Novel two-component transmembrane transcription control: regulation of iron dicitrate transport in Escherichia coli K-12
Novel two-component transmembrane transcription control: regulation of iron dicitrate transport in Escherichia coli K-12
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新型双组分跨膜转录控制：大肠杆菌 K-12 中二柠檬酸铁转运的调节
DOI：
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发表时间：
1990
影响因子：
3.2
通讯作者：
Volkmar Braun
中科院分区：
文献类型：
--
作者：
B. V. Hove;H. Staudenmaier;Volkmar Braun
柠檬酸和铁只需进入周质空间，就能诱导大肠杆菌依赖柠檬酸的铁(III)转运系统。这五个运输基因形成一个操纵子，从FECA转录到FESE。在FECA上游发现了两个基因，分别命名为FECI和FeCr，它们介导了二硝酸铁的诱导作用。FECI基因编码173个氨基酸(相对分子质量，19478)；FeCr基因编码一个317个氨基酸(相对分子质量，35,529)的蛋白质。染色体FECI：：MU D 1突变体不能以柠檬酸铁为唯一铁源生长，也不能合成FECA外膜受体蛋白。通过转化编码FECI或FECI和FeCr的质粒，恢复生长。FECB基因转录调控下的FECA和β-半乳糖苷酶合成(FECB：：MU D1)在FECI转化子中是组成性的，并且在FECI FeCr转化子中受二柠檬酸铁的调节。FECI蛋白的氨基酸序列包含一个靠近羧基末端的区域，该区域预测了一个螺旋-转弯-螺旋基序，这是DNA结合调节蛋白的典型特征。FECI蛋白存在于细胞膜中，FeCr蛋白存在于周质部分。有人认为FeCr蛋白是识别周质中柠檬酸铁(III)的传感器。FECI蛋白通过与FEC操纵区结合来激活FEC基因的表达。在没有柠檬酸盐的情况下，FeCr使FECI失活。与其他跨膜信号蛋白序列同源性的缺乏和这两个蛋白的位置表明了一种新的跨膜调控机制。
Citrate and iron have to enter only the periplasmic space in order to induce the citrate-dependent iron(III) transport system of Escherichia coli. The five transport genes fecABCDE form an operon and are transcribed from fecA to fecE. Two genes, termed fecI and fecR, that mediate induction by iron(III) dicitrate have been identified upstream of fecA. The fecI gene encodes a protein of 173 amino acids (molecular weight, 19,478); the fecR gene encodes a protein of 317 amino acids (molecular weight, 35,529). Chromosomal fecI::Mu d1 mutants were unable to grow with iron(III) dicitrate as the sole iron source and synthesized no FecA outer membrane receptor protein. Growth was restored by transformation with plasmids encoding fecI or fecI and fecR. FecA and beta-galactosidase syntheses under transcription control of the fecB gene (fecB::Mu d1) were constitutive in fecI transformants and were regulated by iron(III) dicitrate in fecI fecR transformants. The amino acid sequence of the FecI protein contains a region close to the carboxy-terminal end for which a helix-turn-helix motif is predicted, which is typical for DNA-binding regulatory proteins. The FecI protein was found in the membrane, and the FecR protein was found in the periplasmic fraction. It is proposed that the FecR protein is the sensor that recognizes iron(III) dicitrate in the periplasm. The FecI protein activates fec gene expression by binding to the fec operator region. In the absence of citrate, FecR inactivates FecI. The lack of sequence homologies to other transmembrane signaling proteins and the location of the two proteins suggest a new type of transmembrane control mechanism.
DOI：
10.1073/pnas.84.14.4767
发表时间：
1987-07-01
影响因子：
11.1
作者：
TABOR, S;RICHARDSON, CC
通讯作者：
RICHARDSON, CC
DOI：
10.1073/pnas.82.4.1074
发表时间：
1985-01-01
影响因子：
11.1
作者：
TABOR, S;RICHARDSON, CC
通讯作者：
RICHARDSON, CC