The Plastid Envelope CHLOROPLAST MANGANESE TRANSPORTER1 Is Essential for Manganese Homeostasis in Arabidopsis
The Plastid Envelope CHLOROPLAST MANGANESE TRANSPORTER1 Is Essential for Manganese Homeostasis in Arabidopsis
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DOI：
10.1016/j.molp.2018.04.008
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发表时间：
2018-07-02
期刊：
影响因子：
27.5
通讯作者：
Schneider, Anja
中科院分区：
文献类型：
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作者：
Eisenhut, Marion;Hoecker, Natalie;Schneider, Anja
过渡金属锰（Mn）是不可缺少的光自养生长，因为光系统II（PSII）采用了无机Mn 4CaO 5集群的水分解。在这里，我们表明，拟南芥膜蛋白叶绿体锰转运蛋白1（CMT 1）参与叶绿体锰稳态。CMT 1是先前表征的类囊体Mn转运蛋白受光合作用影响的突变体71（PAM 71）的最接近的同源物。与PAM 71相反，CMT 1位于叶绿体被膜上并广泛表达。然而，与PAM 71一样，CMT 1的表达也可以减轻酵母突变体Delta pmr 1的Mn敏感表型。cmt 1突变体的生长，叶绿体超微结构和PSII活性受到严重抑制，由于色素和类囊体膜蛋白的量减少。CMT 1叶绿体锰稳态的重要性证明了显着减少叶绿体锰浓度cmt 1 -1，表现出减少PS Ⅱ复合物中的锰结合。此外，CMT 1的表达在锰过剩条件下下调。pam 71 cmt 1 - 1双突变体在大多数方面类似于cmt 1 -1单突变体，而不是pam 71。综上所述，我们的研究结果表明，CMT 1介导Mn-2（+）吸收到叶绿体基质中，CMT 1和PAM 71功能顺序在Mn传递到PSII通过叶绿体包膜和类囊体膜。
The transition metal manganese (Mn) is indispensable for photoautotrophic growth since photosystem II (PSII) employs an inorganic Mn4CaO5 cluster for water splitting. Here, we show that the Arabidopsis membrane protein CHLOROPLAST MANGANESE TRANSPORTER1 (CMT1) is involved in chloroplast Mn homeostasis. CMT1 is the closest homolog of the previously characterized thylakoid Mn transporter PHOTOSYNTHESIS-AFFECTED MUTANT71 (PAM71). In contrast to PAM71, CMT1 resides at the chloroplast envelope and is ubiquitously expressed. Nonetheless, like PAM71, the expression of CMT1 can also alleviate the Mn-sensitive phenotype of yeast mutant Delta pmr1. The cmt1 mutant is severely suppressed in growth, chloroplast ultrastructure, and PSII activity owing to a decrease in the amounts of pigments and thylakoid membrane proteins. The importance of CMT1 for chloroplast Mn homeostasis is demonstrated by the significant reduction in chloroplast Mn concentrations in cmt1-1, which exhibited reduced Mn binding in PSII complexes. Moreover, CMT1 expression is downregulated in Mn-surplus conditions. The pam71 cmt1-1double mutant resembles the cmt1-1 single mutant rather than pam71 in most respects. Taken together, our results suggest that CMT1 mediates Mn-2(+) uptake into the chloroplast stroma, and that CMT1 and PAM71 function sequentially in Mn delivery to PSII across the chloroplast envelope and the thylakoid membrane.