A plasma membrane-type Ca2+-ATPase co-localizes with a vacuolar H+-pyrophosphatase to acidocalcisomes of Toxoplasma gondii
A plasma membrane-type Ca2+-ATPase co-localizes with a vacuolar H+-pyrophosphatase to acidocalcisomes of Toxoplasma gondii
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DOI：
10.1093/emboj/20.1.55
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发表时间：
2001-01-15
期刊：
影响因子：
11.4
通讯作者：
Moreno, SNJ
中科院分区：
文献类型：
--
作者：
Luo, SH;Vieira, M;Moreno, SNJ
Ca 2 +-ATP酶可能在弓形虫的生物化学中起关键作用，因为这些原生动物是专性细胞内寄生虫，并且其细胞内位置的Ca 2+浓度比细胞外介质低三个数量级。本文报道了刚地弓形虫质膜型Ca ~（2+）-ATP酶（PMCA）基因（TgA_1）的克隆和序列分析。TgA_1与克氏锥虫、酿酒酵母、溶组织内阿米巴和盘基网柄线虫的液泡型Ca ~（2+）-ATP酶具有32-36%的同源性。对弓形虫cDNA和基因组DNA的序列分析表明，TgA 1在C端附近含有两个内含子，蛋白质的亲水性特征表明其具有10个跨膜结构域。TgA 1抑制酿酒酵母突变体的Ca 2+超敏性，该突变体在液泡Ca 2+积累中具有缺陷。间接免疫荧光和免疫电子显微镜分析表明，TgA 1定位于质膜和co-localizes与液泡H+-焦磷酸酶的细胞内空泡确定形态学和X-射线微量分析作为acidocalcisomes。这种空泡型Ca 2 +-ATP酶可能在刚地氏锥虫的Ca 2+稳态中发挥重要作用。
Ca2+-ATPases are likely to play critical roles in the biochemistry of Toxoplasma gondii, since these protozoa are obligate intracellular parasites and the Ca2+ concentration in their intracellular location is three orders of magnitude lower than in the extracellular medium. Here, we report the cloning and sequencing of a gene encoding a plasma membrane-type Ca2+ ATPase (PMCA) of T.gondii (TgA1), The predicted protein (TgA1) exhibits 32-36% identity to vacuolar Ca2+-ATPases of Trypanosoma cruzi, Saccharomyces cerevisiae, Entamoeba histolytica and Dictyostelium discoideum, Sequencing of both cDNA and genomic DNA from T.gondii indicated that TgA1 contains two introns near the C-terminus, A hydropathy profile of the protein suggests 10 transmembrane domains. TgA1 suppresses the Ca2+ hypersensitivity of a mutant of S.cerevisiae that has a defect in vacuolar Ca2+ accumulation. Indirect immunofluorescence and immunoelectron microscopy analysis indicate that TgA1 localizes to the plasma membrane and co-localizes with the vacuolar H+-pyrophosphatase to intracellular vacuoles identified morphologically and by X-ray microanalysis as the acidocalcisomes. This vacuolar-type Ca2+-ATPase could play an important role in Ca2+ homeostasis in T.gondii.