Klionsky D J, Skalnik D G, Simoni R D
J Biol Chem. 1986 Jun 25;261(18):8096-9.
Translation of the gene for the b subunit of the Escherichia coli proton-translocating ATPase has been examined. Oligonucleotide-directed site-specific mutagenesis was used to mutate certain nucleotides in the intergenic region between uncE (c) and uncF (b). One of the changes was predicted to lower the stability of a proposed stem structure which blocked the ribosome binding site of the uncF mRNA segment. The result of the mutation is a nearly 3-fold increase in the rate of synthesis of the b polypeptide. Another mutation was introduced which changed the initiation codon for uncF from GUG to AUG. This change resulted in an approximately 2-fold increase in the synthesis rate of the b polypeptide. These results suggest that secondary structure in the mRNA and the use of a less efficient initiation codon play a role in restricting translation initiation of the uncF mRNA segment. These mechanisms may, in part, explain how the polypeptides of the ATPase complex are synthesized in approximately the same relative amounts as they appear in the assembled complex.
对大肠杆菌质子转运ATP酶b亚基基因的翻译进行了研究。采用寡核苷酸定向位点特异性诱变技术，对uncE（c）和uncF（b）之间基因间区域的某些核苷酸进行诱变。其中一个变化预计会降低一种推测的茎环结构的稳定性，该结构会阻碍uncF mRNA片段的核糖体结合位点。突变的结果是b多肽的合成速率提高了近3倍。引入了另一个突变，将uncF的起始密码子从GUG变为AUG。这一变化导致b多肽的合成速率提高了约2倍。这些结果表明，mRNA中的二级结构以及使用效率较低的起始密码子在限制uncF mRNA片段的翻译起始中发挥作用。这些机制可能部分解释了ATP酶复合物的多肽是如何以与它们在组装复合物中出现的相对量大致相同的比例合成的。
