The CorA magnesium transporter gene family.
The CorA magnesium transporter gene family.
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DOI：
10.1089/omi.1.1998.3.151
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发表时间：
1998-01-01
期刊：
影响因子：
--
通讯作者：
Maguire, M E
中科院分区：
文献类型：
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作者：
Kehres, D G;Lawyer, C H;Maguire, M E
CorA转运系统是鼠伤寒沙门氏菌和大肠杆菌的主要Mg 2+内流系统。CorA蛋白与任何其他已知的蛋白质家族没有同源性。它有一个不寻常的膜拓扑结构，具有一个大的，可溶的，高电荷的周质N-末端结构域，在一个较短的，疏水的C-末端结构域中有三个跨膜片段。先前的表型和分子数据表明，这种转运系统在细菌中广泛存在。在这份报告中，我们表明，CorA是几乎无处不在的细菌和细菌，形成一个独特的运输蛋白家族。迄今为止，基因组序列已经揭示了细菌和酵母中至少22个CorA家族成员，其中6个更远的成员在酵母中。只有三种最小的细菌基因组缺乏CorA同源物。引人注目的是，系统发育分析并没有显示出相关物种的聚类，甚至没有显示出王国内部的聚类。一些细菌含有两个甚至三个CorA旁系同源物。在物种内，这些旁系同源物并不密切相关，但是，我们认为，他们可能有不同的运输功能。多重比对表明CorA的N-末端可溶性结构域内有三个扩展的共有区域，预测其几乎都是α-螺旋。第四个共有区包括可溶性结构域的最后20个残基，并继续通过整个膜结构域。该最后一个共有结构域的前半部分可以形成从可溶性结构域延伸到第一跨膜区段中的两亲性α-螺旋。在第一个跨膜段的电荷的程度是相当可变的，我们认为，这个运输家庭可能包括只有两个，而不是三个跨膜段的成员。如果是这样的话，这将使N-末端可溶性结构域位于该家族不同成员的膜的不同侧。我们认为，CorA的Mg ~（2+）运输系统形成的主要Mg ~（2+）吸收系统的细菌和细菌，但一些家庭成员可能有一个功能以外的Mg ~（2+）运输。
The CorA transport system is the primary Mg2+ influx system of Salmonella typhimurium and Escherichia coli. The CorA protein has no homology to any other known family of proteins. It has an unusual membrane topology, with a large, soluble, highly charged periplasmic N-terminal domain with three transmembrane segments in a shorter, hydrophobic C-terminal domain. Previous phenotypic and molecular data had suggested that this transport system was widespread in the Bacteria. In this report we show that CorA is virtually ubiquitous in the Bacteria and Archaea, forming a distinct family of transport proteins. Genomic sequences to date have revealed at least 22 members of the CorA family in the Bacteria and the Archaea, with 6 more distant members in the yeasts. Only three of the smallest bacterial genomes lack a CorA homologue. Strikingly, phylogenetic analysis does not show clustering by related species or even within kingdom. Several species of Bacteria contain two or even three CorA paralogues. Within species, these paralogues are not closely related, however, and we suggest that they might have distinct transport functions. A multiple alignment suggests three extended consensus regions within the N-terminal soluble domain of CorA, which is predicted to be virtually all alpha-helical. A fourth consensus region includes the last 20 residues of the soluble domain and continues through the entire membrane domain. The first half of this last consensus domain may form an amphipathic alpha-helix that extends from the soluble domain into the first transmembrane segment. The degree of charge in the first transmembrane segment is quite variable, and we suggest that this transport family may include members with only two rather than three transmembrane segments. If so, this would place the N-terminal soluble domain on different sides of the membrane in different members of the family. We suggest that the CorA Mg2+ transport system forms the major Mg2+ uptake system in the Bacteria and Archaea but that some family members may have a function other than Mg2+ transport.