Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy.
Department of Chemical Sciences, University of Naples Federico II, Naples, Italy.
Sci Rep. 2018 Mar 15;8(1):4610. doi: 10.1038/s41598-018-22861-1.
The major yolk protein toposome plays crucial roles during gametogenesis and development of sea urchins. We previously found that nitration of toposome increases in the gonads of a Paracentrotus lividus population living in a marine protected area affected by toxic blooms of Ostreospsis cf. ovata, compared to control populations. This modification is associated with ovatoxin accumulation, high levels of nitric oxide in the gonads, and a remarkable impairment of progeny development. However, nothing is known about the environmental-mediated-regulation of the structure and biological function of toposome. Here, we characterize through wide-ranging biochemical and structural analyses the nitrated toposome of sea urchins exposed to the bloom, and subsequently detoxified. The increased number of nitrated tyrosines in toposome of sea urchins collected during algal bloom induced structural changes and improvement of the Ca-binding affinity of the protein. After 3 months' detoxification, ovatoxin was undetectable, and the number of nitric oxide-modified tyrosines was reduced. However, the nitration of specific residues was irreversible and occurred also in embryos treated with metals, used as a proxy of environmental pollutants. The structural and functional changes of toposome caused by nitration under adverse environmental conditions may be related to the defective development of sea urchins' progeny.
卵黄主要蛋白拓扑异构酶在海胆的配子发生和发育过程中起着至关重要的作用。我们之前发现，在受有毒牡蛎藻水华影响的海洋保护区中生活的绿海胆种群的性腺中，拓扑异构酶的硝化增加，与对照组相比。这种修饰与卵形毒素的积累、性腺中高水平的一氧化氮以及后代发育的显著受损有关。然而，对于拓扑异构酶的结构和生物学功能的环境介导调节，我们一无所知。在这里，我们通过广泛的生化和结构分析来描述暴露于藻类水华并随后解毒的海胆硝化拓扑异构酶。在藻类水华期间收集的海胆拓扑异构酶中增加的硝化酪氨酸数量诱导了结构变化，并改善了蛋白质的 Ca 结合亲和力。经过 3 个月的解毒，卵形毒素无法检测到，并且一氧化氮修饰的酪氨酸数量减少。然而，特定残基的硝化是不可逆的，并且也发生在胚胎中，胚胎被用作环境污染物的替代物。在不利的环境条件下硝化引起的拓扑异构酶的结构和功能变化可能与海胆后代发育缺陷有关。
