Synth-Bio Group, Institute of Systems and Synthetic Biology, Universite d'Evry Val d'Essonne-Genopole®, 5 rue Henri Desbruères, Evry Cedex, France.
Biotechnol J. 2011 Jul;6(7):773-83. doi: 10.1002/biot.201100084. Epub 2011 Jun 16.
Synthetic biology uses modeling to facilitate the design of new genetic constructions. In particular, it is of utmost importance to model the reaction of the cellular chassis when expressing heterologous systems. We constructed a mathematical model for the response of a bacterial cell chassis under heterologous expression. For this, we relied on previous characterization of the growth-rate dependence on cellular resource availability (in this case, DNA and RNA polymerases and ribosomes). Accordingly, we estimated the maximum capacities of the cell for heterologous expression to be 46% of the total RNA and the 33% of the total protein. To experimentally validate our model, we engineered two genetic constructions that involved the constitutive expression of a fluorescent reporter in a vector with a tunable origin of replication. We performed fluorescent measurements using population and single-cell fluorescent measurements. Our model predicted cell growth for several heterologous constructions under five different culture conditions and various plasmid copy numbers with significant accuracy, and confirmed that ribosomes act as the limiting resource. Our study also confirmed that the bacterial response to synthetic gene expression could be understood in terms of the requirement for cellular resources and could be predicted from relevant cellular parameters.
合成生物学利用建模来促进新遗传构建体的设计。特别是，对表达异源系统时细胞底盘的反应进行建模非常重要。我们构建了一个用于异源表达下细菌细胞底盘响应的数学模型。为此，我们依赖于先前对细胞资源可用性（在这种情况下，DNA 和 RNA 聚合酶和核糖体）对生长速率的依赖性的特征化。因此，我们估计细胞进行异源表达的最大能力为总 RNA 的 46%和总蛋白质的 33%。为了实验验证我们的模型，我们设计了两个遗传构建体，它们涉及在具有可调节复制起点的载体中组成型表达荧光报告基因。我们使用群体和单细胞荧光测量进行了荧光测量。我们的模型以显著的准确性预测了五种不同培养条件和不同质粒拷贝数下的几个异源构建体的细胞生长情况，并证实核糖体是限制资源。我们的研究还证实，细菌对合成基因表达的反应可以根据对细胞资源的需求来理解，并可以从相关的细胞参数来预测。
