The plant homolog to the human sodium/dicarboxylic cotransporter is the vacuolar malate carrier
The plant homolog to the human sodium/dicarboxylic cotransporter is the vacuolar malate carrier
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DOI：
10.1073/pnas.1832002100
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发表时间：
2003-09-16
影响因子：
11.1
通讯作者：
Neuhaus, HE
中科院分区：
文献类型：
--
作者：
Emmerlich, V;Linka, N;Neuhaus, HE
苹果酸盐在植物代谢中起着核心作用。它是克雷布斯和乙醛酸循环的中间体，是C4和天冬氨酸代谢植物中二氧化碳的储存，保护植物免受铝毒性，对维持渗透压和电荷平衡至关重要，因此参与气孔孔径的调节。为了发挥这些作用，苹果酸盐必须在大的中央液泡中积累。在过去，许多不成功的努力已经做了确定液泡苹果酸转运体；在这里，我们描述了液泡苹果酸转运体的鉴定[A]。拟南芥叶绿体二羧酸转运体[AttDT]。该转运蛋白与人类钠/二羧酸盐共转运蛋白序列相似性最高。独立的T-DNA[转入植物细胞的Ti（肿瘤诱导）质粒的一部分]拟南芥突变体表现出显著降低的苹果酸水平，但呼吸外源应用[C-14]苹果酸的速度比WT快。AttDT-GFP融合蛋白定位于液泡。拟南芥WT叶片液泡中存在不受钠刺激的羰基氰化物间氯苯腙和柠檬酸盐抑制的苹果酸盐转运。从突变植物中分离出的液泡进口[C-14]-苹果酸的速率大大降低，证实该蛋白是液泡苹果酸转运蛋白。
Malate plays a central role in plant metabolism. It is an intermediate in the Krebs and glyoxylate cycles, it is the store for CO2 in C4 and crassulacean acid metabolism plants, it protects plants from aluminum toxicity, it is essential for maintaining the osmotic pressure and charge balance, and it is therefore involved in regulation of stomatal aperture. To fulfil many of these roles, malate has to be accumulated within the large central vacuole. Many unsuccessful efforts have been made in the past to identify the vacuolar malate transporter; here, we describe the identification of the vacuolar malate transporter [A. thaliana tonoplast dicarboxylate transporter (AttDT)]. This transporter exhibits highest sequence similarity to the human sodium/dicarboxylate cotransporter. Independent T-DNA [portion of the Ti (tumor-inducing) plasmid that is transferred to plant cells] Arabidopsis mutants exhibit substantially reduced levels of leaf malate, but respire exogenously applied [C-14]malate faster than the WT. An AttDT-GFP fusion protein was localized to vacuole. Vacuoles isolated from Arabidopsis WT leaves exhibited carbonylcyanide m-chlorophenylhydrazone and citrate inhibitable malate transport, which was not stimulated by sodium. Vacuoles isolated from mutant plants import [C-14]-malate at strongly reduced rates, confirming that this protein is the vacuolar malate transporter.