In silico Evolution of Lysis-Lysogeny Strategies Reproduces Observed Lysogeny Propensities in Temperate Bacteriophages.
In silico Evolution of Lysis-Lysogeny Strategies Reproduces Observed Lysogeny Propensities in Temperate Bacteriophages.
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DOI：
10.3389/fmicb.2017.01386
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发表时间：
2017
影响因子：
5.2
通讯作者：
Krishna S
中科院分区：
文献类型：
--
作者：
Sinha V;Goyal A;Svenningsen SL;Semsey S;Krishna S
噬菌体是地球上最丰富的生物体，溶解性噬菌体和温带噬菌体作为生态系统的塑造者和细菌进化的驱动者发挥着关键作用。温带细菌可以在以下两者之间进行选择：（i）裂解：通过产生多个噬菌体颗粒并通过裂解宿主细胞释放它们来利用它们的细菌宿主，和（ii）溶原性：通过将它们的染色体整合到宿主细胞的基因组中来与宿主建立潜在的互利关系。温带蚯蚓的溶原性倾向在5- 15%的范围内。对于一些温和的感染，这种倾向进一步受到感染多样性的调节，例如单一感染主要是溶解性的，而多重感染主要是溶原性的。我们问这些观察结果是否可以解释为选择压力的环境中，多个噬菌体变体竞争相同的主机。我们的成对竞争模型，不同的噬菌体变体之间的唯一的倾向溶源化，预测最佳溶源性倾向落在实验观察到的范围内。该预测对于参数如噬菌体感染率、爆发大小、判定率以及细菌生长速率和初始噬菌体与细菌比率的大的变化是稳健的。当我们竞争其溶原性策略允许依赖于感染多重性的噬菌体变体时，我们发现最佳策略是从单次感染的完全裂解切换到多次感染的完全溶原性的策略。以前试图解释溶原性倾向的人认为赌注对冲优化了对波动环境条件的反应。我们的研究结果表明，有一个额外的选择压力内的噬菌体感染细菌宿主的溶原性倾向，独立于环境条件。
Bacteriophages are the most abundant organisms on the planet and both lytic and temperate phages play key roles as shapers of ecosystems and drivers of bacterial evolution. Temperate phages can choose between (i) lysis: exploiting their bacterial hosts by producing multiple phage particles and releasing them by lysing the host cell, and (ii) lysogeny: establishing a potentially mutually beneficial relationship with the host by integrating their chromosome into the host cell's genome. Temperate phages exhibit lysogeny propensities in the curiously narrow range of 5–15%. For some temperate phages, the propensity is further regulated by the multiplicity of infection, such that single infections go predominantly lytic while multiple infections go predominantly lysogenic. We ask whether these observations can be explained by selection pressures in environments where multiple phage variants compete for the same host. Our models of pairwise competition, between phage variants that differ only in their propensity to lysogenize, predict the optimal lysogeny propensity to fall within the experimentally observed range. This prediction is robust to large variation in parameters such as the phage infection rate, burst size, decision rate, as well as bacterial growth rate, and initial phage to bacteria ratio. When we compete phage variants whose lysogeny strategies are allowed to depend upon multiplicity of infection, we find that the optimal strategy is one which switches from full lysis for single infections to full lysogeny for multiple infections. Previous attempts to explain lysogeny propensity have argued for bet-hedging that optimizes the response to fluctuating environmental conditions. Our results suggest that there is an additional selection pressure for lysogeny propensity within phage populations infecting a bacterial host, independent of environmental conditions.
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