Matsufuji S, Matsufuji T, Miyazaki Y, Murakami Y, Atkins J F, Gesteland R F, Hayashi S
Howard Hughes Medical Institute, University of Utah, Salt Lake City 84112.
Cell. 1995 Jan 13;80(1):51-60. doi: 10.1016/0092-8674(95)90450-6.
Rat antizyme gene expression requires programmed, ribosomal frameshifting. A novel autoregulatory mechanism enables modulation of frameshifting according to the cellular concentration of polyamines. Antizyme binds to, and destabilizes, ornithine decarboxylase, a key enzyme in polyamine synthesis. Rapid degradation ensues, thus completing a regulatory circuit. In vitro experiments with a fusion construct using reticulocyte lysates demonstrate polyamine-dependent expression with a frameshift efficiency of 19% at the optimal concentration of spermidine. The frameshift is +1 and occurs at the codon just preceding the terminator of the initiating frame. Both the termination codon of the initiating frame and a pseudoknot downstream in the mRNA have a stimulatory effect. The shift site sequence, UCC-UGA-U, is not similar to other known frameshift sites. The mechanism does not seem to involve re-pairing of peptidyl-tRNA in the new frame but rather reading or occlusion of a fourth base.
大鼠抗酶基因的表达需要程序性核糖体移码。一种新的自我调节机制能够根据细胞内多胺的浓度调节移码。抗酶与多胺合成中的关键酶鸟氨酸脱羧酶结合并使其不稳定。随后迅速降解，从而完成一个调节回路。使用网织红细胞裂解物的融合构建体进行的体外实验表明，在亚精胺的最佳浓度下，多胺依赖性表达的移码效率为19%。移码为+1，发生在起始阅读框终止密码子之前的密码子处。起始阅读框的终止密码子和mRNA下游的假结都有刺激作用。移码位点序列UCC-UGA-U与其他已知的移码位点不同。该机制似乎不涉及新阅读框中肽基-tRNA的重新配对，而是涉及第四个碱基的读取或封闭。
