The Mycobacterium tuberculosis ino1 gene is essential for growth and virulence
The Mycobacterium tuberculosis ino1 gene is essential for growth and virulence
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DOI：
10.1046/j.1365-2958.2003.03900.x
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发表时间：
2004-02-01
影响因子：
3.6
通讯作者：
Stoker, NG
中科院分区：
文献类型：
--
作者：
Movahedzadeh, F;Smith, DA;Stoker, NG
肌醇被结核分枝杆菌用于生产其主要硫醇和必需的细胞壁脂聚糖。我们构建了一个缺乏编码肌醇-1-磷酸合酶（ino1）基因的突变体，该基因催化肌醇合成的第一个关键步骤。该突变体仅在肌醇水平极高的情况下才可行。在无肌醇培养基中培养四个星期的突变细菌显示菌硫醇水平降低，但磷脂酰肌醇甘露糖苷、脂甘露聚糖和脂阿拉伯甘露聚糖水平没有改变。 ino1 突变体在静息巨噬细胞和 SCID 小鼠中减弱。我们使用定点诱变来改变四个假定的活性位点残基；所有四种改变均导致活性丧失，并且我们证明 D310N 突变导致活性位点 Zn2+ 离子的丧失以及 NAD(+) 辅因子的构象变化。
Inositol is utilized by Mycobacterium tuberculosis in the production of its major thiol and of essential cell wall lipoglycans. We have constructed a mutant lacking the gene encoding inositol-1-phosphate synthase (ino1), which catalyses the first committed step in inositol synthesis. This mutant is only viable in the presence of extremely high levels of inositol. Mutant bacteria cultured in inositol-free medium for four weeks showed a reduction in levels of mycothiol, but phosphatidylinositol mannoside, lipomannan and lipoarabinomannan levels were not altered. The ino1 mutant was attenuated in resting macrophages and in SCID mice. We used site-directed mutagenesis to alter four putative active site residues; all four alterations resulted in a loss of activity, and we demonstrated that a D310N mutation caused loss of the active site Zn2+ ion and a conformational change in the NAD(+) cofactor.