Activity of tonoplast proton pumps and Na+/H+ exchange in potato cell cultures is modulated by salt
Activity of tonoplast proton pumps and Na+/H+ exchange in potato cell cultures is modulated by salt
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DOI：
10.1093/jxb/erp011
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发表时间：
2009-03-01
影响因子：
6.9
通讯作者：
Fidalgo, Fernanda
中科院分区：
文献类型：
--
作者：
Queiros, Filipa;Fontes, Natacha;Fidalgo, Fernanda
植物对盐胁迫的适应机制主要是将过量的Na+从细胞质中排出和液泡中积累。这通常通过跨膜转运蛋白进行，跨膜转运蛋白将Na+从胞质溶胶中排除以交换H+，这是一种能量依赖性的次级转运过程，并由质膜和液泡膜质子泵产生的质子动力驱动。以马铃薯（Solanum tuberosum）耐盐愈伤组织和对照愈伤组织的液泡膜丰富囊泡为模型系统，研究了V-H+-PPase和V-H+-ATPase的活性以及Na+区室化进入液泡的机制。ATP和焦磷酸盐（PPi）依赖的H+-运输更高的液泡膜囊泡从耐盐线比在控制细胞的囊泡。液泡膜蛋白质的Western印迹证实V-H+-PPase活性的变化与蛋白质量的增加相关。相反，V-H+-ATP酶的A-亚基的免疫检测显示，可能涉及翻译后调节的机制。预先建立的pH梯度的Na+依赖性耗散用于测量液泡膜囊泡中的Na+/H+交换。质子流出的初始速率遵循Michaelis-Menten动力学和质子耗散的最大速度是2倍高NaCl耐受愈伤组织相比，控制。H+-偶联交换对Na+和Li+具有特异性，而对K+没有特异性。盐胁迫下液泡膜pH梯度和Na+/H+逆向转运活性的增加表明，Na+螯合到液泡中有助于马铃薯的耐盐性。
The efficient exclusion of excess Na from the cytoplasm and vacuolar Na+ accumulation are the main mechanisms for the adaptation of plants to salt stress. This is typically carried out by transmembrane transport proteins that exclude Na+ from the cytosol in exchange for H+, a secondary transport process which is energy-dependent and driven by the proton-motive force generated by plasma-membrane and tonoplast proton pumps. Tonoplast enriched-vesicles from control and 150 mM NaCl-tolerant calli lines were used as a model system to study the activity of V-H+-PPase and V-H+-ATPase and the involvement of Na+ compartmentalization into the vacuole as a mechanism of salt tolerance in Solanum tuberosum. Both ATP- and pyrophosphate (PPi)-dependent H+-transport were higher in tonoplast vesicles from the salt-tolerant line than in vesicles from control cells. Western blotting of tonoplast proteins confirmed that changes in V-H+-PPase activity are correlated with increased protein amount. Conversely, immunodetection of the A-subunit of V-H+-ATPase revealed that a mechanism of post-translational regulation is probably involved. Na+-dependent dissipation of a pre-established pH gradient was used to measure Na+/H+ exchange in tonoplast vesicles. The initial rates of proton efflux followed Michaelis-Menten kinetics and the V-max of proton dissipation was 2-fold higher in NaCl-tolerant calli when compared to the control. H+-coupled exchange was specific for Na+ and Li+ and not for K+. The increase of both the pH gradient across the tonoplast and the Na+/H+ antiport activity in response to salt strongly suggests that Na+ sequestration into the vacuole contributes to salt tolerance in potato.