The Dual-Targeted Purple Acid Phosphatase Isozyme AtPAP26 Is Essential for Efficient Acclimation of Arabidopsis to Nutritional Phosphate Deprivation
The Dual-Targeted Purple Acid Phosphatase Isozyme AtPAP26 Is Essential for Efficient Acclimation of Arabidopsis to Nutritional Phosphate Deprivation
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DOI：
10.1104/pp.110.153270
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发表时间：
2010-07-01
期刊：
影响因子：
7.4
通讯作者：
Plaxton, William C.
中科院分区：
文献类型：
--
作者：
Hurley, Brenden A.;Tran, Hue T.;Plaxton, William C.
细胞内和分泌的酸性磷酸酶（AP酶）的诱导是正磷酸盐（Pi）饥饿（-Pi）植物的广泛反应。APases催化Pi在酸性pH下从广泛的磷酸单酯水解。最大的一类非特异性植物APases由紫色APases（PAP）组成。虽然已经描述了几种植物PAP的生化性质、亚细胞定位和表达，但它们的生理功能尚未完全解决。最近的生化研究表明，AtPAP 26，由拟南芥（Arabidopsis thaliana）基因组编码的29个PAP之一，是主要的细胞内AP酶，以及一个主要的分泌型AP酶同工酶上调-Pi拟南芥。缺乏AtPAP 26转录物和55-kD免疫反应性AtPAP 26多肽的atpap 26 T-DNA插入突变体表现出：（1）茎和根APase活性分别降低9倍和5倍，但不随磷饥饿而改变，（2）在磷剥夺期间分泌的APase活性降低40%，（3）游离和总磷浓度降低35%和50%，以及土壤生长的Pi植物的芽中的5倍更高的花青素水平，和（4）当经受Pi缺乏时，芽和根的发育受损。相比之下，没有有害的影响AtPAP 26功能丧失发生在Pi-充满条件下，或在氮或钾限制的生长，或氧化应激。AtPAP 26-mCherry在拟南芥悬浮细胞中的瞬时表达证实AtPAP 26靶向于细胞液泡。我们的研究结果证实，AtPAP 26是一个主要的贡献者Pi胁迫诱导的AP酶活性，它在Pi代谢的-Pi拟南芥中起着重要的作用。
Induction of intracellular and secreted acid phosphatases (APases) is a widespread response of orthophosphate (Pi)-starved (-Pi) plants. APases catalyze Pi hydrolysis from a broad range of phosphomonoesters at an acidic pH. The largest class of nonspecific plant APases is comprised of the purple APases (PAPs). Although the biochemical properties, subcellular location, and expression of several plant PAPs have been described, their physiological functions have not been fully resolved. Recent biochemical studies indicated that AtPAP26, one of 29 PAPs encoded by the Arabidopsis (Arabidopsis thaliana) genome, is the predominant intracellular APase, as well as a major secreted APase isozyme up-regulated by -Pi Arabidopsis. An atpap26 T-DNA insertion mutant lacking AtPAP26 transcripts and 55-kD immunoreactive AtPAP26 polypeptides exhibited: (1) 9- and 5-fold lower shoot and root APase activity, respectively, which did not change in response to Pi starvation, (2) a 40% decrease in secreted APase activity during Pi deprivation, (3) 35% and 50% reductions in free and total Pi concentration, respectively, as well as 5-fold higher anthocyanin levels in shoots of soil-grown -Pi plants, and (4) impaired shoot and root development when subjected to Pi deficiency. By contrast, no deleterious influence of AtPAP26 loss of function occurred under Pi-replete conditions, or during nitrogen or potassium-limited growth, or oxidative stress. Transient expression of AtPAP26-mCherry in Arabidopsis suspension cells verified that AtPAP26 is targeted to the cell vacuole. Our results confirm that AtPAP26 is a principal contributor to Pi stress-inducible APase activity, and that it plays an important role in the Pi metabolism of -Pi Arabidopsis.