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山東大學(xué)、山東省農(nóng)科院丨線粒體丙酮酸載體調(diào)控植物耐鎘的機(jī)理
期刊：Plant Physiology
主題：線粒體丙酮酸載體調(diào)控植物耐鎘的機(jī)理
標(biāo)題：Mitochondrial Pyruvate Carriers Prevent Cadmium Toxicity by Sustaining the TCA Cycle and Glutathione Synthesis
影響因子：5.949
監(jiān)測指標(biāo)：Cd2+流速
檢測部位：擬南芥根（距離根尖400μm）
Cd2+流速流實驗處理方法：
擬南芥種子萌發(fā)3天后，50μMCdCl2處理7天
Cd2+流速流實驗測試液成份：
0.1 mM KCl, 0.05 mM CdCl2, 0.3 mM MES, pH 5.8
作者：山東大學(xué)、山東省農(nóng)科院張偉、高建偉、賀立龍
英文摘要
Cadmium (Cd) is a major heavy metal pollutant, and Cd toxicity is a serious cause of abiotic stress in the environment. Plants protect themselves against Cd stress through a variety of pathways.
In a recent study, we found that mitochondrial pyruvate carriers (MPCs) are involved in Cd tolerance in Arabidopsis (Arabidopsis thaliana). Following the identification of MPCs in yeast (Saccharomyces cerevisiae) in 2012, most studies have focused on the function of MPCs in animals, as a possible approach to reduce the risk of cancer developing.
The results of this study show that AtMPC protein complexes are required for Cd tolerance and prevention of Cd accumulation in Arabidopsis. AtMPC complexes are composed of two elements, AtMPC1 and AtMPC2 (AtNRGA1 or AtMPC3). When the formation of AtMPCs was interrupted by the loss of AtMPC1, glutamate could supplement the synthesis of acetyl-coenzyme A and sustain the TCA cycle. With the up-regulation of glutathione synthesis following exposure to Cd stress, the supplementary pathway could not efficiently drive the tricarboxylic acid cycle without AtMPC. The ATP content decreased concomitantly with the deletion of tricarboxylic acid activity, which led to Cd accumulation in Arabidopsis.
More importantly, ScMPCs were also required for Cd tolerance in yeast. Our results suggest that the mechanism of Cd tolerance may be similar in other species.
中文摘要（谷歌機(jī)翻）
鎘（Cd）是一種主要的重金屬污染物，Cd毒性是環(huán)境中非生物脅迫的嚴(yán)重原因。植物通過各種途徑保護(hù)自己免受Cd脅迫。
在近的一項研究中，我們發(fā)現(xiàn)線粒體丙酮酸載體（MPCs）參與擬南芥（Arabidopsis thaliana）的Cd耐受。繼2012年在酵母（釀酒酵母）中鑒定MPC后，大多數(shù)研究都集中在MPCs在動物體內(nèi)的功能，作為降低癌癥發(fā)展風(fēng)險的可能方法。
該研究的結(jié)果表明，AtMPC蛋白復(fù)合物是擬南芥中Cd耐受和預(yù)防Cd積累所必需的。AtMPC復(fù)合物由兩種元素組成，AtMPC1和AtMPC2（AtNRGA1或AtMPC3）。當(dāng)AtMPC的形成中斷AtMPC的形成時，谷氨酸可以補(bǔ)充乙酰輔酶A的合成并維持TCA循環(huán)。隨著暴露于Cd脅迫后谷胱甘肽合成的上調(diào)，補(bǔ)充途徑不能在沒有AtMPC的情況下有效地驅(qū)動三羧酸循環(huán)。隨著三羧酸活性的缺失，ATP含量同時下降，導(dǎo)致擬南芥中Cd的積累。
更重要的是，ScMPCs也是酵母中Cd耐受性所必需的。我們的研究結(jié)果表明，其他物種的鎘耐受機(jī)制可能相似。
結(jié)果表明：結(jié)果表明：在50μMCdCl2處理下，mpc1-1根系中的Cd2+吸收遠(yuǎn)高于野生型和互補(bǔ)株系（圖C和D））。
結(jié)果表明：通過在野生型和mpc1-1的根中添加1mM ATP，Cd2+吸收受到顯著影響并變?yōu)橥馀拧４送?，野生型的Cd2+流速變化比mpc1-1更明顯。野生型Cd2+流速從大約-10pmolcm-2s-1變?yōu)?0pmol cm-2s-1，而mpc1-1從大約-20pmolcm-2s-1變?yōu)?0pmol cm-2s-1（圖b和c）。在MPC存在下，ATP有助于Cd2+的外排。