PDF(Pubmed)
Abstract：
The GO DNA repair system protects against GC → TA mutations by finding and removing oxidized guanine. The system is mechanistically well understood but its origins are unknown. We searched metagenomes and abundantly found the genes encoding GO DNA repair at the Lost City Hydrothermal Field (LCHF). We recombinantly expressed the final enzyme in the system to show MutY homologs function to suppress mutations. Microbes at the LCHF thrive without sunlight, fueled by the products of geochemical transformations of seafloor rocks, under conditions believed to resemble a young Earth. High levels of the reductant H2 and low levels of O2 in this environment raise the question, why are resident microbes equipped to repair damage caused by oxidative stress? MutY genes could be assigned to metagenome-assembled genomes (MAGs), and thereby associate GO DNA repair with metabolic pathways that generate reactive oxygen, nitrogen and sulfur species. Our results indicate that cell-based life was under evolutionary pressure to cope with oxidized guanine well before O2 levels rose following the great oxidation event.
摘要：
GODNA修复系统通过发现和去除氧化的鸟嘌呤来防止GC→TA突变。该系统在机械上很好地理解，但其起源未知。我们搜索了宏基因组，并在失落的城市热液场（LCHF）大量发现了编码GODNA修复的基因。我们在系统中重组表达最终的酶以显示MutY同源物抑制突变的功能。LCHF的微生物在没有阳光的情况下茁壮成长，以海底岩石地球化学转化的产物为燃料，在被认为像年轻地球的条件下。在这种环境中，高水平的还原剂H2和低水平的O2提出了这个问题，为什么常驻微生物能够修复由氧化应激引起的损伤？MutY基因可以分配给宏基因组组装的基因组（MAGs），从而将GODNA修复与产生活性氧的代谢途径联系起来，氮和硫物种。我们的结果表明，在大氧化事件后O2水平升高之前，基于细胞的生命处于进化压力下，以应对氧化的鸟嘌呤。
