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Nature Plants：陆生植物液泡无机磷输出转运体鉴定

已有 3909 次阅读 2019-1-17 10:23 |个人分类:每日摘要|系统分类:论文交流

Identification of vacuolar phosphate efflux transporters in land plants

First author: Lei Xu; Affiliations: Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences (中国农业科学院农业资源与农业区划研究所): Beijing, China

Corresponding author: Keke Yi

Inorganic phosphate (Pi) is an essential component of all life forms. Land plants acquire Pi from the soil through roots and associated symbioses, and it is then transported throughout the plant. When sufficient, excess Pi is stored in vacuoles for remobilization following Pi deficiency. Although Pi release from the vacuoles to the cytoplasm serves as a critical mechanism for plants to adapt to low-Pi stress, the transporters responsible for vacuolar Pi efflux have not been identified. Here, we identified a pair of Oryza sativa vacuolar Pi efflux transporters (OsVPE1 and OsVPE2) that were more abundant in plants grown under Pi-deficient conditions. These OsVPE proteins can transport Pi into yeast cells and Xenopus laevis oocytes. Vacuolar Pi content was higher in the loss-of-function Osvpe1 Osvpe2 double mutant than in wild type, particularly under low-Pi stress. Overexpression of either OsVPE1 or OsVPE2 in transgenic plants reduced vacuolar Pi content, consistent with a role in vacuolar Pi efflux. We demonstrate that these VPE proteins evolved from an ancient plasma membrane glycerol-3-phosphate transporter protein. Together, these data indicate that this transporter was recruited to the vacuolar membrane to catalyse Pi efflux during the course of land plant evolution.

无机磷酸盐Pi是所有生命形式的基本元素。陆地植物通过根和共生菌从土壤中吸收Pi，然后再转运至整个植株的各个组织部位。当Pi有剩余时，过多的Pi会储存在液泡中，以便在植物缺乏时再活化。尽管Pi从液泡中释放到细胞质是植物应对低Pi胁迫的重要手段，但还未有研究鉴定到能够将液泡中的Pi转运出去的转运体。本文中，作者鉴定到了一对水稻液泡Pi输出转运体OsVPE1和OsVPE2，这对转运体显著在Pi缺乏条件下的植物中富集。这些OsVPE蛋白能够将Pi转运至酵母细胞和爪蟾卵母细胞。Osvpe1 Osvpe2双突变体相比于野生型植株，液泡中的Pi含量要更高，这种情况在低Pi胁迫下更为明显。过表达OsVPE1或OsVPE2的转基因植株降低了液泡中的Pi含量，从另一方面证实了这对OsVPE蛋白在液泡Pi输出中的作用。本文的研究揭示了这些VPE从一个古老的质膜甘油-3-磷酸酯转运体演化而来。综上，本文的研究数据揭示了在陆地植物的演化过程中，这些转运体被招募到液泡膜上以催化Pi的输出。