Identification of the Escherichia coli K-12 Nramp orthologue (MntH) as a selective divalent metal ion transporter
Identification of the Escherichia coli K-12 Nramp orthologue (MntH) as a selective divalent metal ion transporter
复制标题
DOI：
10.1046/j.1365-2958.2000.01774.x
复制
发表时间：
2000-03-01
影响因子：
3.6
通讯作者：
Cellier, MFM
中科院分区：
文献类型：
--
作者：
Makui, H;Roig, E;Cellier, MFM
大肠杆菌mntH（以前的yfeP）基因编码一个推定的膜蛋白（MntH）高度相似的真核Nramp家庭的成员的二价金属离子转运蛋白。确定E. coliMntH，构建了一个无效突变体，并在野生型E.大肠杆菌和金属依赖突变体hflB 1（Ts）中的表达。在限制性温度42 ℃下，mntH无效突变减少了外源二价金属对hflB 1（Ts）热敏性的抑制。相反，MntH的过表达在42 ℃下恢复生长，增加Fe（II）和Ni（II）对ts表型的抑制，并使hflB 1（Ts）细胞对Mn（II）超敏感。在完整的细胞中的运输研究表明，MntH选择性地促进吸收Mn-54（II）和Fe-55（II）在温度，时间和质子依赖性的方式。在hflB 1（Ts）突变体中的摄取测定和生长抑制实验中的竞争研究一起表明MntH是具有广泛底物特异性的二价金属阳离子转运蛋白。MntH的功能特征表明它对应于先前描述的E.杆菌这项研究表明，质子依赖的二价金属离子的摄取已被保存在Nramp家族从细菌到人类。
The Escherichia coli mntH (formerly yfeP) gene encodes a putative membrane protein (MntH) highly similar to members of the eukaryotic Nramp family of divalent metal ion transporters. To determine the function of E. coli MntH, a null mutant was created and MntH was overexpressed both in wild-type E. coli and in the metal-dependent mutant hflB1(Ts). At the restrictive temperature 42 degrees C, the mntH null mutation reduces the suppression of hflB1(Ts) thermosensitivity by exogenous divalent metals. Conversely, overexpression of MntH restores growth at 42 degrees C, increases suppression of the ts phenotype by Fe(II) and Ni(II) and renders hflB1(Ts) cells hypersensitive to Mn(II). Transport studies in intact cells show that MntH selectively facilitates uptake of Mn-54(II) and Fe-55(II) in a temperature-, time- and proton-dependent manner. Competition studies in uptake assays and growth inhibition experiments in hflB1(Ts) mutants together indicate that MntH is a divalent metal cation transporter of broad substrate specificity. The functional characteristics of MntH suggest that it corresponds to the previously described manganese transporter of E. coli. This study indicates that proton-dependent divalent metal ion uptake has been preserved in the Nramp family from bacteria to humans.