HemZ is essential for heme biosynthesis in Mycobacterium tuberculosis
HemZ is essential for heme biosynthesis in Mycobacterium tuberculosis
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DOI：
10.1016/j.tube.2005.01.002
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发表时间：
2005-05-01
期刊：
影响因子：
3.2
通讯作者：
Duncan, K
中科院分区：
文献类型：
--
作者：
Parish, T;Schaeffer, M;Duncan, K
结核分枝杆菌基因组的全序列和随后的注释允许通过同源性预测许多基因和基因功能。HemZ是一种预测的亚铁螯合酶，其与参与分枝菌酸生物合成的两个基因mabA和inhA在表观操纵子中结合。我们试图：构建hemZ缺失突变体在结核杆菌使用两步重组策略，但只能。当我们提供第二个功能性拷贝时，删除染色体拷贝：在整合质粒上。我们进一步证实，hemZ是必不可少的，在正常培养条件下，通过证明，hemZ的整合拷贝不能被删除，如果它是唯一的野生型等位基因在细胞中。我们能够通过补充氯化血红素而不是原卟啉IX或血红蛋白获得hemZ突变体，证实该基因确实在血红素生物合成中起作用，并且M.结核病可以在细胞内运输氯化血红素。氯化高铁血红素营养缺陷型需要2 μ g/ml氯化高铁血红素才能生长，并且在停止氯化高铁血红素后发生活力的迅速丧失。这些数据证实了hemZ在血红素生物合成中的作用，并表明血红素是M.结核© 2005爱思唯尔有限公司版权所有。
The complete sequence and subsequent annotation of the Mycobocterium tuberculosis genome has allowed the, prediction of many genes and gene functions by homology. HemZ is a predicted ferrochelatase which ties in an apparent operon with two genes involved in mycolic, acid biosynthesis, mabA and inhA. We tried to :construct hemZ deletion mutants in A tuberculosis using a two-step recombination strategy, but could only. delete the chromosomal copy when we provided a second functional copy:on an integrating plasmid. We further confirmed that hemZ is essential under normal culture conditions by demonstrating that the integrated copy of hemZ could not be removed if it was the only wild-type allele in the cell. We were able to obtain hemZ mutants by supplementation with hemin but not with protoporphyrin IX or hemoglobin confirming that this gene does have a role in heme biosynthesis,and that M. tuberculosis can transport hemin intracelullarly. The hemin auxotroph required 2 μ g/ml hemin for growth and rapid loss of viability occurred after withdrawal of hemin. These data confirm the rote of hemZ in heme biosynthesis and indicate that heme is an essential requirement for M. tuberculosis. © 2005 Elsevier Ltd. All rights reserved.