Arabidopsis PAP17 is a dual-localized purple acid phosphatase up-regulated during phosphate deprivation, senescence, and oxidative stress
Arabidopsis PAP17 is a dual-localized purple acid phosphatase up-regulated during phosphate deprivation, senescence, and oxidative stress
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DOI：
10.1093/jxb/erab409
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发表时间：
2021-09
影响因子：
6.9
通讯作者：
Bryden O'Gallagher;M. Ghahremani;Kyla A. Stigter;E. L. Walker;Michal Pyc;Ang-Yu Liu;G. C. Macintosh;R. Mullen;W. Plaxton
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文献类型：
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作者：
Bryden O'Gallagher;M. Ghahremani;Kyla A. Stigter;E. L. Walker;Michal Pyc;Ang-Yu Liu;G. C. Macintosh;R. Mullen;W. Plaxton
从Pi饥饿（-Pi）拟南芥悬浮细胞细胞壁提取物中纯化出一种分子量为35 kDa的紫色酸性磷酸酶（APase），经质谱和n端微测序鉴定为AtPAP17 （At3g17790）。AtPAP17是从头合成的，双定位于-Pi或盐胁迫植物或衰老叶片的分泌组和/或细胞内部分。瞬时表达定位于拟南芥悬浮细胞溶泡中的atpap17绿色荧光蛋白。在Pi剥夺、叶片衰老或盐度胁迫下，AtPAP17突变体没有观察到与AtPAP17功能丧失相关的显著生化或表型变化。然而，AtPAP17在Pi饥饿和叶片衰老期间显著上调，广泛的APase底物选择性和pH活性谱，以及在Pi重新供应给-Pi植物后迅速抑制和周转，因此被认为有助于Pi代谢。虽然AtPAP17也能催化鲁米诺的过氧化反应，在pH 9.2时效果最佳，但相对于辣根过氧化物酶，它具有较低的Vmax和对过氧化氢的亲和力。这些结果，再加上盐胁迫或-Pi atpap17突变体中缺乏表型，不支持atpap17过氧化物酶活性在触发atpap17上调的胁迫过程中有助于活性氧解毒的建议。
A 35 kDa monomeric purple acid phosphatase (APase) was purified from cell wall extracts of Pi starved (–Pi) Arabidopsis thaliana suspension cells and identified as AtPAP17 (At3g17790) by mass spectrometry and N-terminal microsequencing. AtPAP17 was de novo synthesized and dual-localized to the secretome and/or intracellular fraction of –Pi or salt-stressed plants, or senescing leaves. Transiently expressed AtPAP17–green fluorescent protein localized to lytic vacuoles of the Arabidopsis suspension cells. No significant biochemical or phenotypical changes associated with AtPAP17 loss of function were observed in an atpap17 mutant during Pi deprivation, leaf senescence, or salinity stress. Nevertheless, AtPAP17 is hypothesized to contribute to Pi metabolism owing to its marked up-regulation during Pi starvation and leaf senescence, broad APase substrate selectivity and pH activity profile, and rapid repression and turnover following Pi resupply to –Pi plants. While AtPAP17 also catalyzed the peroxidation of luminol, which was optimal at pH 9.2, it exhibited a low Vmax and affinity for hydrogen peroxide relative to horseradish peroxidase. These results, coupled with absence of a phenotype in the salt-stressed or –Pi atpap17 mutant, do not support proposals that the peroxidase activity of AtPAP17 contributes to the detoxification of reactive oxygen species during stresses that trigger AtPAP17 up-regulation.