The last RNA-binding repeat of the Escherichia coli ribosomal protein S1 is specifically involved in autogenous control
The last RNA-binding repeat of the Escherichia coli ribosomal protein S1 is specifically involved in autogenous control
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DOI：
10.1128/jb.182.20.5872-5879.2000
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发表时间：
2000-10-01
影响因子：
3.2
通讯作者：
Dreyfus, M
中科院分区：
文献类型：
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作者：
Boni, IV;Artamonova, VS;Dreyfus, M
SsyF29突变最初被选为蛋白质输出缺陷的基因外抑制因子，现已被定位在编码核糖体蛋白S1的rpsA基因内，在这里，我们检测该突变的性质及其对翻译的影响。对ssyF突变体的rpsA基因进行测序表明，由于IS10R插入，其产物缺少野生型S1蛋白的最后92个残基，对应于RNA结合域的四个同源重复之一。为了研究这种截短对翻译的影响，我们创造了两个系列的大肠杆菌菌株(rpsA(+)和ssyF)，它们含有与染色体LacZ基因融合的不同翻译起始区(TIR)。使用β-半乳糖苷酶分析，我们表明这些TIR在ssyF和rpsA(+)细胞之间的活性没有不同，除了rpsA TIR：在ssyF细胞中碎裂被刺激三倍，如果它至少保留起始密码子上游的大约90个核苷酸，类似地，这个TIR的活性可以被过量的S1严重抑制反式，同样地，如果它保持相同的最小上游序列。因此。SsyF刺激需要rpsA翻译自体操纵子的存在。作为一种解释，我们认为ssyF突变解除了由正常的S1供应引起的残余抑制(即，它损害了自身控制)。因此，S1RNA结合域的C末端重复似乎是自我调节所必需的，但对整个mRNA识别并不是必需的。
The ssyF29 mutation, originally selected as an extragenic suppressor of a protein export defect, has been mapped within the rpsA gene encoding ribosomal protein S1, Here, we examine the nature of this mutation and its effect on translation. Sequencing of the rpsA gene from the ssyF mutant has revealed that, due to an IS10R insertion its product lacks the last 92 residues of the wild-type S1 protein corresponding to one of the four homologous repeats of the RNA-binding domain. To investigate how this truncation affects translation, we hare created two series of Escherichia coli strains (rpsA(+) and ssyF) bearing various translation initiation regions (TIRs) fused to the chromosomal lacZ gene. Using a beta-galactosidase assay, we show that none of these TIRs differ in activity between ssyF and rpsA(+) cells, except for the rpsA TIR: the tatter is stimulated threefold in ssyF cells, provided it retains at least ca, 90 nucleotides upstream of the start codon, Similarly, the activity of this TIR can be severely repressed in trans by excess S1, again provided it retains the same minimal upstream sequence. Thus. the ssyF stimulation requires the presence of the rpsA translational autogenous operator. As an interpretation, we propose that the ssyF mutation relieves the residual repression caused by normal supply of S1 (i.e., that it impairs autogenous control). Thus, the C-terminal repeat of the S1 RNA-binding domain appears to be required for autoregulation, but not for overall mRNA recognition.