Expression of the heme biosynthetic pathway genes hemCD, hemH, hemM, and hemA of Escherichia coli.
Expression of the heme biosynthetic pathway genes hemCD, hemH, hemM, and hemA of Escherichia coli.
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DOI：
10.1111/j.1574-6968.1997.tb10184.x
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发表时间：
1997
影响因子：
2.1
通讯作者：
P. McNicholas;G. Javor;S. Darie;R. Gunsalus
中科院分区：
文献类型：
--
作者：
P. McNicholas;G. Javor;S. Darie;R. Gunsalus
关于大肠杆菌血红素生物合成后期步骤的控制知之甚少。在这项研究中，我们检查了编码两种中间血红素途径酶、胆色素原脱氨酶 (hemC) 和尿卟啉原 III 辅合酶 (hemD) 以及该途径的最终酶亚铁螯合酶 (hemH) 的基因的转录调控。我们还重新检查了hemA和紧邻hemA上游的基因hemM的调节。 hemC、hemH、hemA 和 hemM 的调节区与 lacZ 融合。将所得操纵子融合体以单拷贝插入大肠杆菌染色体，并在氧和血红素限制的条件下监测表达。在此处测试的条件下，hemM 的表达似乎是组成型的。相比之下，hemCD、hemH 和 hemA 的表达因血红素可用性而受到轻微调节。因此，大肠杆菌血红素途径的九个基因中的四个基因的转录似乎仅因血红素限制而受到轻微调节。
Little is known about the control of latter steps of heme biosynthesis in Escherichia coli. In this study we examined the transcriptional regulation of genes that encode two intermediate heme pathway enzymes, porphobilinogen deaminase (hemC) and uroporphyrinogen III cosynthase (hemD), and the final enzyme of the pathway, ferrochelatase (hemH). We also reexamined the regulation of hemA and the gene located immediately upstream of hemA, hemM. The regulatory regions of hemC, hemH, hemA and hemM were fused to lacZ. The resultant operon fusions were inserted into the E. coli chromosome in single copy and expression monitored under conditions of oxygen and heme limitation. Expression of hemM appeared constitutive under the conditions tested here. In contrast, expression of hemCD, hemH and hemA were shown to be mildly regulated in response to heme availability. Thus, transcription of four of the nine genes of the E. coli heme pathway appears to be only mildly regulated in response to heme limitation.