Job Sharing in the Endomembrane System: Vacuolar Acidification Requires the Combined Activity of V-ATPase and V-PPase
Job Sharing in the Endomembrane System: Vacuolar Acidification Requires the Combined Activity of V-ATPase and V-PPase
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DOI：
10.1105/tpc.15.00733
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发表时间：
2015-12-01
期刊：
影响因子：
11.6
通讯作者：
Schumacher, Karin
中科院分区：
文献类型：
--
作者：
Kriegel, Anne;Andres, Zaida;Schumacher, Karin
存在一个大的中央液泡是典型植物细胞的标志之一，这个隔间的多种功能需要大量的分子流经其限制膜-液泡膜。运输被认为是由膜电位和两个质子泵--液泡H+-焦磷酸酶(V-PPase)和液泡H+-ATPase(V-ATPase)的共同活性建立的质子梯度所提供的。这两种酶之间的劳动到底是如何分配的仍然是个谜。在这里，我们使用功能增益法和功能损失法提供证据，证明V-ATPase的缺乏不能通过V-PPase活性的增加来补偿。此外，我们还表明，在冷驯化过程中，V-ATPase活性的提高需要V-PPase的存在。最重要的是，我们证明了缺乏这两个质子泵的突变体在条件下是可行的，并保留了显著的空泡酸化，指出到目前为止尚未检测到的反高尔基网络/早期内体定位的V-ATPase对空泡pH的贡献。
The presence of a large central vacuole is one of the hallmarks of a prototypical plant cell, and the multiple functions of this compartment require massive fluxes of molecules across its limiting membrane, the tonoplast. Transport is assumed to be energized by the membrane potential and the proton gradient established by the combined activity of two proton pumps, the vacuolar H+-pyrophosphatase (V-PPase) and the vacuolar H+-ATPase (V-ATPase). Exactly how labor is divided between these two enzymes has remained elusive. Here, we provide evidence using gain-and loss-of-function approaches that lack of the V-ATPase cannot be compensated for by increased V-PPase activity. Moreover, we show that increased V-ATPase activity during cold acclimation requires the presence of the V-PPase. Most importantly, we demonstrate that a mutant lacking both of these proton pumps is conditionally viable and retains significant vacuolar acidification, pointing to a so far undetected contribution of the trans-Golgi network/early endosome-localized V-ATPase to vacuolar pH.