具有缺陷型钠/氢反向转运蛋白的大肠杆菌突变体的分离与特性
Isolation and properties of a mutant of Escherichia coli possessing defective Na+/H+ antiporter.
作者信息
Ishikawa T, Hama H, Tsuda M, Tsuchiya T
出版信息
J Biol Chem. 1987 Jun 5;262(16):7443-6.
A mutant of Escherichia coli with defective Na+/H+ antiporter was isolated. The rationale for its isolation was that cells possessing defective Na+/H+ antiporter, which is essential for establishment of a Na+ gradient, could not grow with a carbon source that was taken up with Na+. The mutant had no appreciable Na+/H+ antiporter activity, but its K+/H+ antiporter and Ca2+/H+ antiporter activities were normal. Judging from the reversion frequency, the defect seems to be due to a single mutation. The mutant could not grow at alkaline pH. Therefore, the Na+/H+ antiporter, but not the K+/H+ antiporter or the Ca2+/H+ antiporter, seems to be responsible for pH regulation in alkaline medium. This mutant will be useful for cloning the Na+/H+ antiporter gene and for detection of Na+-substrate cotransport systems.
分离出了一株具有缺陷型Na⁺/H⁺逆向转运蛋白的大肠杆菌突变体。分离该突变体的理论依据是，拥有缺陷型Na⁺/H⁺逆向转运蛋白（这对建立Na⁺梯度至关重要）的细胞，无法利用通过Na⁺转运进入细胞的碳源生长。该突变体几乎没有明显的Na⁺/H⁺逆向转运蛋白活性，但其K⁺/H⁺逆向转运蛋白和Ca²⁺/H⁺逆向转运蛋白活性正常。从回复突变频率判断，该缺陷似乎是由单个突变引起的。该突变体在碱性pH条件下无法生长。因此，似乎是Na⁺/H⁺逆向转运蛋白，而非K⁺/H⁺逆向转运蛋白或Ca²⁺/H⁺逆向转运蛋白，负责碱性培养基中的pH调节。该突变体将有助于克隆Na⁺/H⁺逆向转运蛋白基因以及检测Na⁺-底物共转运系统。
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