Solioz M, Mathews S, Fürst P
J Biol Chem. 1987 May 25;262(15):7358-62.
The K+-ATPase of Streptococcus faecalis consists of a single polypeptide component of relative Mr = 78,000 and serves as an ATP-driven pump for the accumulation of potassium by the bacterial cell. The gene encoding this ATPase was isolated by immunological screening of an S. faecalis genomic library in the Escherichia coli/pUC8 host/vector system. Two independently derived clones express the full-size ATPase polypeptide. Transcription and translation of the cloned DNA apparently proceed by means of the respective S. faecalis signals. DNA sequencing revealed a gene encoding a protein of 583 amino acids and a calculated Mr of 63,070. This protein exhibits in its primary structure regions of homology with the KdpB-subunit of the K+-ATPase of E. coli and, to a lesser extent, with eukaryotic ion-motive ATPases. The hydropathy profiles and secondary structure predictions, respectively, for the S. faecalis ATPase and the E. coli KdpB-protein show striking similarity. Even regions with low homology in the amino acid sequence exhibit structural features that have clearly been conserved in the two proteins. This points to a fundamental role of these domains in the structure and/or function of these transport ATPases.
粪肠球菌的钾离子 - ATP酶由一个相对分子质量为78,000的单一多肽组分组成，作为一种由ATP驱动的泵，用于细菌细胞积累钾离子。编码这种ATP酶的基因是通过在大肠杆菌/pUC8宿主/载体系统中对粪肠球菌基因组文库进行免疫筛选而分离得到的。两个独立获得的克隆表达全长ATP酶多肽。克隆DNA的转录和翻译显然是通过粪肠球菌各自的信号进行的。DNA测序揭示了一个编码583个氨基酸的蛋白质的基因，计算得到的相对分子质量为63,070。该蛋白质在其一级结构中与大肠杆菌钾离子 - ATP酶的KdpB亚基具有同源区域，与真核离子驱动ATP酶的同源性较低。粪肠球菌ATP酶和大肠杆菌KdpB蛋白的亲水性图谱和二级结构预测分别显示出惊人的相似性。即使在氨基酸序列中同源性较低的区域也表现出在这两种蛋白质中明显保守的结构特征。这表明这些结构域在这些转运ATP酶的结构和/或功能中起着基本作用。
