The Vacuolar Zinc Transporter TgZnT Protects Toxoplasma gondii from Zinc Toxicity
The Vacuolar Zinc Transporter TgZnT Protects Toxoplasma gondii from Zinc Toxicity
复制标题
DOI：
10.1128/msphere.00086-19
复制
发表时间：
2019-05-01
期刊：
影响因子：
4.8
通讯作者：
Moreno, Silvia N. J.
中科院分区：
文献类型：
--
作者：
Chasen, Nathan M.;Stasic, Andrew J.;Moreno, Silvia N. J.
锌是除铁以外最丰富的生物金属离子，是许多生物系统中的必需元素，是许多酶和调节蛋白的辅因子。由于细胞内游离锌离子的缺乏和过量都对细胞有害，因此必须严格调控锌离子。锌离子转运体在细胞中发挥着重要的作用，它通过将离子转运出细胞质来降低细胞内的锌离子水平。我们克隆了一个弓形虫基因(TgGT1_251630，TgZnT)，该基因是弓形虫中唯一的锌离子转运蛋白家族。TgZnT定位于与植物样液泡(PLV)融合的新型囊泡，PLV是一种内吞体样细胞器。在体外试验中，缺乏TgZnT的突变寄生虫的存活率降低。增加细胞外培养液中的锌浓度会加剧这种表型，而减少锌的培养基会挽救这种表型。在一株对锌离子敏感的酿酒酵母菌株中异源表达TgZnT，部分恢复了酵母在高锌浓度条件下的生长。这些结果表明，TgZnT将锌离子转运到PLV内，在弓形虫胞外速殖子对锌的耐受性中起重要作用。弓形虫的致病机制与其裂解周期有关，包括入侵、复制、排出宿主细胞和入侵新的宿主细胞。弓形虫必须能够在其裂解周期中容忍周围环境成分的突然变化。我们报道了弓形虫的一种锌离子转运蛋白(TgZnT)的特征，它对寄生虫的生长至关重要。TgZnT使不能在高浓度锌离子培养中生长的酵母突变株恢复了对锌的耐性。我们推测TgZnT在弓形虫裂解循环中对锌离子的动态平衡起作用。
Zinc (Zn2+) is the most abundant biological metal ion aside from iron and is an essential element in numerous biological systems, acting as a cofactor for a large number of enzymes and regulatory proteins. Zn2+ must be tightly regulated, as both the deficiency and overabundance of intracellular free Zn(2+ )are harmful to cells. Zn2+ transporters (ZnTs) play important functions in cells by reducing intracellular Zn2+ levels by transporting the ion out of the cytoplasm. We characterized a Toxoplasma gondii gene (TgGT1_251630, TgZnT), which is annotated as the only ZnT family Zn2+ transporter in T. gondii. TgZnT localizes to novel vesicles that fuse with the plant-like vacuole (PLV), an endosome-like organelle. Mutant parasites lacking TgZnT exhibit reduced viability in in vitro assays. This phenotype was exacerbated by increasing zinc concentrations in the extracellular media and was rescued by media with reduced zinc. Heterologous expression of TgZnT in a Zn2+-sensitive Saccharomyces cerevisiae yeast strain partially restored growth in media with higher Zn(2+ )concentrations. These results suggest that TgZnT transports Zn2+ into the PLV and plays an important role in the Zn2+ tolerance of T. gondii extracellular tachyzoites.IMPORTANCE Toxoplasma gondii is an intracellular pathogen of human and animals. T. gondii pathogenesis is associated with its lytic cycle, which involves invasion, replication, egress out of the host cell, and invasion of a new one. T. gondii must be able to tolerate abrupt changes in the composition of the surrounding milieu as it progresses through its lytic cycle. We report the characterization of a Zn2+ transporter of T. gondii (TgZnT) that is important for parasite growth. TgZnT restored Zn2+ tolerance in yeast mutants that were unable to grow in media with high concentrations of Zn2+. We propose that TgZnT plays a role in Zn2+ homeostasis during the T. gondii lytic cycle.