Microalgal AstaP is a natural solubilizer of astaxanthin with broad binding ability for carotenoids and related compounds
Microalgal AstaP is a natural solubilizer of astaxanthin with broad binding ability for carotenoids and related compounds
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DOI：
10.1016/j.algal.2023.102982
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发表时间：
2023-01-19
影响因子：
5.1
通讯作者：
Takaichi, Shinichi
中科院分区：
文献类型：
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作者：
Kawasaki, Shinji;Mitsui, Tamaki;Takaichi, Shinichi
虾青素结合水溶性蛋白（称为 AstaPs）被鉴定为在栅藻科微藻中发现的光氧化应激诱导性水性胡萝卜素蛋白。尽管 AstaPs 结合虾青素，但选择性结合虾青素的特性仍不清楚。在本研究中，我们制备了不含类胡萝卜素的 apo-AstaP，并研究了结合类胡萝卜素的能力。 Apo-AstaP-orange1 选择性结合从含有次生类胡萝卜素、叶绿素和 8-胡萝卜素的应激细胞中提取的色素中的类胡萝卜素，尤其是虾青素。重构测定表明，apo-AstaP-orange1 对虾青素的结合亲和力比其他测试的类胡萝卜素更高。其他 AstaP 家族蛋白，例如来自 Sce-nedesmus obtusus Oki-4N 的 AstaP-orange2 和 AstaP-pink1，以及在大肠杆菌中表达的重组 AstaP-pink1，也表现出对结合虾青素的偏好。 Apo-AstaP-orange1 结合虾青素和虾青素单酯，但不结合虾青素二酯，表明该蛋白质需要至少一个非酯化的 8 端基团来结合类胡萝卜素。在体外混合时，apo-AstaP-orange1 还具有结合叶黄素、金盏花黄素、角黄素和其他测试的叶黄素和类胡萝卜素衍生物（如类维生素A）的能力。我们的结果表明，AstaPs 在体内是虾青素的选择性增溶剂，在体外是类胡萝卜素和类胡萝卜素衍生物的潜在天然增溶剂。
Astaxanthin-binding water-soluble proteins, named AstaPs, were identified as photooxidative-stress inducible aqueous carotenoprotein found in microalgae of the family Scenedesmaceae. Although AstaPs bind astaxanthin, the properties of selective binding of astaxanthin remain unclear. In this study, we prepared carotenoid-free apo-AstaPs and investigated the ability to bind carotenoids. Apo-AstaP-orange1 selectively bound carotenoids, especially astaxanthin, from the pigments extracted from stressed cells containing secondary carotenoids, chlorophylls, and 8-carotene. Reconstitution assays revealed that apo-AstaP-orange1 showed higher affinity for binding astaxanthin than the other tested carotenoids. Other AstaP family proteins, such as AstaP-orange2 and AstaP-pink1 from Sce-nedesmus obtusus Oki-4N, and recombinant AstaP-pink1 expressed in E. coli, also displayed a preference for binding astaxanthin. Apo-AstaP-orange1 bound astaxanthin and astaxanthin-monoesters but not astaxanthin-diesters, indicating that the protein requires at least one non-esterified 8-end group for binding of the carotenoids. On mixing in vitro, apo-AstaP-orange1 also had the ability to bind lutein, adonixanthin, canthaxanthin, and other tested xanthophylls and carotenoid derivatives such as retinoids. Our results indicate that AstaPs are selective solubilizers of astaxanthin in vivo and potential natural solubilizers of carotenoids and carotenoid derivatives in vitro.