Hecht S M, Chinualt A C
Proc Natl Acad Sci U S A. 1976 Feb;73(2):405-9. doi: 10.1073/pnas.73.2.405.
Transfer RNAs terminating 2'-or 3'-deoxyadenosine were prepared from unfractionated E. coli and yeast (Saccharomyces cerevisiae) tRNAs and purified to remove unmodified tRNAs. The modified tRNA species were assayed for aminoacylation with each of the 20 amino acids to determine the initial position of tRNA aminoacylation. The E. coli and yeast aminoacyl-tRNA synthetases specific for arginine, isoleucine, leucine, methionine, phenylalanine, and valine, as well as the E. coli glutamyl-tRNA synthetase, aminoacylated only those cognate tRNAs terminating in 3'-deoxyadenosine (i.e., those having a 2'-OH group). On the other hand, those E. coli and yeast synthetases specific for alanine, glycine, histidine, lysine, proline, serine, and threonine, as well as the yeast synthetase specific for glutamine, utilized exclusively those tRNAs having an available 3'-OH group on the 3'-terminal nucleoside, while the E. coli and yeast synthetases specific for asparagine, cysteine, and tyrosine, and the yeast aspartyl-tRNA synthetase, utilized both of the modified cognate tRNAs. The only observed difference in specificity between the E. coli and yeast systems was for tRNATrp, which was aminoacylated on the 2'-position in E. coli and the 3'-position in yeast. The results indicate that the initial position of aminoacylation is not uniform for all tRNAs, although for individual tRNAs the specificity has been conserved during the evolution from a prokaryotic to eukaryotic organism.
从未经分级分离的大肠杆菌和酵母（酿酒酵母）转运RNA（tRNA）中制备了以2'-或3'-脱氧腺苷结尾的tRNA，并进行纯化以去除未修饰的tRNA。对这些修饰的tRNA种类进行20种氨基酸中每种氨基酸的氨酰化测定，以确定tRNA氨酰化的起始位置。对精氨酸、异亮氨酸、亮氨酸、甲硫氨酸、苯丙氨酸和缬氨酸具有特异性的大肠杆菌和酵母氨酰-tRNA合成酶，以及大肠杆菌谷氨酰-tRNA合成酶，仅对那些以3'-脱氧腺苷结尾的同源tRNA（即那些具有2'-OH基团的tRNA）进行氨酰化。另一方面，对丙氨酸、甘氨酸、组氨酸、赖氨酸、脯氨酸、丝氨酸和苏氨酸具有特异性的那些大肠杆菌和酵母合成酶，以及对谷氨酰胺具有特异性的酵母合成酶，仅利用那些在3'-末端核苷上具有可用3'-OH基团的tRNA，而对天冬酰胺、半胱氨酸和酪氨酸具有特异性的大肠杆菌和酵母合成酶，以及酵母天冬氨酰-tRNA合成酶，则利用这两种修饰的同源tRNA。在大肠杆菌和酵母系统之间观察到的唯一特异性差异是针对tRNATrp，它在大肠杆菌中在2'-位置被氨酰化，而在酵母中在3'-位置被氨酰化。结果表明，尽管对于单个tRNA而言，其特异性在从原核生物到真核生物的进化过程中得以保留，但并非所有tRNA的氨酰化起始位置都是一致的。
