Molecular and Biochemical Characterization of AtPAP15, a Purple Acid Phosphatase with Phytase Activity, in Arabidopsis
Molecular and Biochemical Characterization of AtPAP15, a Purple Acid Phosphatase with Phytase Activity, in Arabidopsis
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DOI：
10.1104/pp.109.143180
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发表时间：
2009-09-01
期刊：
影响因子：
7.4
通讯作者：
Lim, Boon Leong
中科院分区：
文献类型：
--
作者：
Kuang, Ruibin;Chan, Kam-Ho;Lim, Boon Leong
紫色酸性磷酸酶（PAP）在酸性pH范围内催化磷酸单酯和酸酐水解以释放磷酸盐。在拟南芥（Arabidopsis thaliana）中的29种PAP样蛋白中，AtPAP 15（At 3g 07130）显示出与大豆（Glycine max; GmPHY）和烟草（Nicotiana tabacum）PAP（NtPAP）具有比其他AtPAP更大程度的具有植酸酶活性的氨基酸同一性。在这项研究中，转基因拟南芥，表达AtPAP 15启动子：：β-葡萄糖醛酸酶（GUS）融合蛋白表明，AtPAP 15的表达是发育和时间调节，在幼苗生长和花粉萌发的早期阶段具有较强的GUS染色。该表达也是器官/组织特异性的，在脉管系统、花粉粒和根中具有最强的GUS染色。从转基因烟草中纯化的重组AtPAP具有广泛的底物特异性和中等的植酸酶活性。AtPAP 15 T-DNA插入系在幼苗和萌发花粉中的植酸酶和磷酸酶活性均低于野生型及其互补系，花粉萌发率也低于野生型及其互补系。因此，AtPAP 15可能动员植物中的磷储备，特别是在种子和花粉萌发期间。由于AtPAP 15在根毛或表皮细胞中不表达，因此它不太可能在外部磷同化中发挥任何作用。
Purple acid phosphatase (PAP) catalyzes the hydrolysis of phosphate monoesters and anhydrides to release phosphate within an acidic pH range. Among the 29 PAP-like proteins in Arabidopsis (Arabidopsis thaliana), AtPAP15 (At3g07130) displays a greater degree of amino acid identity with soybean (Glycine max; GmPHY) and tobacco (Nicotiana tabacum) PAP (NtPAP) with phytase activity than the other AtPAPs. In this study, transgenic Arabidopsis that expressed an AtPAP15 promoter:: beta-glucuronidase (GUS) fusion protein showed that AtPAP15 expression was developmentally and temporally regulated, with strong GUS staining at the early stages of seedling growth and pollen germination. The expression was also organ/tissue specific, with strongest GUS staining in the vasculature, pollen grains, and roots. The recombinant AtPAP purified from transgenic tobacco exhibited broad substrate specificity with moderate phytase activity. AtPAP15 T-DNA insertion lines exhibited a lower phytase and phosphatase activity in seedling and germinating pollen and lower pollen germination rate compared with the wild type and their complementation lines. Therefore, AtPAP15 likely mobilizes phosphorus reserves in plants, particularly during seed and pollen germination. Since AtPAP15 is not expressed in the root hair or in the epidermal cells, it is unlikely to play any role in external phosphorus assimilation.