Knowledge on the evolution of antioxidant systems in cyanobacteria is crucial for elucidating the cause and consequence of the rise of atmospheric oxygen in the Earth’s history. In this study, to elucidate the origin and evolution of cyanobacterial antioxidant enzymes, we analyzed the occurrence of genes encoding four types of superoxide dismutases and three types of catalases in 85 complete cyanobacterial genomes, followed by phylogenetic analyses. We found that Fe superoxide dismutase (FeSOD), Mn superoxide dismutase (MnSOD), and Mn catalase (MnCat) are widely distributed among modern cyanobacteria, whereas CuZn superoxide dismutase (CuZnSOD), bifunctional catalase (KatG), and monofunctional catalase (KatE) are less common. Ni superoxide dismutase (NiSOD) is distributed among marine Prochlorococcus and Synechococcus species. Phylogenetic analyses suggested that bacterial MnSOD evolved from cambialistic Fe/MnSOD before the diversification of major bacterial lineages. The analyses suggested that FeSOD evolved from MnSOD before the origin of cyanobacteria. MnCat also evolved in the early stages of bacterial evolution, predating the emergence of cyanobacteria. KatG, KatE, and NiSOD appeared 2.3–2.5 billion years ago. Thus, almost all cyanobacterial antioxidant enzymes emerged before or during the rise of atmospheric oxygen. The loss and appearance of these enzymes in marine cyanobacteria may be also related to the change in the metal concentration induced by the increased oxygen concentration in the ocean.

关于蓝藻抗氧化系统进化的知识对于阐明地球历史上大气氧含量升高的原因和后果至关重要。在这项研究中，为了阐明蓝藻抗氧化酶的起源和进化，我们分析了 85 个完整蓝藻基因组中编码四种超氧化物歧化酶和三种过氧化氢酶的基因的出现，然后进行了系统发育分析。我们发现铁超氧化物歧化酶 (FeSOD)、锰超氧化物歧化酶 (MnSOD) 和锰过氧化氢酶 (MnCat) 在现代蓝藻中广泛分布，而铜锌超氧化物歧化酶 (CuZnSOD)、双功能过氧化氢酶 (KatG) 和单功能过氧化氢酶 (KatE)不太常见。Ni 超氧化物歧化酶 (NiSOD) 分布于海洋原绿球藻和聚球藻属物种。系统发育分析表明，细菌 MnSOD 在主要细菌谱系多​​样化之前从形成环境的 Fe/MnSOD 进化而来。分析表明，FeSOD 是在蓝藻起源之前从 MnSOD 进化而来的。MnCat 也在细菌进化的早期阶段进化，早于蓝藻出现。KatG、KatE 和 NiSOD 出现在 2.3-25 亿年前。因此，几乎所有的蓝藻抗氧化酶都是在大气氧气上升之前或期间出现的。这些酶在海洋蓝藻中的丢失和出现也可能与海洋中氧气浓度增加引起的金属浓度变化有关。