Several RNase T2 enzymes function in induced tRNA and rRNA turnover in the ciliate Tetrahymena.
Several RNase T2 enzymes function in induced tRNA and rRNA turnover in the ciliate Tetrahymena.
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DOI：
10.1091/mbc.e11-08-0689
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发表时间：
2012-01
影响因子：
3.3
通讯作者：
Collins K
中科院分区：
文献类型：
--
作者：
Andersen KL;Collins K
在缺乏一个RNT 2基因或基因组合的菌株中探索编码RNase T2家族蛋白（RNT 2蛋白）的八个嗜热四膜虫基因的功能。至少三种四膜虫RNase T2酶参与条件诱导的tRNA和rRNA周转。RNase T2酶由广泛的生物体产生，并且已经涉及在不同的细胞过程中起作用，包括成熟tRNA的应激诱导的反密码子环切割以产生tRNA半体。在这里，我们描述了一个家庭的8 RNase T2基因（RNT 2A-RNT 2 H）的纤毛虫四膜虫thermophila。我们构建了缺乏这些RNT 2基因的个体或组合的菌株，这些RNT 2基因是可行的，但具有不同的细胞和分子表型。在菌株缺乏只有一个Rnt 2蛋白或缺乏一个亚家族的三个催化失活的Rnt 2蛋白，饥饿诱导的tRNA片段继续积累，只有一个小的变化，在一个菌株的片段配置文件。因此，我们产生了缺乏Rnt 2 tRNA酶的前三个候选物的成对组合的菌株。这些菌株中的每一个都表现出不同的饥饿特异性的tRNA和rRNA片段积累的配置文件。这些结果，划定了一个更宽的范围内的条件，诱导积累的tRNA的一半，并演示了一个主要的核糖核蛋白的状态tRNA的一半在细胞提取物表明，纤毛虫tRNA的一半是降解中间体诱导的自噬途径的生长停滞，其功能是回收闲置的蛋白质合成机器。
The functions of eight Tetrahymena thermophila genes encoding RNase T2 family proteins (Rnt2 proteins) are explored in strains lacking one RNT2 gene or combinations of genes. At least three Tetrahymena RNase T2 enzymes are involved in the conditionally induced turnover of tRNA and rRNA. RNase T2 enzymes are produced by a wide range of organisms and have been implicated to function in diverse cellular processes, including stress-induced anticodon loop cleavage of mature tRNAs to generate tRNA halves. Here we describe a family of eight RNase T2 genes (RNT2A–RNT2H) in the ciliate Tetrahymena thermophila. We constructed strains lacking individual or combinations of these RNT2 genes that were viable but had distinct cellular and molecular phenotypes. In strains lacking only one Rnt2 protein or lacking a subfamily of three catalytically inactive Rnt2 proteins, starvation-induced tRNA fragments continued to accumulate, with only a minor change in fragment profile in one strain. We therefore generated strains lacking pairwise combinations of the top three candidates for Rnt2 tRNases. Each of these strains showed a distinct starvation-specific profile of tRNA and rRNA fragment accumulation. These results, the delineation of a broadened range of conditions that induce the accumulation of tRNA halves, and the demonstration of a predominantly ribonucleoprotein-free state of tRNA halves in cell extract suggest that ciliate tRNA halves are degradation intermediates in an autophagy pathway induced by growth arrest that functions to recycle idle protein synthesis machinery.