A BACTERIAL AMBER SUPPRESSOR IN SACCHAROMYCES-CEREVISIAE IS SELECTIVELY RECOGNIZED BY A BACTERIAL AMINOACYL-TRANSFER RNA-SYNTHETASE
A BACTERIAL AMBER SUPPRESSOR IN SACCHAROMYCES-CEREVISIAE IS SELECTIVELY RECOGNIZED BY A BACTERIAL AMINOACYL-TRANSFER RNA-SYNTHETASE
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DOI：
10.1128/mcb.10.4.1633
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发表时间：
1990-04-01
影响因子：
5.3
通讯作者：
SCHIMMEL, P
中科院分区：
文献类型：
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作者：
EDWARDS, H;SCHIMMEL, P
对于生物体之间 tRNA 特性决定因素的保守性知之甚少。我们之前表明，大肠杆菌酪氨酸 tRNA 合成酶可以在体内为酿酒酵母线粒体酪氨酸 tRNA 充电，尽管酵母线粒体和细菌 tRNA 之间存在显着的序列差异。酿酒酵母细胞质酪氨酸 tRNA 的序列与其酵母线粒体和大肠杆菌对应物的序列不同。为了测试酵母细胞质酪氨酰-tRNA 合成酶是否识别大肠杆菌 tRNA，我们在酿酒酵母中表达了不同量的大肠杆菌酪氨酸 tRNA 琥珀抑制子。细菌 tRNA 不会抑制三个酵母琥珀等位基因中的任何一个，这表明酵母酶对其同源 tRNA 在体内保留了高度特异性。此外，大肠杆菌抑制子序列中不与酵母细胞质酪氨酸tRNA共享的核苷酸不会产生被其他酵母充电酶有效识别的决定簇。因此，至少一些影响酪氨酸 tRNA 体内识别的决定因素是细胞区室和生物体特有的。相反，同源细菌酪氨酰-tRNA 合成酶与细菌抑制性 tRNA 的表达导致所有三个琥珀等位基因的抑制。即使细菌 tRNA 的量低于总细胞质 tRNA 的约 0.05%，细菌酶也能在体内识别其底物。
Little is known about the conservation of determinants for the identities of tRNAs between organisms. We showed previously that Escherichia coli tyrosine tRNA synthetase can charge the Saccharomyces cerevisiae mitochondrial tyrosine tRNA in vivo, even though there are substantial sequence differences between the yeast mitochondrial and bacterial tRNAs. The S. cerevisiae cytoplasmic tyrosine tRNA differs in sequence from both its yeast mitochondrial and E. coli counterparts. To test whether the yeast cytoplasmic tyrosyl-tRNA synthetase recognizes the E. coli tRNA, we expressed various amounts of an E. coli tyrosine tRNA amber suppressor in S. cerevisiae. The bacterial tRNA did not suppress any of three yeast amber alleles, suggesting that the yeast enzymes retain high specificity in vivo for their homologous tRNAs. Moreover, the nucleotides in the sequence of the E. coli suppressor that are not shared with the yeast cytoplasmic tyrosine tRNA do not create determinants which are efficiently recognized by other yeast charging enzymes. Therefore, at least some of the determinants that influence in vivo recognition of the tyrosine tRNA are specific to the cell compartment and organism. In contrast, expression of the cognate bacterial tyrosyl-tRNA synthetase together with the bacterial suppressor tRNA led to suppression of all three amber alleles. The bacterial enzyme recognized its substrate in vivo, even when the amount of bacterial tRNA was less than about 0.05% of that of the total cytoplasmic tRNA.