Evidence that transport of iron from the lysosome to the cytosol in African trypanosomes is mediated by a mucolipin orthologue
Evidence that transport of iron from the lysosome to the cytosol in African trypanosomes is mediated by a mucolipin orthologue
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DOI：
10.1111/mmi.12285
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发表时间：
2013-08-01
影响因子：
3.6
通讯作者：
Kelly, John M.
中科院分区：
文献类型：
--
作者：
Taylor, Martin C.;McLatchie, Alex P.;Kelly, John M.
布鲁氏锥虫通过受体介导的宿主转铁蛋白内吞作用获得铁。然而，铁从溶酶体转移到细胞质的机制(S)还没有解决。在这里，我们提供了与哺乳动物内溶酶体阳离子通道Mucolipin 1同源的蛋白(TbMLP)参与的证据。在布氏锥虫中，我们发现该蛋白定位于单个寄生虫溶酶体。只有在表达的异位拷贝存在的情况下，才能产生TbMLP零突变，这表明该蛋白质是必不可少的。RNAi介导的消融导致了体外生长缺陷，并导致铁螯合剂去铁胺和水杨基异羟肟酸的敏感性增加了七倍。当异位拷贝被抑制时，条件零突变体仍然有效，但对去铁胺高度敏感，并显示出与RNAi后观察到的生长缺陷类似的生长缺陷。在没有多西环素诱导剂的情况下，条件空体在体内也保持了毒力。这些数据提供了强有力的证据，表明TbMLP在将铁输入非洲锥虫胞浆中起到了作用。它们还表明，即使表达大大减少，也有足够的蛋白质或替代机制为寄生虫提供足够的胞质铁供应。
Bloodstream-form Trypanosoma brucei acquire iron by receptor-mediated endocytosis of host transferrin. However, the mechanism(s) by which iron is then transferred from the lysosome to the cytosol are unresolved. Here, we provide evidence for the involvement of a protein (TbMLP) orthologous to the mammalian endolysosomal cation channel Mucolipin 1. In T. brucei, we show that this protein is localized to the single parasite lysosome. TbMLP null mutants could only be generated in the presence of an expressed ectopic copy, suggesting that the protein is essential. RNAi-mediated ablation resulted in a growth defect in vitro and led to a sevenfold increase in susceptibility to the iron-chelators deferoxamine and salicylhydroxamic acid. Conditional null mutants remained viable when the ectopic copy was repressed, but were hypersensitive to deferoxamine and displayed a growth defect similar to that observed following RNAi. The conditional nulls also retained virulence in vivo in the absence of the doxycycline inducer. These data provide strong evidence that TbMLP has a role in import of iron into the cytosol of African trypanosomes. They also indicate that even when expression is greatly reduced, there is sufficient protein, or an alternative mechanism, to provide the parasite with an adequate supply of cytosolic iron.