Functional conservation of tRNase ZL among Saccharomyces cerevisiae, Schizosaccharomyces pombe and humans.
Functional conservation of tRNase ZL among Saccharomyces cerevisiae, Schizosaccharomyces pombe and humans.
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DOI：
10.1042/bj20090743
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发表时间：
2009-09
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影响因子：
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通讯作者：
Zhenqin Zhao;Wencheng Su;Sheng Yuan;Ying Huang
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文献类型：
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作者：
Zhenqin Zhao;Wencheng Su;Sheng Yuan;Ying Huang
尽管来自各种生物体的tRNase Z显示出在体外加工核tRNA 3'末端，但只有非常有限数量的研究报道了其体内生物学功能。tRNase Z以短形式tRNase Z（S）和长形式tRNase Z（L）存在。与酿酒酵母（Saccharomyces cerevisiae）含有一个tRNase Z（L）基因（scTRZ 1）和人类（人类含有一个由前列腺癌易感基因ELAC 2编码的tRNase Z（L）和一个tRNase Z（S））不同，裂殖酵母含有两个tRNase Z（L）基因，命名为sptrz 1（+）和sptrz 2（+）。我们报告sptrz 1（+）和sptrz 2（+）对生长都是必不可少的。此外，sptrz 1（+）是在不存在Sla 1 p的情况下细胞活力所必需的，Sla 1 p被认为是酵母中核酸内切酶介导的前体tRNA 3'末端成熟所必需的。scTRZ 1和ELAC 2都可以与sptrz 1（+）的温度敏感等位基因sptrz 1 -1互补，但不能与sptrz 1无效突变体互补，这表明尽管具有物种特异性，但tRNase Z（L）s在S.酿酒酵母，S.粟酒和人类sptrz 1（+）、scTRZ 1和ELAC 2的过表达可以通过促进介导抑制的缺陷型抑制基因tRNA的3'末端加工来增加对UGA无义突变ade 6 -704的抑制。我们的发现揭示了3'端加工是缺陷型tRNA成熟的限制性步骤，并证明了sptrz 1（+）、scTRZ 1和ELAC 2的过表达可以促进体内缺陷型tRNA 3'端加工。我们的研究结果也支持酵母tRNase Z（L）是绝对需要的3'端加工至少一些前tRNA，即使在Sla 1 p的情况下。
Although tRNase Z from various organisms was shown to process nuclear tRNA 3' ends in vitro, only a very limited number of studies have reported its in vivo biological functions. tRNase Z is present in a short form, tRNase Z(S), and a long form, tRNase Z(L). Unlike Saccharomyces cerevisiae, which contains one tRNase Z(L) gene (scTRZ1) and humans, which contain one tRNase Z(L) encoded by the prostate-cancer susceptibility gene ELAC2 and one tRNase Z(S), Schizosaccharomyces pombe contains two tRNase Z(L) genes, designated sptrz1(+) and sptrz2(+). We report that both sptrz1(+) and sptrz2(+) are essential for growth. Moreover, sptrz1(+) is required for cell viability in the absence of Sla1p, which is thought to be required for endonuclease-mediated maturation of pre-tRNA 3' ends in yeast. Both scTRZ1 and ELAC2 can complement a temperature-sensitive allele of sptrz1(+), sptrz1-1, but not the sptrz1 null mutant, indicating that despite exhibiting species specificity, tRNase Z(L)s are functionally conserved among S. cerevisiae, S. pombe and humans. Overexpression of sptrz1(+), scTRZ1 and ELAC2 can increase suppression of the UGA nonsense mutation ade6-704 through facilitating 3' end processing of the defective suppressor tRNA that mediates suppression. Our findings reveal that 3' end processing is a limiting step for defective tRNA maturation and demonstrate that overexpression of sptrz1(+), scTRZ1 and ELAC2 can promote defective tRNA 3' processing in vivo. Our results also support the notion that yeast tRNase Z(L) is absolutely required for 3' end processing of at least a few pre-tRNAs even in the absence of Sla1p.