Experimental evolution of an Escherichia coli line lacking ribonucleotide reduction.

We created a line of Escherichia coli that lacks ribonucleotide reduction and evolved this line under conditions where deoxyribonucleoside access in growth media was limited. The primary goal was to understand the steps by which obligate intracellular bacteria that have lost of ribonucleotide reduction have adapted to this state. We sequenced the genomes of the ancestral knockout line, the wild-type line it derives from, and evolved knockout and wild-type control lines grown under conditions where availability of deoxyribonucleosides required for growth was reduced. We identified mutations in our knockout lines to genes that are also mutated in obligate intracellular symbionts and pathogens that lack ribonucleotide reductase genes.

本研究构建了一株缺失核糖核苷酸还原功能的大肠杆菌（Escherichia coli）菌株，并在生长培养基中脱氧核苷（deoxyribonucleoside）可及性受限的条件下对该菌株开展定向进化实验。本研究的核心目标是解析丧失核糖核苷酸还原能力的专性胞内菌适应这一状态的分子路径。我们对祖先敲除菌株、其衍生的野生型菌株，以及在生长必需脱氧核苷可用性降低的条件下经定向进化得到的敲除菌株与野生型对照菌株的基因组进行了测序。我们在敲除菌株中鉴定到了一批基因突变，这些基因同时也在缺失核糖核苷酸还原酶（ribonucleotide reductase）基因的专性胞内共生菌与病原菌中发生突变。