Toxin-antitoxin systems homologous with relBE of Escherichia coli plasmid P307 are ubiquitous in prokaryotes
Toxin-antitoxin systems homologous with relBE of Escherichia coli plasmid P307 are ubiquitous in prokaryotes
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DOI：
10.1006/jmbi.1998.2416
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发表时间：
1999-01-29
影响因子：
5.6
通讯作者：
Gerdes, K
中科院分区：
文献类型：
--
作者：
Gronlund, H;Gerdes, K
由细菌质粒和染色体编码的毒素-抗毒素系统指定两种蛋白质，一种细胞毒素和一种抗毒素。抗毒素通过与同源毒素形成紧密的复合物来中和它们。抗毒素由于被细胞蛋白酶（Lon或Clp）降解而不稳定，而毒素则是稳定的。本研究表明，大肠杆菌质粒P307的orf7（标记为relB(P307)）和orf6（标记为relle (P307)）与大肠杆菌的relBE基因同源，构成了一个双组分的毒素-抗毒素系统：(i) relle （P307）编码一种对宿主细胞致命或抑制的细胞毒素；relB（P307）编码一种抗毒素，阻止relB编码毒素的致死作用；（iii） RelB（P307）抗毒素被Lon蛋白酶降解；（iv） RelB（P307）抗毒素在转录水平上自动调控P307的relBE操纵子；(v) RelE（P307）毒素作为转录的共同抑制因子；（vi） relBE系统通过杀死无质粒细胞来稳定迷你p307复制子。通过数据库检索，我们在许多革兰氏阴性菌和革兰氏阳性菌的染色体上发现了relBE同源物。更令人惊讶的是，在古菌的染色体上存在着大量的同源基因系统。因此，与大肠杆菌relBE同源的毒素-抗毒素系统在原核生物中普遍存在。(C) 1999学术出版社。
Toxin-antitoxin systems encoded by bacterial plasmids and chromosomes specify two proteins, a cytotoxin and an antitoxin. The antitoxins neutralize the cognate toxins by forming tight complexes with them. The antitoxins are unstable due to degradation by cellular proteases (Lon or Clp), whereas the toxins are stable. Here we show that orf7 (denoted relB(P307)) and orf6 (denoted relE(P307)) of Escherichia coli plasmid P307 are homologous to the relBE genes of E. coli and constitute a two-component toxin-antitoxin system: (i) relE(P307) encodes a cytotoxin lethal or inhibitory to host cells; (ii) relB(P307) encodes an antitoxin that prevents the lethal action of the relE-encoded toxin; (iii) RelB(P307) antitoxin is degraded by Lon protease; (iv) RelB(P307) antitoxin autoregulates the relBE operon of P307 at the level of transcription; (v) RelE(P307) toxin acts as a co-repressor of transcription; and (vi) the relBE system stabilizes a mini-P307 replicon by the killing of plasmid-free cells. Using database searching, we found relBE homologues on the chromosomes of many Gram-negative and Grampositive bacteria. Even more surprising, numerous relBE-homologous gene systems are present on the chromosomes of Archae. Thus, toxin-antitoxin systems homologous with relBE of E. coli are ubiquitous in prokaryotic organisms. (C) 1999 Academic Press.