Weiser K, Litt M
Eur J Biochem. 1979 Jan 15;93(2):295-300. doi: 10.1111/j.1432-1033.1979.tb12823.x.
In eukaryotes, the levels of specific tRNAs are closely correlated with the demands for their cognate amino acids in protein synthesis. To account for this phenomenon, we have proposed that the extent of aminoacylation of a given tRNA species in vivo controls the relative rate of synthesis or turnover of that species. Previously, we reported that Friend leukemia cells respond to histidine deprivation by increasing their relative level of tRNAHis by as much as two-fold, with no change in the relative level of tRNALeu. In this paper, we show that deprivation of leucine or tryptophan also causes a specific increase in the relative level of tRNAs cognate to the deprived amino acid. At least in the case of tRNATrp, the increases in relative tRNA levels are preceded by extensive declines in the steady-state extent of aminoacylation of the tRNA in vitro. We also find that different isoacceptors may respond differently to amino acid deprivation. These results suggest that decreased extents of aminoacylation of a given tRNA species in vivo cause increases in the relative rate of synthesis or decreases in the relative rate of degradation of that species.
在真核生物中，特定tRNA的水平与蛋白质合成中对其同源氨基酸的需求密切相关。为了解释这一现象，我们提出，体内给定tRNA种类的氨酰化程度控制着该种类的相对合成速率或周转速率。此前，我们报道，弗瑞德白血病细胞通过将其tRNAHis的相对水平提高多达两倍来应对组氨酸缺乏，而tRNALeu的相对水平没有变化。在本文中，我们表明，亮氨酸或色氨酸的缺乏也会导致与缺乏的氨基酸同源的tRNA的相对水平特异性增加。至少就tRNATrp而言，tRNA相对水平的增加之前，其体外氨酰化的稳态程度会大幅下降。我们还发现，不同的同功受体对氨基酸缺乏的反应可能不同。这些结果表明，体内给定tRNA种类的氨酰化程度降低会导致该种类的相对合成速率增加或相对降解速率降低。
