The salicylate-derived mycobactin siderophores of Mycobacterium tuberculosis are essential for growth in macrophages
The salicylate-derived mycobactin siderophores of Mycobacterium tuberculosis are essential for growth in macrophages
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DOI：
10.1073/pnas.97.3.1252
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发表时间：
2000-02-01
影响因子：
11.1
通讯作者：
Barry, CE
中科院分区：
文献类型：
--
作者：
De Voss, JJ;Rutter, K;Barry, CE
结核分枝杆菌是哺乳动物的重要病原体，其依赖于称为分枝杆菌素的含2-羟基苯基恶唑啉的铁载体分子在哺乳动物巨噬细胞的限制性环境中获得铁。已经提出这些化合物通过包括非核糖体肽合酶和聚酮合酶组分的基因簇的作用而生物合成。这些基因之一编码一种蛋白质MbtB，该蛋白质将活化的水杨酸与丝氨酸或苏氨酸偶联，然后将该前体环化为苯基恶唑啉环系统。我们已经通过同源重组使用基因替换来删除mbtB基因，并用M强毒株中的潮霉素抗性盒替换该基因。结核病H37 Rv，所得突变体在铁限制培养基中生长受限，但在铁充满培养基中正常生长。铁载体生产的分析表明，所有水杨酸衍生的铁载体的生物合成被中断。该突变体在巨噬细胞样THP-1细胞中的生长受到抑制，表明铁载体的产生是M.这些结果提供了确凿的证据，将该遗传位点与铁载体的产生联系起来。
Mycobacterium tuberculosis is an important pathogen of mammals that relies on 2-hydroxyphenyloxazoline-containing siderophore molecules called mycobactins for the acquisition of iron in the restrictive environment of the mammalian macrophage, These compounds have been proposed to be biosynthesized through the action of a cluster of genes that include both nonribosomal peptide synthase and polyketide synthase components. One of these genes encodes a protein, MbtB, that putatively couples activated salicylic acid with serine or threonine and then cyclizes this precursor to the phenyloxazoline ring system. We have used gene replacement through homologous recombination to delete the mbtB gene and replace this with a hygromycin-resistance cassette in the virulent strain of M. tuberculosis H37Rv, The resulting mutant is restricted for growth in iron-limited media but grows normally in iron-replete media. Analysis of siderophore production by this organism revealed that the biosynthesis of all salicylate-derived siderophores was interrupted. The mutant was found to be impaired for growth in macrophage-like THP-1 cells, suggesting that siderophore production is required for virulence of M. tuberculosis, These results provide conclusive evidence linking this genetic locus to siderophore production.