Three new RelE-homologous mRNA interferases of Escherichia coli differentially induced by environmental stresses.
Three new RelE-homologous mRNA interferases of Escherichia coli differentially induced by environmental stresses.
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DOI：
10.1111/j.1365-2958.2009.06969.x
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发表时间：
2010-01
影响因子：
3.6
通讯作者：
Gerdes K
中科院分区：
文献类型：
--
作者：
Christensen-Dalsgaard M;Jørgensen MG;Gerdes K
前毒素-抗毒素（TA）基因座编码通过在核糖体A位点切割mRNA密码子或通过特异性切割任何RNA位点来抑制翻译的mRNA干扰酶。到目前为止，已经鉴定了7种大肠杆菌的mRNA干扰酶，其中4种通过抑制依赖性机制切割mRNA。在这里，我们实验证实了三个新的TA基因座在E。杆菌我们发现yafNO、higBA（ygjNM）和ygiUT基因座编码与RelE相关的mRNA干扰酶。YafO和HigB仅切割翻译的mRNA，而YgiU在GC[A/U]处位点特异性地切割RNA，独立于翻译。因此，YgiU是第一个在体内不依赖于翻译切割mRNA的RelE相关mRNA干扰酶。这三个位点都受到氨基酸饥饿和翻译抑制的诱导，尽管程度不同。碳饥饿诱导只有两个位点。yafNO位点由DNA损伤诱导，但转录起源于dinB启动子。因此，我们的研究结果表明，不同的TA位点对环境压力的反应不同。这三个位点的诱导依赖于Lon蛋白酶，该蛋白酶可以感知环境胁迫并通过切割抗毒素来激活TA位点。三个TA操纵子的转录受抗毒素的自动调节。
Prokaryotic toxin – antitoxin (TA) loci encode mRNA interferases that inhibit translation, either by cleaving mRNA codons at the ribosomal A site or by cleaving any RNA site-specifically. So far, seven mRNA interferases of Escherichia coli have been identified, four of which cleave mRNA by a translation-dependent mechanism. Here, we experimentally confirmed the presence of three novel TA loci in E. coli. We found that the yafNO, higBA (ygjNM) and ygiUT loci encode mRNA interferases related to RelE. YafO and HigB cleaved translated mRNA only, while YgiU cleaved RNA site-specifically at GC[A/U], independently of translation. Thus, YgiU is the first RelE-related mRNA interferase that cleaves mRNA independently of translation, in vivo. All three loci were induced by amino acid starvation, and inhibition of translation although to different degrees. Carbon starvation induced only two of the loci. The yafNO locus was induced by DNA damage, but the transcription originated from the dinB promoter. Thus, our results showed that the different TA loci responded differentially to environmental stresses. Induction of the three loci depended on Lon protease that may sense the environmental stresses and activate TA loci by cleavage of the antitoxins. Transcription of the three TA operons was autoregulated by the antitoxins.
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