Qu Cui Lan, Jin Hui, Zhang Bing, Chen Wei Jian, Zhang Yang, Xu Yuan Yuan, Wang Rui, Lao Yong Min
Shenzhen Institute of Quality & Safety Inspection and Research, Shenzhen 518055, China.
Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou 511458, China.
Life (Basel). 2024 Apr 30;14(5):576. doi: 10.3390/life14050576.
(1) Background: Oxygen has exerted a great effect in shaping the environment and driving biological diversity in Earth's history. Green lineage has evolved primary and secondary carotenoid biosynthetic systems to adapt to Earth's oxygenation, e.g., , which accumulates the highest amount of secondary astaxanthin under stresses. The two systems are controlled by lycopene ε-cyclase (LCYE) and β-cyclase (LCYB), which leave an important trace in Earth's oxygenation. (2) Objectives: This work intends to disclose the underlying molecular evolutionary mechanism of Earth's oxygenation in shaping green algal carotenogensis with a special focus on lycopene cyclases. (3) Methods: The two kinds of cyclases were analyzed by site-directed mutagenesis, phylogeny, divergence time and functional divergence. (4) Results: Green lineage LCYEs appeared at ~1.5 Ga after the first significant appearance and accumulation of atmospheric oxygen, the so-called Great Oxygenation Event (GOE), from which LCYBs diverged by gene duplication. Bacterial β-bicyclases evolved from β-monocyclase. Enhanced catalytic activity accompanied evolutionary transformation from ε-/β-monocyclase to β-bicyclase. Strong positive selection occurred in green lineage LCYEs after the GOE and in algal LCYBs during the second oxidation, the Neoproterozoic Oxygenation Event (NOE). Positively selected sites in the catalytic cavities of the enzymes controlled the mono-/bicyclase activity, respectively. Carotenoid profiling revealed that oxidative adaptation has been wildly preserved in evolution. (5) Conclusions: the functionalization of the two enzymes is a result of primary to secondary adaptations to Earth's oxygenation.
(1) 背景：在地球历史上，氧气对塑造环境和推动生物多样性发挥了巨大作用。绿色谱系进化出了初级和次级类胡萝卜素生物合成系统以适应地球的氧化过程，例如，在压力下积累大量次级虾青素。这两个系统由番茄红素ε-环化酶（LCYE）和β-环化酶（LCYB）控制，它们在地球氧化过程中留下了重要痕迹。(2) 目的：这项工作旨在揭示地球氧化在塑造绿藻类胡萝卜素生成过程中的潜在分子进化机制，特别关注番茄红素环化酶。(3) 方法：通过定点诱变、系统发育、分歧时间和功能分歧分析这两种环化酶。(4) 结果：绿色谱系的LCYEs在大气中首次显著出现和积累氧气之后约1.5 Ga出现，即所谓的大氧化事件（GOE），LCYBs从那时起通过基因复制而分化。细菌β-双环化酶由β-单环化酶进化而来。从ε-/β-单环化酶到β-双环化酶的进化转变伴随着催化活性的增强。在大氧化事件之后绿色谱系的LCYEs以及在新元古代氧化事件（NOE）即第二次氧化期间的藻类LCYBs中发生了强烈的正选择。酶催化腔中的正选择位点分别控制单环/双环化酶活性。类胡萝卜素谱分析表明氧化适应性在进化过程中得到了广泛保留。(5) 结论：这两种酶的功能化是对地球氧化从初级适应到次级适应的结果。
