A pyrophosphatase regulating polyphosphate metabolism in acidocalcisomes is essential for Trypanosoma brucei virulence in mice
A pyrophosphatase regulating polyphosphate metabolism in acidocalcisomes is essential for Trypanosoma brucei virulence in mice
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DOI：
10.1074/jbc.m309974200
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发表时间：
2004-01-30
影响因子：
4.8
通讯作者：
Bakalara, N
中科院分区：
文献类型：
--
作者：
Lemercier, G;Espiau, B;Bakalara, N
我们报告的功能特性的可溶性焦磷酸酶（TbVSP 1），它定位于酸钙体，囊泡酸性室的布氏锥虫。取决于pH和辅因子Mg 2+或Zn 2+（两者都存在于隔室中），酶水解无机焦磷酸盐（PPi）（k（cat）=385 s（-1））或三聚P（polyP（3））和28个残基的聚磷酸盐（polyP（28）），其中k（cat）值分别为52和3.5 s（-1）。一个不寻常的N-末端结构域的160个氨基酸，含有一个推定的钙EF-手结合域，参与蛋白质寡聚化。使用双链RNA干扰方法，我们产生了TbVSP 1蛋白（BFiVSP 1）的诱导型血流形式（BF）缺陷。这些突变体的长链polyP水平降低了60%。他们的表型显示了一个缺陷的聚磷代谢，其缺陷的反应，磷酸盐饥饿和低渗应力所示。BFiVSP 1在小鼠中没有引起急性毒性感染，表明TbVSP 1对于哺乳动物宿主中血流形式的生长是必需的。
We report the functional characterization of a soluble pyrophosphatase (TbVSP1), which localizes to acidocalcisomes, a vesicular acidic compartment of Trypanosoma brucei. Depending on the pH and the cofactors Mg2+ or Zn2+, both present in the compartment, the enzyme hydrolyzes either inorganic pyrophosphate (PPi) (k(cat)=385 s(-1)) or tripolyP (polyP(3)) and polyphosphate (polyP) of 28 residues (polyP(28)) with k(cat) values of 52 and 3.5 s(-1), respectively. An unusual N-terminal domain of 160 amino acids, containing a putative calcium EF-hand-binding domain, is involved in protein oligomerization. Using double-stranded RNA interference methodology, we produced an inducible bloodstream form (BF) deficient in the TbVSP1 protein (BFiVSP1). The long-chain polyP levels of these mutants were reduced by 60%. Their phenotypes revealed a deficient polyP metabolism, as indicated by their defective response to phosphate starvation and hyposmotic stress. BFiVSP1 did not cause acute virulent infection in mice, demonstrating that TbVSP1 is essential for growth of bloodstream forms in the mammalian host.