Gassel M, Siebers A, Epstein W, Altendorf K
Universität Osnabrück, Fachbereich Biologie/Chemie, Abteilung Mikrobiologie, D-49069 Osnabrück, Germany.
Biochim Biophys Acta. 1998 Dec 9;1415(1):77-84. doi: 10.1016/s0005-2736(98)00179-5.
Kdp, the high affinity ATP-driven K+-transport system of Escherichia coli, is a complex of the membrane-bound subunits KdpA, KdpB, KdpC and the small peptide KdpF. The assembly of this complex was studied by the analysis of mutants that expressed two of the three large subunits and inserted them into the cytoplasmic membrane. In the strains that do not express KdpC or KdpA the other two subunits did not copurify on dye-ligand affinity columns after solubilization with non-ionic detergent. In the mutant lacking KdpB the other two subunits copurified under the same conditions. It is concluded that KdpC forms strong interactions with the KdpA subunit, serving to assemble and stabilise the Kdp complex. A structure in which KdpC could be one of the connecting links between the energy-delivering subunit KdpB and the K+-transporting subunit KdpA is suggested by these data.
Kdp是大肠杆菌中由ATP驱动的高亲和力钾离子转运系统，它是由膜结合亚基KdpA、KdpB、KdpC和小肽KdpF组成的复合体。通过分析表达三个大亚基中的两个并将它们插入细胞质膜的突变体，对该复合体的组装进行了研究。在不表达KdpC或KdpA的菌株中，在用非离子去污剂溶解后，其他两个亚基在染料配体亲和柱上不能共纯化。在缺乏KdpB的突变体中，其他两个亚基在相同条件下共纯化。得出的结论是，KdpC与KdpA亚基形成强相互作用，有助于组装和稳定Kdp复合体。这些数据表明了一种结构，其中KdpC可能是能量传递亚基KdpB和钾离子转运亚基KdpA之间的连接环节之一。
