Johnsen M, Christensen T, Dennis P P, Fiil N P
EMBO J. 1982;1(8):999-1004. doi: 10.1002/j.1460-2075.1982.tb01284.x.
Ribosomal proteins L10 and L12 are encoded in the L10 operon, situated at position 89.5 min on the Escherichia coli genetic map, and are able to regulate their own translation. The two proteins form a L10-L12 complex that is able to bind specifically to the leader sequence of the L10 operon mRNA and prevent translation. We show that the leader sequence: (i) is required for the translation of mRNA into L10 and L12 proteins; and (ii) contains a unique binding site for the inhibitory L10-L12 complex. We suggest that a specific secondary structure of the leader RNA is required for translation. When this structure is perturbed by L10-L12 binding, by deletion, or point mutations, translation is inhibited. The block on the synthesis of L10 and L12 can presumably be removed by the incorporation of the inhibitory L10-L12 complex into assembling 50S ribosome subunits. We observed that rRNA prevents the binding of L10-L12 to the mRNA. Furthermore, we have identified extended sequence homologies within the 23S rRNA and L10 leader region RNA. The L10-L12 binding site on the mRNA includes part of the homologous sequences.
核糖体蛋白L10和L12由位于大肠杆菌遗传图谱89.5分钟位置的L10操纵子编码，并且能够调节自身的翻译。这两种蛋白形成L10-L12复合物，该复合物能够特异性结合L10操纵子mRNA的前导序列并阻止翻译。我们发现前导序列：（i）是mRNA翻译成L10和L12蛋白所必需的；（ii）包含抑制性L10-L12复合物的独特结合位点。我们认为前导RNA的特定二级结构是翻译所必需的。当这种结构因L10-L12结合、缺失或点突变而受到干扰时，翻译就会受到抑制。L10和L12合成的阻断大概可以通过将抑制性L10-L12复合物掺入组装中的50S核糖体亚基来消除。我们观察到rRNA会阻止L10-L12与mRNA的结合。此外，我们在23S rRNA和L10前导区RNA中鉴定出了延伸的序列同源性。mRNA上的L10-L12结合位点包括部分同源序列。
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