The Redox-Sensitive Chloroplast Trehalose-6-Phosphate Phosphatase AtTPPD Regulates Salt Stress Tolerance
The Redox-Sensitive Chloroplast Trehalose-6-Phosphate Phosphatase AtTPPD Regulates Salt Stress Tolerance
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DOI：
10.1089/ars.2013.5693
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发表时间：
2014-09-20
影响因子：
6.6
通讯作者：
Jonak, Claudia
中科院分区：
文献类型：
--
作者：
Krasensky, Julia;Broyart, Caroline;Jonak, Claudia
目的：高盐胁迫损害植物的生长和发育。海藻糖代谢与糖信号转导有关，增强的海藻糖代谢可以积极地调节非生物胁迫耐受性。然而，与胁迫相关的海藻糖途径的分子机制(S)以及单个海藻糖生物合成酶在胁迫耐受性中的作用尚不清楚。结果：海藻糖-6-磷酸磷酸酶(TPP)催化海藻糖代谢的最后一步。通过对拟南芥TPP家族成员亚细胞定位的研究，我们发现AtTPPD是一种叶绿体定位酶。缺乏AtTPPD的植株对高盐胁迫反应敏感，而过量表达AtTPPD的植株对高盐胁迫的耐受性更强。AtTPPD高表达基因的耐逆性增强与高淀粉水平和可溶性糖积累增加相关，表明AtTPPD在盐胁迫条件下调节糖代谢。生化分析表明，AtTPPD是翻译后氧化还原调节的靶标，可被氧化条件可逆灭活。两个半胱氨酸残基被鉴定为氧化还原敏感部位。结构和突变分析表明，分子内二硫键的形成调节了AtTPPD的活性。创新：位于细胞质、细胞核和叶绿体中的不同AtTPP亚型的活性可以被氧化还原调节，这表明海藻糖代谢可能依赖于不同细胞间的氧化还原状态来调节不同的生物过程，如应激反应。结论：TPP的两个氧化还原调节半胱氨酸残基在种子植物中的进化保守性表明，TPP的氧化还原调节可能是使植物快速调节海藻糖代谢以适应当时的环境和发育条件的共同机制。
Aims: High salinity stress impairs plant growth and development. Trehalose metabolism has been implicated in sugar signaling, and enhanced trehalose metabolism can positively regulate abiotic stress tolerance. However, the molecular mechanism(s) of the stress-related trehalose pathway and the role of individual trehalose biosynthetic enzymes for stress tolerance remain unclear. Results: Trehalose-6-phosphate phosphatase (TPP) catalyzes the final step of trehalose metabolism. Investigating the subcellular localization of the Arabidopsis thaliana TPP family members, we identified AtTPPD as a chloroplast-localized enzyme. Plants deficient in AtTPPD were hypersensitive, whereas plants overexpressing AtTPPD were more tolerant to high salinity stress. Elevated stress tolerance of AtTPPD overexpressors correlated with high starch levels and increased accumulation of soluble sugars, suggesting a role for AtTPPD in regulating sugar metabolism under salinity conditions. Biochemical analyses indicate that AtTPPD is a target of post-translational redox regulation and can be reversibly inactivated by oxidizing conditions. Two cysteine residues were identified as the redox-sensitive sites. Structural and mutation analyses suggest that the formation of an intramolecular disulfide bridge regulates AtTPPD activity. Innovation: The activity of different AtTPP isoforms, located in the cytosol, nucleus, and chloroplasts, can be redox regulated, suggesting that the trehalose metabolism might relay the redox status of different cellular compartments to regulate diverse biological processes such as stress responses. Conclusion: The evolutionary conservation of the two redox regulatory cysteine residues of TPPs in spermatophytes indicates that redox regulation of TPPs might be a common mechanism enabling plants to rapidly adjust trehalose metabolism to the prevailing environmental and developmental conditions.