Key Laboratory of Marine Biotechnology of Zhejiang Province, Ningbo University, Post Box 71, Ningbo, 315211, Zhejiang Province, China.
Ningbo Institute of Oceanography, Ningbo, 315832, Zhejiang, China.
BMC Plant Biol. 2019 Jul 19;19(1):325. doi: 10.1186/s12870-019-1928-2.
The heteroside floridoside is a primary photosynthetic product that is known to contribute to osmotic acclimation in almost all orders of Rhodophyta. However, the encoding genes and enzymes responsible for the synthesis of floridoside and its isomeric form, L- or D-isofloridoside, are poorly studied.
Here, four putative trehalose-6-phosphate synthase (TPS) genes, designated as PhTPS1, PhTPS2, PhTPS3, and PhTPS4, were cloned and characterized from the red alga Pyropia haitanensis (Bangiophyceae). The deduced amino acid sequence is similar to the annotated TPS proteins of other organisms, especially the UDP-galactose substrate binding sites of PhTPS1, 2, which are highly conserved. Of these, PhTPS1, 4 are involved in the biosynthesis of floridoside and isofloridoside, with isofloridoside being the main product. PhTPS3 is an isofloridoside phosphate synthase, while PhTPS2 exhibits no activity. When challenged by desiccation, high temperature, and salt stress, PhTPS members were expressed to different degrees, but the responses to thermal stress and desiccation were stronger.
Thus, in P. haitanensis, PhTPSs encode the enzymatical activity of floridoside and isofloridoside phosphate synthase and are crucial for the abiotic stress defense response.
异头糖苷岩藻糖苷是一种主要的光合产物，几乎存在于所有红藻目中，已知其对渗透适应有贡献。然而，负责岩藻糖苷及其异构体 L-或 D-异岩藻糖苷合成的编码基因和酶研究甚少。
从红藻 Pyropia haitanensis（红藻门）中克隆和表征了四个假定的海藻糖-6-磷酸合酶（TPS）基因，分别命名为 PhTPS1、PhTPS2、PhTPS3 和 PhTPS4。推断的氨基酸序列与其他生物的已注释 TPS 蛋白相似，特别是 PhTPS1、2 的 UDP-半乳糖底物结合位点高度保守。其中，PhTPS1、4 参与岩藻糖苷和异岩藻糖苷的生物合成，异岩藻糖苷是主要产物。PhTPS3 是异岩藻糖苷磷酸合酶，而 PhTPS2 没有活性。在受到干燥、高温和盐胁迫时，PhTPS 成员的表达程度不同，但对热应激和干燥的反应更强。
因此，在 P. haitanensis 中，PhTPS 编码岩藻糖苷和异岩藻糖苷磷酸合酶的酶活性，对非生物胁迫防御反应至关重要。
