Competition favours reduced cost of plasmids to host bacteria
Competition favours reduced cost of plasmids to host bacteria
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DOI：
10.1038/ismej.2009.22
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发表时间：
2009-07-01
期刊：
影响因子：
11
通讯作者：
Traxler, Beth
中科院分区：
文献类型：
--
作者：
Haft, Rembrandt J. F.;Mittler, John E.;Traxler, Beth
革兰氏阴性菌的接合质粒有垂直和水平两种传播方式：它们在分裂过程中被分离到子细胞，并通过质粒编码的接合机制在宿主之间传递。尽管保持水平迁移率，许多质粒携带抑制生育(FIN)系统，抑制自身的接合转移。为了评估自我转移抑制的生态学基础，我们使用计算模型和共培养竞争比较了质粒R1的FIN(+)和FIN(-)变体对细菌种群的入侵。我们观察到，FIN(+)变种对寄主的成本适中(通过生长速度的降低来衡量)，而FIN(-)变种产生的成本较大。在模拟和经验竞赛中，FIN(-)质粒迅速侵入培养物，但随后被FIN(+)质粒取代。这表明减少水平传播并允许增加主机复制具有竞争优势。计算模拟预测，与宿主成本降低相关的优势将在广泛的环境条件和质粒成本范围内保持。我们推断，垂直传递与竞争排斥相结合有利于减少质粒的水平迁移率。类似的动态可能会对寄生虫施加进化压力，如温带噬菌体和垂直传播的动物病毒，以限制它们的水平传播率。《ISME期刊》(2009年)3761-769；DOI：10.1038/ISMEJ。2009.22；2009年4月2日在线发布
Conjugative plasmids of Gram-negative bacteria have both vertical and horizontal modes of transmission: they are segregated to daughter cells during division, and transferred between hosts by plasmid-encoded conjugative machinery. Despite maintaining horizontal mobility, many plasmids carry fertility inhibition (fin) systems that repress their own conjugative transfer. To assess the ecological basis of self-transfer repression, we compared the invasion of bacterial populations by fin(+) and fin(-) variants of the plasmid R1 using a computational model and co-culture competitions. We observed that the fin(+) variant had a modest cost to the host (measured by reduction in growth rate), while the fin(-) variant incurred a larger cost. In simulations and empirical competitions the fin(-) plasmid invaded cultures quickly, but was subsequently displaced by the fin(+) plasmid. This indicated a competitive advantage to reducing horizontal transmission and allowing increased host replication. Computational simulations predicted that the advantage associated with reduced cost to the host would be maintained over a wide range of environmental conditions and plasmid costs. We infer that vertical transmission in concert with competitive exclusion favour decreased horizontal mobility of plasmids. Similar dynamics may exert evolutionary pressure on parasites, such as temperate bacteriophages and vertically transmitted animal viruses, to limit their rates of horizontal transfer. The ISME Journal (2009) 3, 761-769; doi: 10.1038/ismej. 2009.22; published online 2 April 2009