Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt; Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
Microbiol Res. 2017 Jan;194:47-52. doi: 10.1016/j.micres.2016.10.006. Epub 2016 Nov 4.
Most Escherichia coli strains are naturally unable to grow on 1,2-propanediol (PDO) as a sole carbon source. Recently, however, a K-12 descendent E. coli strain was evolved to grow on 1,2-PDO, and it was hypothesized that this evolved ability was dependent on the aldehyde dehydrogenase, AldA, which is highly conserved among members of the family Enterobacteriacea. To test this hypothesis, we first performed computational model simulation, which confirmed the essentiality of the aldA gene for 1,2-PDO utilization by the evolved PDO-degrading E. coli. Next, we deleted the aldA gene from the evolved strain, and this deletion was sufficient to abolish the evolved phenotype. On re-introducing the gene on a plasmid, the evolved phenotype was restored. These findings provide experimental evidence for the computationally predicted role of AldA in 1,2-PDO utilization, and represent a good example of E. coli robustness, demonstrated by the bacterial deployment of a generalist enzyme (here AldA) in multiple pathways to survive carbon starvation and to grow on a non-native substrate when no native carbon source is available.
大多数大肠杆菌菌株自然无法将 1,2-丙二醇（PDO）用作唯一碳源。然而，最近一种 K-12 衍生的大肠杆菌菌株已经进化到可以在 1,2-PDO 上生长，并且有人假设这种进化能力依赖于醛脱氢酶 AldA，该酶在肠杆菌科成员中高度保守。为了验证这一假设，我们首先进行了计算模型模拟，该模拟证实了 aldA 基因对于进化的 PDO 降解大肠杆菌利用 1,2-PDO 的必要性。接下来，我们从进化株中删除 aldA 基因，这足以消除进化表型。在质粒上重新引入该基因后，进化表型得到恢复。这些发现为 AldA 在 1,2-PDO 利用中的计算预测作用提供了实验证据，并且代表了大肠杆菌鲁棒性的一个很好的例子，这种鲁棒性通过细菌在多种途径中部署一种通用酶（这里是 AldA）来应对碳饥饿并在没有天然碳源时利用非天然底物进行生长。
