Bakker E P, Borchard A, Michels M, Altendorf K, Siebers A
J Bacteriol. 1987 Sep;169(9):4342-8. doi: 10.1128/jb.169.9.4342-4348.1987.
During growth with low levels of K+, Bacillus acidocaldarius expressed a high-affinity K+ uptake system. The following observations indicate that this system strongly resembles the Kdp-ATPase of Escherichia coli: (i) its high affinity for K+ (Km of 20 microM or below); (ii) its poor transport of Rb+; (iii) the enhanced ATPase activity of membranes derived from cells grown with low levels of K+ (this activity was stimulated by K+ and inhibited by vanadate); (iv) the expression of an extra protein with a molecular weight of 70,000 in cells grown with low levels of K+; and (v) the immunological cross-reactivity of this 70,000-molecular-weight protein with antibodies against the catalytic subunit B of the E. coli Kdp system. Antibodies against the complete E. coli Kdp system, which immunoprecipitated the whole E. coli KdpABC complex, almost exclusively precipitated the 70,000-molecular-weight protein from detergent-solubilized B. acidocaldarius membranes. The possibility that the B. acidocaldarius Kdp system consists of a single, KdpB-type subunit is discussed.
在低钾水平条件下生长时，嗜酸热硫化叶菌表达了一种高亲和力的钾离子摄取系统。以下观察结果表明，该系统与大肠杆菌的Kdp - ATP酶极为相似：（i）其对钾离子具有高亲和力（Km为20微摩尔或更低）；（ii）对铷离子的转运能力较差；（iii）源自低钾水平条件下生长细胞的膜具有增强的ATP酶活性（该活性受钾离子刺激并受钒酸盐抑制）；（iv）在低钾水平条件下生长的细胞中表达了一种分子量为70,000的额外蛋白质；以及（v）这种分子量为70,000的蛋白质与抗大肠杆菌Kdp系统催化亚基B的抗体具有免疫交叉反应性。抗完整大肠杆菌Kdp系统的抗体可免疫沉淀整个大肠杆菌KdpABC复合物，该抗体几乎能从去污剂溶解的嗜酸热硫化叶菌膜中特异性沉淀出分子量为70,000的蛋白质。本文讨论了嗜酸热硫化叶菌Kdp系统由单一KdpB型亚基组成的可能性。
