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Abstract：
BACKGROUND: 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.
RESULTS: 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.
CONCLUSIONS: Thus, in P. haitanensis, PhTPSs encode the enzymatical activity of floridoside and isofloridoside phosphate synthase and are crucial for the abiotic stress defense response.
RESULTS: 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.
CONCLUSIONS: Thus, in P. haitanensis, PhTPSs encode the enzymatical activity of floridoside and isofloridoside phosphate synthase and are crucial for the abiotic stress defense response.
摘要：
背景：异侧氟菊糖苷是一种主要的光合产物，已知在几乎所有的红藻中都有助于渗透适应。然而,负责合成Floridoside及其异构形式的编码基因和酶，L-或D-异氟代甙，研究不足。
结果：这里，四个推定的海藻糖-6-磷酸合成酶（TPS）基因，命名为PhTPS1，PhTPS2，PhTPS3和PhTPS4，是从红色藻类PyropiaHaitanensis（Bangiophyceae）中克隆并表征。推导的氨基酸序列与其他生物体的注释TPS蛋白相似，特别是PhTPS1，2的UDP-半乳糖底物结合位点，它们是高度保守的。其中,PhTPS1，4参与了氟代糖苷和异氟代糖苷的生物合成，主要产品为异氟甲苷。PhTPS3是异氟甲苷磷酸合成酶，而PhTPS2没有活性。当受到干燥的挑战时，高温,和盐胁迫，PhTPS成员的表达程度不同，但是对热应力和干燥的反应更强。
结论：因此，在海地假单胞菌，PhTPSs编码氟碘苷和异氟碘苷磷酸合酶的酶活性，对于非生物胁迫防御反应至关重要。
结果：这里，四个推定的海藻糖-6-磷酸合成酶（TPS）基因，命名为PhTPS1，PhTPS2，PhTPS3和PhTPS4，是从红色藻类PyropiaHaitanensis（Bangiophyceae）中克隆并表征。推导的氨基酸序列与其他生物体的注释TPS蛋白相似，特别是PhTPS1，2的UDP-半乳糖底物结合位点，它们是高度保守的。其中,PhTPS1，4参与了氟代糖苷和异氟代糖苷的生物合成，主要产品为异氟甲苷。PhTPS3是异氟甲苷磷酸合成酶，而PhTPS2没有活性。当受到干燥的挑战时，高温,和盐胁迫，PhTPS成员的表达程度不同，但是对热应力和干燥的反应更强。
结论：因此，在海地假单胞菌，PhTPSs编码氟碘苷和异氟碘苷磷酸合酶的酶活性，对于非生物胁迫防御反应至关重要。
