Department of Microbiology, University of Minnesota, Minneapolis, Minnesota 55455; email:
Annu Rev Genet. 2013;47:457-82. doi: 10.1146/annurev-genet-111212-133449. Epub 2013 Sep 11.
In Enterococcus faecalis, lateral transfer of conjugative plasmids that encode antibiotic resistance and virulence determinants can be induced by peptide sex pheromones. The tetracycline-resistance plasmid pCF10 represents a paradigm for illustrating important conserved features of a large family of pheromone-responsive enterococcal plasmids. The pheromone is released into the growth medium by plasmid-free recipient cells and sensed by plasmid-containing donors. The activity of the pheromone is antagonized by a plasmid-encoded inhibitor peptide that prevents conjugation in the absence of an inducing signal and is also required to return the system to the ground state following an induction cycle. The pheromone response involves multiple transcriptional and posttranscriptional mechanisms as well as bi-stable biological switch behavior. Multiple layers of regulation are essential for proper function, and evolution of this tight control system may have been favored by reduction of the fitness cost of plasmid maintenance to the host cell.
在粪肠球菌中，通过肽性信息素可诱导编码抗生素抗性和毒力决定因子的可接合质粒的侧向转移。四环素抗性质粒 pCF10 代表了一个范例，说明了一大类信息素反应性肠球菌质粒的重要保守特征。性信息素由无质粒受体细胞释放到生长培养基中，并被含有质粒的供体细胞感知。该信息素的活性受到质粒编码的抑制肽的拮抗，在没有诱导信号的情况下，抑制肽会阻止接合，并且在诱导循环后，抑制肽也需要将系统返回到基础状态。该信息素反应涉及多个转录和转录后机制以及双稳态生物开关行为。适当功能需要多层次的调节，这种严格控制系统的进化可能是由于降低了质粒维持对宿主细胞的适应性成本而受到青睐的。
