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首页> 外文期刊>Plasmid: An International Journal Devoted to Extrachromosomal Gene Systems >A 'retrocidal' plasmid in Enterococcus faecalis: passage and protection.
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A 'retrocidal' plasmid in Enterococcus faecalis: passage and protection.

机译：粪肠球菌中的一种“可逆”质粒：传代和保护。

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摘要

Enterococcus faecalis MC4 harbors a 130 kb conjugative, pheromone (cCF10)-responding plasmid, pAMS1, conferring chloramphenicol, streptomycin and tetracycline resistances. A plasmid-borne class IIa bacteriocin (MC4-1) determinant and cognate immunity gene were present, but not expressed in MC4. However, pAMS1 transfer to E. faecalis JH2-2 (but not to the non-isogenic OG1SS) generated the surprising ability to express bacteriocin activity against the plasmid donor, MC4. The bacteriocin target spectrum includes E. faecalis, Enterococcus faecium, Enterococcus gallinarum, Enterococcus hirae, and Listeria monocytogenes. Those donors unable to express bacteriocin or immunity could protect themselves from the "retrocidal" behavior of transconjugants by a switch to bacteriocin resistance at a frequency of approximately 10(-3). Reversion to sensitivity occurred at a relatively high frequency, suggestive of involvement of a phase variation event. These observations concerning a conjugative plasmid with novel "retrocidal" properties, coupled with a defense mechanism independent of plasmid-borne immunity functions, may relate to phenomena exploiting regulatory features with broader ecological and evolutionary implications.
机译：粪肠球菌MC4带有一个130 kb的偶联，信息素（cCF10）响应质粒pAMS1，赋予氯霉素，链霉素和四环素抗性。存在质粒携带的IIa类细菌素（MC4-1）决定簇和同源免疫基因，但未在MC4中表达。然而，pAMS1转移至粪肠球菌JH2-2（而不是非等基因OG1SS）却产生了令人惊讶的表达针对质粒供体MC4的细菌素活性的能力。细菌素的目标谱包括粪肠球菌，粪肠球菌，鸡肠球菌，平肠肠球菌和单核细胞增生李斯特菌。那些无法表达细菌素或免疫力的供体可以通过以大约10（-3）的频率切换到细菌素抗性来保护自己免受转导结合剂的“杀回”行为。恢复灵敏度的频率相对较高，表明存在相变事件。这些关于具有新颖的“杀回”特性的共轭质粒的观察结果，再加上独立于质粒携带的免疫功能的防御机制，可能与利用具有更广泛的生态学和进化意义的调节特征的现象有关。

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