The Phosphate Transporter PHT4;6 Is a Determinant of Salt Tolerance that Is Localized to the Golgi Apparatus of Arabidopsis
The Phosphate Transporter PHT4;6 Is a Determinant of Salt Tolerance that Is Localized to the Golgi Apparatus of Arabidopsis
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DOI：
10.1093/mp/ssp013
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发表时间：
2009-05-01
期刊：
影响因子：
27.5
通讯作者：
Pardo, Jose M.
中科院分区：
文献类型：
--
作者：
Cubero, Beatriz;Nakagawa, Yuko;Pardo, Jose M.
中断PHT4；6功能的插入突变(At5g44370)导致拟南芥幼苗对盐敏感，其特征是初生根生长减少，侧枝增强，根尖肿大。蔗糖可加重突变表型，但等摩尔浓度的甘露醇不会加重突变表型，而低无机磷则使突变表型减弱。PHT4；6蛋白属于渗透膜主要促进剂超家族，与哺乳动物的I型PI转运蛋白和囊泡谷氨酸转运蛋白有显著的序列相似性，是植物细胞内磷酸转运蛋白PHT4家族的成员。PHT4；6定位于高尔基体膜，转运研究表明，PHT4；6促进了PI的选择性转运，但不利于氯或无机阴离子的转运。与其他表现根膨大的突变体的表型相似性表明，PHT4；6可能在蛋白质N-糖基化和细胞壁生物合成中发挥功能，这是耐盐性所必需的。综上所述，我们的结果表明，PHT4；6将PI转运出高尔基体腔间隙，以重新循环糖基化过程中释放的PI。
Insertion mutations that disrupt the function of PHT4;6 (At5g44370) cause NaCl hypersensitivity of Arabidopsis seedlings that is characterized by reduced growth of the primary root, enhanced lateral branching, and swelling of root tips. Mutant phenotypes were exacerbated by sucrose, but not by equiosmolar concentrations of mannitol, and attenuated by low inorganic phosphate in the medium. Protein PHT4;6 belongs to the Major Facilitator Superfamily of permeases that shares significant sequence similarity to mammalian type-I Pi transporters and vesicular glutamate transporters, and is a member of the PHT4 family of putative intracellular phosphate transporters of plants. PHT4;6 localizes to the Golgi membrane and transport studies indicate that PHT4;6 facilitates the selective transport of Pi but not of chloride or inorganic anions. Phenotypic similarities with other mutants displaying root swelling suggest that PHT4;6 likely functions in protein N-glycosylation and cell wall biosynthesis, which are essential for salt tolerance. Together, our results indicate that PHT4;6 transports Pi out of the Golgi lumenal space for the re-cycling of the Pi released from glycosylation processes.