真核生物中，tRNase Z酶以两种形式存在：约250至300个氨基酸的短形式和约700至900个氨基酸的长形式。所有的真核基因组分析日期编码至少一个长tRNase Z蛋白。其中，拟南芥（Arabidopsis thaliana）是唯一编码四种tRNase Z蛋白的生物，两种短形式和两种长形式。我们在这里表明，这四种蛋白质分布在植物细胞的不同亚细胞区室：细胞核，细胞质，叶绿体，叶绿体。一种tRNase Z仅存在于细胞质中，一种蛋白质仅存在于线粒体中，而第三种蛋白质具有双重位置：细胞核和线粒体。这三种tRNase Z蛋白都不是必需的。第四种tRNase Z蛋白存在于叶绿体中，其基因的缺失导致胚胎致死表型。用重组蛋白进行的体外分析表明，所有四种tRNase Z酶都具有tRNA 3'加工活性。此外，线粒体tRNase Z蛋白切割tRNA样元件，其在线粒体mRNA成熟中充当加工信号。
Functional transfer RNA (tRNA) molecules are a prerequisite for protein biosynthesis. Several processing steps are required to generate the mature functional tRNA from precursor molecules. Two of the early processing steps involve cleavage at the tRNA 5' end and the tRNA 3' end. While processing at the tRNA 5' end is performed by RNase P, cleavage at the 3' end is catalyzed by the endonuclease tRNase Z. In eukaryotes, tRNase Z enzymes are found in two versions: a short form of about 250 to 300 amino acids and a long form of about 700 to 900 amino acids. All eukaryotic genomes analyzed to date encode at least one long tRNase Z protein. Of those, Arabidopsis (Arabidopsis thaliana) is the only organism that encodes four tRNase Z proteins, two short forms and two long forms. We show here that the four proteins are distributed to different subcellular compartments in the plant cell: the nucleus, the cytoplasm, the mitochondrion, and the chloroplast. One tRNase Z is present only in the cytoplasm, one protein is found exclusively in mitochondria, while the third one has dual locations: nucleus and mitochondria. None of these three tRNase Z proteins is essential. The fourth tRNase Z protein is present in chloroplasts, and deletion of its gene results in an embryo-lethal phenotype. In vitro analysis with the recombinant proteins showed that all four tRNase Z enzymes have tRNA 3' processing activity. In addition, the mitochondrial tRNase Z proteins cleave tRNA-like elements that serve as processing signals in mitochondrial mRNA maturation.