Department of Microbiology, University of Georgia, Athens, GA 30602.
National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO 80401.
Proc Natl Acad Sci U S A. 2018 Jul 3;115(27):7105-7110. doi: 10.1073/pnas.1803745115. Epub 2018 Jun 18.
Experimental evolution is a critical tool in many disciplines, including metabolic engineering and synthetic biology. However, current methods rely on the chance occurrence of a key step that can dramatically accelerate evolution in natural systems, namely increased gene dosage. Our studies sought to induce the targeted amplification of chromosomal segments to facilitate rapid evolution. Since increased gene dosage confers novel phenotypes and genetic redundancy, we developed a method, Evolution by Amplification and Synthetic Biology (EASy), to create tandem arrays of chromosomal regions. In , EASy was demonstrated on an important bioenergy problem, the catabolism of lignin-derived aromatic compounds. The initial focus on guaiacol (2-methoxyphenol), a common lignin degradation product, led to the discovery of genes () encoding a cytochrome P450 enzyme that converts guaiacol to catechol. However, chromosomal integration of in or did not enable guaiacol to be used as the sole carbon source despite catechol being a growth substrate. In ∼1,000 generations, EASy yielded alleles that in single chromosomal copy confer growth on guaiacol. Different variants emerged, including fusions between GcoA and CatA (catechol 1,2-dioxygenase). This study illustrates the power of harnessing chromosomal gene amplification to accelerate the evolution of desirable traits.
实验进化是许多学科的重要工具，包括代谢工程和合成生物学。然而，目前的方法依赖于一个关键步骤的偶然发生，这个步骤可以极大地加速自然系统中的进化，即增加基因剂量。我们的研究旨在诱导靶向染色体片段的扩增，以促进快速进化。由于增加基因剂量赋予新的表型和遗传冗余，我们开发了一种方法，即通过扩增和合成生物学进行进化（EASy），以创建染色体区域的串联阵列。在[文章名称]中，EASy 被应用于一个重要的生物能源问题，即木质素衍生芳香化合物的分解代谢。最初的重点是愈创木酚（2-甲氧基苯酚），一种常见的木质素降解产物，导致发现了[基因数量]个编码细胞色素 P450 酶的基因，该酶将愈创木酚转化为儿茶酚。然而，尽管儿茶酚是生长底物，但在 或 中染色体整合 并不能使愈创木酚能够作为唯一的碳源。在大约 1000 代中，EASy 产生了等位基因，这些等位基因在单个染色体拷贝中赋予了利用愈创木酚生长的能力。出现了不同的变体，包括 GcoA 和 CatA（儿茶酚 1,2-双加氧酶）之间的融合。这项研究说明了利用染色体基因扩增来加速理想性状进化的力量。
