A ROLE FOR MESSENGER-RNA SECONDARY STRUCTURE IN THE CONTROL OF TRANSLATION INITIATION
A ROLE FOR MESSENGER-RNA SECONDARY STRUCTURE IN THE CONTROL OF TRANSLATION INITIATION
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DOI：
10.1038/295616a0
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发表时间：
1982-01-01
期刊：
影响因子：
64.8
通讯作者：
SCHWARTZ, M
中科院分区：
文献类型：
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作者：
HALL, MN;GABAY, J;SCHWARTZ, M
信使RNA （mRNA）二级结构在控制翻译起始中的作用已被假定多年1 - 3。现在，对大肠杆菌的amb基因的研究提供了支持这一观点的有力证据，该基因编码一种主要的外膜蛋白，该蛋白既是噬菌体λ、K-10和TP1的受体，也是麦芽糖和麦芽糖糊精运输系统的组成部分。影响ambmrna翻译起始的突变已经在之前被描述过10。DNA序列分析表明，其中一个这样的突变lamB701位于ambshine - dalgarno序列的两个核苷酸启动子-近端。第二个突变，lamB708，位于amb基因的第六个密码子（见图1）。Schwartzet等人认为，这两个点突变通过有利于在lamp转录本中形成碱基配对的发夹结构来影响翻译起始，从而使Shine-Dalgarno序列11无法进入核糖体（见图2）。这一结论在遗传学上是可检验的，因为它预测了在alamB701-708双突变体中，由两个突变中的任何一个单独引起的翻译起始缺陷都会被抑制（见图2）。在这里，我们证明了701和708突变确实相互抑制，正如mRNA二级结构所预测的那样。
A role for messenger RNA (mRNA) secondary structure in the control of translation initiation has been assumed for many years1–3. Strong additional evidence supporting this notion is now provided by work on thelamBgene ofEscherichia coli, which codes for a major outer membrane protein that functions both as a receptor for phagesλ, K-10 and TP1, and as a component of the maltose and maltodextrin transport system4–9. Mutations that affect translation initiation of thelamBmRNA have been described previously10. DNA sequence analysis indicated that one such mutation,lamB701, is located two nucleotides promoter-proximal to thelamBShine–Dalgarno sequence. A second mutation,lamB708, is located in the sixth codon of thelamBgene (see Fig. 1). Schwartzet al.10suggested that these two point mutations affect translation initiation by favouring the formation of a base-paired hairpin structure in thelamBtranscript which makes the Shine–Dalgarno sequence11inaccessible to ribosomes (see Fig. 2). This suggestion was genetically testable because it predicted that the translation initiation defect caused by either of the two mutations alone would be suppressed in alamB701–708 double mutant (see Fig. 2). Here we demonstrate that the 701 and 708 mutations do indeed suppress each other, as predicted by an effect attributable to mRNA secondary structure.