Characterization of a Mycobacterium tuberculosis proteasomal ATPase homologue
Characterization of a Mycobacterium tuberculosis proteasomal ATPase homologue
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DOI：
10.1111/j.1365-2958.2004.04403.x
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发表时间：
2005-01-01
影响因子：
3.6
通讯作者：
Nathan, CF
中科院分区：
文献类型：
--
作者：
Darwin, KH;Lin, G;Nathan, CF
筛选对活性氮中间体敏感的结核分枝杆菌（Mtb）突变体，在假定的蛋白酶体ATP酶基因mpa（分枝杆菌蛋白酶体ATP酶; Rv 2115 c）中发现了转座子插入。MPA突变体在野生型和一氧化氮合酶2缺陷型小鼠中均减毒。在这项工作中，我们表明，MPA突变体的衰减是严重的，Mpa是一个ATP酶与各种细胞活动（AAA）ATP酶，形成六聚体环类似的真核复合物p97/valosin含蛋白（VCP）。Mpa保守的步行者盒ATP酶基序中的点突变大大降低或废除了体外ATP酶活性，并废除了Mtb对酸化亚硝酸盐的保护。一个突变Mpa蛋白质丢失只有其最后两个氨基酸保留ATP酶活性，但未能保护Mtb对亚硝酸盐。相应的菌株在小鼠中减毒。因此，Mpa是一种ATP酶，其酶活性是必要的，但不足以保护免受活性氮中间体的影响。
A screen for Mycobacterium tuberculosis (Mtb) mutants sensitive to reactive nitrogen intermediates identified transposon insertions in the presumptive proteasomal ATPase gene mpa (mycobacterium proteasome ATPase; Rv2115c). mpa mutants are attenuated in both wild type and nitric oxide synthase 2 deficient mice. In this work, we show that attenuation of mpa mutants is severe, and that Mpa is an ATPase associated with various cellular activities (AAA) ATPase that forms hexameric rings resembling the eukaryotic complex p97/valosin-containing protein (VCP). Point mutations in the conserved Walker box ATPase motifs of Mpa greatly reduced or abolished ATPase activity in vitro and abrogated protection of Mtb against acidified nitrite. A mutant Mpa protein missing only its last two amino acids retained ATPase activity, yet failed to protect Mtb against nitrite. The corresponding strain was attenuated in mice. Thus, Mpa is an ATPase whose enzymatic activity is necessary but not sufficient to protect against reactive nitrogen intermediates.