Utilization of host iron sources by Corynebacterium diphtheriae: Identification of a gene whose product is homologous to eukaryotic heme oxygenases and is required for acquisition of iron from heme and hemoglobin
Utilization of host iron sources by Corynebacterium diphtheriae: Identification of a gene whose product is homologous to eukaryotic heme oxygenases and is required for acquisition of iron from heme and hemoglobin
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DOI：
10.1128/jb.179.3.838-845.1997
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发表时间：
1997-02-01
影响因子：
3.2
通讯作者：
Schmitt, MP
中科院分区：
文献类型：
--
作者：
Schmitt, MP
检测白喉棒状杆菌利用各种宿主化合物作为铁源的能力。C.白喉C7（-）从血红素、血红蛋白和转铁蛋白中获得铁。菌株C7的铁载体摄取突变体不能利用转铁蛋白，但在从血红素和血红蛋白中获得铁方面不受影响，这表明C.白喉具有利用血红素和血红蛋白作为铁源的新机制。突变体C.在化学诱变和链黑菌素富集后，分离了在从血红素和血红蛋白获得铁方面有缺陷的白喉杆菌和溃疡棒状杆菌。从C7（-）基因组质粒文库中获得的重组克隆pCD 293与几种C. ulcerans突变株和3株C.白喉突变株确定了互补所需的基因（hmuO）的核苷酸序列，并显示其编码预测质量为24，123Da的蛋白质。序列分析显示，HmuO与人血红素加氧酶HO-1具有33%的同一性和70%的相似性，血红素加氧酶HO-1在真核生物中已被充分表征，但在原核生物中尚未被鉴定，参与血红素的氧化和随后从血红素部分释放铁。推测HmuO蛋白是C.白喉和血红素氧合酶的HmuO的活性参与铁从血红素的释放。这是首次报道细菌基因的产物与血红素加氧酶具有同源性。
Corynebacterium diphtheriae was examined for the ability to utilize various host compounds as iron sources. C. diphtheriae C7(-) acquired iron from heme, hemoglobin, and transferrin. A siderophore uptake mutant of strain C7 was unable to utilize transferrin but was unaffected in acquisition of iron from heme and hemoglobin, which suggests that C. diphtheriae possesses a novel mechanism for utilizing heme and hemoglobin as iron sources. Mutants of C. diphtheriae and Corynebacterium ulcerans that are defective in acquiring iron from heme and hemoglobin were isolated following chemical mutagenesis and streptonigrin enrichment. A recombinant clone, pCD293, obtained from a C7(-) genomic plasmid library complemented several of the C. ulcerans mutants and three of the C. diphtheriae mutants. The nucleotide sequence of the gene (hmuO) required for complementation was determined and shown to encode a protein with a predicted mass of 24,123 Da. Sequence analysis revealed that HmuO has 33% identity and 70% similarity with the human heme oxygenase enzyme HO-1, Heme oxygenases, which have been well characterized in eukaryotes but have not been identified in prokaryotes, are involved in the oxidation of heme and subsequent release of iron from the heme moiety. It is proposed that the HmuO protein is essential for the utilization of heme as an iron source by C. diphtheriae and that the heme oxygenase activity of HmuO is involved in the release of iron from heme. This is the first report of a bacterial gene whose product has homology to heme oxygenases.