Dreher T W, Hall T C
Department of Biology, Texas A & M University, College Station 77843-3258.
J Mol Biol. 1988 May 5;201(1):41-55. doi: 10.1016/0022-2836(88)90437-8.
The genomic RNAs of brome mosaic virus (BMV) exhibit various tRNA-like properties, including specific tyrosylation by tyrosyl-tRNA synthetases and adenylation of the 3'-CCOH derivative by tRNA nucleotidyl transferases. We have studied the effect of numerous mutations in all domains of the tRNA-like structure of BMV RNA on tyrosylation and adenylation in vitro. Surprisingly few mutations resulted in more than 50% decrease in tyrosylation rates with either wheat germ or yeast synthetases; those mutations were at the 3' terminus, the pseudoknot, and the bases of arms B and E. The results suggest an interaction of synthetase with arm A as the analog of the aminoacyl acceptor stem of tRNAs, and arm B as the analog of the anticodon arm of tRNAs, although there is no apparent interaction with the terminal loop of arm B analogous to the interaction with the anticodon in tRNAs. Mutations at several loci resulted in large losses of adenylation activity catalyzed by wheat germ and Escherichia coli nucleotidyl transferases; those loci were the pseudoknot, the bases of arms B, C and D, and at the junctions of these arms with arm A. These studies have identified mutants specifically defective in one of the tRNA-like activities, which are appropriate for investigating the role of these activities during infection in vivo.
雀麦花叶病毒（BMV）的基因组RNA具有多种类似tRNA的特性，包括酪氨酸-tRNA合成酶对其进行特异性酪氨酸化以及tRNA核苷酸转移酶对3'-CCOH衍生物进行腺苷酸化。我们研究了BMV RNA类似tRNA结构所有结构域中众多突变对体外酪氨酸化和腺苷酸化的影响。令人惊讶的是，很少有突变会导致小麦胚芽或酵母合成酶催化的酪氨酸化速率降低超过50%；这些突变位于3'末端、假结以及臂B和E的碱基处。结果表明，合成酶与作为tRNA氨酰基受体茎类似物的臂A以及作为tRNA反密码子臂类似物的臂B存在相互作用，尽管与臂B的末端环没有明显的相互作用，而这种相互作用类似于与tRNA反密码子的相互作用。几个位点的突变导致小麦胚芽和大肠杆菌核苷酸转移酶催化的腺苷酸化活性大幅丧失；这些位点是假结、臂B、C和D的碱基以及这些臂与臂A的连接处。这些研究鉴定出了在一种类似tRNA活性中存在特异性缺陷的突变体，这些突变体适合用于研究这些活性在体内感染过程中的作用。
