The EF-Hand Ca2+ Binding Protein MICU Choreographs Mitochondrial Ca2+ Dynamics in Arabidopsis[OPEN]
The EF-Hand Ca2+ Binding Protein MICU Choreographs Mitochondrial Ca2+ Dynamics in Arabidopsis[OPEN]
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DOI：
10.1105/tpc.15.00509
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发表时间：
2015-11
期刊：
影响因子：
11.6
通讯作者：
Stephan Wagner;Smrutisanjita Behera;Sara De Bortoli;D. Logan;Philippe Fuchs;Luca Carraretto;E. Teardo;L. Cendron;Thomas Nietzel;Magdalena Füßl;F. G. Doccula;L. Navazio;M. Fricker;Olivier Van Aken;I. Finkemeier;A. Meyer;I. Szabó;Alex Costa;M. Schwarzländer
中科院分区：
文献类型：
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作者：
Stephan Wagner;Smrutisanjita Behera;Sara De Bortoli;D. Logan;Philippe Fuchs;Luca Carraretto;E. Teardo;L. Cendron;Thomas Nietzel;Magdalena Füßl;F. G. Doccula;L. Navazio;M. Fricker;Olivier Van Aken;I. Finkemeier;A. Meyer;I. Szabó;Alex Costa;M. Schwarzländer
线粒体Ca 2+摄取蛋白At-MICU塑造了线粒体Ca 2+动力学，为植物线粒体单向转运体复合物的存在和功能提供了体内分子证据。植物细胞器的功能必须不断地适应环境条件，这需要动态的协调。Ca 2+信号可能在这一过程中发挥了重要作用。游离Ca 2+动力学受到严格的调控，并且在胞质、质体基质和线粒体基质之间存在显著差异。隔室特定的Ca 2+动力学的机制基础知之甚少。在这里，我们研究了At-MICU的功能，拟南芥EF-手蛋白的同源性，在哺乳动物的线粒体Ca 2+单向转运体机制的组成部分。MICU结合Ca 2+并定位于拟南芥中的线粒体。在线粒体基质中表达基因编码的Ca 2+传感器的根的体内成像显示，缺乏MICU增加了基质中游离Ca 2+的静息浓度。此外，由生长素和细胞外ATP引发的Ca 2+升高发生得更快，并在micu突变体的线粒体中达到更高的最大浓度，而胞浆Ca 2+签名保持不变。这些研究结果支持了这样的想法，保守的uniporter系统，与组成和调节不同的哺乳动物的机器，介导的线粒体Ca 2+在植物体内条件下的吸收。他们进一步表明，MICU作为一种节流阀，通过调节内流来控制Ca 2+摄取，从而在基质中形成Ca 2+特征并保持线粒体稳态。我们的研究结果打开了大门，在植物线粒体Ca 2+信号的遗传解剖。
The mitochondrial Ca2+ uptake protein At-MICU shapes mitochondrial Ca2+ dynamics, providing molecular in vivo evidence for the existence and function of a mitochondrial uniporter complex in plants. Plant organelle function must constantly adjust to environmental conditions, which requires dynamic coordination. Ca2+ signaling may play a central role in this process. Free Ca2+ dynamics are tightly regulated and differ markedly between the cytosol, plastid stroma, and mitochondrial matrix. The mechanistic basis of compartment-specific Ca2+ dynamics is poorly understood. Here, we studied the function of At-MICU, an EF-hand protein of Arabidopsis thaliana with homology to constituents of the mitochondrial Ca2+ uniporter machinery in mammals. MICU binds Ca2+ and localizes to the mitochondria in Arabidopsis. In vivo imaging of roots expressing a genetically encoded Ca2+ sensor in the mitochondrial matrix revealed that lack of MICU increased resting concentrations of free Ca2+ in the matrix. Furthermore, Ca2+ elevations triggered by auxin and extracellular ATP occurred more rapidly and reached higher maximal concentrations in the mitochondria of micu mutants, whereas cytosolic Ca2+ signatures remained unchanged. These findings support the idea that a conserved uniporter system, with composition and regulation distinct from the mammalian machinery, mediates mitochondrial Ca2+ uptake in plants under in vivo conditions. They further suggest that MICU acts as a throttle that controls Ca2+ uptake by moderating influx, thereby shaping Ca2+ signatures in the matrix and preserving mitochondrial homeostasis. Our results open the door to genetic dissection of mitochondrial Ca2+ signaling in plants.